CVE-2008-2519 in Core FTP
Summary
by MITRE
Directory traversal vulnerability in Core FTP client 2.1 Build 1565 allows remote FTP servers to create or overwrite arbitrary files via .. (dot dot) sequences in responses to LIST commands, a related issue to CVE-2002-1345. NOTE: this can be leveraged for code execution by writing to a Startup folder.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 11/19/2017
The vulnerability described in CVE-2008-2519 represents a critical directory traversal flaw within the Core FTP client version 2.1 Build 1565 that enables malicious remote FTP servers to manipulate the local filesystem through crafted responses to LIST commands. This vulnerability operates by exploiting the client's insufficient input validation when processing directory listing responses from FTP servers, allowing attackers to inject .. (dot dot) sequences that traverse the directory structure. The flaw is particularly dangerous because it can be leveraged to create or overwrite arbitrary files on the victim's system, effectively bypassing normal file access controls and potentially leading to complete system compromise. The vulnerability is classified under CWE-22 as Directory Traversal, which specifically addresses the improper handling of directory path references in software applications. This issue demonstrates a fundamental weakness in input sanitization and path resolution mechanisms within the FTP client's file handling routines, where the software fails to properly validate or sanitize the directory paths contained in FTP server responses.
The operational impact of this vulnerability extends far beyond simple file manipulation, as it can be exploited to achieve code execution through strategic file placement in system startup folders. When an attacker successfully writes malicious files to locations such as the Windows Startup folder or equivalent system directories, the compromised system will automatically execute these payloads upon user login or system reboot. This creates a persistent backdoor that can remain undetected for extended periods while maintaining access to the compromised system. The attack vector is particularly insidious because it requires no user interaction beyond normal FTP usage, making it difficult to detect through standard security monitoring. The vulnerability's relationship to CVE-2002-1345 indicates a recurring pattern in FTP client implementations where directory traversal flaws are not properly addressed, suggesting systemic issues in how these applications handle remote directory listings and path resolution. From an operational security perspective, this vulnerability enables attackers to establish persistent presence on systems and can be combined with other techniques to escalate privileges or establish further footholds within network environments.
Mitigation strategies for CVE-2008-2519 must address both immediate defensive measures and long-term architectural improvements to prevent similar vulnerabilities. The most effective immediate solution involves updating to a patched version of Core FTP client that properly validates and sanitizes directory paths from FTP server responses, implementing strict path validation that prevents any .. sequences from being processed as legitimate directory navigation commands. Organizations should also implement network segmentation and firewall rules that restrict FTP traffic to trusted servers only, reducing the attack surface available to malicious actors. Additionally, system administrators should monitor for suspicious file creation patterns, particularly in system startup directories, and implement file integrity monitoring solutions that can detect unauthorized modifications to critical system locations. The ATT&CK framework categorizes this vulnerability under T1059 Command and Scripting Interpreter and T1547 Registry Run Keys or Startup Folder, emphasizing the persistence mechanisms that can be established through such directory traversal exploits. Regular security assessments should include testing for similar vulnerabilities in other FTP client implementations and file transfer protocols, as this represents a common pattern in software that fails to properly validate user-supplied data before processing it as part of file system operations. System hardening practices should also include disabling automatic execution of files from network locations and implementing strict access controls on system startup directories to prevent unauthorized modifications.