CVE-2022-23943
📋 TL;DR
CVE-2022-23943 is a critical heap memory corruption vulnerability in Apache HTTP Server's mod_sed module that allows attackers to write data beyond allocated memory boundaries. This can lead to remote code execution, denial of service, or information disclosure. Affected systems are Apache HTTP Server versions 2.4.52 and earlier with mod_sed enabled.
💻 Affected Systems
- Apache HTTP Server
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Fedora by Fedoraproject
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains full control of the web server, executes arbitrary code with web server privileges, and potentially compromises the entire host system.
Likely Case
Remote code execution leading to web server compromise, data theft, or installation of malware/backdoors on affected systems.
If Mitigated
Denial of service causing web server crashes or instability if exploit attempts fail or are partially successful.
🎯 Exploit Status
Proof-of-concept exploit code is publicly available. The vulnerability is easily exploitable with publicly available tools and requires no authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apache HTTP Server 2.4.53 and later
Vendor Advisory: https://httpd.apache.org/security/vulnerabilities_24.html
Restart Required: Yes
Instructions:
1. Download Apache HTTP Server 2.4.53 or later from https://httpd.apache.org/download.cgi
2. Stop the Apache service: 'systemctl stop apache2' or 'apachectl stop'
3. Backup configuration files
4. Install the new version following your OS package manager or compilation instructions
5. Restart Apache: 'systemctl start apache2' or 'apachectl start'
🔧 Temporary Workarounds
Disable mod_sed module
allRemove or comment out mod_sed module loading to eliminate the vulnerable component
# Edit httpd.conf or apache2.conf
# Comment out: LoadModule sed_module modules/mod_sed.so
# Or remove the line entirely
# Then restart Apache: systemctl restart apache2
🧯 If You Can't Patch
- Disable mod_sed module immediately if not required for functionality
- Implement network segmentation and restrict access to Apache servers to only trusted sources
🔍 How to Verify
Check if Vulnerable:
Check Apache version with 'httpd -v' or 'apache2 -v' and verify mod_sed is loaded with 'httpd -M | grep sed' or 'apache2ctl -M | grep sed'Check Version:
httpd -v 2>/dev/null || apache2 -v 2>/dev/null || echo 'Apache not found'Verify Fix Applied:
Confirm version is 2.4.53 or higher with 'httpd -v' and verify mod_sed is either disabled or the new version is running📡 Detection & Monitoring
Log Indicators:
- Multiple 500 Internal Server Error responses
- Apache process crashes or restarts
- Unusual mod_sed related errors in error_log
Network Indicators:
- Unusual HTTP requests targeting mod_sed functionality
- Exploit pattern detection in web traffic
SIEM Query:
source="apache_access" AND (status=500 OR uri CONTAINS "sed" OR user_agent CONTAINS exploit)🔗 References
- http://www.openwall.com/lists/oss-security/2022/03/14/1
- https://httpd.apache.org/security/vulnerabilities_24.html
- https://lists.debian.org/debian-lts-announce/2022/03/msg00033.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGWILBORT67SHMSLYSQZG2NMXGCMPUZO/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X73C35MMMZGBVPQQCH7LQZUMYZNQA5FO/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7H26WJ6TPKNWV3QKY4BHKUKQVUTZJTD/
- https://security.gentoo.org/glsa/202208-20
- https://security.netapp.com/advisory/ntap-20220321-0001/
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.tenable.com/security/tns-2022-08
- https://www.tenable.com/security/tns-2022-09
- http://www.openwall.com/lists/oss-security/2022/03/14/1
- https://httpd.apache.org/security/vulnerabilities_24.html
- https://lists.debian.org/debian-lts-announce/2022/03/msg00033.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGWILBORT67SHMSLYSQZG2NMXGCMPUZO/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X73C35MMMZGBVPQQCH7LQZUMYZNQA5FO/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7H26WJ6TPKNWV3QKY4BHKUKQVUTZJTD/
- https://security.gentoo.org/glsa/202208-20
- https://security.netapp.com/advisory/ntap-20220321-0001/
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.tenable.com/security/tns-2022-08
- https://www.tenable.com/security/tns-2022-09
