Software Engineering Institute

Overview

Versions 1.1.5 and earlier of the mu HTTP deamon (muhttpd) are vulnerable to path traversal via crafted HTTP request from an unauthenticated user. This vulnerability can allow unauthenticated users to download arbitrary files and collect private information on the target device.

Description

The muhttpd, hosted at SourceForge as an opensource project, is a lightweight webserver. This software is commonly used in customer premise equipment (CPE), such as home routers and small office routers, to provide device management capability through a web interface. The muhttpd supports the use of CGI scripts that enable remote management of CPE devices.

A path traversal vulnerability in muhttpd (version 1.1.5 and earlier) could allow an unauthenticated attacker to read arbitrary content on the target device, including usernames and passwords, Wireless SSID configurations, ISP connection information, and private keys. If remote management is enabled on a device running vulnerable version of muhttpd, this attack is possible from a remote network. Even in cases with restricted Local Area Network access, a vulnerable version of muhttpd can be accessed using other attack methods such as DNS Rebinding.

Impact

An unauthenticated attacker can use crafted HTTP request to download arbitrary files or gather sensitive information from a vulnerable target device. In cases where remote management is enabled on a vulnerable device, a remote unauthenticated attacker can perform these attacks.

Solution

Apply Updates

Update to the latest version of firmware/software provided by your vendor; see Vendor Information section for details. Downstream developers of embedded systems should update muhttpd software (to version 1.1.7 or later) from SourceForget git repository.

Disable remote management

Disabling remote management access, which thereby limits access strictly to local area network, can minimize the exposure introduced by the vulnerable software. Use access control to limit remote management if remote management is desired from specific IP network locations. Additional mitigations are described in the security researcher's advisory.

Acknowledgements

Thanks to Derek Abdine for reporting this vulnerability.

This document was written by Brad Runyon, Vijay Sarvepalli, and Eric Hatleback.

Vendor Information

References

• https://derekabdine.com/blog/2022-arris-advisory
• https://blog.malwarebytes.com/exploits-and-vulnerabilities/2022/08/millions-of-arris-routers-are-vulnerable-to-path-traversal-attacks
• https://www.cisa.gov/uscert/ncas/tips/ST15-002