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TITLE:
FreeBSD ipfw Packet Matching Security Issue

SECUNIA ADVISORY ID:
SA15871

VERIFY ADVISORY:
http://secunia.com/advisories/15871/

CRITICAL:
Less critical

IMPACT:
Security Bypass

WHERE:
>From remote

OPERATING SYSTEM:
FreeBSD 5.x
http://secunia.com/product/1132/

DESCRIPTION:
A security issue has been reported in FreeBSD, which can be exploited
by malicious people to bypass the firewall ruleset.

The problem is caused due to insufficient concurrency handling in the
ipfw tables lookup code. This may lead to the corruption of cached
address entries and cause some packets to be incorrectly matched.

Successful exploitation may allow some packets to pass through the
firewall when they should have been dropped.

The security issue only affects Symmetric Multi-Processor (SMP)
systems, or Uni-Processor (UP) systems with the non-default
PREEMPTION kernel option enabled.

SOLUTION:
Update FreeBSD or apply patch.

Fixed versions:
2005-06-29 21:38:48 UTC (RELENG_5, 5.4-STABLE)
2005-06-29 21:41:03 UTC (RELENG_5_4, 5.4-RELEASE-p3)

Patch for FreeBSD 5.x:
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:13/ipfw.patch
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:13/ipfw.patch.asc

PROVIDED AND/OR DISCOVERED BY:
The vendor credits Max Laier.

ORIGINAL ADVISORY:
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:13.ipfw.asc

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About:
This Advisory was delivered by Secunia as a free service to help
everybody keeping their systems up to date against the latest
vulnerabilities.

Subscribe:
http://secunia.com/secunia_security_advisories/

Definitions: (Criticality, Where etc.)
http://secunia.com/about_secunia_advisories/


Please Note:
Secunia recommends that you verify all advisories you receive by
clicking the link.
Secunia NEVER sends attached files with advisories.
Secunia does not advise people to install third party patches, only
use those supplied by the vendor.

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