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Date: Mon, 11 May 2015 09:45:03 -0400
From: Mathieu Laprise <mathlaprise@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: [core john] [Johnny] Windows event loop
Shinnok said:
> Mathieu, I'm not sure you have been exhaustive enough in assertions
> regarding the exploitation of the CTRL_ events.
>
> What we know:
>
> 1. We can signal CTRL_ events to JtR on Windows with
> GenerateConsoleCtrlEvent. (#ifdef'ed of course)
> https://msdn.microsoft.com/en-us/library/windows/desktop/ms683155(v=vs.85).aspx
> 2. We can ignore CTRL_ events in Johnny by doing:
> " • Calling SetConsoleCtrlHandler with the NULL and TRUE arguments causes
> the calling process to ignore CTRL+C signals. This attribute is inherited
> by child processes, but it can be enabled or disabled by any process
> without affecting existing processes."
> https://msdn.microsoft.com/en-us/library/windows/desktop/ms686016(v=vs.85).aspx
> 3. We can re-enable CTRL_ events back in JtR. Simple patch to core.
> 4. Verify in signals.c that JtR does indeed kill itself upon doing that
> for Windows.
> 5. Hail that we don't have --fork there.
>
> Let's focus on CTRL_C_EVENT until we have reason to do otherwise.
>
I tried this solution a few days ago which is based on KingDragon(
http://stackoverflow.com/questions/813086/can-i-send-a-ctrl-c-sigint-to-an-application-on-windows)
but as I stated at the end of this answer
http://www.openwall.com/lists/john-dev/2015/05/08/16.
So, sending event CTRL_C_EVENT or CTRL_BREAK_EVENT, both call
sig_handle_abord(SIGINT) which will handle cleaning or other stuff needed
by John like if it was from the tty. So john saves its state.
However, in my tests, I got the same result as Shaktra(from the same
stackoverflow article) for CTRL_C (returned true but wasn't sent). Here is
what he said on stackoverflow.
> It is very important that each step is done like this. I've been trying
> all different kinds of combinations but this combination is the only one
> that works. You can't send a CTRL_C event. It will return success but will
> be ignored by the process. CTRL_BREAK is the only one that works. Doesn't
> really matter since they will both call ExitProcess() in the end. (EDIT by
> me: In our specific case, we reimplemented the handler so
> sig_handle_abort_ctrl() will be called before)
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