CVE-2025-3681
📋 TL;DR
CVE-2025-3681 is a critical buffer overflow vulnerability in PCMan FTP Server 2.0.7's MODE command handler that allows 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, potentially followed by remote code execution if exploit is weaponized.
If Mitigated
Service disruption with limited impact if proper network segmentation and monitoring are in place.
🎯 Exploit Status
Public exploit code exists and requires minimal technical skill to execute.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: Yes
Instructions:
1. Check for updated version from vendor (none currently available). 2. If no patch, migrate to alternative FTP server software. 3. Remove vulnerable version from all systems.
🔧 Temporary Workarounds
Network Access Control
allBlock FTP port 21 at network perimeter and restrict internal access
firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="0.0.0.0/0" port port="21" protocol="tcp" reject'
netsh advfirewall firewall add rule name="Block FTP" dir=in action=block protocol=TCP localport=21
Service Disablement
windowsStop and disable PCMan FTP Server service
sc stop "PCMan FTP Server"
sc config "PCMan FTP Server" start= disabled
🧯 If You Can't Patch
- Replace PCMan FTP Server with alternative secure FTP solution like FileZilla Server or vsftpd
- Implement strict network segmentation to isolate FTP server from critical systems
🔍 How to Verify
Check if Vulnerable:
Check installed version of PCMan FTP Server - if version is 2.0.7, system is vulnerable.Check Version:
Check program files directory for PCMan FTP Server version or examine installed programs listVerify Fix Applied:
Verify PCMan FTP Server is no longer running or has been replaced with alternative software.📡 Detection & Monitoring
Log Indicators:
- Multiple failed MODE command attempts
- Unusual buffer overflow errors in FTP logs
- Service crash events in system logs
Network Indicators:
- Unusual traffic patterns on FTP port 21
- MODE commands with abnormally long parameters
- Exploit signature patterns from public PoC
SIEM Query:
source="ftp_logs" AND (command="MODE" AND parameter_length>100) OR (event_type="buffer_overflow" AND service="pcman_ftp")