Apache Httpd 2.4.18 Exploit | [patched]

Note on intent: This report is written for educational and defensive purposes. It analyzes the historical vulnerabilities associated with this specific version to help system administrators understand risks, patch management, and forensic indicators.

The Prime Exploit: HTTP Request Smuggling (CVE-2016-4979)

The most technically viable remote exploit for Apache 2.4.18 is CVE-2016-4979, a request smuggling vulnerability that arises from improper handling of the Content-Length and Transfer-Encoding headers in conjunction with mod_cache and mod_proxy. apache httpd 2.4.18 exploit

Mitigation and Remediation

If you discover Apache 2.4.18 in your environment: Note on intent: This report is written for

1. Immediate Patching: Upgrade to Apache 2.4.46 or higher. The vulnerability chain was mitigated by:
   • Restricting Transfer-Encoding handling to strictly RFC-compliant mode.
   • Backporting patches for mod_proxy and mod_http2.
2. Configuration Hardening (if upgrade impossible):
   • Disable mod_http2: Protocols http/1.1
   • In mod_proxy, set ProxyBadHeader Ignore|Reject
   • Disable mod_cache and mod_session unless required.
3. WAF Rules: Deploy a WAF rule that rejects any request containing both Content-Length and Transfer-Encoding headers.

6. Mitigation & Remediation

1. Executive Summary

Apache HTTP Server 2.4.18 was released on December 13, 2015. As a version over a decade old, it is considered end-of-life (EOL) and no longer receives security backports from the Apache Software Foundation. While no single “universal remote code execution (RCE)” exploit exists exclusively for 2.4.18, the version is vulnerable to a chain of publicly disclosed high-severity vulnerabilities (CVE-2016-5387, CVE-2016-8743, CVE-2017-9798, CVE-2017-15710). Adversaries actively target systems running this version due to its prevalence in legacy IoT devices, outdated LAMP stacks, and unmaintained web hosting environments. Immediate Patching: Upgrade to Apache 2

Key Finding: Systems running Apache 2.4.18 should be considered compromised if exposed to the internet without a Web Application Firewall (WAF) or OS-level ACLs.

Dockerfile for Vanilla 2.4.18 (Unsafe - Lab Only)

FROM ubuntu:16.04
RUN apt-get update && apt-get install -y apache2=2.4.18-2ubuntu3
# Enable mod_cgi, mod_http2, and set AllowOverride All
COPY vulnerable.cgi /usr/lib/cgi-bin/
CMD ["/usr/sbin/apache2ctl", "-D", "FOREGROUND"]

Log-based detection

• HTTPOXY: grep " Proxy: http" /var/log/apache2/access.log
• Optionsbleed: Look for OPTIONS * HTTP/1.1 with Limit: header.
• HTTP/2 smuggling: Abnormal :method or :path pseudo-headers (requires request tracing).

6.1 Immediate Actions (if 2.4.18 found in production)

| Action | Command / Configuration | |--------|--------------------------| | Upgrade Apache | sudo apt-get upgrade apache2 (or compile 2.4.58+) | | Disable HTTP/2 | Protocols http/1.1 in httpd.conf | | Remove mod_cgi/cgid | sudo a2dismod cgi cgid | | Set ProxyRequest Off | Prevents HTTPOXY (Not a complete fix) | | Deploy WAF rule | Block Proxy header containing http:// or Proxy: * |

Testing OptionsBleed

git clone https://github.com/hannob/optionsbleed
python3 optionsbleed.py http://victim

You will find that unless tweaked, most exploits yield limited results. This is the reality of Apache security post-2018.