bugtraq - Problems with syscall filtering technologies on Linux

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Message-ID: <72daeffd0901231342g4a174794jc50aea715a6762da@mail.gmail.com>
Date: Fri, 23 Jan 2009 13:42:03 -0800
From: Chris Evans <scarybeasts@...il.com>
To: bugtraq@...urityfocus.com, full-disclosure@...ts.grok.org.uk
Subject: Problems with syscall filtering technologies on Linux

Hi,

There's a trick which may permit the bypassing of policies in
technologies which do syscall filtering on the Linux x86_64 kernel.

The trick is made possible by the fact that the 32-bit and 64-bit
kernel tables are different, combined with the fact that a 64-bit
process can make a 32-bit syscall and visa versa. The syscall "number"
check can get confused and permit a syscall it did not intend to.

Advisory: http://scary.beasts.org/security/CESA-2009-001.html

Blog post: http://scarybeastsecurity.blogspot.com/2009/01/bypassing-syscall-filtering.html

Cheers
Chris