CVE-2022-27924
📋 TL;DR
CVE-2022-27924 is an unauthenticated memcache command injection vulnerability in Zimbra Collaboration Suite. It allows attackers to overwrite arbitrary cached entries, potentially leading to authentication bypass or data manipulation. Affects Zimbra Collaboration 8.8.15 and 9.0 installations.
💻 Affected Systems
- Zimbra Collaboration Suite
- Zimbra Collaboration
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via authentication bypass leading to unauthorized access to email accounts, data theft, or further network penetration.
Likely Case
Authentication bypass allowing unauthorized access to user accounts and email data.
If Mitigated
Limited impact if proper network segmentation and access controls prevent external memcache access.
🎯 Exploit Status
Exploitation requires network access to Zimbra's memcache service (default port 11211). Public exploit code available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 8.8.15 Patch 24 and 9.0.0 Patch 24
Vendor Advisory: https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
Restart Required: Yes
Instructions:
1. Download appropriate patch from Zimbra support portal. 2. Stop Zimbra services. 3. Apply patch using zimbra-patch command. 4. Restart Zimbra services. 5. Verify patch installation.
🔧 Temporary Workarounds
Network Access Restriction
linuxBlock external access to memcache port (11211) using firewall rules.
iptables -A INPUT -p tcp --dport 11211 -j DROP
iptables -A INPUT -p udp --dport 11211 -j DROP
Memcache Binding Restriction
linuxConfigure memcache to bind only to localhost/127.0.0.1 instead of all interfaces.
Edit /opt/zimbra/conf/localconfig.xml and set memcached_bind_address to 127.0.0.1
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Zimbra servers from untrusted networks
- Deploy web application firewall (WAF) with memcache injection detection rules
🔍 How to Verify
Check if Vulnerable:
Check Zimbra version: /opt/zimbra/bin/zmcontrol -v. If output shows 8.8.15 or 9.0 without patch 24, system is vulnerable.Check Version:
/opt/zimbra/bin/zmcontrol -vVerify Fix Applied:
Run: /opt/zimbra/bin/zmcontrol -v. Should show 8.8.15_P24 or 9.0.0_P24. Also verify memcache service binds only to localhost.📡 Detection & Monitoring
Log Indicators:
- Unusual memcache connection attempts in Zimbra logs
- Authentication failures followed by successful logins from same IP
Network Indicators:
- TCP/UDP connections to port 11211 from external IPs
- Unusual memcache protocol traffic patterns
SIEM Query:
source="zimbra.logs" AND ("memcache" OR "11211") AND ("injection" OR "malformed" OR "unauthorized")🔗 References
- https://wiki.zimbra.com/wiki/Security_Center
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P24
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
- https://wiki.zimbra.com/wiki/Security_Center
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P24
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2022-27924
