CVE-2020-2279
📋 TL;DR
CVE-2020-2279 is a critical sandbox bypass vulnerability in Jenkins Script Security Plugin that allows attackers with permission to define sandboxed scripts to craft return values or script bindings that escape the sandbox and execute arbitrary code on the Jenkins controller JVM. This affects Jenkins administrators and users with script definition permissions. The vulnerability enables full compromise of the Jenkins controller.
💻 Affected Systems
- Jenkins Script Security Plugin
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the Jenkins controller with full administrative access, allowing installation of backdoors, credential theft, lateral movement, and persistent access to the entire CI/CD pipeline.
Likely Case
Attackers with script permissions gain full code execution on the controller, enabling data exfiltration, pipeline manipulation, and deployment of malicious artifacts.
If Mitigated
With proper access controls limiting script permissions to trusted users only, impact is reduced but still critical if any authorized user is compromised.
🎯 Exploit Status
Exploitation requires authenticated access with script permissions. Public proof-of-concept exists in security advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Script Security Plugin 1.75 or later
Vendor Advisory: https://www.jenkins.io/security/advisory/2020-09-23/#SECURITY-2020
Restart Required: Yes
Instructions:
1. Update Jenkins Script Security Plugin to version 1.75 or later via Jenkins Plugin Manager. 2. Restart Jenkins service. 3. Verify plugin version in Installed Plugins list.
🔧 Temporary Workarounds
Restrict Script Permissions
allTemporarily remove 'Run Scripts' permission from all non-essential users until patching is complete.
Navigate to Jenkins > Manage Jenkins > Configure Global Security > Matrix-based security or Role-based strategy
🧯 If You Can't Patch
- Implement strict access controls to limit script permissions to absolutely necessary administrators only
- Monitor Jenkins logs for unusual script execution patterns and implement network segmentation
🔍 How to Verify
Check if Vulnerable:
Check Jenkins Plugin Manager for Script Security Plugin version. If version is 1.74 or earlier, system is vulnerable.Check Version:
Check via Jenkins web UI: Manage Jenkins > Plugin Manager > Installed plugins, or check JENKINS_HOME/plugins/script-security/META-INF/MANIFEST.MFVerify Fix Applied:
Verify Script Security Plugin version is 1.75 or later in Jenkins > Manage Jenkins > Plugin Manager > Installed tab.📡 Detection & Monitoring
Log Indicators:
- Unusual Groovy script execution patterns in Jenkins logs
- ScriptSecurity exceptions or sandbox bypass attempts
Network Indicators:
- Unexpected outbound connections from Jenkins controller
- Unusual API calls to Jenkins script endpoints
SIEM Query:
source="jenkins.log" AND ("script-security" OR "sandbox" OR "Groovy") AND ("bypass" OR "exception" OR "unauthorized")