CVE-2001-0421 in Solaris
Summary
by MITRE
FTP server in Solaris 8 and earlier allows local and remote attackers to cause a core dump in the root directory, possibly with world-readable permissions, by providing a valid username with an invalid password followed by a CWD ~ command, which could release sensitive information such as shadowed passwords, or fill the disk partition.
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Analysis
by VulDB Data Team • 01/06/2025
The vulnerability described in CVE-2001-0421 represents a critical flaw in the File Transfer Protocol implementation of Solaris 8 and earlier versions. This issue stems from improper handling of user authentication sequences within the FTP server daemon, specifically when processing commands following failed authentication attempts. The vulnerability manifests when an attacker provides a legitimate username with an incorrect password, followed by a CWD ~ command that attempts to change the working directory to the user's home directory. This sequence triggers a condition where the system generates a core dump file in the root directory with potentially world-readable permissions.
The technical exploitation of this vulnerability occurs at the protocol level within the FTP server's state machine processing. When the authentication fails, the server does not properly validate or sanitize subsequent commands, allowing the CWD command to execute with elevated privileges. This flaw is classified under CWE-20 as "Improper Input Validation" and specifically relates to improper handling of directory traversal commands. The vulnerability demonstrates a classic case of insufficient privilege checking during command execution, where the server fails to properly verify that the user has adequate permissions to execute certain directory operations even after authentication failure.
The operational impact of this vulnerability is severe and multifaceted in nature. Attackers can leverage this flaw to either extract sensitive information from core dump files or consume disk space rapidly through massive file creation. Core dump files typically contain memory contents of the running process including potentially sensitive data such as shadowed passwords, system memory structures, and other confidential information. The world-readable permissions on these dump files pose an additional risk as they allow any user on the system to access the sensitive data contained within. This vulnerability can be exploited both locally and remotely, making it particularly dangerous in networked environments where the FTP service is exposed to external networks.
The potential for information disclosure through this vulnerability aligns with tactics described in the MITRE ATT&CK framework under T1005 - Data from Local System and T1083 - File and Directory Discovery. The ability to cause disk space exhaustion represents a denial of service vector that can be used to disrupt system operations and potentially facilitate further attacks. Organizations running affected Solaris versions face significant risk as this vulnerability can be exploited without requiring special privileges beyond basic network access to the FTP service. The impact extends beyond immediate information disclosure to include potential system instability and resource exhaustion that could affect other services running on the same system.
Mitigation strategies for this vulnerability require immediate patching of affected Solaris systems with the appropriate security updates from Oracle. System administrators should also implement network segmentation to limit access to FTP services and consider disabling FTP services entirely if they are not required for business operations. Additional protective measures include monitoring for unusual core dump file creation patterns and implementing proper file permission controls to prevent unauthorized access to sensitive system files. The vulnerability highlights the importance of proper input validation and privilege checking in server applications, emphasizing the need for comprehensive security testing and code review processes. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts and establish proper logging and alerting mechanisms for anomalous FTP server behavior.