CVE-2025-4251
📋 TL;DR
A critical buffer overflow vulnerability in PCMan FTP Server 2.0.7 allows remote attackers to execute arbitrary code or crash the service by sending specially crafted RMDIR commands. This affects all systems running the vulnerable FTP server version. The exploit is publicly available and can be triggered without authentication.
💻 Affected Systems
- PCMan FTP Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with SYSTEM/root privileges leading to complete system compromise, data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Service crash causing denial of service, or successful remote code execution leading to malware installation and lateral movement.
If Mitigated
Service crash only if exploit fails, with minimal impact due to network segmentation and limited service privileges.
🎯 Exploit Status
Public exploit code is available. Attack requires only network access to FTP port (default 21).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None known
Restart Required: No
Instructions:
No official patch available. Consider migrating to alternative FTP server software or implementing workarounds.
🔧 Temporary Workarounds
Disable RMDIR command via FTP server configuration
windowsConfigure PCMan FTP Server to reject or disable RMDIR commands entirely.
Edit server configuration file to remove RMDIR command support
Network segmentation and firewall rules
windowsRestrict access to FTP server to trusted IP addresses only.
netsh advfirewall firewall add rule name="Block FTP Except Trusted" dir=in action=block protocol=TCP localport=21 remoteip=!192.168.1.0/24,10.0.0.0/8 enable=yes
🧯 If You Can't Patch
- Replace PCMan FTP Server with alternative software like FileZilla Server, vsftpd, or IIS FTP
- Implement strict network segmentation and firewall rules to limit FTP server exposure
🔍 How to Verify
Check if Vulnerable:
Check PCMan FTP Server version in interface or configuration files. If version is 2.0.7, system is vulnerable.Check Version:
Check PCMan FTP Server GUI or configuration files for version informationVerify Fix Applied:
Verify PCMan FTP Server is no longer running or has been replaced with alternative software.📡 Detection & Monitoring
Log Indicators:
- Multiple failed RMDIR commands
- Unusual long RMDIR command parameters
- FTP service crash logs
Network Indicators:
- Excessive RMDIR commands to FTP port 21
- Malformed FTP commands with buffer overflow patterns
SIEM Query:
source="ftp.log" AND command="RMDIR" AND (parameter_length>100 OR contains(parameter, "\x90"))