Software Engineering Institute

Cisco Catalyst 6000, 6500, and Cisco 7600 series switches may utilize Cisco's NAM to monitor and analyze network traffic using Management Information Bases (MIBs). Cisco Catalyst 6000, 6500 and Cisco 7600 series switches that have a NAM installed contain a vulnerability in the way SNMP packets are handled. According to Cisco Security Advisory: cisco-sa-20070228-nam:

NAMs communicate with the Catalyst system by using the Simple Network Management Protocol (SNMP). By spoofing the SNMP communication between the Catalyst system and the NAM an attacker may obtain complete control of the Catalyst system.

Note that only Cisco Catalyst 6000, 6500 and Cisco 7600 series systems with a NAM on them are affected by this issue. According to Cisco, none of their other products, including the Network Analysis Modules for Cisco Branch Routers (NM-NAM), are affected by this issue .

By successfully exploiting this vulnerability, an attacker may gain complete control of the device.

Upgrade
See the Software Version and Fixes section of Cisco Security Advisory: cisco-sa-20070228-nam for information on available upgrades.

Filter SNMP traffic

This vulnerability can be mitigated by filtering SNMP traffic from the IP address of the NAM to an affected device. Filters cannot be applied to the affected device itself; to be effective, they must be applied to systems that are deployed in front of it.

Apply an access control list

Users that are unable to upgrade should apply an access control list (ACL) on the vulnerable device to restrict access to trusted management systems. Details on creating and uploading an ACL can be found in Cisco's Protecting Your Core document.


More details on these and additional workarounds can be found in the Cisco Applied Intelligence companion document for this advisory.