Cisco AnyConnect Secure Mobility Client VPNAPI COM Buffer Overflow Vulnerability

A vulnerability in the Active Template Library (ATL) framework used by a component of the Cisco AnyConnect Secure Mobility Client could allow an unauthenticated, remote attacker to execute arbitrary commands with the privilege of the user executing the web browser.

The vulnerability is due to insufficient input validation when the ATL framework is called by the VPNAPI COM module. An attacker could exploit this vulnerability by persuading the a user with the Cisco AnyConnect Secure Mobility Client to visit a crafted HTML page. An exploit could allow the attacker to create a buffer overflow condition and possibly execute arbitrary code. Arbitrary code injection is theoretical and has not been proven.

Note: The COM component is not marked safe for scripting or initialization; therefore, a user would be prompted multiple times before the control would load.

Depending on the device operating system where Cisco AnyConnect Secure Mobility Client is installed, the command execution will be performed with the privilege of the user accessing the malicious HTML. This vulnerability affects Cisco AnyConnect Secure Mobility Client version 2.x only. Cisco AnyConnect Secure Mobility Client 3.x is not affected.

Cisco would like to thank Alex Nikitin and Jarrod Johnson from Ixia BreakingPoint for reporting this vulnerability.

Cisco has confirmed the vulnerability in a security notice and released software updates.

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