A newly discovered vulnerability, identified as CVE-2022-20853, affects the REST API of Cisco Expressway Series and Cisco TelePresence VCS, which could potentially allow an unauthenticated remote attacker to conduct a cross-site request forgery (CSRF) attack on affected systems. Insufficient CSRF protections in the web-based management interface of affected systems have made this exploit possible.

Exploit Details

The vulnerability stems from inadequate CSRF protections in the web-based management interface. Attackers can exploit this vulnerability by convincing a user of the REST API to follow a maliciously crafted link, which will cause the affected system to reload upon a successful attack. The attacker will not require any authentication to perform this exploit. Unfortunately, there are currently no workarounds that address this vulnerability.

Original References

Cisco has published an official advisory detailing this specific vulnerability, which can be found at:
- Official Cisco Advisory

Cisco has also provided updated software that mitigates this vulnerability. Updates can be obtained through the following link:
- Download updated Cisco software

Code Snippet/Example

A potential scenario for exploiting this vulnerability can be illustrated using the following code snippet:

<!DOCTYPE html>
<html>
  <body>
    <h1>CSRF Exploit - CVE-2022-20853</h1>
    <form id="csrfForm" method="POST" action="https://vulnerable-rest-api.example.com/api/endpoint/">;
      <input type="hidden" name="craftedData" value="{malicious data}" />
    </form>
    <script>
      window.onload = () => document.getElementById("csrfForm").submit();
    </script>
  </body>
</html>

This HTML example demonstrates how an attacker can use a CSRF attack by embedding a hidden form, which sends a POST request to the vulnerable REST API upon being loaded. Through social engineering techniques, the attacker lures the targeted user to open and load the malicious webpage containing the exploit.

To stay protected against such attacks, it is crucial for Cisco Expressway Series and Cisco TelePresence VCS users to apply the software updates provided by Cisco immediately.

Conclusion

CVE-2022-20853 is a severe CSRF vulnerability affecting Cisco Expressway Series and Cisco TelePresence VCS REST API. Consequently, it can be exploited by remote attackers without authentication. Users are strongly recommended to apply the latest software updates shared by Cisco to mitigate this vulnerability as no other workarounds are presently available.

Timeline

Published on: 11/15/2024 15:27:23 UTC