CVE-2024-39573 - Uncovering a Potential SSRF Vulnerability in Apache HTTP Server's mod_rewrite and How to Protect Yourself

In today's cybersecurity landscape, it's more crucial than ever for organizations to stay ahead of emerging threats. One such vulnerability is CVE-2024-39573, which could potentially lead to a server-side request forgery (SSRF) attack in an Apache HTTP server environment.

This long read post will delve into the specifics of CVE-2024-39573, including the code snippet associated with the vulnerability, original references to the report, and details on the exploit itself. We will also discuss how to protect your Apache HTTP server by upgrading to the latest version that fixes this issue.

Understanding CVE-2024-39573

CVE-2024-39573 is a potential SSRF vulnerability in the mod_rewrite module of the Apache HTTP Server, specifically versions 2.4.59 and earlier. mod_rewrite enables server administrators to create custom URL rewriting rules. However, this vulnerability arises when unsafe RewriteRules are unexpectedly set up, causing URLs to be handled by the mod_proxy module.

Exploit Details

An attacker looking to exploit this vulnerability could potentially gain unauthorized access to internal resources, as well as execute unauthorized requests on the affected server. This may lead to sensitive information disclosure and further compromise of the server's security.

The following code snippet illustrates how this vulnerability could be triggered

RewriteEngine on
RewriteRule ^proxy/(.*)&host=(.+)$ http://%2/$1 [L,P]

This RewriteRule can potentially lead to an SSRF attack when it unexpectedly sets up URLs to be handled by mod_proxy, resulting in handling user-supplied domains in an unsafe manner.

For detailed technical information and remediation guidance, refer to the following official sources

1. Apache HTTP Server project's official CVE-2024-39573 announcement: https://httpd.apache.org/security/vulnerabilities_24.html

2. CVE-2024-39573 entry in the National Vulnerability Database (NVD): https://nvd.nist.gov/vuln/detail/CVE-2024-39573

Mitigation and Protection

The best way to protect your Apache HTTP server from this vulnerability is by upgrading to version 2.4.60, which contains a fix for the issue. To upgrade, follow the steps below:

Check your current Apache HTTP Server version by running the following command: httpd -v

2. Download the latest version (2.4.60) from the Apache HTTP Server website: https://httpd.apache.org/download.cgi
3. Follow the installation and upgrade instructions in the official Apache documentation: https://httpd.apache.org/docs/2.4/upgrading.html

In summary, CVE-2024-39573 is a potential SSRF vulnerability in mod_rewrite, affecting Apache HTTP Server versions 2.4.59 and earlier. By understanding the exploit details and taking prompt action to upgrade your server, you can ensure the continued security of your system and prevent possible attacks from malicious actors.

Timeline

Published on: 07/01/2024 19:15:05 UTC
Last modified on: 07/12/2024 14:15:16 UTC