CVE-2025-3683
📋 TL;DR
A critical buffer overflow vulnerability in PCMan FTP Server 2.0.7 allows remote attackers to execute arbitrary code by sending specially crafted SIZE commands. This affects all systems running the vulnerable FTP server version, potentially leading to complete system compromise. The vulnerability is remotely exploitable without authentication.
💻 Affected Systems
- PCMan FTP Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full system compromise, data theft, ransomware deployment, or creation of persistent backdoors.
Likely Case
Remote code execution allowing attackers to gain control of the FTP server process, potentially escalating to system-level access.
If Mitigated
Denial of service if exploit fails or is blocked, but system remains vulnerable to more sophisticated attacks.
🎯 Exploit Status
Public exploit code is available, making exploitation straightforward for attackers. No authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None found in provided references
Restart Required: Yes
Instructions:
1. Check for updated version from vendor. 2. If no patch available, consider alternative FTP server software. 3. Apply workarounds immediately.
🔧 Temporary Workarounds
Network Segmentation and Blocking
allBlock SIZE command at network perimeter or disable FTP service entirely
# Use firewall to block FTP port 21/tcp
iptables -A INPUT -p tcp --dport 21 -j DROP
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
- Immediately isolate affected systems from internet and critical networks
- Implement strict network monitoring for SIZE command anomalies and buffer overflow attempts
🔍 How to Verify
Check if Vulnerable:
Check PCMan FTP Server version in interface or installation directory. Version 2.0.7 is vulnerable.Check Version:
# Check Windows service version or examine program files directoryVerify Fix Applied:
Verify version is no longer 2.0.7 or service is disabled/blocked📡 Detection & Monitoring
Log Indicators:
- Multiple SIZE command failures
- Unusual SIZE command parameters
- Buffer overflow error messages in FTP logs
Network Indicators:
- SIZE commands with unusually long parameters
- Traffic patterns suggesting buffer overflow attempts
SIEM Query:
source="ftp_logs" AND command="SIZE" AND (parameter_length>100 OR contains(error, "buffer"))