CVE-2001-0406 in Samba
Summary
by MITRE
Samba before 2.2.0 allows local attackers to overwrite arbitrary files via a symlink attack using (1) a printer queue query, (2) the more command in smbclient, or (3) the mput command in smbclient.
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Analysis
by VulDB Data Team • 10/30/2024
The vulnerability described in CVE-2001-0406 represents a critical file system security flaw within Samba implementations prior to version 2.2.0. This issue stems from improper handling of symbolic links during file operations within the Samba network file sharing system, creating a privilege escalation vector that allows local attackers to manipulate file system contents through carefully crafted operations. The vulnerability specifically affects the way Samba processes symbolic links in printer queue queries and smbclient commands, exposing the system to unauthorized file overwrites and potential data corruption.
The technical implementation of this vulnerability exploits the lack of proper symlink resolution checks within Samba's file handling mechanisms. When local users execute printer queue queries, utilize the more command in smbclient, or employ the mput command in smbclient, the system fails to validate whether the target files are symbolic links. This oversight enables attackers to create malicious symlink structures that, when processed by Samba, result in arbitrary file overwrite operations. The flaw operates at the file system level where Samba's security model does not adequately distinguish between legitimate file operations and potentially harmful symlink manipulations, creating a direct path for privilege escalation.
The operational impact of this vulnerability extends beyond simple file overwrites to encompass broader system compromise potential. Attackers can leverage this weakness to replace critical system files, modify configuration data, or inject malicious code into the Samba environment, potentially leading to complete system takeover. The local nature of the attack means that any user with access to the Samba system can exploit this vulnerability, making it particularly dangerous in multi-user environments where privilege separation is crucial. This vulnerability directly relates to CWE-59, which describes improper handling of symbolic links, and represents a classic case of insufficient input validation and inadequate access control mechanisms.
The attack vectors identified in this vulnerability encompass three specific Samba client operations that all share the common weakness of inadequate symlink handling. Printer queue queries, which are used to retrieve information about available printers and their associated queues, provide a legitimate interface that attackers can abuse to manipulate file system state through symlink attacks. The more command in smbclient, typically used to display file contents, and the mput command, which allows for batch file uploads, both present opportunities for attackers to exploit the symlink handling weakness. These operations demonstrate how legitimate administrative tools can be weaponized when underlying security checks are insufficient.
Mitigation strategies for CVE-2001-0406 require immediate deployment of Samba version 2.2.0 or later, which includes proper symlink handling and validation mechanisms. Organizations should implement comprehensive patch management procedures to ensure all Samba installations are updated promptly. Additional protective measures include restricting local access to Samba services, implementing strict file system permissions, and monitoring for suspicious file operations. The vulnerability highlights the importance of secure coding practices and proper input validation, aligning with ATT&CK technique T1068 which covers local privilege escalation through system weaknesses. Security teams should also consider implementing file integrity monitoring solutions to detect unauthorized file modifications that might result from exploitation of this vulnerability, as well as conducting regular security audits to identify similar weaknesses in other system components.