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Add vmprotect trap flag check #295

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Add vmprotect trap flag check #295

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32 changes: 16 additions & 16 deletions al-khaser/AntiDebug/TrapFlag.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -22,30 +22,30 @@ static LONG CALLBACK VectoredHandler(
)
{
SwallowedException = FALSE;

if (ExceptionInfo->ExceptionRecord->ExceptionCode == EXCEPTION_SINGLE_STEP)
return EXCEPTION_CONTINUE_EXECUTION;

if (ExceptionInfo->ExceptionRecord->ExceptionCode == EXCEPTION_SINGLE_STEP)
{
// Check if the exception address is correctly set (VMProtect antidebug & antivm check)
uint8_t mem_val = *static_cast<uint8_t *>(
ExceptionInfo->ExceptionRecord->ExceptionAddress);
if (mem_val == 0x90)
return EXCEPTION_CONTINUE_EXECUTION;
}
return EXCEPTION_CONTINUE_SEARCH;
}



// Disable optimization for the following function
// otherwise when building in release mode the compiler removes the nops
#pragma optimize("", off)
BOOL TrapFlag()
{
PVOID Handle = AddVectoredExceptionHandler(1, VectoredHandler);
SwallowedException = TRUE;

#ifdef _WIN64
UINT64 eflags = __readeflags();
#else
UINT eflags = __readeflags();
#endif

// Set the trap flag
eflags |= 0x100;
__writeeflags(eflags);

__writeeflags(__readeflags() | 0x100);
__nop();
__nop();

RemoveVectoredExceptionHandler(Handle);
return SwallowedException;
}
#pragma optimize("", on)