CVE-2018-10878 in Linux
Summary
by MITRE
A flaw was found in the Linux kernel's ext4 filesystem. A local user can cause an out-of-bounds write and a denial of service or unspecified other impact is possible by mounting and operating a crafted ext4 filesystem image.
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Analysis
by VulDB Data Team • 04/27/2023
The vulnerability identified as CVE-2018-10878 represents a critical flaw within the Linux kernel's ext4 filesystem implementation that exposes systems to potential exploitation by local attackers. This issue stems from improper validation of filesystem metadata during the mounting process, creating a scenario where maliciously crafted ext4 filesystem images can trigger unexpected behavior in the kernel's handling routines. The vulnerability specifically affects the ext4 filesystem driver's ability to properly process certain metadata structures, leading to memory corruption conditions that can manifest in various security and stability impacts.
The technical root cause of this vulnerability lies in the kernel's ext4 filesystem code failing to adequately validate array indices when processing filesystem superblock and inode structures. When a maliciously constructed ext4 filesystem image is mounted, the kernel's parsing routines attempt to access memory locations beyond the allocated bounds due to insufficient boundary checks. This out-of-bounds write condition occurs during the initialization phase of filesystem operations, particularly when the kernel attempts to process extended attributes or inode metadata that contains crafted values designed to exceed expected array dimensions. The flaw operates at the kernel level and requires local access to the system since mounting a crafted filesystem image is necessary to trigger the vulnerability.
The operational impact of CVE-2018-10878 extends beyond simple denial of service scenarios to potentially enable more sophisticated attacks. While the primary consequence manifests as system instability and potential denial of service, the out-of-bounds write condition creates opportunities for privilege escalation or information disclosure depending on the specific memory corruption patterns. Attackers can leverage this vulnerability to cause system crashes, data corruption, or potentially execute arbitrary code with kernel privileges. The vulnerability affects all Linux kernel versions that implement the ext4 filesystem and are running kernel versions prior to the applicable security patches, making it particularly concerning for enterprise environments where kernel updates may be delayed or restricted.
Mitigation strategies for CVE-2018-10878 focus primarily on applying the relevant kernel security patches released by the Linux kernel development team and upstream distributions. System administrators should prioritize updating their kernel versions to include fixes that implement proper bounds checking in the ext4 filesystem driver's metadata processing routines. Additional protective measures include disabling unnecessary filesystem mounting capabilities, implementing strict file system access controls, and monitoring for suspicious filesystem mounting activities. The vulnerability aligns with CWE-129 which specifically addresses insufficient validation of array indices, and represents a clear example of how filesystem implementation flaws can create kernel-level security risks. Organizations should also consider implementing runtime monitoring solutions that can detect anomalous filesystem behavior patterns and provide early warning of potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting kernel-level vulnerabilities that allow local users to gain elevated system privileges through improper input validation in system-level components.