CVE-2008-7262 in pyftpdlib
Summary
by MITRE
Multiple directory traversal vulnerabilities in FTPServer.py in pyftpdlib before 0.3.0 allow remote authenticated users to access arbitrary files and directories via vectors involving a symlink in a pathname to a (1) CWD, (2) DELE, (3) STOR, or (4) RETR command.
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Analysis
by VulDB Data Team • 02/07/2019
The vulnerability identified as CVE-2008-7262 represents a critical directory traversal flaw in the pyftpdlib FTP server implementation prior to version 0.3.0. This vulnerability specifically affects the FTPServer.py component and exploits weaknesses in how the system handles symbolic links within file pathnames during common FTP operations. The flaw enables authenticated remote attackers to bypass normal file access restrictions and gain unauthorized access to arbitrary files and directories on the affected system. The vulnerability manifests through four distinct command vectors including CWD (Change Working Directory), DELE (Delete File), STOR (Store File), and RETR (Retrieve File) operations, making it particularly dangerous as it can be exploited across multiple FTP functions.
The technical implementation of this vulnerability stems from insufficient input validation and path resolution mechanisms within the pyftpdlib FTP server. When processing FTP commands that involve file paths, the system fails to properly canonicalize or sanitize symbolic link references in the pathname. This allows attackers to craft malicious path sequences that, when processed through the vulnerable FTP commands, can traverse beyond the intended directory boundaries. The flaw specifically leverages the ability of symbolic links to create alternate path resolutions that bypass directory restrictions, enabling access to files outside the designated FTP root directory. This type of vulnerability falls under CWE-22 Directory Traversal and aligns with ATT&CK technique T1078.002 Valid Accounts, as it requires only authenticated access to exploit the path traversal mechanism.
The operational impact of CVE-2008-7262 is substantial, as it provides attackers with the ability to access sensitive files and directories that should be restricted to authorized users only. This includes system configuration files, user data, application files, and potentially system binaries that could be used for further exploitation or privilege escalation. The vulnerability's exploitation does not require special privileges beyond legitimate FTP authentication, making it particularly concerning for systems where FTP services are exposed to untrusted networks. Attackers can use this vulnerability to exfiltrate confidential data, modify critical system files, or establish persistence mechanisms within the affected environment. The impact extends beyond simple data theft as the vulnerability can be combined with other techniques to escalate privileges or gain deeper system access.
Organizations should implement immediate mitigations including upgrading to pyftpdlib version 0.3.0 or later, which contains the necessary patches to address the directory traversal vulnerability. Additionally, administrators should implement proper access controls and network segmentation to limit FTP service exposure, ensuring that FTP servers are not directly accessible from untrusted networks. The implementation of proper path validation mechanisms and input sanitization should be enforced at multiple levels including application-level checks and network-level firewalls. Regular security auditing and penetration testing should be conducted to identify similar vulnerabilities in other FTP implementations or custom server configurations. System monitoring should be enhanced to detect anomalous FTP activity patterns that might indicate exploitation attempts, particularly around directory traversal operations and unauthorized file access patterns. The vulnerability serves as a reminder of the importance of proper input validation and path canonicalization in network services, particularly those handling user-supplied file paths.