CVE-2005-0090 in Red Hat
Summary
by MITRE
A regression error in the Red Hat Enterprise Linux 4 kernel 4GB/4GB split patch omits an "access check," which allows local users to cause a denial of service (crash).
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 06/01/2019
The vulnerability identified as CVE-2005-0090 represents a critical regression error within the Red Hat Enterprise Linux 4 kernel implementation that specifically affects the 4GB/4GB memory split patch. This patch was designed to address memory management concerns in 32-bit x86 architectures where the kernel and user space shared the same address space, creating potential security risks. The implementation of the 4GB/4GB split was intended to separate kernel and user space memory regions to prevent unauthorized access and improve system stability. However, the regression introduced a significant flaw that undermines the intended security benefits of this memory management approach.
The technical flaw manifests as an omitted access check within the kernel's memory management subsystem, specifically in how it handles memory address translations and virtual memory mappings. When local users execute certain operations that trigger memory access patterns, the kernel fails to properly validate whether the requested memory access is permitted or valid. This absence of access validation creates a condition where malicious or malformed memory operations can cause the kernel to crash, resulting in a denial of service scenario that affects the entire system. The vulnerability is particularly dangerous because it occurs within kernel space, where unauthorized access can lead to complete system compromise, and the lack of proper access controls means that local users can exploit this weakness without requiring elevated privileges.
The operational impact of CVE-2005-0090 extends beyond simple system crashes as it represents a fundamental breakdown in kernel memory protection mechanisms. Local users can exploit this vulnerability to crash the kernel, potentially causing system-wide service disruption and requiring manual intervention to restore normal operations. The vulnerability is classified under CWE-284, which addresses improper access control, and aligns with ATT&CK technique T1068, which involves local privilege escalation through kernel vulnerabilities. This regression demonstrates how seemingly minor implementation errors in kernel code can have severe consequences for system stability and security, particularly in enterprise environments where Red Hat Enterprise Linux 4 was widely deployed. The vulnerability affects systems running the specific kernel versions that include the problematic 4GB/4GB split patch, making it a targeted issue for organizations using older enterprise Linux distributions.
Mitigation strategies for this vulnerability focus primarily on applying the appropriate kernel patches provided by Red Hat to correct the regression error and restore proper access checking mechanisms. System administrators should prioritize updating their kernel versions to include the corrected implementation of the 4GB/4GB split patch, ensuring that all access validation checks are properly enforced. Additionally, monitoring systems should be implemented to detect unusual memory access patterns that might indicate exploitation attempts, and network segmentation strategies can help limit the potential impact of successful exploits. Organizations should also consider implementing kernel hardening measures such as disabling unnecessary kernel features and employing mandatory access controls to reduce the attack surface. The vulnerability underscores the critical importance of thorough testing during kernel updates and patch implementations, as regressions can introduce more severe security issues than the original problems they were intended to solve.