CVE-2000-0263 in Linux
Summary
by MITRE
The X font server xfs in Red Hat Linux 6.x allows an attacker to cause a denial of service via a malformed request.
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Analysis
by VulDB Data Team • 11/11/2024
The vulnerability identified as CVE-2000-0263 targets the X font server xfs component within Red Hat Linux 6.x systems, representing a classic denial of service flaw that exploits malformed input processing. This vulnerability resides in the X Window System font server implementation, which serves as a critical component for managing font resources in graphical environments. The flaw specifically manifests when the xfs daemon processes malformed requests that do not conform to expected protocol specifications, leading to unexpected behavior and system instability. The vulnerability falls under the category of improper input validation, where the server fails to properly sanitize or reject malformed data before processing, creating an opportunity for malicious actors to disrupt service availability.
The technical exploitation of this vulnerability occurs through the manipulation of protocol requests sent to the xfs daemon, which typically operates on TCP port 1712. When an attacker crafts and submits a malformed request that contains invalid data structures or unexpected parameter values, the server's processing logic fails to handle these edge cases gracefully. This failure results in the daemon entering an unstable state where it either crashes, becomes unresponsive, or consumes excessive system resources. The flaw demonstrates a lack of robust error handling mechanisms within the server's request processing pipeline, allowing malformed input to propagate through the system without proper validation or sanitization. The vulnerability is particularly concerning as it requires minimal privileges to exploit, making it accessible to any user with network connectivity to the affected system.
The operational impact of CVE-2000-0263 extends beyond simple service disruption, as it represents a fundamental weakness in the system's resilience against malicious input. When exploited successfully, the denial of service attack can render the entire font server unavailable, potentially affecting multiple applications that depend on font rendering capabilities within the graphical environment. This vulnerability affects systems running Red Hat Linux 6.x versions where the xfs service is active, typically in desktop environments or server configurations that utilize X Window System for graphical user interfaces. The consequences include reduced system availability, potential cascading effects on dependent services, and disruption of user productivity in environments where graphical interfaces are essential for operations. Organizations may experience downtime during exploitation attempts, and the vulnerability could be leveraged as part of broader attack campaigns targeting system stability.
Mitigation strategies for CVE-2000-0263 should focus on immediate patching and configuration hardening measures. The most effective solution involves applying the vendor-supplied security patches that address the input validation flaws in the xfs daemon implementation, which typically include enhanced request validation and improved error handling mechanisms. System administrators should disable the xfs service if font server functionality is not required, as this eliminates the attack surface entirely. Network-level protections can be implemented through firewall rules that restrict access to port 1712, limiting connections to trusted sources only. Additionally, monitoring and logging configurations should be enhanced to detect unusual patterns in font server access attempts, which could indicate exploitation attempts. The vulnerability aligns with CWE-20, which addresses improper input validation, and could be mapped to ATT&CK technique T1499.004 for network denial of service attacks. Regular system updates and vulnerability assessments should be conducted to prevent similar issues in other components of the X Window System stack, ensuring comprehensive protection against related exploitation vectors.