CVE-2009-4800 in Multi Server
Summary
by MITRE
Directory traversal vulnerability in Sysax Multi Server 4.3 and 4.5 allows remote authenticated users to delete arbitrary files via a ..// (dot dot slash slash) in a DELE command.
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Analysis
by VulDB Data Team • 11/25/2024
The vulnerability identified as CVE-2009-4800 represents a critical directory traversal flaw within Sysax Multi Server versions 4.3 and 4.5, specifically affecting the File Transfer Protocol implementation. This weakness enables authenticated remote attackers to manipulate file deletion operations through maliciously crafted DELE commands containing ..// sequences. The vulnerability stems from inadequate input validation and path normalization mechanisms within the server's file handling routines, allowing attackers to escape the intended directory boundaries and target files outside the restricted access scope.
The technical exploitation of this vulnerability occurs when an authenticated user submits a DELE command with a path containing ..// sequences that traverse upward through the directory structure. This allows the attacker to delete files in parent directories, potentially accessing and removing sensitive system files, configuration data, or user documents. The flaw specifically impacts the FTP server's handling of file deletion operations, where the system fails to properly sanitize or validate the input paths before executing the deletion process. This type of vulnerability falls under CWE-22, which categorizes path traversal weaknesses in software systems.
The operational impact of this vulnerability extends beyond simple file deletion capabilities, as it provides attackers with the ability to compromise the integrity and availability of the entire file system. An attacker with valid credentials can potentially delete critical system files, user data, or application components, leading to complete system compromise or denial of service conditions. The vulnerability affects organizations using Sysax Multi Server in environments where FTP services are exposed to untrusted networks, making it particularly dangerous in scenarios where the server hosts sensitive data or serves as a critical infrastructure component. This weakness directly relates to ATT&CK technique T1078 which covers valid accounts and T1486 which covers data destruction.
Mitigation strategies for this vulnerability require immediate patching of the Sysax Multi Server software to versions that properly implement input validation and path sanitization. Organizations should also implement network segmentation to limit access to FTP services, enforce strict access controls, and monitor FTP activity for suspicious deletion patterns. Additional defensive measures include disabling unnecessary FTP services, implementing proper file system permissions, and conducting regular security assessments of file transfer protocols. System administrators should also consider implementing intrusion detection systems that can identify and alert on suspicious FTP commands containing directory traversal sequences, ensuring that the exploitation attempts are detected and prevented before they can cause damage to the system.