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[Full-disclosure] Problems with syscall filtering technologies on Linux

From: Chris Evans <scarybeasts_at_nospam>
Date: Fri Jan 23 2009 - 21:42:03 GMT
To: bugtraq@securityfocus.com, full-disclosure@lists.grok.org.uk

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

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