CVE-2001-1503 in Solaris
Summary
by MITRE
The finger daemon (in.fingerd) in Sun Solaris 2.5 through 8 and SunOS 5.5 through 5.8 allows remote attackers to list all accounts on a host by typing finger a b c d e f g h @host.
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Analysis
by VulDB Data Team • 09/24/2025
The vulnerability described in CVE-2001-1503 represents a significant security flaw in the finger daemon implementation across multiple versions of Sun Solaris and SunOS operating systems. This issue affects systems running Solaris 2.5 through 8 and SunOS 5.5 through 5.8, where the in.fingerd service exhibits improper input validation behavior that can be exploited by remote attackers to enumerate all user accounts on the target system. The finger protocol was historically designed for user information lookup but became a security concern when implemented without proper access controls or input sanitization measures. This vulnerability falls under the category of information disclosure flaws that can provide attackers with valuable reconnaissance data for subsequent attacks.
The technical exploitation mechanism relies on the finger daemon's handling of command-line arguments when processing requests with multiple parameters. When an attacker sends a finger request containing numerous arguments followed by an at-sign and hostname, the daemon fails to properly validate or sanitize the input, causing it to respond with a complete list of all accounts on the system. This behavior stems from insufficient bounds checking and argument parsing logic within the daemon implementation, allowing attackers to bypass normal authentication requirements and access account information without proper credentials. The vulnerability is classified as a command injection or information disclosure issue that directly violates secure coding practices for network services.
The operational impact of this vulnerability extends beyond simple account enumeration, as it provides attackers with comprehensive user account information that can be leveraged for various malicious activities. Security professionals should note that this vulnerability aligns with attack patterns documented in the MITRE ATT&CK framework under the information discovery tactics, specifically targeting account enumeration and credential access phases. The ability to list all accounts on a system creates a significant risk for privilege escalation attacks, as attackers can identify valid usernames to target for password spraying, brute force attacks, or social engineering campaigns. Additionally, this information can be used to map network infrastructure and identify potential targets for further exploitation.
Mitigation strategies for this vulnerability should prioritize immediate service disablement or removal of the finger daemon from production systems, as the service provides minimal legitimate functionality in modern network environments. Organizations should implement network segmentation to restrict access to finger services, deploy firewall rules to block finger protocol traffic on port 79, and ensure that all systems have been patched to the latest security updates provided by Sun Microsystems. The vulnerability demonstrates the importance of the principle of least privilege and proper service hardening practices, as documented in various security standards including those from the Center for Internet Security and NIST guidelines for system hardening. System administrators should also conduct comprehensive security audits to identify and disable any other legacy services that may present similar information disclosure risks within their network infrastructure.