CVE-2025-5637
📋 TL;DR
CVE-2025-5637 is a critical buffer overflow vulnerability in PCMan FTP Server 2.0.7's SYSTEM command handler that allows remote attackers to execute arbitrary code or crash the service. This affects anyone running the vulnerable FTP server version. Attackers can exploit this without authentication to potentially gain full control of affected systems.
💻 Affected Systems
- PCMan FTP Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, ransomware deployment, or creation of persistent backdoors.
Likely Case
Service crash causing denial of service, with potential for remote code execution by skilled attackers using the public exploit.
If Mitigated
Limited to service disruption if exploit attempts are blocked by network controls, though RCE remains possible if traffic reaches the server.
🎯 Exploit Status
Public exploit code is available, making weaponization trivial for attackers with basic skills.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: Yes
Instructions:
1. Check for updated version from PCMan FTP Server vendor. 2. If no patch exists, migrate to alternative FTP server software. 3. Uninstall vulnerable version immediately.
🔧 Temporary Workarounds
Network Access Control
windowsBlock all external access to FTP server ports (default TCP 21) using firewall rules.
Windows Firewall: netsh advfirewall firewall add rule name="Block FTP" dir=in action=block protocol=TCP localport=21
Disable FTP Service
windowsStop and disable the PCMan FTP Server service to prevent exploitation.
sc stop "PCMan FTP Server"
sc config "PCMan FTP Server" start= disabled
🧯 If You Can't Patch
- Isolate the vulnerable server in a restricted network segment with no internet access
- Implement strict network monitoring and IDS/IPS rules to detect exploit attempts
🔍 How to Verify
Check if Vulnerable:
Check installed version via Windows Programs and Features or by examining the server executable properties. Version 2.0.7 is vulnerable.Check Version:
wmic product where "name like 'PCMan FTP Server%'" get versionVerify Fix Applied:
Verify PCMan FTP Server is uninstalled or upgraded to a non-vulnerable version. Confirm service is stopped and ports are closed.📡 Detection & Monitoring
Log Indicators:
- Multiple failed FTP connection attempts
- Unusual SYSTEM command usage patterns
- Server crash logs
Network Indicators:
- Excessive traffic to FTP port 21 with malformed commands
- Exploit pattern detection in packet captures
SIEM Query:
source="ftp_server.log" AND (event="SYSTEM" OR event="buffer_overflow" OR event="crash")