FreeBSD <= 6.1 kqueue() NULL pointer dereference

2009.08.23

Credit: Przemyslaw Frasunek

Risk: Medium

Local: Yes

Remote: No

CVE: CVE-2009-3527

CWE: CWE-362

CVSS Base Score: 6.9/10

Impact Subscore: 10/10

Exploitability Subscore: 3.4/10

Exploit range: Local

Attack complexity: Medium

Authentication: No required

Confidentiality impact: Complete

Integrity impact: Complete

Availability impact: Complete

FreeBSD <= 6.1 suffers from classical check/use race condition on SMP systems in kevent() syscall, leading to kernel mode NULL pointer dereference. It can be triggered by spawning two threads: 1st thread looping on open() and close() syscalls, and the 2nd thread looping on kevent(), trying to add possibly invalid filedescriptor.

The bug was fixed in 6.1-STABLE, just before release of 6.2-RELEASE, but was not recognized as security vulnerability.

The following code exploits this vulnerability to run root shell: http://www.frasunek.com/kqueue.txt

-- 
* Fido: 2:480/124 ** WWW: http://www.frasunek.com/ ** NICHDL: PMF9-RIPE *
* JID: venglin_at_jabber.atman.pl ** PGP ID: 2578FCAD ** HAM-RADIO: SQ8JIV *

References:

http://www.securitytracker.com/id?1022982

http://www.securityfocus.com/bid/36375

http://security.freebsd.org/advisories/FreeBSD-SA-09:13.pipe.asc

http://www.securityfocus.com/archive/1/506449

http://osvdb.org/58544

See this note in RAW Version

Vote for this issue:

50%

Thanks for you vote!

Thanks for you comment!
Your message is in quarantine 48 hours.

Comment it here.

Nick (*)

Email (*)

Video

Text (*)

(*) - required fields.

{{ x.nick }} | Date: {{ x.ux * 1000 | date:'yyyy-MM-dd' }} {{ x.ux * 1000 | date:'HH:mm' }} CET+1

{{ x.comment }}

FreeBSD <= 6.1 kqueue() NULL pointer dereference

References:

Thanks for you vote!

Thanks for you comment!Your message is in quarantine 48 hours.

Thanks for you comment!
Your message is in quarantine 48 hours.