CVE-2018-10381
📋 TL;DR
TunnelBear 3.2.0.6 for Windows has a privilege escalation vulnerability where the TunnelBearMaintenance service exposes a NetNamedPipe endpoint. Any local application can connect to this endpoint and use the OpenVPNConnect method to execute arbitrary code as SYSTEM by specifying a malicious OpenVPN plugin. This affects all Windows users running the vulnerable version.
💻 Affected Systems
- TunnelBear VPN Client
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, allowing attackers to install persistent malware, steal credentials, disable security controls, and pivot to other systems.
Likely Case
Local attackers or malware gaining SYSTEM privileges to bypass security software, install backdoors, or access protected system resources.
If Mitigated
Limited impact if proper endpoint protection and least privilege principles are enforced, though SYSTEM access would still be possible.
🎯 Exploit Status
Exploitation requires local access but no authentication. Public proof-of-concept code exists in the advisory references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 3.2.0.6
Vendor Advisory: https://www.tunnelbear.com/blog/tunnelbear-security-update/
Restart Required: Yes
Instructions:
1. Open TunnelBear application. 2. Check for updates in settings. 3. Install latest version. 4. Restart computer to ensure service updates apply.
🔧 Temporary Workarounds
Disable TunnelBearMaintenance Service
windowsStop and disable the vulnerable service to prevent exploitation.
sc stop TunnelBearMaintenance
sc config TunnelBearMaintenance start= disabled
Remove Named Pipe Access
windowsRestrict access to the vulnerable named pipe endpoint.
icacls \\.\pipe\TunnelBearMaintenance /deny Everyone:(F)
🧯 If You Can't Patch
- Uninstall TunnelBear 3.2.0.6 and use alternative VPN software
- Implement strict application control policies to prevent unauthorized local code execution
🔍 How to Verify
Check if Vulnerable:
Check if TunnelBearMaintenance service exists and is running, and verify TunnelBear version is 3.2.0.6.Check Version:
Check TunnelBear 'About' section in application or examine installed programs in Control PanelVerify Fix Applied:
Verify TunnelBear version is newer than 3.2.0.6 and check that named pipe \\.\pipe\TunnelBearMaintenance is no longer accessible or service is removed.📡 Detection & Monitoring
Log Indicators:
- Windows Event Logs showing unexpected SYSTEM privilege processes spawned from TunnelBearMaintenance
- Security logs showing named pipe connections to TunnelBearMaintenance
Network Indicators:
- Local named pipe connections to \\.\pipe\TunnelBearMaintenance from non-TunnelBear processes
SIEM Query:
Process Creation where Parent Process Name contains 'TunnelBear' AND Integrity Level = 'System'