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Cisco IPSec Unspecified IKE Traffic Denial Of Service Vulnerabilities


Date Discovered

Various Cisco IOS, PIX Firewall, Firewall Services Module (FWSM), VPN 3000 Series Concentrator, and MDS Series SanOS releases are prone to denial of service attacks. These issues are due to security flaws in Cisco's IPSec implementation. The vulnerabilities may be triggered by malformed IKE traffic.

Successful attacks will cause most affected devices to restart. For Cisco MDS Series devices, this is limited to causing the IKE process to restart.

Symantec Enterprise Security Manager Network Assessment Module

Symantec Enterprise Security Manager Network Assessment Module detects and reports this vulnerability. Click here for the advisory released December 22, 2005.

Platforms Affected
Cisco PIX Firewall 515
Cisco PIX Firewall 520

Components Affected
Cisco Firewall Services Module
Cisco Firewall Services Module 1.1 (3.005)
Cisco Firewall Services Module 1.1.2
Cisco Firewall Services Module 1.1.3
Cisco Firewall Services Module 2.1 (0.208)
Cisco IOS 12.2 SXD

Block external access at the network boundary, unless service is required by external parties.
Configure network access control lists to explicitly deny IKE traffic from unauthorized sources. This may limit exposure to this vulnerabilities.

Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Monitor network traffic to the device for signs of anomalous or suspicious activity. Such activity may be logged by deployed network intrusion detection systems or may be evident in the logs generated by affected devices.

Cisco has released an advisory detailing fixes for affected devices. Please see the attached advisory for further information.

Cisco Firewall Services Module :
Cisco Firewall Services Module 1.1 (3.005):
Cisco Firewall Services Module 1.1.2:
Cisco Firewall Services Module 1.1.3:
Cisco Firewall Services Module 2.1 (0.208):
Cisco IOS 12.2 SXD:

Source: Multiple Vulnerabilities Found by PROTOS IPSec Test Suite
URL: http://www.cisco.com/warp/public/707/cisco-sa-20051114-ipsec.shtml

Source: Multiple Vulnerability Issues in Implementations of ISAKMP Protocol
URL: http://www.niscc.gov.uk/niscc/docs/re-20051114-01014.pdf?lang=en

Discovery is credited to Cisco in cooperation with CERT-FI and NISCC.

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