TITLE:
FreeBSD IPsec Sequence Number Verification Bypass

SECUNIA ADVISORY ID:
SA19366

VERIFY ADVISORY:
http://secunia.com/advisories/19366/

CRITICAL:
Moderately critical

IMPACT:
Security Bypass

WHERE:
>From remote

OPERATING SYSTEM:
FreeBSD 4.x
http://secunia.com/product/139/
FreeBSD 5.x
http://secunia.com/product/1132/
FreeBSD 6.x
http://secunia.com/product/6778/

DESCRIPTION:
A security issue has been reported in FreeBSD, which potentially can
be exploited by malicious people to bypass certain security
restrictions.

The security issue is caused due to the incorrect update of the
sequence number associated with a Security Association in the
"fast_ipsec" implementation. This allows certain packets to
unconditionally bypass sequence number verification checks.

Successful exploitation allows an attacker to capture IPSec packets
and subsequently replay them.

The security issue has been reported in all FreeBSD versions since
4.8-RELEASE.

SOLUTION:
Update FreeBSD or apply patch.

Fixed versions:
2006-03-22 16:01:08 UTC (RELENG_6, 6.1-STABLE)
2006-03-22 16:01:38 UTC (RELENG_6_0, 6.0-RELEASE-p6)
2006-03-22 16:01:56 UTC (RELENG_5, 5.5-STABLE)
2006-03-22 16:02:17 UTC (RELENG_5_4, 5.4-RELEASE-p13)
2006-03-22 16:02:35 UTC (RELENG_5_3, 5.3-RELEASE-p28)
2006-03-22 16:02:49 UTC (RELENG_4, 4.11-STABLE)
2006-03-22 16:03:05 UTC (RELENG_4_11, 4.11-RELEASE-p16)
2006-03-22 16:03:25 UTC (RELENG_4_10, 4.10-RELEASE-p22)

Patch for FreeBSD 4.10, 4.11, 5.3, 5.4, and 6.0:
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:11/ipsec.patch
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:11/ipsec.patch.asc

PROVIDED AND/OR DISCOVERED BY:
The vendor credits Pawel Jakub Dawidek.

ORIGINAL ADVISORY:
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-06:11.ipsec.asc

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