CVE-2010-20103 in ProFTPD
Summary
by MITRE • 08/20/2025
A malicious backdoor was embedded in the official ProFTPD 1.3.3c source tarball distributed between November 28 and December 2, 2010. The backdoor implements a hidden FTP command trigger that, when invoked, causes the server to execute arbitrary shell commands with root privileges. This allows remote, unauthenticated attackers to run any OS command on the FTP server host.
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Analysis
by VulDB Data Team • 08/20/2025
The CVE-2010-20103 vulnerability represents a sophisticated supply chain attack that compromised the integrity of a widely used open source software component. This backdoor was embedded within the official ProFTPD 1.3.3c source tarball during a specific time window from November 28 to December 2, 2010, demonstrating how attackers can exploit the trust placed in legitimate software distribution channels. The vulnerability specifically targets the ProFTPD FTP server implementation, which was commonly deployed across various server environments and organizations relying on FTP services for file transfer operations. The backdoor implementation represents a classic example of a persistent threat that can remain undetected for extended periods, as it was embedded directly within the source code that would be compiled and deployed by unsuspecting administrators.
The technical flaw within this vulnerability manifests as a hidden FTP command trigger mechanism that operates at the protocol level of the ProFTPD service. When an attacker invokes this specific backdoor command through the FTP interface, the server executes arbitrary shell commands with root privileges, effectively providing attackers with complete system control. This command injection vulnerability stems from improper input validation and lacks proper authentication mechanisms for administrative commands. The implementation follows common patterns seen in backdoor development where the trigger command is designed to be subtle and non-obvious to system administrators, often appearing as legitimate or innocuous FTP commands. The vulnerability operates at the application layer of the network stack and requires no authentication to exploit, making it particularly dangerous for systems exposed to public networks.
The operational impact of CVE-2010-20103 extends far beyond simple unauthorized access, as it provides attackers with complete system compromise capabilities including privilege escalation, data exfiltration, and persistent access. Organizations running affected ProFTPD versions became vulnerable to remote code execution attacks that could result in complete system takeover, data breaches, and potential lateral movement within network environments. The vulnerability's persistence is particularly concerning as it remained undetected for several days during the distribution window, allowing multiple organizations to unknowingly install compromised software versions. The backdoor's ability to execute commands with root privileges means that attackers could modify system files, install additional malware, create persistent access mechanisms, and potentially use the compromised server as a launch point for attacks on other systems within the network infrastructure. This vulnerability directly violates fundamental security principles of integrity and non-repudiation in the software supply chain.
Mitigation strategies for CVE-2010-20103 require immediate action to address the compromised source code and implement comprehensive security monitoring. Organizations should immediately verify their ProFTPD installations against known good source checksums and replace any affected installations with verified, clean versions from trusted sources. The vulnerability aligns with CWE-88, which addresses command injection flaws, and demonstrates the importance of source code integrity verification. Security teams must implement proper software supply chain security measures including digital signature verification, checksum validation, and continuous monitoring of source code repositories. The attack pattern corresponds to techniques documented in the ATT&CK framework under T1505.003 for server-side attacks and T1059 for command and scripting interpreters. Organizations should also establish incident response procedures for detecting backdoor implementations and consider implementing network monitoring to detect suspicious FTP command patterns that could indicate exploitation attempts. Regular security audits of source code repositories and implementation of automated build verification processes are essential to prevent similar supply chain compromises in the future.