FreeBSD SACK handling denial of service

bsd-sack-handling-dos (24453)

Medium Risk

Description:

FreeBSD is vulnerable to a denial of service attack, caused by improper handling of Selective Acknowledgement (SACK) packets. A remote attacker could send a series of specially-crafted packets to a vulnerable system to cause the TCP/IP stack to enter into an infinite loop, resulting in a denial of service.

*CVSS:

Base Score:	3.5
Access Vector:	Remote
Access Complexity:	Low
Authentication:	Not Required
Confidentiality Impact:	None
Integrity Impact:	None
Availability Impact:	Partial
Temporal Score:	2.6
Exploitability:	Unproven
Remediation Level:	Official-Fix
Report Confidence:	Confirmed

Consequences:

Denial of Service

Remedy:

Refer to FreeBSD Security Advisory FreeBSD-SA-06:08.sack for patch or upgrade information. See References.

References:

• FreeBSD Security Advisory FreeBSD-SA-06:08.sack: Infinite loop in SACK handling.
• BID-16466: FreeBSD TCP SACK Remote Denial Of Service Vulnerability
• CVE-2006-0433: Selective Acknowledgement (SACK) in FreeBSD 5.3 and 5.4 does not properly handle an incoming selective acknowledgement when there is insufficient memory, which might allow remote attackers to cause a denial of service (infinite loop).
• OSVDB ID: 22861: FreeBSD TCP/IP SACK Infinite Loop DoS
• SA18696: FreeBSD SACK Handling Denial of Service
• SECTRACK ID: 1015566: FreeBSD TCP SACK Processing May Let Remote Users Deny Service

Platforms Affected:

• FreeBSD FreeBSD 5.3
• FreeBSD FreeBSD 5.4

Reported:

Feb 01, 2006

The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall the author/distributor (IBM Internet Security Systems X-Force) be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.

For corrections or additions please email xforce@iss.net

Return to the main page

* According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES "AS IS" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.
The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall IBM be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.

About IBM Internet Security Systems

IBM Internet Security Systems is a trusted security advisor to thousands of the world's leading businesses and governments, helping to provide pre-emptive protection for networks, desktops and servers. The IBM Proventia? integrated security platform is designed to automatically protect against both known and unknown threats, helping to keep networks up and running and shield customers from online attacks before they impact business assets. IBM Internet Security Systems products and services are based on the proactive security intelligence of its X-Force? research and development team ? an unequivocal world authority in vulnerability and threat research. The IBM Internet Security Systems product line is also complemented by comprehensive Managed Security Services and Professional Security Services. For more information, visit the IBM Internet Security Systems Web site at www.iss.net or call 800-776-2362.