CVE-2000-0094 in FreeBSD
Summary
by MITRE
procfs in BSD systems allows local users to gain root privileges by modifying the /proc/pid/mem interface via a modified file descriptor for stderr.
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Analysis
by VulDB Data Team • 06/24/2024
The vulnerability described in CVE-2000-0094 represents a critical privilege escalation flaw within the procfs implementation of BSD operating systems. This security weakness specifically targets the /proc/pid/mem interface, which serves as a mechanism for accessing and modifying the memory space of running processes. The vulnerability stems from insufficient access controls and validation mechanisms within the procfs subsystem, allowing local attackers to exploit a flaw in how file descriptors are handled when accessing process memory through the standard error stream.
The technical exploitation of this vulnerability occurs through manipulation of file descriptor references, particularly when stderr is modified or replaced with a crafted file descriptor. When a local user can successfully alter the file descriptor associated with stderr, they can then leverage this modified reference to gain unauthorized access to the memory space of other processes. This attack vector specifically targets the process memory mapping interface that should normally be restricted to prevent arbitrary memory modification. The flaw exists because the system does not properly validate or restrict access when a modified file descriptor is used in conjunction with the /proc/pid/mem interface, creating a path for privilege escalation.
The operational impact of this vulnerability is severe as it allows local users to escalate their privileges from standard user level to root access without requiring authentication or specialized tools. This type of privilege escalation can be exploited in environments where multiple users share the same system, potentially enabling attackers to gain complete control over the system. The vulnerability affects the fundamental security model of BSD systems by undermining the principle of least privilege, where processes should not be able to access or modify memory spaces of other processes without proper authorization. This weakness can lead to complete system compromise, data exfiltration, and persistent access to the compromised system.
The vulnerability aligns with CWE-264, which addresses permissions, privileges, and access controls, and represents a classic case of insufficient privilege checking within kernel-level interfaces. From an ATT&CK perspective, this vulnerability maps to privilege escalation techniques, specifically the use of kernel exploits to gain elevated privileges. The flaw demonstrates the importance of proper input validation and access control mechanisms in system interfaces, particularly those that provide low-level access to process memory. Organizations should implement immediate patches to address this vulnerability, as it represents a fundamental flaw in the operating system's security architecture that can be exploited without requiring special privileges or complex attack chains.
Mitigation strategies should include applying the relevant security patches provided by BSD vendors, implementing strict access controls on procfs interfaces, and monitoring for suspicious file descriptor modifications. System administrators should also consider implementing additional security measures such as mandatory access controls, process isolation, and regular security audits. The vulnerability highlights the critical need for comprehensive security testing of kernel interfaces and the importance of maintaining up-to-date security patches to prevent exploitation of known vulnerabilities. Regular system hardening procedures should be implemented to reduce the attack surface and prevent similar privilege escalation exploits from succeeding.