CVE-2022-20814: Cisco Expressway-C and TelePresence VCS Certificate Validation Vulnerability

A recently discovered security vulnerability, designated as CVE-2022-20814, affects the certificate validation process of Cisco Expressway-C and Cisco TelePresence VCS. This vulnerability can potentially grant unauthorized remote access to sensitive data in these devices to unauthenticated attackers. This article will provide an overview of the vulnerability, how it can be exploited, and recommendations on mitigating the risk associated with it. Cisco Expressway-E devices are not affected by this vulnerability.

Vulnerability Details

The root cause of CVE-2022-20814 is the lack of validation of the SSL server certificate that an affected device receives when it establishes a connection to a Cisco Unified Communications Manager (UCM) device. This certificate validation gap can be exploited by an attacker by intercepting the traffic between the devices using a man-in-the-middle (MITM) technique, while impersonating the endpoint using a self-signed certificate.

When successfully exploited, this could allow the attacker to view the intercepted traffic in clear text or alter the contents of the traffic. This poses a significant risk, as sensitive information or control commands could be exposed or modified by the attacker.

Software Updates

In response to this vulnerability, Cisco has released software updates to address the issue. It is highly recommended to apply these updates to the affected devices as soon as possible. The Cisco Security Advisory page has details about the updates and can be found here: Cisco Security Advisory

Here is an example of a code snippet demonstrating the importance of validating SSL certificates properly:

import ssl
import socket

# The hostname and port of the target server
hostname = 'example.com'
port = 443

# Create a socket with SSL
context = ssl.create_default_context()
ssl_socket = context.wrap_socket(socket.socket(socket.AF_INET), server_hostname=hostname)

# Connect to the target server
ssl_socket.connect((hostname, port))

# Obtain the target server's SSL certificate
cert = ssl_socket.getpeercert()

# Verify that the certificate matches the expected subject
if not ssl.match_hostname(cert, hostname):
    raise ValueError("Certificate does not match subject")

# Send and receive data securely over the SSL connection

Workarounds

Currently, there are no workarounds that directly address this vulnerability. Applying the software updates provided by Cisco is the best course of action.

Conclusion

CVE-2022-20814 poses a significant risk to organizations relying on Cisco Expressway-C and TelePresence VCS devices. It is crucial to apply the released software updates to protect sensitive data and maintain the integrity of network communications. By addressing this vulnerability, organizations can protect themselves against potential unauthorized access and maintain the security of their systems.

Timeline

Published on: 11/15/2024 15:32:47 UTC