CVE-2002-2274 in Akfingerd
Summary
by MITRE
akfingerd 0.5 allows local users to read arbitrary files as the akfingerd user (nobody) via a symlink attack on the .plan file.
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Analysis
by VulDB Data Team • 06/28/2021
The vulnerability identified as CVE-2002-2274 affects akfingerd version 0.5, a finger daemon implementation that provides finger service functionality on Unix-like systems. This vulnerability represents a classic privilege escalation and information disclosure issue that exploits the daemon's handling of symbolic links during file processing operations. The flaw specifically manifests when the daemon processes user .plan files, which are typically used to store user information and personal messages in finger service implementations.
The technical flaw resides in the insecure handling of symbolic links within the akfingerd daemon's file processing mechanism. When a local user creates a symbolic link pointing to a sensitive system file and places it as their .plan file, the daemon follows the symlink and reads the target file with the privileges of the akfingerd process, which runs as the nobody user. This represents a direct violation of the principle of least privilege and demonstrates a fundamental flaw in the daemon's file access controls. The vulnerability is particularly dangerous because it allows arbitrary file reading without proper authentication or authorization checks, effectively bypassing normal file system permissions.
The operational impact of this vulnerability is significant for systems running akfingerd 0.5, as it enables local attackers to access sensitive files that would normally be protected from unauthorized access. The attacker can read system configuration files, password files, or other sensitive data that might be accessible to the nobody user account. This vulnerability effectively undermines the security model of the finger service and can be exploited to gather intelligence about the system, potentially leading to further privilege escalation or information disclosure attacks. The attack requires local access but does not need elevated privileges, making it particularly concerning for multi-user systems where users might have varying levels of access.
Mitigation strategies for this vulnerability include immediate patching of the akfingerd daemon to version 0.5.1 or later, which contains the necessary fixes for symbolic link handling. System administrators should also implement proper file permission controls and consider disabling the finger service entirely if it is not required for operations. The vulnerability aligns with CWE-59, which describes improper link resolution without limit checks, and can be categorized under ATT&CK technique T1083 for discovering system information. Additionally, implementing proper input validation and avoiding symbolic link resolution in privilege contexts would prevent similar issues in other applications. Organizations should also consider implementing monitoring for unauthorized file access patterns and ensure that all system services run with minimal required privileges to reduce the potential impact of such vulnerabilities.