CVE-2002-1125 in FreeBSD
Summary
by MITRE
FreeBSD port programs that use libkvm for FreeBSD 4.6.2-RELEASE and earlier, including (1) asmon, (2) ascpu, (3) bubblemon, (4) wmmon, and (5) wmnet2, leave open file descriptors for /dev/mem and /dev/kmem, which allows local users to read kernel memory.
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Analysis
by VulDB Data Team • 08/31/2024
The vulnerability described in CVE-2002-1125 represents a critical security flaw in FreeBSD operating systems version 4.6.2-RELEASE and earlier. This issue affects multiple system monitoring utilities that rely on the libkvm library for kernel access, specifically targeting programs including asmon, ascpu, bubblemon, wmmon, and wmnet2. These utilities are designed to provide system monitoring capabilities but suffer from improper resource management during their execution. The flaw stems from the programs' failure to properly close file descriptors after accessing sensitive kernel memory locations, creating persistent access points that can be exploited by local attackers.
The technical implementation of this vulnerability involves the programs opening file descriptors to /dev/mem and /dev/kmem devices, which provide direct access to physical memory and kernel memory respectively. These device files are typically restricted to root access and require special privileges to open. However, the affected FreeBSD port programs do not properly close these file descriptors after their initial use, leaving them open throughout the program's execution. This behavior creates a persistent security exposure where local users can leverage these open file descriptors to read kernel memory contents, potentially accessing sensitive information such as passwords, encryption keys, or other confidential data stored in kernel space.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with access to kernel memory that could contain critical system information. According to CWE-200, this represents a weakness in which information is disclosed to unauthorized actors, while the persistent open file descriptor behavior aligns with CWE-396, which addresses the failure to properly close file descriptors. The attack surface is particularly concerning for local users who may not have elevated privileges initially, as they can exploit this flaw to gain access to kernel memory that typically requires root access. This vulnerability essentially undermines the kernel's memory protection mechanisms, allowing unauthorized access to sensitive data that should remain isolated from user-space processes.
From an attack perspective, this vulnerability follows patterns consistent with the MITRE ATT&CK framework, particularly in the privilege escalation and credential access domains. The local users can leverage this flaw to escalate their privileges by accessing kernel memory that contains sensitive information, potentially leading to further exploitation opportunities. The attack vector is straightforward: a local user runs one of the affected monitoring programs, which leaves open file descriptors to kernel memory, then uses these descriptors to read kernel memory contents. The implications are significant as this vulnerability affects system monitoring tools that are commonly installed and used on FreeBSD systems, making it a widespread concern across affected installations. The vulnerability demonstrates poor security practices in resource management and highlights the importance of proper file descriptor handling in system utilities that interface with kernel memory.
Mitigation strategies for this vulnerability involve immediate patching of affected FreeBSD systems to version 4.7-RELEASE or later, where the issue has been addressed through proper file descriptor management. System administrators should also implement monitoring for unauthorized access to kernel memory devices and ensure that system monitoring utilities are regularly updated. The fix typically involves modifying the affected programs to properly close file descriptors after use, preventing the persistent open file descriptor issue. Additionally, organizations should conduct security audits of their system monitoring tools to identify other potential vulnerabilities in similar utilities that may exhibit the same improper resource management patterns, ensuring comprehensive protection against similar attacks.