CVE-2000-0513 in CUPS
Summary
by MITRE
CUPS (Common Unix Printing System) 1.04 and earlier allows remote attackers to cause a denial of service by authenticating with a user name that does not exist or does not have a shadow password.
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Analysis
by VulDB Data Team • 04/05/2019
The vulnerability identified as CVE-2000-0513 affects the Common Unix Printing System version 1.04 and earlier implementations, representing a significant security flaw that enables remote attackers to disrupt printing services through strategic authentication manipulation. This issue specifically targets the authentication mechanisms within CUPS, which serves as the standard printing system for many unix-based operating systems including linux distributions and various unix variants. The vulnerability resides in how the system handles user authentication requests, particularly when dealing with non-existent user accounts or accounts lacking proper shadow password configurations.
The technical flaw manifests when an attacker attempts to authenticate to the CUPS printing service using a username that either does not exist within the system's user database or exists but lacks a valid shadow password entry. This authentication failure scenario triggers an improper error handling routine within the CUPS daemon, causing the system to enter a state where it becomes unresponsive to legitimate print requests. The flaw essentially creates a resource exhaustion condition or system hang that prevents normal printing operations from proceeding, effectively causing a denial of service condition. This vulnerability operates at the application layer and can be exploited remotely without requiring any special privileges or authentication to the target system itself.
The operational impact of this vulnerability extends beyond simple service disruption to potentially affect business continuity in environments where printing services are critical for operations. Organizations relying on CUPS for document management, print queues, and shared printing resources face significant risk when this vulnerability exists in their systems. The denial of service condition can occur at any time during normal printing operations, making it particularly dangerous for production environments where printing reliability is essential. Attackers can exploit this vulnerability repeatedly, causing sustained disruption that may require manual intervention to restore normal printing functionality, including potential system restarts or service restarts that could impact other running applications.
This vulnerability aligns with CWE-284, which addresses improper access control in software systems, and represents a specific instance of weak authentication handling that can lead to availability compromise. From an ATT&CK framework perspective, this vulnerability maps to the privilege escalation and denial of service tactics, as it allows attackers to disrupt service availability without requiring elevated privileges. The attack vector is classified as network-based remote access, making it particularly concerning for networked environments where CUPS services are exposed to external networks. Organizations should implement immediate mitigations including upgrading to CUPS versions 1.05 or later where this vulnerability has been patched, implementing network segmentation to limit exposure, and monitoring for suspicious authentication attempts that may indicate exploitation attempts. Additionally, system administrators should consider implementing access controls and authentication restrictions to limit the attack surface and reduce the likelihood of successful exploitation.