CVE-2024-37894 - Squid Proxy Memory Corruption Vulnerability: Out-of-bounds Write in ESI Variable Assignment

Squid is a widely used caching proxy service that supports multiple protocols such as HTTP, HTTPS, FTP, and more. It is designed to improve the performance of web requests by caching and delivering content from previous requests to reduce bandwidth usage and latency. However, a recent vulnerability has been discovered (CVE-2024-37894) that can potentially lead to Memory Corruption and Denial of Service (DoS) attacks.

Details

Due to an Out-of-bounds Write error when assigning Edge Side Includes (ESI) variables, Squid is susceptible to a Memory Corruption error. ESI is a markup language used to define web page components for caching purposes. The issue occurs when Squid incorrectly handles the assignment of ESI variables, which can lead to writing data outside of the intended memory space. This vulnerability can then be exploited by a remote attacker to trigger a Denial of Service (DoS) attack, causing the proxy service to crash or become unresponsive.

Exploit

An attacker can exploit this vulnerability by sending a specially crafted HTTP request with malicious ESI variables to the vulnerable Squid proxy server. This request will cause an Out-of-bounds Write error when Squid tries to assign the ESI variables, leading to memory corruption. This can result in a Denial of Service attack when the proxy server crashes or becomes unresponsive.

For example, a malicious HTTP request may look like this

GET /index.html HTTP/1.1
Host: vulnerable-squid-server.com
User-Agent: Mozilla/5.
Accept: */*
ESI-Variable: MALICIOUS_CODE_HERE

This will trigger the Out-of-bounds Write error and potentially cause memory corruption in the Squid proxy server.

Links to Original References

The Squid project has acknowledged this vulnerability and issued an official advisory detailing the issue, its severity, and possible mitigation strategies: Squid Advisory

Additionally, more information about the vulnerability and its technical details can be found in the following CVE reference: CVE-2024-37894

Mitigation

To mitigate this vulnerability, it is recommended to update Squid to the latest patched version that has addressed the Out-of-bounds Write error. Specifically, upgrading to Squid version 4.13 or later will resolve this issue. Squid can be updated using the package manager for your operating system or by compiling and installing the latest source code from the Squid website.

Also, it is advised to limit access to the Squid proxy server to trusted users only, and employ network security best practices, such as using firewalls and intrusion detection systems, to protect against unauthorized access and potential attacks.

Conclusion

This post discussed the CVE-2024-37894 vulnerability in the Squid caching proxy service and its potential impact on affected systems, including Memory Corruption and Denial of Service attacks. By staying informed about this issue, keeping your Squid installation updated, and following security best practices, you can help protect your systems from potential exploits and reduce the risk of experiencing a successful attack.

Timeline

Published on: 06/25/2024 20:15:11 UTC
Last modified on: 07/19/2024 14:15:05 UTC