CVE-2008-5175 in AceFTP
Summary
by MITRE
Directory traversal vulnerability in the FTP client in AceFTP Freeware 3.80.3 and AceFTP Pro 3.80.3 allows remote FTP servers to create or overwrite arbitrary files via a .. (dot dot) in a response to a LIST command, a related issue to CVE-2002-1345.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 10/14/2018
The vulnerability identified as CVE-2008-5175 represents a critical directory traversal flaw within the FTP client component of AceFTP Freeware and Pro versions 3.80.3. This security weakness stems from inadequate input validation mechanisms that fail to properly sanitize directory paths received from remote FTP servers during LIST command responses. The vulnerability operates by exploiting the fundamental behavior of the .. (dot dot) sequence in file system navigation, which allows attackers to traverse directory structures beyond the intended scope of file operations. When a remote FTP server responds to a LIST command with directory entries containing .. sequences, the vulnerable AceFTP client processes these paths without proper validation, potentially leading to arbitrary file creation or overwriting on the local system. This issue constitutes a direct exploitation of the classic directory traversal attack pattern that has been documented in various security advisories including CVE-2002-1345, establishing it as a well-known and persistent weakness in FTP client implementations.
The technical implementation of this vulnerability occurs at the FTP client's file system interaction layer where directory listing responses are parsed and processed without adequate sanitization of path components. When the client encounters a .. sequence in a filename or directory name returned by the LIST command, it interprets this as a legitimate navigation instruction rather than a potential malicious payload. This failure to validate path components against a whitelist of acceptable characters and sequences creates a pathway for attackers to manipulate the local file system through remote server responses. The vulnerability specifically affects the FTP client's handling of directory listings where filenames or directory names may contain directory traversal sequences, allowing remote attackers to specify absolute paths or paths that traverse beyond the intended working directory. The flaw demonstrates a clear violation of secure coding principles that emphasize input validation and proper path handling, particularly in applications that process data from untrusted sources.
The operational impact of CVE-2008-5175 extends beyond simple file manipulation to potentially compromise entire system security through unauthorized file creation, modification, or deletion. An attacker could leverage this vulnerability to overwrite critical system files, install malicious software, or create backdoor access points on the victim's machine. The vulnerability's exploitation requires only that a user connects to a malicious FTP server and executes a LIST command, making it particularly dangerous in environments where users frequently connect to external FTP servers. This weakness can be exploited to gain persistent access to systems, as attackers might create or modify configuration files, system binaries, or user data that could be executed or accessed later. The vulnerability's severity is compounded by its ability to work silently in the background without user intervention, potentially allowing attackers to establish footholds in systems without detection. From an attacker's perspective, this vulnerability provides a straightforward path to system compromise with minimal technical skill required, making it particularly attractive for automated exploitation campaigns.
Mitigation strategies for CVE-2008-5175 must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities from emerging. The most direct approach involves updating to patched versions of AceFTP software where the vulnerability has been resolved through proper input validation and path sanitization. Organizations should implement network segmentation and access controls to limit exposure to potentially malicious FTP servers, particularly in environments where users may connect to untrusted external systems. The implementation of secure coding practices including proper path validation, input sanitization, and the use of safe file system operations should be enforced throughout the development lifecycle. Additionally, network monitoring solutions should be deployed to detect unusual FTP activity patterns that might indicate exploitation attempts. Security awareness training for users regarding the risks of connecting to untrusted FTP servers can help reduce the attack surface. This vulnerability aligns with CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, and follows attack patterns documented in the ATT&CK framework under initial access and persistence techniques. Organizations should also consider implementing network-level controls such as firewall rules that restrict FTP traffic to known, trusted servers and deploy endpoint protection solutions that can detect and prevent unauthorized file system modifications. The vulnerability underscores the importance of maintaining up-to-date software versions and implementing defense-in-depth strategies that protect against multiple attack vectors simultaneously.