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Date: Mon, 11 May 2015 18:27:35 +0300
From: Shinnok <admin@...nnok.com>
To: john-dev@...ts.openwall.com
Subject: Re: [core john] [Johnny] Windows event loop


> On May 11, 2015, at 6:15 PM, Shinnok <admin@...nnok.com> wrote:
> 
> 
>> On May 11, 2015, at 4:45 PM, Mathieu Laprise <mathlaprise@...il.com <mailto:mathlaprise@...il.com>> wrote:
>> 
>> 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 <https://msdn.microsoft.com/en-us/library/windows/desktop/ms683155%28v=vs.85%29.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 <https://msdn.microsoft.com/en-us/library/windows/desktop/ms686016%28v=vs.85%29.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 <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 <http://www.openwall.com/lists/john-dev/2015/05/08/16>.

To stress this option a bit more, have you explicitly re-enabled CTRL events in JtR after disabling in Johnny? like this:
SetConsoleCtrlHandler(NULL, FALSE)

As per the doc:
"If the HandlerRoutine parameter is NULL, a TRUE value causes the calling process to ignore CTRL+C input, and a FALSE value restores normal processing of CTRL+C input. This attribute of ignoring or processing CTRL+C is inherited by child processes."

Shinnok
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