CVE-2002-0164 in Openlinux Server
Summary
by MITRE
Vulnerability in the MIT-SHM extension of the X server on Linux (XFree86) 4.2.1 and earlier allows local users to read and write arbitrary shared memory, possibly to cause a denial of service or gain privileges.
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Analysis
by VulDB Data Team • 05/16/2019
The vulnerability described in CVE-2002-0164 represents a critical security flaw within the MIT-SHM (MIT Shared Memory) extension of the X server implementation in XFree86 versions 4.2.1 and earlier. This issue specifically targets the shared memory management mechanisms that allow applications to communicate efficiently with the X server through shared memory segments. The MIT-SHM extension was designed to improve performance by enabling direct memory access between client applications and the X server, but this optimization introduced significant security risks when improperly implemented.
The technical flaw stems from inadequate access controls and memory management within the X server's shared memory handling code. Local users can exploit this vulnerability to manipulate arbitrary shared memory segments that should normally be restricted to specific processes or users. This occurs because the X server fails to properly validate memory access requests, allowing unauthorized processes to read or write to shared memory regions that contain sensitive data or control structures. The vulnerability is particularly dangerous because it operates at the kernel level where shared memory segments are managed, giving attackers the potential to access memory that should remain protected from unauthorized access. This flaw directly maps to CWE-264, which covers permissions, privileges, and access control issues in software systems.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and denial of service conditions. Attackers with local access can leverage this weakness to read sensitive information stored in shared memory segments, potentially extracting authentication credentials, encryption keys, or other confidential data. The ability to write arbitrary data to shared memory segments can lead to memory corruption, application crashes, or even system instability that results in denial of service. In certain configurations, this vulnerability may provide a pathway for privilege escalation, allowing local users to gain elevated system privileges. The attack surface is particularly concerning because shared memory segments are often used for inter-process communication and can contain critical system data that should remain isolated from unauthorized access.
Mitigation strategies for CVE-2002-0164 should focus on immediate system updates and configuration hardening. The primary remediation involves upgrading to XFree86 version 4.2.2 or later, which includes fixed implementations of the MIT-SHM extension with proper access controls. System administrators should also implement the principle of least privilege by restricting local user access to X server functionality where possible. Additional protective measures include disabling the MIT-SHM extension entirely if it is not required for specific applications, implementing proper memory access controls through system call filtering, and monitoring for unauthorized shared memory access patterns. Organizations should also consider implementing intrusion detection systems that can identify suspicious memory access attempts and conduct regular security audits of X server configurations to ensure that shared memory mechanisms are properly secured. The vulnerability demonstrates the importance of proper access control implementation in system-level components and aligns with ATT&CK technique T1068, which covers local privilege escalation through the exploitation of system vulnerabilities.