CVE-2015-4167 in Linux
Summary
by MITRE
The udf_read_inode function in fs/udf/inode.c in the Linux kernel before 3.19.1 does not validate certain length values, which allows local users to cause a denial of service (incorrect data representation or integer overflow, and OOPS) via a crafted UDF filesystem.
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Analysis
by VulDB Data Team • 05/20/2022
The vulnerability identified as CVE-2015-4167 resides within the Linux kernel's Universal Disk Format UDF filesystem implementation, specifically in the udf_read_inode function located in fs/udf/inode.c. This flaw represents a classic case of insufficient input validation that can be exploited by local attackers to disrupt system operations. The vulnerability affects Linux kernel versions prior to 3.19.1, making it a significant concern for systems running older kernel versions. The issue manifests when the kernel processes UDF filesystem structures without properly validating length parameters, creating opportunities for malformed data to cause system instability. From a cybersecurity perspective, this vulnerability demonstrates how filesystem-level flaws can be leveraged for denial of service attacks, potentially compromising system availability and integrity.
The technical root cause of CVE-2015-4167 stems from the absence of proper validation mechanisms within the udf_read_inode function. When processing UDF filesystem metadata, the function fails to validate length values that are read from the filesystem structure, allowing maliciously crafted UDF filesystems to contain invalid or excessively large length fields. This validation gap leads to two primary failure modes: incorrect data representation and integer overflow conditions. The integer overflow occurs when the kernel attempts to process length values that exceed the maximum representable values for the underlying data types, causing unexpected behavior in memory allocation and data handling operations. The resulting system crashes manifest as kernel OOPS messages, which are kernel-level error reports indicating critical internal inconsistencies that occur when the kernel encounters unexpected conditions during execution.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be exploited to cause system instability and potential data corruption. Local attackers with access to the system can craft malicious UDF filesystems containing specially constructed length fields that trigger the vulnerability when the kernel attempts to read inode information. The consequences include system crashes, kernel panics, and complete system unresponsiveness, effectively rendering the affected system unavailable to legitimate users. This type of vulnerability is particularly concerning in environments where local access is possible, as it can be exploited by users with minimal privileges to disrupt system operations. The vulnerability's classification under CWE-129 indicates it involves insufficient validation of length values, while its operational characteristics align with ATT&CK technique T1499.001 for network denial of service, though applied to local system resources.
Mitigation strategies for CVE-2015-4167 primarily focus on kernel version updates and system hardening measures. The most effective remediation involves upgrading to Linux kernel version 3.19.1 or later, where the validation checks have been implemented to prevent the exploitation of malformed length values. System administrators should prioritize patch management processes to ensure all systems are running patched kernel versions. Additionally, implementing filesystem access controls and monitoring for unusual UDF filesystem usage can help detect potential exploitation attempts. The vulnerability highlights the importance of proper input validation in kernel space operations and demonstrates how seemingly minor validation gaps can lead to significant system stability issues. Organizations should also consider implementing automated patch deployment mechanisms and regular security assessments to identify and remediate similar vulnerabilities in their system components.