Didier Stevens

Monday 20 March 2017

That Is Not My Child Process!

Filed under: Forensics,Hacking — Didier Stevens @ 0:00

Years ago I released a tool to create a Windows process with selected parent process: SelectMyParent.

You can not blindly trust parent-child process relations in Windows: the parent of a process can be different from the process that created that process.

Here I start selectmyparent from cmd.exe to launch notepad.exe with parent explorer.exe (PID 328):

Process Explorer reports explorer.exe as the parent (and not selectmyparent.exe):

Process Monitor also reports explorer.exe as the parent:

If we look in the call stack of the process creation of notepad.exe, we see 2 frames (6 and 7) with unknown modules:

We should see entries in the call stack for explorer.exe if notepad.exe was started by explorer.exe, but we don’t.

The <unknown> module is actually selectmyparent.exe.

0x11b1461 is the address of the instruction after the call to _main in ___tmainCRTStarup in selectmyparent.exe.

0x11b12a8 is the address of the instruction after the call to CreateProcessW in _main in selectmyparent.exe.

 

System Monitor also reports explorer.exe as the parent:

Finally, Volatility’s pstree command also reports explorer.exe as the parent:

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