Cisco ASA Software DNS Denial of Service Vulnerability

A vulnerability in the DNS code of Cisco ASA Software could allow an unauthenticated, remote attacker to cause an affected device to reload or corrupt the information present in the device’s local DNS cache.

The vulnerability is due to a flaw in handling crafted DNS response messages. An attacker could exploit this vulnerability by triggering a DNS request from the Cisco ASA Software and replying with a crafted response. A successful exploit could cause the device to reload, resulting in a denial of service (DoS) condition or corruption of the local DNS cache information.

Note: Only traffic directed to the affected device can be used to exploit this vulnerability. This vulnerability affects Cisco ASA Software configured in routed or transparent firewall mode and single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic.

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-20170419-asa-dns [“https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170419-asa-dns”]