CVE-2020-2299
📋 TL;DR
The Jenkins Active Directory Plugin 2.19 and earlier contains an authentication bypass vulnerability where attackers can log in as any user by using a specific magic constant as the password. This affects all Jenkins instances using the vulnerable plugin version with Active Directory authentication enabled. Attackers can gain unauthorized access to Jenkins with any username.
💻 Affected Systems
- Jenkins Active Directory Plugin
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of Jenkins instance allowing attackers to execute arbitrary code, steal credentials, modify builds, and pivot to internal systems.
Likely Case
Unauthorized access to Jenkins with privileges of compromised user account, potentially leading to code execution, data theft, or build manipulation.
If Mitigated
Limited impact if network segmentation, strong authentication controls, and monitoring are in place to detect anomalous login attempts.
🎯 Exploit Status
Exploitation requires only knowledge of the magic constant password value, which has been publicly disclosed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Active Directory Plugin 2.20
Vendor Advisory: https://www.jenkins.io/security/advisory/2020-11-04/#SECURITY-2117
Restart Required: Yes
Instructions:
1. Update Jenkins to latest version. 2. Navigate to Manage Jenkins > Manage Plugins. 3. Update Active Directory Plugin to version 2.20 or later. 4. Restart Jenkins service.
🔧 Temporary Workarounds
Disable Active Directory Plugin
linuxTemporarily disable the vulnerable plugin until patching is possible
mv $JENKINS_HOME/plugins/active-directory.jpi $JENKINS_HOME/plugins/active-directory.jpi.disabled
Implement Network Controls
allRestrict access to Jenkins management interface
🧯 If You Can't Patch
- Implement IP whitelisting for Jenkins access
- Enable multi-factor authentication for all users
🔍 How to Verify
Check if Vulnerable:
Check plugin version in Jenkins web interface: Manage Jenkins > Manage Plugins > Installed tab, look for Active Directory Plugin versionCheck Version:
grep -r 'active-directory' $JENKINS_HOME/plugins/active-directory/META-INF/MANIFEST.MF | grep 'Plugin-Version'Verify Fix Applied:
Verify Active Directory Plugin version is 2.20 or higher in plugin management interface📡 Detection & Monitoring
Log Indicators:
- Failed login attempts with unusual usernames
- Successful logins from unexpected IP addresses
- Authentication events with suspicious timing patterns
Network Indicators:
- Unusual authentication traffic to Jenkins
- Login attempts from unexpected geographic locations
SIEM Query:
source="jenkins.log" AND ("authentication" OR "login") AND ("success" OR "failed") | stats count by src_ip, user