CVE-2002-1826 in Kernel Patch
Summary
by MITRE
grsecurity 1.9.4 for Linux kernel 2.4.18 allows local users to bypass read-only permissions by using mmap to directly map /dev/mem or /dev/kmem to kernel memory.
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Analysis
by VulDB Data Team • 11/22/2024
The vulnerability identified as CVE-2002-1826 represents a critical security flaw in the grsecurity kernel patch version 1.9.4 for Linux kernel 2.4.18. This issue specifically targets the kernel's memory management subsystem and undermines the fundamental security model that protects against unauthorized access to kernel memory spaces. The vulnerability exists within the memory mapping mechanisms that are designed to prevent direct access to sensitive kernel memory regions, creating a pathway for local attackers to circumvent these protections through legitimate system calls.
The technical implementation of this vulnerability exploits the mmap system call functionality to directly map kernel memory devices such as /dev/mem and /dev/kmem into user-space memory. These device files traditionally provide access to physical memory and kernel memory respectively, and are typically restricted to prevent unauthorized access to kernel data structures and code. However, the grsecurity implementation in version 1.9.4 failed to properly enforce restrictions on these mappings, allowing local users to bypass the intended read-only permissions that should prevent direct kernel memory access. This flaw operates at the kernel level and leverages the underlying memory management capabilities that are essential for system operation but can be abused when proper access controls are circumvented.
The operational impact of this vulnerability is significant as it provides local attackers with direct access to kernel memory spaces, potentially enabling them to read sensitive kernel data, modify kernel structures, or even execute arbitrary code within kernel context. This type of privilege escalation allows attackers to gain elevated privileges and potentially compromise the entire system, as kernel memory access can reveal critical system information, modify security controls, and enable further attacks. The vulnerability affects systems running the specific kernel version 2.4.18 with the grsecurity patch applied, making it particularly concerning for organizations that rely on these security enhancements for system protection.
This vulnerability aligns with CWE-264, which addresses permissions, privileges, and access controls, specifically focusing on the failure to properly enforce access restrictions on kernel memory mappings. The issue also relates to ATT&CK technique T1068, which involves local privilege escalation through the exploitation of system vulnerabilities. The flaw demonstrates how security enhancements designed to protect systems can themselves contain implementation weaknesses that create new attack vectors. Organizations should implement immediate mitigations including updating to patched kernel versions, disabling unnecessary memory mapping capabilities, and monitoring for unauthorized access attempts to kernel memory regions. The vulnerability underscores the importance of thorough security testing of kernel patches and the need for continuous vigilance in protecting against privilege escalation attacks that target fundamental system mechanisms.