CVE-2020-27519
📋 TL;DR
CVE-2020-27519 is a local privilege escalation vulnerability in Pritunl Client's pritunl-service component. Attackers can exploit malicious OpenVPN configurations using log injection to create or modify privileged script files, potentially executing arbitrary code with root/SYSTEM privileges. This affects users of Pritunl Client version 1.2.2550.20.
💻 Affected Systems
- Pritunl Client
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Local attacker gains full root/SYSTEM privileges, enabling complete system compromise, data theft, persistence mechanisms, and lateral movement.
Likely Case
Local attacker escalates privileges to execute arbitrary commands as root/SYSTEM, potentially installing malware, accessing sensitive data, or modifying system configurations.
If Mitigated
Attack fails due to patched software, restricted local access, or proper privilege separation preventing log injection.
🎯 Exploit Status
Exploitation requires local access and ability to manipulate OpenVPN configuration files. The attacker needs to craft malicious log directives to inject code into privileged script files.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after commit 87ceeae9b8ee415541d7d71de10675e699a76e5e
Vendor Advisory: https://github.com/pritunl/pritunl-client-electron/commit/87ceeae9b8ee415541d7d71de10675e699a76e5e
Restart Required: Yes
Instructions:
1. Update Pritunl Client to the latest version. 2. Restart the pritunl-service. 3. Verify the service is running with the updated version.
🔧 Temporary Workarounds
Restrict OpenVPN Configuration Access
linuxLimit who can create or modify OpenVPN configuration files to prevent malicious configurations.
chmod 600 /path/to/openvpn/configs/*.ovpn
chown root:root /path/to/openvpn/configs/*.ovpn
Run Pritunl Client with Reduced Privileges
allConfigure pritunl-service to run with minimal necessary privileges instead of root/SYSTEM.
🧯 If You Can't Patch
- Restrict local user access to systems running vulnerable Pritunl Client
- Monitor for suspicious log file modifications and privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check Pritunl Client version: On Linux/macOS: 'pritunl-client --version' or check installed package version. On Windows: Check installed programs list or run 'pritunl-client --version' from command line.Check Version:
pritunl-client --versionVerify Fix Applied:
Verify version is newer than 1.2.2550.20. Check that the commit 87ceeae9b8ee415541d7d71de10675e699a76e5e is included in your build.📡 Detection & Monitoring
Log Indicators:
- Unusual modifications to system log files
- Suspicious OpenVPN configuration files with log or log-append directives
- Privilege escalation attempts in system logs
Network Indicators:
- Local connections to pritunl-service from unauthorized users
SIEM Query:
EventID=4688 AND ProcessName LIKE '%pritunl%' AND NewProcessName LIKE '%sh%' OR EventID=4688 AND ProcessName LIKE '%pritunl%' AND NewProcessName LIKE '%cmd%'🔗 References
- https://github.com/pritunl/pritunl-client-electron/commit/87ceeae9b8ee415541d7d71de10675e699a76e5e
- https://github.com/pritunl/pritunl-client-electron/commit/87ceeae9b8ee415541d7d71de10675e699a76e5e#diff-5c6a264bee3576f2a147b8db70332e9a16dd43d073782cf6d32a372abb22b899
- https://github.com/pritunl/pritunl-client-electron/commit/c0aeb159351e5e99d752c27b87133eca299bdfce
- https://github.com/pritunl/pritunl-client-electron/commit/87ceeae9b8ee415541d7d71de10675e699a76e5e
- https://github.com/pritunl/pritunl-client-electron/commit/87ceeae9b8ee415541d7d71de10675e699a76e5e#diff-5c6a264bee3576f2a147b8db70332e9a16dd43d073782cf6d32a372abb22b899
- https://github.com/pritunl/pritunl-client-electron/commit/c0aeb159351e5e99d752c27b87133eca299bdfce
