CVE-2024-38473
📋 TL;DR
This vulnerability in Apache HTTP Server's mod_proxy module allows attackers to send specially crafted requests with incorrect URL encoding to backend services. This can potentially bypass authentication mechanisms on those backends. It affects Apache HTTP Server versions 2.4.59 and earlier when mod_proxy is enabled.
💻 Affected Systems
- Apache HTTP Server
📦 What is this software?
Ontap by Netapp
⚠️ Risk & Real-World Impact
Worst Case
Attackers bypass authentication on backend applications, gaining unauthorized access to sensitive data or administrative functions.
Likely Case
Authentication bypass on specific backend services that rely on URL-based access controls, potentially exposing internal applications.
If Mitigated
Limited impact if backend services have additional authentication layers or don't rely solely on URL-based access controls.
🎯 Exploit Status
Exploitation requires knowledge of backend service authentication mechanisms and ability to craft specific URL encoding patterns.
🛠️ 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 official Apache website. 2. Stop Apache service. 3. Backup current configuration. 4. Install new version. 5. Restore configuration. 6. Start Apache service.
🔧 Temporary Workarounds
Disable mod_proxy
allRemove or comment out mod_proxy module loading if not required
# In httpd.conf: Comment out 'LoadModule proxy_module modules/mod_proxy.so' and related proxy modules
Restrict proxy destinations
allLimit proxy configurations to trusted backend services only
# In proxy configuration: Use explicit ProxyPass directives with specific paths
🧯 If You Can't Patch
- Implement WAF rules to detect and block malformed URL encoding patterns
- Add additional authentication layers on backend services that don't rely solely on URL-based controls
🔍 How to Verify
Check if Vulnerable:
Check Apache version and mod_proxy configuration: 'httpd -v' and verify mod_proxy is loaded in configuration filesCheck Version:
httpd -vVerify Fix Applied:
Verify Apache version is 2.4.60 or later: 'httpd -v' should show version 2.4.60+📡 Detection & Monitoring
Log Indicators:
- Unusual URL encoding patterns in access logs
- Failed authentication attempts followed by successful access to protected resources
Network Indicators:
- HTTP requests with malformed URL encoding sent to proxy endpoints
SIEM Query:
source="apache_access" AND (url CONTAINS "%" OR url MATCHES "%[^0-9A-Fa-f]%")