CVE-2020-25989
📋 TL;DR
This vulnerability allows local attackers to write arbitrary files in the Pritunl VPN client, potentially leading to privilege escalation to root. It affects users running Pritunl client versions 1.0.1116.6 through 1.2.2550.20. Successful exploitation could give attackers full system control.
💻 Affected Systems
- Pritunl Client (Electron-based VPN client)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attacker gains root privileges and complete control over the system, enabling installation of persistent malware, data theft, or lateral movement.
Likely Case
Local attacker escalates privileges to install additional malware, modify system files, or access sensitive data.
If Mitigated
Attack fails due to proper file permissions, sandboxing, or the vulnerability being patched before exploitation.
🎯 Exploit Status
Exploitation requires local access to the system. The vulnerability is well-documented with public proof-of-concept references available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 1.2.2550.20
Vendor Advisory: https://github.com/pritunl/pritunl-client-electron/commit/89f8c997c6f93e724f68f76f7f47f8891d9acc2d
Restart Required: Yes
Instructions:
1. Update Pritunl client to version 1.2.2550.21 or later. 2. Download from official Pritunl repository. 3. Install the update. 4. Restart the client application.
🔧 Temporary Workarounds
Remove vulnerable versions
allUninstall affected Pritunl client versions and use alternative VPN client until patched version is available.
sudo apt remove pritunl-client
brew uninstall pritunl
Uninstall via system package manager
Restrict file permissions
linuxSet strict file permissions on Pritunl client directories to limit arbitrary file writes.
sudo chmod 750 /opt/pritunl
sudo chown root:root /opt/pritunl/*
🧯 If You Can't Patch
- Disable or uninstall Pritunl client on critical systems
- Implement strict access controls to prevent local user access to vulnerable systems
🔍 How to Verify
Check if Vulnerable:
Check Pritunl client version: On Linux: 'pritunl-client --version' or check installed package version. On Windows: Check program version in Control Panel > Programs.Check Version:
pritunl-client --versionVerify Fix Applied:
Verify version is 1.2.2550.21 or later using version check command. Test that arbitrary file writes to privileged locations are blocked.📡 Detection & Monitoring
Log Indicators:
- Unexpected file writes to system directories by pritunl process
- Privilege escalation attempts from pritunl user context
- Suspicious child processes spawned from pritunl
Network Indicators:
- Unusual outbound connections from systems running vulnerable Pritunl client
SIEM Query:
process_name='pritunl-client' AND (file_path CONTAINS '/etc/' OR file_path CONTAINS '/root/' OR file_path CONTAINS 'C:\Windows\')