Cisco Email Security Appliance Anti-Spam Scanner Bypass Vulnerability

A vulnerability in the anti-spam scanner of Cisco AsyncOS for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass the anti-spam functionality of the ESA.

The vulnerability is due to improper error handling of a malformed packet in the anti-spam scanner. An attacker could exploit this vulnerability by sending a crafted DNS Sender Policy Framework (SPF) text record. A successful exploit could allow the attacker to bypass the anti-spam scanner and generate a malformed packet alert.

Cisco has released software updates that address this vulnerability. There are no workarounds that mitigate this vulnerability.

This advisory is available at the following link:

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20150612-esa[“https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20150612-esa”]