CVE-2000-0129 in Serv-U FTP Server
Summary
by MITRE
Buffer overflow in the SHGetPathFromIDList function of the Serv-U FTP server allows attackers to cause a denial of service by performing a LIST command on a malformed .lnk file.
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Analysis
by VulDB Data Team • 04/22/2025
The vulnerability identified as CVE-2000-0129 represents a critical buffer overflow flaw within the Serv-U FTP server software that specifically affects the SHGetPathFromIDList function. This function is part of the Windows API and serves to retrieve the file system path from a shell item identifier list structure commonly used in Windows file system operations. The vulnerability manifests when the FTP server processes a LIST command that encounters a malformed .lnk file, which is a Windows shortcut file format that typically contains a path reference to another file or directory. The buffer overflow occurs because the server fails to properly validate the length of data contained within the .lnk file's structure before attempting to copy it into a fixed-size buffer, creating an exploitable condition that can be leveraged by remote attackers to disrupt service availability.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking occurs during data copying operations. The flaw specifically targets the Windows shell integration functionality within the Serv-U FTP server, where the server attempts to process shortcut files as part of its directory listing capabilities. When an attacker uploads a specially crafted .lnk file containing an oversized path string or malformed data structure, the SHGetPathFromIDList function fails to properly handle the excessive data, causing the buffer to overflow and potentially leading to memory corruption. This type of vulnerability falls under the ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion or system instability.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a fundamental security flaw in how the FTP server handles file system metadata processing. Attackers can exploit this vulnerability without requiring authentication or specialized privileges, making it particularly dangerous in publicly accessible FTP environments where malicious users can upload files and trigger the exploit. The vulnerability affects the availability of the FTP service itself, potentially causing the server to crash or become unresponsive, which can disrupt legitimate user access and create service interruptions. Additionally, the nature of buffer overflows in Windows API functions can sometimes be leveraged for more sophisticated attacks if the server environment allows for code execution or memory manipulation, though the primary impact in this case is focused on service disruption.
Mitigation strategies for this vulnerability should prioritize immediate patching of the Serv-U FTP server software to address the buffer overflow condition in the SHGetPathFromIDList function. Organizations should implement network-level controls to prevent unauthorized file uploads, particularly of .lnk files or other Windows shortcut formats that may trigger the vulnerable code path. The implementation of input validation and bounds checking on all file system metadata processing within the FTP server can help prevent similar issues from occurring in other components. Security monitoring should be enhanced to detect unusual LIST command patterns or file upload activities that may indicate exploitation attempts. Additionally, system administrators should consider implementing network segmentation and access controls to limit exposure of vulnerable FTP services to untrusted networks, while maintaining regular vulnerability assessments to identify and remediate similar buffer overflow conditions in other software components that may be subject to similar exploitation vectors.