From: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
To: John Wood <john.wood@gmx.com>
Cc: kernelnewbies@kernelnewbies.org, Andi Kleen <ak@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
kernel-hardening@lists.openwall.com
Subject: Re: Notify special task kill using wait* functions
Date: Wed, 07 Apr 2021 16:38:46 -0400 [thread overview]
Message-ID: <184666.1617827926@turing-police> (raw)
In-Reply-To: <20210407175151.GA3301@ubuntu>
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On Wed, 07 Apr 2021 19:51:51 +0200, John Wood said:
> When brute detects a brute force attack through the fork system call
> (killing p3) it will mark the binary file executed by p3 as "not allowed".
> From now on, any execve that try to run this binary will fail. This way it
> is not necessary to notify nothing to userspace and also we avoid an exec
> brute force attack due to the respawn of processes [2] by a supervisor
> (abused or not by a bad guy).
You're not thinking evil enough. :)
I didn't even finish the line that starts "From now on.." before I started
wondering "How can I abuse this to hang or crash a system?" And it only took
me a few seconds to come up with an attack. All you need to do is find a way to
sigsegv /bin/bash... and that's easy to do by forking, excecve /bin/bash, and
then use ptrace() to screw the child process's stack and cause a sigsegv.
Say goodnight Gracie...
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next prev parent reply other threads:[~2021-04-07 20:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210330173459.GA3163@ubuntu>
[not found] ` <79804.1617129638@turing-police>
[not found] ` <20210402124932.GA3012@ubuntu>
[not found] ` <106842.1617421818@turing-police>
[not found] ` <20210403070226.GA3002@ubuntu>
[not found] ` <145687.1617485641@turing-police>
[not found] ` <20210404094837.GA3263@ubuntu>
[not found] ` <193167.1617570625@turing-police>
[not found] ` <20210405073147.GA3053@ubuntu>
[not found] ` <115437.1617753336@turing-police>
2021-04-07 17:51 ` Notify special task kill using wait* functions John Wood
2021-04-07 20:38 ` Valdis Klētnieks [this message]
2021-04-08 1:51 ` Andi Kleen
2021-04-09 14:29 ` John Wood
2021-04-09 15:06 ` Andi Kleen
2021-04-09 16:08 ` John Wood
2021-04-09 23:28 ` Valdis Klētnieks
2021-04-11 8:46 ` John Wood
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