CVE-2000-0915 in FreeBSD
Summary
by MITRE
fingerd in FreeBSD 4.1.1 allows remote attackers to read arbitrary files by specifying the target file name instead of a regular user name.
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Analysis
by VulDB Data Team • 10/12/2025
The vulnerability identified as CVE-2000-0915 represents a critical security flaw in the finger daemon implementation within FreeBSD 4.1.1 systems. This issue stems from improper input validation within the fingerd service which fails to properly sanitize user-provided input when processing requests. The finger protocol typically operates on TCP port 79 and is designed to provide information about users on a remote system. However, the flawed implementation in this specific FreeBSD version allows malicious actors to exploit the service by substituting legitimate user names with arbitrary file paths, thereby enabling unauthorized file access across the system.
The technical root cause of this vulnerability aligns with CWE-22, known as "Improper Limitation of a Pathname to a Restricted Directory." The fingerd service in FreeBSD 4.1.1 lacks proper validation mechanisms to prevent directory traversal attacks, allowing attackers to specify file paths that extend beyond the intended user information scope. When a remote attacker sends a request to the finger daemon with a file path instead of a username, the service processes the request without adequate restrictions, resulting in the disclosure of arbitrary files from the system. This flaw essentially transforms a legitimate user information service into a potential file disclosure mechanism, bypassing normal access controls and file system permissions.
From an operational perspective, this vulnerability presents a significant risk to FreeBSD systems running the affected fingerd service. Attackers can leverage this weakness to access sensitive files including system configuration data, user credentials, authentication files, and other confidential information stored on the target system. The remote nature of the attack means that no local system access is required, making the exploitation particularly dangerous for networked environments. The impact extends beyond simple information disclosure as attackers may discover additional vulnerabilities through the exposed system files, potentially leading to further compromise of the affected systems.
The exploitation of this vulnerability aligns with several ATT&CK techniques including T1083 (File and Directory Discovery) and T1005 (Data from Local System). Security professionals should note that this vulnerability demonstrates the importance of input validation and proper access control implementation in network services. The attack vector operates through standard network protocols without requiring special privileges or complex exploitation techniques, making it particularly concerning for environments where the finger service remains enabled. Organizations should implement immediate mitigations including disabling the finger service entirely, implementing proper network segmentation, and ensuring that all systems are updated to versions that address this specific vulnerability.
Mitigation strategies for CVE-2000-0915 should prioritize the immediate disabling of the finger service on affected systems, as this represents the most effective immediate solution. System administrators should verify that the fingerd service is not running and that the associated port 79 is not accessible from external networks. Additionally, implementing proper firewall rules to block access to port 79 and conducting thorough system audits to identify any remaining instances of the vulnerable service is essential. Long-term solutions should include upgrading to patched versions of FreeBSD, implementing robust input validation mechanisms in all network services, and establishing comprehensive monitoring for unauthorized access attempts. The vulnerability also underscores the importance of regularly reviewing and disabling unnecessary network services to minimize the attack surface of systems.