CVE-2024-38476
📋 TL;DR
Apache HTTP Server 2.4.59 and earlier contain a vulnerability where malicious response headers from backend applications can lead to information disclosure, server-side request forgery (SSRF), or local script execution. This affects any Apache server configured to proxy requests to backend applications. The vulnerability is in the core server functionality.
💻 Affected Systems
- Apache HTTP Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could execute arbitrary scripts on the server with the privileges of the Apache process, potentially leading to full system compromise.
Likely Case
Information disclosure or SSRF allowing attackers to access internal systems or sensitive data through the vulnerable server.
If Mitigated
With proper network segmentation and minimal privileges, impact could be limited to the Apache server itself.
🎯 Exploit Status
Exploitation requires the ability to control response headers from backend applications that Apache proxies to.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.4.60
Vendor Advisory: https://httpd.apache.org/security/vulnerabilities_24.html
Restart Required: Yes
Instructions:
1. Download Apache HTTP Server 2.4.60 from the official website. 2. Stop the Apache service. 3. Backup configuration files. 4. Install the new version. 5. Restore configuration files. 6. Start the Apache service.
🔧 Temporary Workarounds
Disable proxy modules
linuxIf proxy functionality is not required, disable mod_proxy and related modules to eliminate the attack vector.
a2dismod proxy
a2dismod proxy_http
systemctl restart apache2
Restrict backend applications
allEnsure backend applications that Apache proxies to are trusted and properly secured.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Apache servers from sensitive internal systems.
- Deploy a web application firewall (WAF) with rules to detect and block malicious response headers.
🔍 How to Verify
Check if Vulnerable:
Check Apache version and configuration for proxy modules. Run: httpd -v and check for proxy-related directives in configuration files.Check Version:
httpd -vVerify Fix Applied:
Verify Apache version is 2.4.60 or later with: httpd -v📡 Detection & Monitoring
Log Indicators:
- Unusual response headers from backend applications in proxy logs
- Errors related to header parsing in error logs
Network Indicators:
- Unexpected outbound requests from Apache server to internal systems
- Anomalous traffic patterns to backend applications
SIEM Query:
source="apache" AND ("mod_proxy" OR "proxy" OR "backend") AND ("error" OR "malformed" OR "header")🔗 References
- https://httpd.apache.org/security/vulnerabilities_24.html
- https://security.netapp.com/advisory/ntap-20240712-0001/
- http://seclists.org/fulldisclosure/2024/Oct/11
- http://www.openwall.com/lists/oss-security/2024/07/01/9
- https://httpd.apache.org/security/vulnerabilities_24.html
- https://security.netapp.com/advisory/ntap-20240712-0001/
