full-disclosure-uk January 2009 archive
Main Archive Page > Month Archives  > full-disclosure-uk archives
full-disclosure-uk: [Full-disclosure] Problems with syscall filt

[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



Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/