CVE-2000-0512 in CUPS
Summary
by MITRE
CUPS (Common Unix Printing System) 1.04 and earlier does not properly delete request files, which allows a remote attacker to cause a denial of service.
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Analysis
by VulDB Data Team • 04/05/2019
The vulnerability identified as CVE-2000-0512 affects the Common Unix Printing System version 1.04 and earlier implementations, representing a significant security flaw in print server functionality that has persisted for over two decades. This issue resides within the core file management mechanisms of CUPS, which serves as the standard printing system for most unix-like operating systems including linux distributions and various unix variants. The vulnerability specifically targets the request file handling process where temporary files are created to manage print jobs and communication between clients and print servers. These temporary files contain critical information about print requests and are essential for proper job scheduling and completion. When the system fails to properly delete these request files, it creates a persistent state where file descriptors remain open or file system resources are not properly released, leading to a cascading effect that impacts system stability and availability. The flaw exists in the fundamental file lifecycle management within the CUPS daemon process, which operates with elevated privileges to manage print services across networked systems.
The technical implementation of this vulnerability stems from inadequate resource cleanup mechanisms within the CUPS print processing pipeline. When print requests are submitted to the system, temporary files are created in designated temporary directories to store job parameters, document data, and communication metadata. These files typically contain unique identifiers, timestamps, and job configuration information that the system uses to track and manage print operations. The flaw occurs during the request processing cycle where the system successfully processes the print job but fails to execute the proper cleanup routine that would remove these temporary files from the file system. This failure can occur due to various conditions including interrupted processing, premature termination of processes, or errors in the file deletion logic itself. The improper handling of these temporary files creates a resource exhaustion scenario where the file system becomes cluttered with stale temporary files that consume disk space and file descriptors. This issue is particularly concerning because it can be triggered through legitimate network requests, making it exploitable by remote attackers who do not require special privileges or authentication to cause the denial of service condition.
The operational impact of CVE-2000-0512 extends beyond simple service disruption to potentially compromise entire print server operations within networked environments. When the system begins accumulating temporary files without proper cleanup, it creates a gradual degradation of system performance that eventually leads to complete service unavailability. The denial of service condition manifests when the file system reaches capacity limits or when the system runs out of available file descriptors, preventing new print jobs from being processed. This vulnerability affects both local and remote print operations since the CUPS service listens on network ports for incoming print requests, making it accessible to attackers from external networks. The impact is particularly severe in enterprise environments where print servers handle hundreds or thousands of jobs daily, as the accumulation of stale files can quickly overwhelm system resources and cause cascading failures. Network administrators may observe symptoms including slow response times, failed print job submissions, and complete print service outages that require manual intervention to resolve. The vulnerability also creates potential security implications beyond simple denial of service, as the accumulation of temporary files may expose sensitive information contained within print job data or system configuration parameters.
Mitigation strategies for CVE-2000-0512 require immediate implementation of software updates and system hardening measures to address the root cause of the vulnerability. The most effective approach involves upgrading to CUPS version 1.05 or later, which includes proper file cleanup mechanisms and improved resource management. System administrators should also implement automated monitoring solutions to track temporary file accumulation and trigger alerts when file system usage exceeds predetermined thresholds. Regular system maintenance procedures should include manual cleanup of temporary directories and monitoring of file descriptor usage to prevent accumulation of stale files. Network segmentation and access controls should be implemented to limit exposure of print servers to untrusted networks, reducing the attack surface for remote exploitation attempts. Additionally, implementing proper logging and auditing mechanisms allows administrators to track print job processing and identify patterns that may indicate the vulnerability is being exploited. This vulnerability aligns with CWE-459, which describes improper cleanup of resources, and can be mapped to ATT&CK technique T1499.1 for the specific sub-technique of network denial of service, demonstrating how this issue fits into broader cybersecurity frameworks and attack patterns. Organizations should also consider implementing redundant print server configurations and backup systems to minimize impact when such vulnerabilities are exploited in production environments.