CVE-2025-65318
📋 TL;DR
Canary Mail versions 5.1.40 and below fail to apply Mark-of-the-Web (MOTW) tags to downloaded attachments, allowing attackers to bypass Windows and third-party security protections. This vulnerability enables malicious files to execute without standard security warnings. All users of affected Canary Mail versions on Windows are at risk.
💻 Affected Systems
- Canary Mail
📦 What is this software?
Canary Mail by Canarymail
⚠️ Risk & Real-World Impact
Worst Case
Attackers deliver malicious attachments that execute without security warnings, leading to full system compromise, data theft, or ransomware deployment.
Likely Case
Phishing campaigns using weaponized attachments bypass security warnings, leading to malware infections and credential theft.
If Mitigated
With proper email filtering and endpoint protection, malicious attachments are blocked before reaching users.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious attachment). Public proof-of-concept code exists in GitHub repositories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.1.41 or later
Vendor Advisory: http://canarymail.com
Restart Required: No
Instructions:
1. Open Canary Mail. 2. Go to Settings > About. 3. Check for updates. 4. Install version 5.1.41 or later. 5. Restart Canary Mail if prompted.
🔧 Temporary Workarounds
Disable automatic attachment saving
windowsConfigure Canary Mail to not automatically save attachments to disk
Enable Windows Defender Application Guard
windowsUse Windows Defender Application Guard for Office to isolate email attachments
🧯 If You Can't Patch
- Block Canary Mail at network perimeter until patched
- Implement strict email filtering to block suspicious attachments
🔍 How to Verify
Check if Vulnerable:
Check Canary Mail version in Settings > About. If version is 5.1.40 or below, you are vulnerable.Check Version:
Not applicable - check through GUI in Settings > AboutVerify Fix Applied:
After updating, download a test attachment and verify it has MOTW tag (right-click > Properties > Security).📡 Detection & Monitoring
Log Indicators:
- Unusual attachment downloads from Canary Mail
- Security warning bypass events
Network Indicators:
- Suspicious email attachments with executable content
SIEM Query:
source="canarymail" AND event="attachment_download" AND file_type IN ("exe", "ps1", "bat", "vbs")