CVE-2025-4079
📋 TL;DR
A critical buffer overflow vulnerability exists in PCMan FTP Server's RENAME command handler, allowing remote attackers to execute arbitrary code or crash the service. This affects PCMan FTP Server versions up to 2.0.7. Attackers can exploit this without authentication over the network.
💻 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, potentially followed by remote code execution.
If Mitigated
Limited to denial of service if exploit fails or controls prevent code execution.
🎯 Exploit Status
Public exploit code is available, making attacks straightforward for attackers with basic skills.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: No
Instructions:
No official patch exists. Consider upgrading to a different FTP server software or implementing workarounds.
🔧 Temporary Workarounds
Disable FTP Service
windowsStop and disable the PCMan FTP Server service if not required.
sc stop PCManFTPServer
sc config PCManFTPServer start= disabled
Network Segmentation
windowsRestrict FTP server access to trusted networks using firewall rules.
netsh advfirewall firewall add rule name="Block FTP" dir=in action=block protocol=TCP localport=21 remoteip=any
🧯 If You Can't Patch
- Replace PCMan FTP Server with a maintained alternative like FileZilla Server or vsftpd.
- Implement network-based intrusion prevention systems (IPS) to detect and block buffer overflow attempts.
🔍 How to Verify
Check if Vulnerable:
Check PCMan FTP Server version in Help > About menu or examine installed program version.Check Version:
Not available via command line; check GUI or installed programs list.Verify Fix Applied:
Verify service is stopped/disabled or replaced with alternative software.📡 Detection & Monitoring
Log Indicators:
- Multiple failed RENAME commands
- FTP service crash logs
- Unusual RENAME command patterns with long arguments
Network Indicators:
- FTP traffic with abnormally long RENAME commands
- Multiple connection attempts to FTP port 21
SIEM Query:
source="ftp.log" AND command="RENAME" AND (length(arguments) > 100 OR contains(arguments, ".."))