CVE-2021-41807
📋 TL;DR
This vulnerability allows attackers to perform unlimited login attempts against certain M-Files user accounts, enabling brute-force attacks to guess passwords. It affects M-Files Server and M-Files Web products before version 21.12.10873.0. Organizations using these vulnerable versions are at risk of account compromise.
💻 Affected Systems
- M-Files Server
- M-Files Web
📦 What is this software?
M Files Web by M Files
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain unauthorized access to sensitive documents and systems by brute-forcing administrative or privileged accounts, leading to data theft, ransomware deployment, or complete system compromise.
Likely Case
Attackers compromise standard user accounts through automated brute-force attacks, potentially accessing confidential documents and performing unauthorized actions within the system.
If Mitigated
With proper rate limiting and monitoring, brute-force attempts are blocked after few attempts, preventing account compromise while alerting security teams to attack attempts.
🎯 Exploit Status
Brute-force attacks are well-understood and easily automated. No authentication is required to attempt login, making exploitation straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 21.12.10873.0 and later
Vendor Advisory: https://empower.m-files.com/security-advisories/CVE-2021-41807
Restart Required: Yes
Instructions:
1. Download M-Files Server/Web version 21.12.10873.0 or later from official M-Files sources. 2. Backup current configuration and data. 3. Install the update following M-Files documentation. 4. Restart M-Files services. 5. Verify the update was successful.
🔧 Temporary Workarounds
Implement Network-Level Rate Limiting
allUse firewall or WAF rules to limit login attempts per IP address
Enable Account Lockout Policies
windowsConfigure M-Files to lock accounts after failed login attempts
🧯 If You Can't Patch
- Implement strong password policies requiring complex, unique passwords for all accounts
- Deploy network monitoring to detect and alert on brute-force patterns
🔍 How to Verify
Check if Vulnerable:
Check M-Files Server/Web version in administration console or via Windows Programs and Features. If version is below 21.12.10873.0, the system is vulnerable.Check Version:
Check M-Files Server version in Windows Control Panel > Programs and Features or via M-Files administration consoleVerify Fix Applied:
Confirm version is 21.12.10873.0 or higher in administration console. Test that login attempts are now rate-limited by attempting multiple failed logins.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts from same IP/user in short time
- Unusual login patterns outside business hours
- Account lockout events
Network Indicators:
- High volume of POST requests to login endpoints
- Traffic patterns showing repeated authentication attempts
SIEM Query:
source="m-files-logs" event_type="login_failure" | stats count by src_ip, user | where count > 10