CVE-2012-5106 in FTP Server
Summary
by MITRE
Stack-based buffer overflow in FreeFloat FTP Server 1.0 allows remote authenticated users to execute arbitrary code via a long string in a PUT command.
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Analysis
by VulDB Data Team • 08/21/2025
The CVE-2012-5106 vulnerability represents a critical stack-based buffer overflow flaw discovered in FreeFloat FTP Server version 1.0 that enables remote authenticated attackers to execute arbitrary code on affected systems. This vulnerability resides within the server's handling of file upload operations through the PUT command, which is a fundamental function in ftp protocols for transferring files from client to server. The flaw specifically manifests when the server processes a maliciously crafted string that exceeds the allocated stack buffer space during PUT command execution, creating a condition where adjacent memory locations become overwritten with attacker-controlled data.
The technical implementation of this vulnerability stems from inadequate input validation within the ftp server's command processing logic. When an authenticated user sends a PUT command with an excessively long string parameter, the server fails to properly bounds-check the input before copying it to a fixed-size stack buffer. This classic buffer overflow condition allows an attacker to overwrite return addresses, stack canaries, and other critical control data structures, ultimately enabling code execution with the privileges of the ftp server process. The vulnerability is particularly dangerous because it requires only authenticated access, meaning that an attacker who has obtained valid credentials can leverage this flaw without needing additional privileges or complex exploitation techniques.
From an operational perspective, the impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and potential lateral movement within network environments. The ftp server process typically runs with elevated privileges to manage file operations, making successful exploitation equivalent to gaining administrative control over the affected system. Attackers can use this vulnerability to establish persistent backdoors, escalate privileges further, or deploy additional malware payloads. The vulnerability also creates opportunities for privilege escalation attacks, as the compromised server process may have access to sensitive system resources, databases, or other network services that are not directly accessible to standard user accounts.
The exploitation of CVE-2012-5106 aligns with several attack patterns documented in the attack tree framework, particularly those involving privilege escalation and code injection techniques. This vulnerability can be categorized under CWE-121, stack-based buffer overflow, which is a well-established weakness pattern in software security. The attack vector represents a common pathway for attackers to gain unauthorized access to systems, as ftp servers often contain sensitive data and are frequently exposed to external networks. Security professionals should note that this vulnerability demonstrates the critical importance of input validation and proper bounds checking in network services, as even authenticated access can be leveraged to achieve remote code execution when proper security controls are absent. Organizations should prioritize patching this vulnerability immediately, as the combination of remote execution capability and the relatively simple exploitation method makes it a high-priority target for threat actors. The vulnerability also highlights the need for comprehensive security testing of network services, particularly those handling user input through protocol commands, and emphasizes the importance of following secure coding practices to prevent such memory corruption vulnerabilities from being introduced into production software.