In early 2024, the Linksys E200 router, running firmware version 1..06 build 1, was found to have a critical security flaw: CVE-2024-27497. This vulnerability is an authentication bypass through the position.js file, letting attackers sneak around login requirements and access the device's sensitive settings. If you’re using an E200, read on — this bug could let an intruder into your network.

In this post, I'll explain the vulnerability in plain English, showing how it works with code snippets, a step-by-step exploitation guide, and links to reliable sources.

What is the Linksys E200?

The Linksys E200 is a popular wireless-N router. It's used in many homes and small offices — and known for its easy-to-use web interface. But those same web controls are where CVE-2024-27497 lives.

What’s at risk?

CVE-2024-27497 allows attackers to bypass authentication controls simply by accessing a hidden JavaScript file: position.js. If someone knows your router’s public IP (and you have remote management on), or is on your Wi-Fi, they can slip in through this flaw with no password at all.

How Does the Exploit Work?

Most routers protect their settings with a web login. But on the E200, the file position.js doesn’t require authentication. When this file is accessed, it exposes device info — and even opens the door for privilege escalation or custom commands, depending on what an attacker sends next.

Attacker browses to:

http://<router-ip>/position.js

Example Exploit with cURL

curl http://192.168.1.1/position.js

If you get a response full of JavaScript and data (even though you never logged in), you’ve confirmed the flaw.

Session tokens or variables used elsewhere in the device's web scripts

With those details, an attacker can either replicate or forge requests that require admin status, without ever knowing the admin password.

Most home networks use 192.168.1.1 or 192.168..1. Try

ping 192.168.1.1

2. Download position.js

curl http://192.168.1.1/position.js

Within the returned JavaScript you could find

var deviceInfo = { model: "E200", version: "1..06", ... }
var sessionID = "...someValue...";

These can be used to build requests imitating a logged-in admin.

4. Possible Unauthenticated Changes

Depending on the router’s implementation (and possibly chained with other flaws), you might use data from position.js to:

Attacker fetches position.js, analyses data

- Using extracted variables, attacker scripts requests to modify DNS settings, redirecting user traffic to malicious servers

Note: If remote management is enabled, this can be done from anywhere — not just inside the network.

Mitigation

- Upgrade firmware (if updates are released). As of writing, Linksys has not publicly patched v1..06.

Notified References

- CVE Database Entry for CVE-2024-27497
- Exploit Database - Position.js Authentication Bypass (Proof of Concept) *(example URL, check for real-time updates)*
- SecurityFocus Advisory *(example URL)*

Conclusion

CVE-2024-27497 is a stark reminder that something as simple as a misconfigured JavaScript file can leave your entire network exposed. If you use a Linksys E200, check your settings and update your firmware when patches arrive. Stay alert for more security advisories — and consider retiring routers that no longer get official updates.

Timeline

Published on: 03/01/2024 15:15:08 UTC
Last modified on: 08/16/2024 16:35:04 UTC