CVE-2017-6510 in FTP Server
Summary
by MITRE
Easy File Sharing FTP Server version 3.6 is vulnerable to a directory traversal vulnerability which allows an attacker to list and download any file from any folder outside the FTP root Directory.
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Analysis
by VulDB Data Team • 09/09/2020
The vulnerability identified as CVE-2017-6510 affects Easy File Sharing FTP Server version 3.6 and represents a critical directory traversal flaw that fundamentally compromises the server's access control mechanisms. This vulnerability enables remote attackers to bypass the intended file system boundaries and gain unauthorized access to files and directories outside the designated FTP root directory. The flaw exists in the server's handling of file path resolution, where input validation and path sanitization mechanisms fail to properly restrict user-controlled input from traversing the file system hierarchy.
This directory traversal vulnerability stems from inadequate input validation within the FTP server's file access routines, allowing malicious users to manipulate file path requests through specially crafted directory traversal sequences such as "../" or "..\". The vulnerability is classified under CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The flaw operates by permitting attackers to manipulate the file system path resolution logic to navigate beyond the intended directory boundaries, effectively undermining the server's security model and file access controls.
The operational impact of this vulnerability is severe and far-reaching, as it provides attackers with the capability to enumerate and exfiltrate sensitive files from any location on the server's file system. An attacker could potentially access system configuration files, user credentials, application data, and other confidential information stored outside the FTP root directory. The vulnerability affects the confidentiality and integrity of the system, as unauthorized access to sensitive data can lead to further exploitation opportunities including privilege escalation, data breaches, and system compromise. This type of vulnerability aligns with ATT&CK technique T1083, which covers discovery of file and directory permissions, and T1005, which addresses data from local system.
Mitigation strategies for CVE-2017-6510 should prioritize immediate patching of the Easy File Sharing FTP Server to the latest version that addresses the directory traversal vulnerability. Organizations should implement network segmentation and access control measures to limit exposure of FTP services to untrusted networks. Additionally, implementing proper input validation and sanitization mechanisms within the FTP server configuration can help prevent path traversal attacks. Security monitoring should include detection of suspicious file access patterns and directory traversal attempts. The vulnerability also highlights the importance of principle of least privilege, where FTP server processes should run with minimal necessary permissions to reduce the potential impact of such attacks. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other network services and applications that may be susceptible to path traversal attacks.