CVE-2007-4756 in Total Commander
Summary
by MITRE
Directory traversal vulnerability in the FTP client in Total Commander before 7.02 allows remote FTP servers to create or overwrite arbitrary files via "..\" (dot dot backslash) sequences in a filename. NOTE: the "..\" are not displayed when the user lists files. NOTE: this can be leveraged for code execution by writing to a Startup folder.
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Analysis
by VulDB Data Team • 01/11/2025
The vulnerability identified as CVE-2007-4756 represents a critical directory traversal flaw within the FTP client component of Total Commander software versions prior to 7.02. This weakness stems from inadequate input validation mechanisms that fail to properly sanitize filename sequences containing "..\" patterns, which are commonly used in directory traversal attacks to navigate outside of intended directories. The vulnerability specifically affects the client-side processing of FTP responses where filenames containing these sequences are not adequately filtered or rejected by the application's file handling routines.
The technical exploitation of this vulnerability occurs when a remote FTP server sends a response containing a filename that includes "..\" sequences, which the vulnerable Total Commander client interprets as commands to traverse directories and write files to arbitrary locations on the local system. This flaw operates at the application layer and specifically targets the file system interaction mechanisms within the FTP client module. The vulnerability is particularly dangerous because the "..\" sequences are not visible during normal file listing operations, making the malicious behavior隐蔽 and difficult to detect through routine monitoring. The implementation flaw resides in the client's failure to validate filename components against known malicious patterns, allowing the application to process these sequences as legitimate file operations rather than potentially harmful directory traversal commands.
The operational impact of this vulnerability extends beyond simple file creation or overwriting, as it can be leveraged for complete system compromise through code execution. When an attacker successfully exploits this vulnerability, they can write malicious files to critical system locations such as the Startup folder, which would then execute automatically upon system reboot or user login. This enables persistent access and can serve as a foundation for more sophisticated attacks including privilege escalation, data exfiltration, or establishment of backdoor access. The vulnerability aligns with CWE-22 - Improper Limiting of a Pathname to a Restricted Directory, which specifically addresses the issue of insufficient validation of file paths that can lead to directory traversal attacks. Additionally, this vulnerability maps to ATT&CK technique T1059.007 - Command and Scripting Interpreter: Python, as it enables attackers to establish persistent execution through file system manipulation, though the specific implementation involves Windows file system traversal rather than scripting.
The exploitation process typically involves an attacker controlling a remote FTP server and sending specially crafted responses containing "..\" sequences in filenames, which the vulnerable Total Commander client processes without proper validation. The attack requires minimal privileges on the remote server and can be executed without user interaction, making it particularly dangerous in environments where users frequently connect to untrusted FTP servers. The vulnerability affects not just the immediate file system operations but also the broader security posture of systems using vulnerable versions of Total Commander, as successful exploitation can lead to complete system compromise through persistent code execution mechanisms. Organizations should consider this vulnerability as part of their broader application security posture and ensure that all versions of Total Commander are updated to 7.02 or later to prevent exploitation through directory traversal attacks that could lead to unauthorized code execution and system compromise.