CVE-2005-2218 in FreeBSD
Summary
by MITRE
The device file system (devfs) in FreeBSD 5.x does not properly check parameters of the node type when creating a device node, which makes hidden devices available to attackers, who can then bypass restrictions on a jailed process.
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Analysis
by VulDB Data Team • 03/11/2021
The vulnerability described in CVE-2005-2218 represents a critical flaw in FreeBSD's device file system implementation that undermines the security boundaries of jail environments. This issue specifically affects FreeBSD 5.x versions and stems from inadequate parameter validation during device node creation processes. The flaw allows attackers to manipulate device node types in ways that were not intended by the system's security model, creating opportunities for privilege escalation and bypass of containment mechanisms.
The technical root cause lies in the devfs subsystem's failure to properly validate node type parameters when establishing device nodes within the file system hierarchy. This validation gap enables malicious actors to create device nodes with unexpected or dangerous node types that can expose hidden system resources. The vulnerability operates at the kernel level where device file system operations are processed, making it particularly dangerous as it can be exploited before standard user-space security checks are applied. The improper parameter checking creates a pathway for attackers to construct device nodes that bypass the normal access control mechanisms that should prevent unauthorized access to system resources.
When exploited, this vulnerability allows attackers to gain access to hidden or restricted device nodes that should normally be unavailable within a jail environment. The impact extends beyond simple information disclosure as it enables bypass of mandatory access controls that are fundamental to the security model of FreeBSD jails. Attackers can leverage this weakness to access device files that contain sensitive system information or provide access to hardware resources that should remain isolated from compromised processes. The operational consequences include potential privilege escalation, complete system compromise, and the ability to circumvent containment strategies that are essential for maintaining multi-tenant security in shared hosting environments.
This vulnerability maps directly to CWE-20, which describes improper input validation, and represents a classic case of insufficient validation of node types in kernel-level file system operations. The attack surface is particularly concerning in environments where FreeBSD jails are used for security isolation, as the vulnerability effectively nullifies the security benefits of the jail mechanism. From an ATT&CK framework perspective, this vulnerability enables multiple techniques including privilege escalation through kernel exploits, defense evasion by bypassing system controls, and access to system resources that should be restricted. The mitigation strategy requires immediate patching of affected FreeBSD 5.x systems and implementation of proper parameter validation checks in device file system operations. Additionally, system administrators should consider restricting device node creation privileges and implementing monitoring for suspicious device file system activities that could indicate exploitation attempts.