CVE-2020-2320
📋 TL;DR
CVE-2020-2320 is a critical vulnerability in Jenkins Plugin Installation Manager Tool 2.1.3 and earlier that fails to verify plugin downloads, allowing attackers to supply malicious plugins. This enables remote code execution on Jenkins servers. All Jenkins instances using the vulnerable Plugin Installation Manager Tool are affected.
💻 Affected Systems
- Jenkins Plugin Installation Manager Tool
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full compromise of Jenkins server with attacker gaining complete control, data exfiltration, lateral movement, and persistence.
Likely Case
Remote code execution leading to unauthorized access, data theft, and potential ransomware deployment.
If Mitigated
Limited impact if network segmentation and strict access controls prevent external plugin installation attempts.
🎯 Exploit Status
Exploitation requires tricking Jenkins into downloading a malicious plugin, which can be achieved through man-in-the-middle attacks or compromised update servers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Jenkins Plugin Installation Manager Tool 2.1.4
Vendor Advisory: https://www.jenkins.io/security/advisory/2020-12-03/#SECURITY-1856
Restart Required: Yes
Instructions:
1. Update Jenkins to version 2.263 or later. 2. Update Plugin Installation Manager Tool to 2.1.4 or later. 3. Restart Jenkins service.
🔧 Temporary Workarounds
Disable Plugin Installation Manager Tool
allTemporarily disable the vulnerable component until patching is possible
# Remove or rename the plugin installation manager tool directory
mv /path/to/plugin-installation-manager-tool /path/to/plugin-installation-manager-tool.disabled
Network Segmentation
linuxRestrict Jenkins server network access to prevent external plugin downloads
# Configure firewall to block Jenkins from downloading plugins from external sources
iptables -A OUTPUT -p tcp --dport 443 -d update.jenkins.io -j DROP
🧯 If You Can't Patch
- Implement strict network controls to prevent Jenkins from downloading plugins from untrusted sources
- Disable automatic plugin updates and only install plugins from verified internal repositories
🔍 How to Verify
Check if Vulnerable:
Check Jenkins version and Plugin Installation Manager Tool version in Jenkins web interface under Manage Jenkins > About JenkinsCheck Version:
java -jar jenkins.war --versionVerify Fix Applied:
Verify Jenkins version is 2.263+ and Plugin Installation Manager Tool is 2.1.4+ in About Jenkins page📡 Detection & Monitoring
Log Indicators:
- Unexpected plugin installation attempts
- Plugin downloads from unusual sources
- Errors in plugin verification
Network Indicators:
- Jenkins server downloading plugins from non-standard update servers
- Unusual outbound connections during plugin installation
SIEM Query:
source="jenkins.log" AND ("plugin install" OR "plugin download") AND NOT source="update.jenkins.io"