CVE-2020-18172
📋 TL;DR
CVE-2020-18172 is a critical code injection vulnerability in Trezor Bridge 2.0.27 that allows attackers to execute arbitrary code with elevated privileges. This affects users of Trezor hardware wallets who have the vulnerable bridge software installed on their systems. Successful exploitation could lead to complete system compromise.
💻 Affected Systems
- Trezor Bridge
📦 What is this software?
Bridge by Trezor
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with SYSTEM/root privileges, allowing installation of persistent malware, credential theft, and lateral movement across networks.
Likely Case
Local privilege escalation enabling attackers to bypass security controls, install keyloggers, or access protected system resources.
If Mitigated
Limited impact if running with minimal privileges, but still potential for local code execution in user context.
🎯 Exploit Status
Exploitation requires local access or ability to execute code in user context. The CWE-94 (Code Injection) nature suggests relatively straightforward exploitation once initial access is achieved.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Trezor Bridge 2.0.28 or later
Vendor Advisory: https://blog.trezor.io/security-update-trezor-bridge-2-0-28-6f2b2b3a5c5c
Restart Required: Yes
Instructions:
1. Download latest Trezor Bridge from official website 2. Uninstall previous version 3. Install new version 4. Restart system to ensure clean state
🔧 Temporary Workarounds
Remove SeDebugPrivilege
windowsModify local security policy to remove SeDebugPrivilege from Trezor Bridge process
secedit /configure /db %windir%\security\local.sdb /cfg remove_debug.cfg /areas USER_RIGHTS
Run with Reduced Privileges
linuxConfigure Trezor Bridge to run with standard user privileges instead of elevated rights
sudo chmod -R 755 /usr/local/bin/trezor-bridge
sudo chown -R $USER:$USER /usr/local/bin/trezor-bridge
🧯 If You Can't Patch
- Uninstall Trezor Bridge completely if not actively using hardware wallet
- Implement application whitelisting to prevent execution of unauthorized binaries
🔍 How to Verify
Check if Vulnerable:
Check Trezor Bridge version in About dialog or via 'trezor-bridge --version' commandCheck Version:
trezor-bridge --versionVerify Fix Applied:
Confirm version is 2.0.28 or higher and verify SeDebugPrivilege is properly restricted📡 Detection & Monitoring
Log Indicators:
- Unexpected process creation with SeDebugPrivilege
- Trezor Bridge spawning unexpected child processes
- Access violations in application logs
Network Indicators:
- Unusual outbound connections from Trezor Bridge process
- DNS requests to suspicious domains
SIEM Query:
ProcessCreation WHERE ParentImage LIKE '%trezor-bridge%' AND CommandLine CONTAINS 'SeDebugPrivilege'