CVE-2023-2124 in Linux
Summary
by MITRE • 05/16/2023
An out-of-bounds memory access flaw was found in the Linux kernel’s XFS file system in how a user restores an XFS image after failure (with a dirty log journal). This flaw allows a local user to crash or potentially escalate their privileges on the system.
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Analysis
by VulDB Data Team • 05/18/2023
The vulnerability identified as CVE-2023-2124 represents a critical out-of-bounds memory access flaw within the Linux kernel's XFS file system implementation. This issue specifically manifests during the recovery process of XFS file systems when dealing with dirty log journals, which occur when the file system experiences an unexpected failure or shutdown. The flaw exists in the kernel's handling of XFS image restoration procedures, where improper bounds checking allows for memory access violations that can lead to system instability. Such vulnerabilities are particularly dangerous because they can be exploited by local attackers who have access to the system, as the attack vector requires no network connectivity and can be executed from within the target environment.
The technical root cause of this vulnerability lies in insufficient input validation and memory boundary checking within the XFS recovery subsystem. When the kernel attempts to restore an XFS image following a failure condition with a dirty log journal, the code fails to properly validate array indices or buffer boundaries before accessing memory locations. This type of flaw falls under the CWE-129 category of Improper Validation of Array Index, which is a well-documented weakness in software systems that can lead to memory corruption. The specific implementation error occurs in the journal recovery logic where the kernel processes metadata structures without adequate bounds checking, allowing attackers to manipulate input parameters that control memory access patterns. This vulnerability is classified as a local privilege escalation vector because the memory corruption can potentially be leveraged to execute arbitrary code with elevated privileges, as the kernel operates at the highest privilege level within the system.
The operational impact of CVE-2023-2124 extends beyond simple system crashes, as it presents a significant threat to system integrity and availability. A local attacker who successfully exploits this vulnerability can cause the kernel to crash, leading to system-wide denial of service conditions that may require manual intervention or system reboot. More concerning is the potential for privilege escalation, where an attacker could gain root access to the system through carefully crafted inputs that trigger the memory corruption. The vulnerability is particularly dangerous in multi-user environments or systems where local access is not strictly controlled, as it provides a pathway for malicious users to compromise the entire system. From an attack perspective, this vulnerability aligns with the ATT&CK technique T1068 which involves exploiting local privilege escalation opportunities, and T1499 which covers network denial of service through system resource exhaustion. The flaw's impact is amplified by the fact that XFS is a widely used file system in enterprise environments, making the potential attack surface extensive.
Mitigation strategies for CVE-2023-2124 should focus on immediate kernel updates and system hardening measures. The primary solution involves applying the latest kernel patches from the Linux kernel security team, which include proper bounds checking and validation of memory access operations within the XFS recovery subsystem. System administrators should prioritize patching critical systems and implementing automated update mechanisms to ensure timely remediation. Additional defensive measures include implementing proper access controls to limit local user privileges, monitoring for unusual system behavior that might indicate exploitation attempts, and maintaining regular system backups to facilitate recovery from potential compromise. Network segmentation and privilege separation can help reduce the attack surface, while logging and monitoring systems should be configured to detect anomalous memory access patterns or kernel crashes. The vulnerability also highlights the importance of comprehensive security testing for file system implementations and the need for continuous vulnerability assessment of kernel subsystems. Organizations should consider implementing runtime protection mechanisms and intrusion detection systems that can identify and block exploitation attempts targeting similar memory corruption vulnerabilities. Regular security audits of file system implementations and kernel modules are essential to identify and remediate similar issues before they can be exploited by malicious actors.