CVE-2020-15076
📋 TL;DR
The Private Tunnel installer for macOS versions 3.0.1 and older contains a symlink vulnerability that allows attackers to corrupt critical system files. This occurs when the installer follows symlinks in the /tmp directory, potentially leading to system compromise. Only macOS users running affected Private Tunnel versions are impacted.
💻 Affected Systems
- Private Tunnel VPN client
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through corruption of critical system files, potentially leading to root access, data loss, or system instability requiring reinstallation.
Likely Case
Local privilege escalation or denial of service through targeted file corruption, allowing attackers to modify system configurations or crash services.
If Mitigated
Minimal impact if proper file permissions and access controls prevent unauthorized symlink creation in /tmp.
🎯 Exploit Status
Exploitation requires local access to create symlinks in /tmp and trigger the installer with elevated privileges.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions newer than 3.0.1
Vendor Advisory: https://swupdate.openvpn.net/downloads/privatetunnel/changelog.txt
Restart Required: No
Instructions:
1. Download latest Private Tunnel version from official source. 2. Uninstall old version. 3. Install updated version. 4. Verify version is newer than 3.0.1.
🔧 Temporary Workarounds
Secure /tmp directory permissions
allRestrict symlink creation in /tmp to prevent exploitation
chmod 1777 /tmp
chmod +t /tmp
Run installer with minimal privileges
allAvoid running installer with elevated privileges when possible
🧯 If You Can't Patch
- Remove or disable Private Tunnel until patched
- Implement strict access controls on /tmp directory and monitor for suspicious symlink creation
🔍 How to Verify
Check if Vulnerable:
Check Private Tunnel version in application settings or via 'defaults read /Applications/Private\ Tunnel.app/Contents/Info.plist CFBundleShortVersionString'Check Version:
defaults read /Applications/Private\ Tunnel.app/Contents/Info.plist CFBundleShortVersionStringVerify Fix Applied:
Confirm version is newer than 3.0.1 using same command📡 Detection & Monitoring
Log Indicators:
- Unusual symlink creation in /tmp directory
- Private Tunnel installer execution with elevated privileges
Network Indicators:
- None - local vulnerability only
SIEM Query:
process_name:"Private Tunnel" AND process_integrity_level:"High" OR file_path:"/tmp/*" AND file_operation:"symlink"