CVE-2025-4871
📋 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 REST commands. This affects all systems running the vulnerable FTP server version. Attackers can exploit this without authentication to potentially gain control of affected systems.
💻 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
Service disruption only if exploit attempts are blocked by network controls
🎯 Exploit Status
Public exploit code available, making exploitation trivial for attackers
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: Yes
Instructions:
1. Check for updated version from vendor (none available as of analysis)
2. If no patch exists, follow workarounds or migrate to alternative FTP server
🔧 Temporary Workarounds
Block REST command at network level
linuxUse firewall or IPS to block REST commands to vulnerable FTP servers
iptables -A INPUT -p tcp --dport 21 -m string --string "REST" --algo bm -j DROP
Disable FTP service
windowsStop and disable the FTP service until patched
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
- Isolate vulnerable servers in separate network segment with strict access controls
🔍 How to Verify
Check if Vulnerable:
Check if PCMan FTP Server version 2.0.7 is installed and running on port 21Check Version:
Check program files directory for PCMan FTP Server and examine version in propertiesVerify Fix Applied:
Verify FTP server is no longer version 2.0.7 or service is stopped📡 Detection & Monitoring
Log Indicators:
- Multiple failed REST commands
- FTP service crash logs
- Unusual buffer overflow errors in FTP logs
Network Indicators:
- Excessive REST commands to FTP port 21
- Malformed FTP commands with long parameters
SIEM Query:
source="ftp.log" AND (REST AND length>100) OR "buffer overflow"