CVE-2001-0063 in FreeBSD
Summary
by MITRE
procfs in FreeBSD and possibly other operating systems allows local users to bypass access control restrictions for a jail environment and gain additional privileges.
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Analysis
by VulDB Data Team • 02/13/2017
The vulnerability identified as CVE-2001-0063 represents a critical access control flaw within the procfs filesystem implementation in FreeBSD and potentially other Unix-like operating systems. This issue specifically targets the jail environment functionality that FreeBSD employs to isolate processes and limit their access to system resources. The procfs filesystem provides a virtual filesystem interface that exposes process information and system statistics to userspace applications, creating a potential attack surface when combined with jail mechanisms designed to contain processes within restricted environments.
The technical flaw stems from improper access control checks within the procfs implementation that fails to properly validate whether processes attempting to access certain kernel information are actually authorized to do so. When a process operates within a jail environment, it should be restricted from accessing kernel-level information or manipulating system resources that could compromise the isolation properties of the jail. However, this vulnerability allows local users to bypass these restrictions by exploiting weaknesses in how procfs handles access control for specific file operations, particularly those related to process information and kernel state queries.
The operational impact of this vulnerability is significant as it enables local users to escalate their privileges within a jail environment, effectively breaking down the security boundaries that separate processes from each other and from the host system. An attacker who gains access to a jail environment could leverage this vulnerability to obtain additional privileges that should normally be restricted, potentially allowing them to access sensitive system information, manipulate other processes, or even escape the jail to gain full system access. This compromise undermines the fundamental security model of jail environments, which are designed to provide process isolation and resource limitation.
The vulnerability aligns with CWE-284, which addresses improper access control issues in software systems, and can be mapped to ATT&CK technique T1068, which covers privilege escalation through local system exploits. Organizations running FreeBSD systems or similar Unix-like operating systems that utilize jail environments are particularly at risk, as this vulnerability directly compromises the isolation properties that make these security mechanisms effective. The flaw demonstrates how seemingly minor access control implementations can create significant security breaches when proper validation mechanisms are absent or insufficiently enforced. Mitigation strategies include applying the appropriate security patches released by FreeBSD, implementing additional monitoring for unauthorized access attempts to procfs, and considering alternative isolation mechanisms that do not rely on potentially vulnerable filesystem interfaces for privilege control.
The broader implications of this vulnerability highlight the importance of comprehensive access control validation in kernel-level filesystem implementations. System administrators should regularly review and update their security configurations, particularly in environments where jail or chroot mechanisms are employed. Additionally, this vulnerability underscores the need for continuous security auditing of core system components and the importance of maintaining current security patches to prevent exploitation of known vulnerabilities that could compromise system integrity and user data confidentiality.