CVE-2001-1386 in WFTPD
Summary
by MITRE
WFTPD 3.00 allows remote attackers to read arbitrary files by uploading a (link) file that ends in a ".lnk." extension, which bypasses WFTPD s check for a ".lnk" extension.
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Analysis
by VulDB Data Team • 05/18/2019
The vulnerability described in CVE-2001-1386 represents a critical file access flaw in WFTPD version 3.00, a widely used FTP server software in the early 2000s. This vulnerability specifically targets the file extension validation mechanism implemented within the FTP server's file handling process. The flaw allows remote attackers to bypass security controls designed to prevent access to sensitive files through a clever manipulation of file naming conventions. The vulnerability operates by exploiting a weakness in the server's extension checking logic, where the software fails to properly validate file extensions that contain additional periods or special characters.
The technical implementation of this vulnerability stems from improper input validation and insufficient sanitization of file names during the upload process. When a user uploads a file with a .lnk extension, the WFTPD server should ideally reject such files to prevent potential exploitation. However, the vulnerability occurs because the server's validation routine does not adequately check for variations in file naming patterns. Attackers can create files with extensions like .lnk. or .lnk.. which appear to have the correct extension but are actually different from the standard .lnk format that would be blocked. This allows malicious users to bypass the security controls and potentially access arbitrary files on the system.
The operational impact of this vulnerability is significant as it provides unauthorized access to potentially sensitive data stored on the FTP server. An attacker who successfully exploits this vulnerability could gain access to system files, configuration data, user credentials, or other confidential information that should remain protected. The remote nature of the attack means that exploitation can occur from anywhere on the network without requiring physical access to the system. This vulnerability directly violates fundamental security principles and could lead to complete system compromise if the FTP server contains sensitive data or if the attacker can escalate privileges through the accessed files.
The vulnerability maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, also known as path traversal. This classification reflects the core issue where the system fails to properly validate file paths and extensions, allowing access to files outside the intended directory structure. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1078 - Valid Accounts and T1566 - Phishing, as it enables attackers to gain unauthorized access to system resources through potentially compromised credentials or by exploiting weak security controls. The vulnerability also relates to T1005 - Data from Local System, indicating that attackers can extract sensitive information from the compromised system.
Mitigation strategies for this vulnerability should include immediate patching of the WFTPD software to the latest available version that addresses the file extension validation flaw. Organizations should implement proper file type validation at the server level, ensuring that all file uploads undergo rigorous sanitization and validation before being accepted. Network segmentation and access controls should be implemented to limit exposure of FTP services to unauthorized users. Additionally, regular security audits and vulnerability assessments should be conducted to identify similar issues in other server software components. System administrators should also consider implementing intrusion detection systems to monitor for suspicious file upload activities and establish proper monitoring protocols for anomalous access patterns that could indicate exploitation attempts.