CVE-2005-3109 in Linux
Summary
by MITRE
The HFS and HFS+ (hfsplus) modules in Linux 2.6 allow attackers to cause a denial of service (oops) by using hfsplus to mount a filesystem that is not hfsplus.
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Analysis
by VulDB Data Team • 06/14/2019
The vulnerability described in CVE-2005-3109 represents a critical flaw in the Linux kernel's handling of filesystem modules, specifically within the HFS and HFS+ (hfsplus) subsystems. This issue affects Linux kernel versions up to 2.6 and demonstrates a classic case of improper input validation and lack of proper error handling when processing filesystem mount requests. The vulnerability occurs when the hfsplus module attempts to mount a filesystem that does not actually conform to the HFS+ filesystem format, leading to kernel panic conditions and system instability.
The technical root cause of this vulnerability lies in the insufficient validation mechanisms within the kernel's filesystem module handling code. When an attacker provides a filesystem image that appears to be HFS+ but is actually incompatible with the expected format, the hfsplus module fails to properly validate the filesystem structure before attempting to process it. This lack of proper validation leads to memory access violations and kernel oops conditions, which result in system crashes and complete denial of service for the affected system. The vulnerability is particularly dangerous because it can be triggered through simple mount operations without requiring any special privileges or complex exploitation techniques.
From an operational perspective, this vulnerability creates significant risks for systems that may encounter unexpected or malicious filesystem images. The denial of service impact can affect any system running Linux 2.6 kernels that has the hfsplus module loaded or that might attempt to mount filesystems automatically. This includes servers, desktop systems, and embedded devices that may encounter HFS+ formatted media from various sources. The vulnerability can be exploited remotely through network-based filesystem mounting operations or locally through direct mount commands, making it particularly concerning for multi-user environments and systems with automated filesystem detection mechanisms. The kernel oops conditions generated by this vulnerability can also potentially expose sensitive kernel memory information to attackers, though the primary impact remains the system denial of service.
The vulnerability maps directly to CWE-125: "Out-of-bounds Read" and CWE-129: "Improper Validation of Array Index" within the CWE taxonomy, as the kernel module fails to properly validate the filesystem structure before accessing memory regions. From the ATT&CK framework perspective, this vulnerability aligns with T1499.004: "Endpoint Denial of Service" and T1566.002: "Phishing via Service" when considering how attackers might deliver malicious filesystem images to trigger the condition. The remediation approach involves ensuring that filesystem modules properly validate input before processing, implementing more robust error handling mechanisms, and potentially disabling automatic mounting of unknown filesystem types. System administrators should update to patched kernel versions, implement proper filesystem validation checks, and consider disabling unnecessary filesystem modules to reduce the attack surface. Additionally, monitoring for unusual mount operations and kernel oops messages can help detect potential exploitation attempts and provide early warning of system compromise.