CVE-2018-11508 in Linux
Summary
by MITRE
The compat_get_timex function in kernel/compat.c in the Linux kernel before 4.16.9 allows local users to obtain sensitive information from kernel memory via adjtimex.
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Analysis
by VulDB Data Team • 11/28/2024
The vulnerability identified as CVE-2018-11508 represents a critical information disclosure flaw within the Linux kernel's compatibility layer that affects systems running kernel versions prior to 4.16.9. This issue resides in the compat_get_timex function located in the kernel/compat.c file, which serves as a compatibility interface for 32-bit applications running on 64-bit systems. The vulnerability specifically manifests when the adjtimex system call is invoked, allowing local attackers with minimal privileges to extract sensitive kernel memory contents through improper handling of time synchronization parameters.
The technical flaw stems from inadequate input validation and memory handling within the compat_get_timex function, which processes time adjustment requests from 32-bit applications. When adjtimex is called with specific parameters, the function fails to properly sanitize or restrict access to kernel memory regions, enabling attackers to read beyond intended boundaries and retrieve confidential information such as kernel stack contents, memory addresses, or other sensitive data structures. This type of vulnerability falls under the CWE-200 category for Information Exposure and represents a classic case of improper access control in kernel space operations.
The operational impact of this vulnerability extends beyond simple information disclosure, as the leaked kernel memory could contain sensitive data including cryptographic keys, memory layout information, or other system-specific details that could aid in further exploitation attempts. Local attackers can leverage this vulnerability to gain insights into kernel memory organization, potentially enabling more sophisticated attacks such as kernel address space layout randomization (ASLR) bypasses or privilege escalation techniques. The vulnerability demonstrates how compatibility layers in operating systems can introduce security gaps that are not present in the native kernel implementation.
Mitigation strategies for CVE-2018-11508 primarily involve applying the official kernel patch released with version 4.16.9, which corrects the memory access handling in the compat_get_timex function. System administrators should prioritize updating their kernel versions to ensure protection against this vulnerability. Additionally, implementing proper access controls and monitoring for unusual adjtimex system call patterns can help detect potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1059 for executing malicious code and T1063 for credential access, as it provides a foothold for more advanced attacks. Organizations should also consider implementing kernel hardening measures such as stack canaries, kernel address space layout randomization, and restricting local user privileges to minimize potential impact. Regular security audits of kernel components and compatibility layers remain essential for identifying similar vulnerabilities that could compromise system integrity and confidentiality.