CVE-2018-12929 in Linux
Summary
by MITRE
ntfs_read_locked_inode in the ntfs.ko filesystem driver in the Linux kernel 4.15.0 allows attackers to trigger a use-after-free read and possibly cause a denial of service (kernel oops or panic) via a crafted ntfs filesystem.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability identified as CVE-2018-12929 represents a critical use-after-free condition within the ntfs.ko filesystem driver of the Linux kernel version 4.15.0. This flaw resides in the ntfs_read_locked_inode function which handles reading locked inodes from ntfs filesystems. The issue manifests when attackers construct malicious ntfs filesystem structures that exploit improper memory management during inode processing. The vulnerability falls under CWE-416, which specifically addresses use-after-free conditions where memory is accessed after it has been freed, creating potential security risks and system instability.
The technical exploitation of this vulnerability occurs when the ntfs filesystem driver encounters specially crafted filesystem structures that cause the ntfs_read_locked_inode function to access memory that has already been deallocated. This use-after-free condition can be triggered through normal filesystem operations when the kernel attempts to read inode data from a malformed ntfs filesystem. The memory corruption resulting from this improper access can lead to kernel oops messages or complete system panics, effectively causing a denial of service condition. The vulnerability's impact extends beyond simple service disruption as it can potentially be leveraged to execute arbitrary code within kernel space, representing a significant threat to system integrity and availability.
From an operational perspective, this vulnerability presents a serious risk to systems that mount ntfs filesystems, particularly those running kernel version 4.15.0 or earlier. The attack vector requires an attacker to either have control over an ntfs filesystem that gets mounted or to convince a victim to mount a malicious ntfs image. The vulnerability can be exploited remotely through network-mounted ntfs shares or locally through physical access to storage devices. The potential for denial of service means that critical systems relying on ntfs filesystem support could experience unexpected outages, while the possibility of arbitrary code execution opens avenues for privilege escalation and persistent system compromise. This vulnerability aligns with ATT&CK technique T1068 which covers local privilege escalation through kernel exploits, and T1499 which addresses network denial of service attacks through filesystem manipulation.
Mitigation strategies for CVE-2018-12929 involve immediate kernel updates to versions that contain the patched ntfs.ko driver code, specifically kernel versions 4.15.1 and later which address the use-after-free condition. System administrators should also implement filesystem access controls to prevent mounting of untrusted ntfs filesystems, particularly in multi-user environments. Additional protective measures include disabling ntfs filesystem support entirely if not required, implementing strict filesystem validation for mounted volumes, and monitoring system logs for kernel oops messages that may indicate exploitation attempts. The patch addresses the root cause by properly managing memory references within the ntfs_read_locked_inode function, ensuring that inode data access occurs only when memory is valid and allocated. Organizations should prioritize patching this vulnerability as it represents a direct threat to system stability and security, particularly in environments where ntfs filesystems are commonly used or mounted from untrusted sources.