CVE-2023-39726
📋 TL;DR
A critical vulnerability in Mintty terminal emulator allows remote attackers to execute arbitrary code by sending specially crafted ANSI escape sequences. This affects all users running vulnerable versions of Mintty, particularly those who connect to untrusted remote systems or view untrusted content in their terminal.
💻 Affected Systems
- Mintty
📦 What is this software?
Mintty by Mintty Project
⚠️ Risk & Real-World Impact
Worst Case
Full remote code execution with the privileges of the Mintty user, potentially leading to complete system compromise, data theft, or lateral movement.
Likely Case
Attackers exploiting this via malicious SSH servers, compromised remote systems, or crafted content (like cat'ing a malicious file) to execute commands on the victim's machine.
If Mitigated
Limited impact if users only connect to trusted systems and avoid viewing untrusted content in Mintty.
🎯 Exploit Status
Exploitation is straightforward - sending crafted ANSI escape sequences triggers the vulnerability. Public proof-of-concept code exists in the referenced advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v3.6.5 and later
Vendor Advisory: https://github.com/mintty/mintty/security/advisories/GHSA-6wvc-8h2h-5pqg
Restart Required: Yes
Instructions:
1. Download Mintty v3.6.5 or later from the official repository. 2. Replace the existing mintty.exe with the new version. 3. Restart any Mintty terminals.
🔧 Temporary Workarounds
Disable OSC 50 support
allDisables the vulnerable ANSI escape sequence handler
Add 'DisableOsc50=yes' to ~/.minttyrc or mintty configuration
Use alternative terminal
allTemporarily switch to a different terminal emulator that is not vulnerable
🧯 If You Can't Patch
- Avoid connecting to untrusted SSH servers or remote systems with Mintty
- Do not cat or view untrusted files in Mintty terminal
🔍 How to Verify
Check if Vulnerable:
Check Mintty version with 'mintty --version'. If version is 3.6.4 or earlier, you are vulnerable.Check Version:
mintty --versionVerify Fix Applied:
After updating, run 'mintty --version' and confirm version is 3.6.5 or later.📡 Detection & Monitoring
Log Indicators:
- Unusual process execution from Mintty terminal
- Suspicious command execution patterns
Network Indicators:
- ANSI escape sequences containing OSC 50 in network traffic to terminals
SIEM Query:
process_name="mintty.exe" AND (parent_process contains "ssh" OR command_line contains suspicious patterns)