CVE-2021-30690
📋 TL;DR
This CVE addresses multiple security vulnerabilities in Apache HTTP Server that could allow remote code execution or denial of service. The vulnerability affects Apache servers running on macOS systems that haven't been updated. Apple addressed these issues in their Security Update 2021-004 for Mojave.
💻 Affected Systems
- Apache HTTP Server
- macOS Mojave
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote attacker could execute arbitrary code with the privileges of the Apache process, potentially leading to complete system compromise.
Likely Case
Denial of service attacks causing Apache server crashes or resource exhaustion.
If Mitigated
Limited impact with proper network segmentation and minimal Apache privileges.
🎯 Exploit Status
Multiple issues were addressed collectively, suggesting various attack vectors. The high CVSS score indicates relatively easy exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apache 2.4.46, macOS Security Update 2021-004 Mojave
Vendor Advisory: https://support.apple.com/en-us/HT212531
Restart Required: Yes
Instructions:
1. For macOS Mojave: Install Security Update 2021-004 via System Preferences > Software Update. 2. For standalone Apache: Update to version 2.4.46 or later from Apache website.
🔧 Temporary Workarounds
Disable vulnerable modules
allDisable Apache modules that may be vulnerable if not needed
# Edit httpd.conf and comment out unnecessary modules
# Example: CommentModule mod_xxx
Network segmentation
linuxRestrict access to Apache servers using firewalls
# Example iptables rule: iptables -A INPUT -p tcp --dport 80 -s trusted_network -j ACCEPT
# iptables -A INPUT -p tcp --dport 443 -s trusted_network -j ACCEPT
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure to trusted sources only
- Run Apache with minimal privileges using non-root user accounts
🔍 How to Verify
Check if Vulnerable:
Check Apache version with 'httpd -v' and macOS version with 'sw_vers'. If Apache < 2.4.46 on macOS Mojave without Security Update 2021-004, system is vulnerable.Check Version:
httpd -v && sw_versVerify Fix Applied:
Verify Apache version is 2.4.46+ and macOS shows Security Update 2021-004 installed.📡 Detection & Monitoring
Log Indicators:
- Unusual Apache process crashes
- Suspicious requests to vulnerable endpoints
- Unexpected child process creation
Network Indicators:
- Multiple malformed HTTP requests from single source
- Traffic patterns suggesting exploit attempts
SIEM Query:
source="apache_access.log" AND (status=500 OR status=400) AND uri CONTAINS suspicious_pattern