CVE-2014-9728 in Linux
Summary
by MITRE
The UDF filesystem implementation in the Linux kernel before 3.18.2 does not validate certain lengths, which allows local users to cause a denial of service (buffer over-read and system crash) via a crafted filesystem image, related to fs/udf/inode.c and fs/udf/symlink.c.
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Analysis
by VulDB Data Team • 05/20/2022
The vulnerability identified as CVE-2014-9728 represents a critical buffer over-read flaw within the Universal Disk Format filesystem implementation in the Linux kernel ecosystem. This issue affects kernel versions prior to 3.18.2 and specifically targets the validation mechanisms that govern filesystem metadata processing. The vulnerability stems from inadequate input validation within the udf filesystem driver, particularly in the inode.c and symlink.c source files where insufficient length checks are performed during filesystem image parsing operations. Such deficiencies create exploitable conditions that can be leveraged by local attackers to manipulate filesystem structures and trigger system instability.
The technical exploitation of this vulnerability occurs when a maliciously crafted filesystem image is mounted on a vulnerable system. The kernel's udf implementation fails to properly validate the lengths of various filesystem structures during parsing, allowing an attacker to provide oversized or malformed data that exceeds the allocated buffer boundaries. This buffer over-read condition manifests when the kernel attempts to process symlink entries or inode metadata where the length fields do not correspond to actual data sizes. The flaw specifically impacts the filesystem's ability to handle extended attribute structures and symbolic link data, where the implementation reads beyond allocated memory regions without proper bounds checking. This type of vulnerability falls under the CWE-129 category of Improper Validation of Array Index, which is a well-documented weakness in memory safety mechanisms.
The operational impact of CVE-2014-9728 extends beyond simple denial of service conditions to potentially compromise entire system stability and availability. Local users with the ability to mount filesystem images can trigger system crashes through controlled buffer over-read conditions that cause kernel memory corruption. The resulting system instability can manifest as immediate kernel panics, system reboots, or more subtle memory corruption that may lead to data loss or system compromise. In environments where udf filesystems are commonly used, such as optical media, digital video recording systems, or enterprise storage solutions, this vulnerability presents a significant risk to operational continuity. The attack vector is particularly concerning because it requires only local access to mount a malicious filesystem, making it exploitable in scenarios where users might mount untrusted optical media or external storage devices containing crafted udf images.
Mitigation strategies for this vulnerability center on kernel version updates and immediate patch deployment to systems running affected kernel versions. The most effective remediation involves upgrading to Linux kernel version 3.18.2 or later where the validation checks have been properly implemented to prevent buffer over-read conditions. System administrators should also consider implementing additional monitoring and logging mechanisms to detect suspicious filesystem mounting activities, particularly for optical media or external storage devices. The vulnerability demonstrates the importance of proper bounds checking in kernel filesystem drivers and aligns with ATT&CK technique T1059.007 for execution through kernel modules and filesystem operations. Organizations should also implement principle of least privilege controls to limit local user access to filesystem mounting capabilities and consider using automated patch management systems to ensure timely deployment of security updates. The remediation process should include thorough testing of updated kernels in development environments before production deployment to ensure compatibility with existing udf filesystem usage patterns and applications.