CVE-2018-10879 in Linux
Summary
by MITRE
A flaw was found in the Linux kernel's ext4 filesystem. A local user can cause a use-after-free in ext4_xattr_set_entry function and a denial of service or unspecified other impact may occur by renaming a file in a crafted ext4 filesystem image.
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Analysis
by VulDB Data Team • 04/27/2023
The vulnerability identified as CVE-2018-10879 represents a critical use-after-free condition within the Linux kernel's ext4 filesystem implementation that arises during the execution of the ext4_xattr_set_entry function. This flaw exists in the handling of extended attributes within ext4 filesystems and specifically manifests when a local user interacts with a crafted ext4 filesystem image through file renaming operations. The vulnerability stems from improper memory management practices where freed memory locations are accessed after the ext4_xattr_set_entry function has been invoked, creating a dangerous scenario that can be exploited by malicious users with local access privileges. The underlying technical issue involves the kernel's failure to properly validate or manage memory references during extended attribute modifications, particularly when filesystem operations involve renaming files within specially constructed filesystem images that trigger the problematic code path.
The operational impact of this vulnerability extends beyond simple denial of service to potentially encompass arbitrary code execution or system instability within affected Linux systems. When a local attacker successfully triggers the use-after-free condition, the kernel's memory management structures become corrupted, which can lead to unpredictable behavior including system crashes, kernel oops messages, or more severe security implications depending on the specific memory corruption patterns. The vulnerability affects systems running Linux kernel versions where the ext4 filesystem implementation has not received the relevant security patches, particularly impacting enterprise servers, desktop systems, and embedded devices that rely on ext4 filesystems for data storage. The local privilege requirement means that while the vulnerability does not allow for remote exploitation, it represents a significant escalation risk for users who already have local access to the system, potentially enabling privilege escalation or persistent denial of service conditions that could affect system availability and data integrity.
Mitigation strategies for CVE-2018-10879 primarily focus on applying the appropriate kernel security patches released by the Linux kernel development team and system vendors. Organizations should prioritize updating their Linux distributions to versions containing the fix for this vulnerability, which typically involves patching the ext4 filesystem implementation to properly handle memory management during extended attribute operations. System administrators should also consider implementing additional security controls such as restricting local user privileges where possible, monitoring for unusual filesystem operations, and maintaining regular system updates to prevent exploitation of similar vulnerabilities. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software implementations, and can be mapped to ATT&CK technique T1068, which covers the exploitation of local privileges for system compromise. Organizations should also conduct thorough vulnerability assessments to identify systems running vulnerable kernel versions and implement proper access controls to limit local user capabilities that could potentially exploit this vulnerability. The security community has documented this as a medium to high severity issue requiring prompt remediation, with the patch typically involving enhanced memory management validation within the ext4 filesystem subsystem to prevent the invalid memory access patterns that lead to the use-after-free condition.