Cisco Email Security Appliance Denial of Service Vulnerability

A vulnerability in the email message filtering feature of Cisco AsyncOS Software for the Cisco Email Security Appliance could allow an unauthenticated, remote attacker to cause an affected device to run out of memory and stop scanning and forwarding email messages. When system memory is depleted, it can cause the filtering process to crash, resulting in a denial of service (DoS) condition on the device.

The vulnerability is due to improper input validation of email attachments that contain corrupted fields. An attacker could exploit this vulnerability by sending an email message with an attachment that contains corrupted fields through a targeted device. When the affected software filters the attachment, the filtering process could crash when the system runs out of memory and the process restarts, resulting in a DoS condition. After the filtering process restarts, the software resumes filtering for the same attachment, causing the filtering process to crash and restart again. A successful exploit could allow the attacker to cause a repeated DoS condition.

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

This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170920-esa [“https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170920-esa”]