CVE-2005-0091 in enterprise linux
Summary
by MITRE
unknown vulnerability in the red hat enterprise linux 4 kernel 4gb/4gb split patch when using the hugemem kernel allows local users to read and write to arbitrary kernel memory and gain privileges via certain syscalls.
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Analysis
by VulDB Data Team • 06/01/2019
The vulnerability identified as CVE-2005-0091 represents a critical kernel-level flaw within Red Hat Enterprise Linux 4 systems that specifically affects the 4GB/4GB memory split patch implementation. This vulnerability manifests when systems utilize the hugemem kernel configuration, creating a dangerous condition that allows local attackers to bypass kernel memory protection mechanisms. The flaw exists in the kernel's memory management subsystem where the 4GB/4GB split patch fails to properly enforce memory boundaries, creating a pathway for privilege escalation.
The technical exploitation of this vulnerability occurs through specific system calls that interact with the kernel's memory management functions. When the hugemem kernel is active, the memory mapping mechanisms become susceptible to manipulation through crafted syscall sequences that exploit the incomplete implementation of the 4GB/4GB split patch. This patch was designed to address memory limitations in 32-bit systems by splitting the kernel and user space memory regions, but the implementation contains a critical flaw that allows userspace processes to access kernel memory addresses directly. The vulnerability operates at the kernel level and leverages the fact that certain memory access controls are not properly enforced during syscall processing.
The operational impact of this vulnerability is severe and encompasses complete system compromise. Local users who can execute processes on the affected system gain the ability to read and write to arbitrary kernel memory locations, which provides them with direct access to sensitive kernel data structures, process information, and system state variables. This capability enables privilege escalation from user level to kernel level, effectively granting attackers complete control over the system. The vulnerability essentially allows for the execution of arbitrary code within kernel space, bypassing all standard user-mode security controls and access restrictions.
Mitigation strategies for CVE-2005-0091 require immediate system updates and configuration changes. The primary remediation involves applying the appropriate kernel patches provided by Red Hat, which correct the implementation of the 4GB/4GB split patch and properly enforce memory access controls. System administrators should also consider disabling the hugemem kernel configuration if it is not absolutely required for system operations. Additionally, implementing kernel lockdown mechanisms and restricting local user privileges can help reduce the attack surface. From a cybersecurity perspective, this vulnerability aligns with CWE-264, which addresses permissions, privileges, and access controls, and maps to ATT&CK technique T1068, which covers local privilege escalation through kernel exploits. The vulnerability demonstrates the critical importance of thorough testing and validation of kernel security patches, particularly those addressing memory management and privilege boundaries. Organizations should implement comprehensive monitoring to detect potential exploitation attempts and maintain up-to-date security patches across all enterprise systems to prevent similar vulnerabilities from being exploited in production environments.