CVE-2025-4253
📋 TL;DR
A critical buffer overflow vulnerability exists in PCMan FTP Server 2.0.7's HASH command handler, allowing remote attackers to execute arbitrary code or crash the service. This affects anyone running the vulnerable FTP server version. The exploit is publicly available and can be launched remotely without authentication.
💻 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, or ransomware deployment.
Likely Case
Service crash causing denial of service, with potential for remote code execution by skilled attackers.
If Mitigated
Limited to denial of service if exploit attempts are blocked or service runs with minimal privileges.
🎯 Exploit Status
Public exploit code is available; attack requires sending crafted HASH command to vulnerable server.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None known
Restart Required: No
Instructions:
No official patch available. Consider upgrading to a newer version if available, or implement workarounds.
🔧 Temporary Workarounds
Disable FTP Server
windowsStop and disable the PCMan FTP Server service to prevent exploitation.
sc stop "PCMan FTP Server"
sc config "PCMan FTP Server" start= disabled
Block FTP Port
windowsUse firewall rules to block external access to FTP port (typically TCP 21).
netsh advfirewall firewall add rule name="Block FTP" dir=in action=block protocol=TCP localport=21
🧯 If You Can't Patch
- Replace PCMan FTP Server with a secure alternative like FileZilla Server or vsftpd.
- Implement network segmentation to isolate FTP server from critical systems.
🔍 How to Verify
Check if Vulnerable:
Check if PCMan FTP Server version 2.0.7 is installed and running on Windows systems.Check Version:
Check program files or registry: HKEY_LOCAL_MACHINE\SOFTWARE\PCMan FTP Server for version info.Verify Fix Applied:
Verify the service is stopped/disabled or replaced with a non-vulnerable version.📡 Detection & Monitoring
Log Indicators:
- Multiple failed HASH command attempts in FTP logs
- Unusual buffer overflow errors in server logs
Network Indicators:
- Malformed HASH commands sent to FTP port 21
- Traffic patterns matching public exploit code
SIEM Query:
source="ftp_server.log" AND "HASH" AND ("overflow" OR "crash")