CVE-2022-29700
📋 TL;DR
CVE-2022-29700 is a vulnerability in Zammad v5.1.0 where lack of password length restriction allows attackers to create extremely long passwords, causing Denial of Service (DoS) during password verification. This affects all Zammad installations running the vulnerable version, potentially disrupting authentication services.
💻 Affected Systems
- Zammad
📦 What is this software?
Zammad by Zammad
⚠️ Risk & Real-World Impact
Worst Case
Complete authentication service disruption preventing all user logins, potentially leading to extended downtime and business impact.
Likely Case
Temporary authentication service degradation or unavailability affecting legitimate user access.
If Mitigated
Minimal impact with proper monitoring and rapid response capabilities in place.
🎯 Exploit Status
Exploitation requires ability to create or modify user accounts, but the attack itself is simple - creating accounts with extremely long passwords.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v5.1.1 and later
Vendor Advisory: https://zammad.com/en/advisories/zaa-2022-03
Restart Required: Yes
Instructions:
1. Backup your Zammad installation and database. 2. Update to Zammad v5.1.1 or later using your package manager or installation method. 3. Restart Zammad services. 4. Verify the update was successful.
🔧 Temporary Workarounds
Implement password length restrictions
allAdd password length validation to prevent extremely long passwords
# Requires modifying Zammad source code to add password length validation
Rate limit authentication attempts
linuxImplement rate limiting on authentication endpoints to mitigate DoS impact
# Configure web server (nginx/apache) rate limiting for /auth/login endpoints
🧯 If You Can't Patch
- Implement WAF rules to block authentication requests with extremely long password parameters
- Monitor authentication logs for unusually long password attempts and implement alerting
🔍 How to Verify
Check if Vulnerable:
Check Zammad version: if running v5.1.0 exactly, you are vulnerable.Check Version:
zammad versionVerify Fix Applied:
Verify Zammad version is v5.1.1 or later and test that password length restrictions are enforced.📡 Detection & Monitoring
Log Indicators:
- Authentication failures with unusually long password fields
- Increased authentication processing time
- Authentication service errors or timeouts
Network Indicators:
- Multiple authentication requests with large payload sizes
- Authentication endpoint response time degradation
SIEM Query:
source="zammad" (auth_failure OR login_failed) AND password_length>1000