Date Discovered November 14, 2005
Description 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.
Block external access at the network boundary, unless external parties require service. 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 has made revision 1.4 of their advisory available. Updates to this advisory modify the affected packages list as well as changes to the 'Additional Details' section. Please see the referenced advisory for further information.
Cisco has made revision 1.5 of their advisory available. Updates to this advisory modify the affected packages list as well as changes to the 'Additional Details' section. Please see the referenced advisory for further information.
Cisco has made revision 1.6 of their advisory available. Some additional details for Cisco IOS were added. Please see the referenced advisory for further information.
Cisco has made revision 1.7 of their advisory available. The release date for fixed software version 12.3(11)T9 has been altered to be 27 Dec. 2005. Please see the referenced advisory for further information.
Credits Discovery is credited to Cisco in cooperation with CERT-FI and NISCC.
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