CVE-2008-4933 in Linux
Summary
by MITRE
Buffer overflow in the hfsplus_find_cat function in fs/hfsplus/catalog.c in the Linux kernel before 2.6.28-rc1 allows attackers to cause a denial of service (memory corruption or system crash) via an hfsplus filesystem image with an invalid catalog namelength field, related to the hfsplus_cat_build_key_uni function.
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Analysis
by VulDB Data Team • 08/21/2019
The vulnerability identified as CVE-2008-4933 represents a critical buffer overflow condition within the Linux kernel's HFS+ filesystem implementation that existed prior to version 2.6.28-rc1. This flaw resides specifically in the hfsplus_find_cat function located in the fs/hfsplus/catalog.c source file, where improper validation of catalog namelength fields leads to memory corruption during filesystem operations. The vulnerability is particularly concerning because it can be exploited through manipulation of HFS+ filesystem images, making it accessible to attackers who can control or influence filesystem data structures.
The technical exploitation of this vulnerability occurs when an attacker constructs or manipulates an HFS+ filesystem image containing an invalid catalog namelength field. The hfsplus_cat_build_key_uni function processes these namelength values without adequate bounds checking, allowing malicious input to overflow allocated buffers within the kernel memory space. This buffer overflow condition directly violates the principles of secure buffer management and can result in arbitrary memory corruption, which may manifest as system crashes, kernel panics, or unpredictable behavior within the operating system's kernel space. The vulnerability specifically targets the kernel's handling of HFS+ catalog entries, which are essential for filesystem metadata management and file system operations.
The operational impact of CVE-2008-4933 extends beyond simple denial of service to potentially enable more sophisticated attacks depending on the execution environment. When exploited successfully, the buffer overflow can cause system crashes that result in complete service disruption, forcing system administrators to reboot affected systems and potentially leading to data loss or corruption. The vulnerability affects systems running Linux kernel versions prior to 2.6.28-rc1, which were widely deployed in enterprise and consumer environments. From an attack perspective, this vulnerability aligns with ATT&CK technique T1499.001 for network denial of service and demonstrates the importance of input validation in kernel space operations. The CWE classification for this vulnerability would fall under CWE-121, which describes stack-based buffer overflow conditions, though the specific implementation involves heap memory corruption due to improper bounds checking in kernel data structures.
Mitigation strategies for CVE-2008-4933 primarily focus on immediate kernel version updates to 2.6.28-rc1 or later, which contain the necessary patches to address the buffer overflow condition. System administrators should prioritize patching affected systems and verify that all HFS+ filesystems are properly validated before mounting. Additionally, implementing proper filesystem validation procedures and monitoring for unusual filesystem access patterns can help detect potential exploitation attempts. The vulnerability also underscores the importance of kernel security hardening measures and proper input validation in kernel space code, particularly for filesystem drivers that handle external data structures. Organizations should consider implementing automated patch management systems to ensure timely deployment of security updates and maintain comprehensive system monitoring to detect any signs of exploitation attempts.