Cisco fixes critical remote command execution vulnerability in Secure Access Control Server

Cisco Systems released security patches for Secure Access Control Server (Secure ACS) for Windows to address a critical vulnerability that could allow unauthenticated attackers to remotely execute arbitrary commands and take control of the underlying operating system.

Cisco Secure ACS is an application that allows companies to centrally manage access to network resources for various types of devices and users. According to Cisco’s documentation, it enforces access control policies for VPN, wireless and other network users and it authenticates administrators, authorizes commands, and provides an audit trail.

Cisco Secure ACS supports two network access control protocols: Remote Access Dial In User Service (RADIUS) and Terminal Access Controller Access-Control System Plus (TACACS+).

The newly patched vulnerability is identified as CVE-2013-3466 and affects Cisco Secure ACS for Windows versions 4.0 through 4.2.1.15 when configured as a RADIUS server with Extensible Authentication Protocol-Flexible Authentication via Secure Tunneling (EAP-FAST) authentication.

“The vulnerability is due to improper parsing of user identities used for EAP-FAST authentication,” Cisco said Wednesday in a security advisory. “An attacker could exploit this vulnerability by sending crafted EAP-FAST packets to an affected device.”

“Successful exploitation of the vulnerability may allow an unauthenticated, remote attacker to execute arbitrary commands and take full control of the underlying operating system that hosts the Cisco Secure ACS application in the context of the System user for Cisco Secure ACS running on Microsoft Windows,” the company said.

The vulnerability received the maximum severity score, 10.0, in the Common Vulnerability Scoring System (CVSS), which indicates that it is highly critical. Cisco Secure ACS for Windows version 4.2.1.15.11 was released to address the flaw.

There are no known workarounds, so upgrading to the patched version of the application is recommended.