Cisco Adaptive Security Appliance Phone Proxy CTL Authentication Vulnerability

A vulnerability in the Phone Proxy function of the Cisco Adaptive Security Appliance (ASA) could allow an unauthenticated, remote attacker to modify the trust of the Certificate Trust List (CTL) of a remote IP phone.

The vulnerability is due to insufficient authentication of the CTL file. An attacker could exploit this vulnerability by injecting a modified CTL file to the phone proxy. An exploit could allow the attacker to impact the entities trusted by the IP phone.

Cisco has confirmed the vulnerability in a security notice; however, software updates are not available.

To exploit this vulnerability, an attacker may require access to trusted, internal networks to inject a modified CTL file to the phone proxy of an affected device. This access requirement decreases the likelihood of a successful exploit.

Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.