109 lines
2.9 KiB
C++
109 lines
2.9 KiB
C++
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/*++
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Copyright (c) 2000-2002 Microsoft Corporation
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Module Name:
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Shrinker.cpp
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Abstract:
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Fix Shrinker library problem. This library is hacking some ntdll and kernel32 opcode
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with unreliable way to do it.
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First, they try to search the matching opcode within 32 bytes from the hacked
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function (the function address retrieved from GetProcAddress and the opcode bytes
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retrieved via ReadProcessMemory).
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If they found it, then they replaced it with their opcode to redirect the call
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into their own routine.
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Unfortunately, opcode in Whistler has changed. So, the result will be unpredictable.
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They could be ended up with unexpected behavior from misreplacement of opcode
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or the app decided to terminated itself since the matching opcode can't be found.
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We fixed this by providing an exact matching opcode.
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Addition: Shrinker also checks against ExitProcess for exact opcodes, these
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values have recently changed and no longer match against their hard coded
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values. We now provide matching opcodes for ExitProcess also.
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Notes:
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Hooking ntdll!LdrAccessResource to emulate Win2K's version of it.
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Hooking Kernel32!ExitProcess to emulate Win2K's version of it.
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History:
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11/17/2000 andyseti Created
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04/30/2001 mnikkel Added ExitProcess
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05/01/2001 mnikkel Corrected calls to ldraccessresource and exitprocess
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02/20/2002 mnikkel Corrected exitprocess parameter to remove w4 warning
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--*/
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#include "precomp.h"
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#include <nt.h>
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IMPLEMENT_SHIM_BEGIN(Shrinker)
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#include "ShimHookMacro.h"
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APIHOOK_ENUM_BEGIN
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APIHOOK_ENUM_ENTRY(LdrAccessResource)
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APIHOOK_ENUM_ENTRY(ExitProcess)
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APIHOOK_ENUM_END
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__declspec(naked)
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NTSTATUS
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APIHOOK(LdrAccessResource)(
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IN PVOID /*DllHandle*/,
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IN const IMAGE_RESOURCE_DATA_ENTRY* /*ResourceDataEntry*/,
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OUT PVOID * /*Address*/ OPTIONAL,
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OUT PULONG /*Size*/ OPTIONAL)
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{
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_asm {
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push [esp+0x10] // shrinker lib needs these opcode signature (found in Win2K), -
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push [esp+0x10] // but the actual LdrAccessResource doesn't have them
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push [esp+0x10]
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push [esp+0x10]
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call dword ptr [LdrAccessResource]
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ret 0x10 // when exit, pop 16 bytes from stack.
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}
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}
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__declspec(naked)
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VOID
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APIHOOK(ExitProcess)(
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UINT /*uExitCode*/
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)
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{
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_asm {
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push ebp // shrinker is looking for these exact op codes in
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mov ebp,esp // ExitProcess, but the routine has changed.
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push 0xFFFFFFFF
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push 0x77e8f3b0
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push [ebp+4]
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call dword ptr [ExitProcess]
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pop ebp
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ret 4
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}
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}
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/*++
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Register hooked functions
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--*/
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HOOK_BEGIN
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APIHOOK_ENTRY(NTDLL.DLL, LdrAccessResource)
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APIHOOK_ENTRY(KERNEL32.DLL, ExitProcess)
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HOOK_END
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IMPLEMENT_SHIM_END
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