CVE-2018-12931 in Linux
Summary
by MITRE
ntfs_attr_find in the ntfs.ko filesystem driver in the Linux kernel 4.15.0 allows attackers to trigger a stack-based out-of-bounds write and cause a denial of service (kernel oops or panic) or possibly have unspecified other impact via a crafted ntfs filesystem.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability identified as CVE-2018-12931 represents a critical stack-based buffer overflow in the ntfs.ko filesystem driver component of the Linux kernel version 4.15.0. This flaw exists within the ntfs_attr_find function which processes attribute searches in ntfs filesystems, creating a potential pathway for attackers to execute arbitrary code or cause system instability. The vulnerability specifically affects systems running Linux kernel versions up to and including 4.15.0, making it particularly concerning given the widespread adoption of these kernel versions in enterprise and consumer environments. The flaw manifests when the kernel attempts to process malformed or crafted ntfs filesystem data structures, leading to improper memory management during attribute lookup operations.
The technical implementation of this vulnerability stems from inadequate bounds checking within the ntfs_attr_find function where the kernel fails to properly validate array indices or buffer sizes when traversing attribute lists in ntfs filesystem metadata. This insufficient validation allows attackers to craft malicious ntfs filesystem images containing specially formatted attribute records that cause the kernel to write beyond allocated stack memory boundaries. The stack-based nature of the overflow means that the attacker can overwrite adjacent stack variables, function return addresses, or other critical execution context information. According to CWE-121, this vulnerability maps directly to stack-based buffer overflow conditions where insufficient bounds checking allows for memory corruption during execution. The improper input validation in the ntfs filesystem driver creates an exploitable condition that can be triggered through normal filesystem operations when the kernel mounts or processes the malicious ntfs volume.
The operational impact of CVE-2018-12931 extends beyond simple denial of service scenarios, presenting significant risks to system availability and potentially enabling more sophisticated attacks. When exploited successfully, the vulnerability can trigger kernel oops messages or complete system panics, effectively causing denial of service for the affected system. However, the potential for unspecified other impacts suggests that under certain conditions, attackers might be able to leverage this flaw for privilege escalation or code execution within kernel space. The vulnerability's exploitation requires an attacker to have control over an ntfs filesystem, which could occur through various attack vectors including malicious USB drives, network attached storage devices, or compromised network shares. Organizations running affected kernel versions face substantial risk as this vulnerability can be exploited remotely through mounted ntfs volumes, particularly in environments where users have the ability to mount external storage devices or access network file systems.
Mitigation strategies for CVE-2018-12931 primarily focus on kernel version updates and filesystem access controls. The most effective immediate solution involves upgrading to Linux kernel versions 4.15.1 or later where the vulnerability has been patched through improved bounds checking in the ntfs_attr_find function. System administrators should also implement strict filesystem access policies, particularly disabling automatic mounting of external ntfs volumes and restricting user permissions for mounting ntfs filesystems. The ATT&CK framework categorizes this vulnerability under T1059.007 for kernel-mode rootkits and T1489 for system shutdown/reboot, as the exploitation can lead to system instability and denial of service conditions. Additional defensive measures include implementing filesystem monitoring to detect suspicious ntfs structures and deploying kernel security modules such as kernel page table isolation or control flow integrity checks to detect and prevent exploitation attempts. Organizations should also conduct vulnerability assessments to identify systems running affected kernel versions and prioritize patching activities based on risk exposure and system criticality.