
In July 2011, it was discovered that the official source tarball of vsftpd (Very Secure FTP Daemon) version 2.0.8 had been compromised. Attackers injected a malicious backdoor into the str.c file, allowing remote attackers to execute arbitrary code with root privileges on any vulnerable server. This paper details the technical mechanics of the backdoor, examines how the exploit is implemented in public GitHub repositories, and provides definitive steps for detection, removal, and long-term remediation.
vsftpd -v
Or for a running process:
netstat -tulpn | grep :21
ps aux | grep vsftpd
If the version string shows 2.3.4, assume compromise.
In 2014, a university’s research FTP server was found to be running vsftpd 2.3.4. The sysadmin had manually compiled it from a compromised tarball years earlier. An automated scanner triggered the :) backdoor, and the attacker gained root access, using the server as a botnet controller for six months. vsftpd 208 exploit github fix
What went wrong?
The fix: Reinstall OS, migrate to vsftpd 3.0.2+ with TLS, and implement daily apt security updates.
sudo apt-get update
sudo apt-get install --reinstall vsftpd
Assume the backdoor was triggered. Run a rootkit scan: The Truth Behind the vsftpd 208 Exploit: GitHub
sudo apt-get install rkhunter chkrootkit
sudo rkhunter --check
sudo chkrootkit
Check logs for failed auth patterns:
grep ":)" /var/log/vsftpd.log
grep "6200" /var/log/auth.log
If you find evidence of compromise, the safest path is to backup data and reinstall the OS.
wget https://security.appspot.com/downloads/vsftpd-3.0.5.tar.gz
tar -xzf vsftpd-3.0.5.tar.gz
cd vsftpd-3.0.5
make
sudo make install
Important: Do NOT download vsftpd from third-party mirrors. Only use the official site: https://security.appspot.com/vsftpd.html Or for a running process: netstat -tulpn |
If you have discovered that your server is running vsftpd 2.3.4 and is vulnerable to the :) backdoor, follow these steps immediately.
| Indicator | Value |
|-----------|-------|
| FTP banner | vsFTPd 2.0.8 |
| Open port after login | 6200/tcp |
| Process list | sh -i owned by root |
| Log anomaly | USER root: (non-standard username) |
| Binary hash (backdoored) | e06c74e8099e9a612a7f217cb6d6a5c8 (MD5) |








































































































































































































































