CVE-2001-0027 in ProFTPD
Summary
by MITRE
mod_sqlpw module in ProFTPD does not reset a cached password when a user uses the "user" command to change accounts, which allows authenticated attackers to gain privileges of other users.
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Analysis
by VulDB Data Team • 04/07/2019
The vulnerability identified as CVE-2001-0027 represents a critical authentication flaw within the mod_sqlpw module of ProFTPD, a widely deployed open source FTP server implementation. This issue stems from improper session management where the module fails to invalidate cached authentication credentials when users switch accounts using the user command. The flaw creates a persistent security weakness that directly violates fundamental principles of access control and privilege separation. The vulnerability specifically affects systems where ProFTPD is configured with SQL-based authentication modules, making it particularly relevant to enterprise environments that rely on database-backed user management for their file transfer services.
The technical root cause of this vulnerability lies in the module's failure to implement proper credential invalidation procedures during account switching operations. When an authenticated user executes the user command to transition to another account, the system should invalidate the cached password for the previous user session and establish new authentication context. However, the mod_sqlpw module maintains the cached password in memory, allowing the attacker to leverage these credentials for unauthorized access. This behavior creates a privilege escalation vector where legitimate authenticated users can potentially impersonate other users within the same authentication domain, effectively bypassing the intended access controls. The flaw operates at the application level within the FTP protocol implementation, making it particularly dangerous as it can be exploited through standard FTP client interactions without requiring additional attack vectors.
The operational impact of this vulnerability extends beyond simple unauthorized access, creating significant risks for organizations relying on ProFTPD for file transfer operations. Attackers exploiting this vulnerability can gain unauthorized access to files and directories accessible to other users within the same authentication realm, potentially leading to data breaches, privilege escalation, and lateral movement within network environments. The vulnerability is particularly concerning in multi-user environments where different users have varying levels of access permissions, as it allows attackers to escalate their privileges and access sensitive data. This flaw directly impacts the integrity and confidentiality of file transfer operations, potentially exposing sensitive organizational data and violating compliance requirements for data protection and access control. The vulnerability can be exploited through standard FTP client commands without requiring specialized tools or complex attack scenarios.
Mitigation strategies for CVE-2001-0027 should focus on immediate patch application and configuration hardening measures. The primary solution involves updating ProFTPD to versions that address this specific credential caching issue, typically through patches released by the ProFTPD development team. Organizations should also implement strict access controls and monitoring of FTP server activities, particularly around account switching operations. Configuration changes may include disabling the mod_sqlpw module if not essential, implementing additional authentication layers, and establishing robust logging mechanisms to detect unauthorized account transitions. Security practitioners should consider implementing network segmentation and access control lists to limit exposure of FTP services to trusted network segments. This vulnerability aligns with CWE-284 Access Control Issues and can be mapped to ATT&CK techniques related to privilege escalation and credential access, emphasizing the need for comprehensive security measures beyond simple patch management. Organizations should conduct thorough security assessments to identify systems running vulnerable versions of ProFTPD and ensure proper remediation procedures are implemented across all affected environments.