CVE-2011-4717 in zFTPServer Suite
Summary
by MITRE
Directory traversal vulnerability in zFTPServer Suite 6.0.0.52 allows remote authenticated users to delete arbitrary directories via a crafted RMD (aka rmdir) command.
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Analysis
by VulDB Data Team • 06/14/2025
The CVE-2011-4717 vulnerability represents a critical directory traversal flaw within the zFTPServer Suite version 6.0.0.52, specifically affecting the Remote Management Directory (RMD) command functionality. This vulnerability operates at the application layer and constitutes a direct violation of proper input validation and access control mechanisms. The flaw enables authenticated remote attackers to manipulate the file system by executing crafted RMD commands that can traverse directory structures beyond their intended scope, thereby gaining unauthorized access to system directories and potentially compromising the entire server environment.
The technical implementation of this vulnerability stems from inadequate sanitization of user-supplied input within the RMD command processing logic. When an authenticated user submits a malicious RMD command containing directory traversal sequences such as ../ or ..\, the server fails to properly validate or normalize these paths before executing the directory removal operation. This weakness directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal vulnerabilities. The vulnerability exists because the software does not adequately check whether the requested directory removal operation remains within the confines of the user's authorized access scope, allowing attackers to navigate upward in the directory hierarchy and target directories outside their intended operational boundaries.
From an operational impact perspective, this vulnerability presents a severe threat to server security and data integrity. An authenticated attacker can leverage this weakness to delete critical system directories, potentially causing system instability, data loss, or complete system compromise. The remote nature of the exploit means that attackers do not require physical access to the system, making the vulnerability particularly dangerous in networked environments. The implications extend beyond simple directory deletion, as the attacker could potentially target system directories containing configuration files, logs, or other critical components that could lead to further system compromise or denial of service conditions. This vulnerability also aligns with ATT&CK technique T1059.001, which involves executing commands through the command and scripting interpreter, as the malicious RMD command execution could be part of a broader exploitation chain.
The mitigation strategies for CVE-2011-4717 should focus on implementing robust input validation and access control measures within the zFTPServer Suite application. Organizations should immediately apply available patches or updates from the software vendor to address this vulnerability, as the manufacturer likely released a fix that properly sanitizes directory paths and enforces strict access controls. Additionally, implementing proper path normalization techniques, such as canonicalizing directory paths and maintaining strict directory access boundaries, would prevent the exploitation of this vulnerability. Network segmentation and access control lists should be deployed to limit the scope of authenticated users who can execute RMD commands, while monitoring systems should be configured to detect and alert on suspicious directory traversal attempts. The implementation of principle of least privilege access controls and regular security audits of file system operations would further reduce the risk associated with this vulnerability. Organizations should also consider implementing intrusion detection systems that can identify patterns consistent with directory traversal attacks, providing additional layers of defense beyond the application-level controls.