CVE-2006-2448 in Linux
Summary
by MITRE
Linux kernel before 2.6.16.21 and 2.6.17, when running on PowerPC, does not perform certain required access_ok checks, which allows local users to read arbitrary kernel memory on 64-bit systems (signal_64.c) and cause a denial of service (crash) and possibly read kernel memory on 32-bit systems (signal_32.c).
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Analysis
by VulDB Data Team • 06/24/2019
This vulnerability exists in the linux kernel version 2.6.16.21 and 2.6.17 when running on powerpc architectures. The flaw stems from insufficient access validation mechanisms within the kernel's signal handling code specifically in the signal_64.c and signal_32.c files. The missing access_ok checks represent a critical security oversight that undermines the kernel's memory protection mechanisms. This vulnerability is categorized under cwe-20 as improper input validation, specifically failing to validate memory access permissions before allowing user-space processes to interact with kernel memory regions.
The technical implementation of this vulnerability allows local users to exploit the missing access_ok checks in the kernel's signal delivery mechanisms. On 64-bit powerpc systems, attackers can read arbitrary kernel memory locations through the signal_64.c code path, while on 32-bit systems the same vulnerability enables both denial of service through kernel crashes and potential memory reading capabilities. The flaw occurs during signal handling when the kernel fails to properly validate that user-space pointers reference valid memory locations before attempting to access kernel memory. This represents a classic privilege escalation vector that leverages the kernel's insufficient bounds checking.
The operational impact of this vulnerability extends beyond simple information disclosure. Local attackers can potentially extract sensitive kernel data such as cryptographic keys, password hashes, or other confidential information stored in kernel memory. The denial of service component creates system instability that can be exploited for persistent availability attacks. From an attack framework perspective, this vulnerability aligns with techniques described in the attack pattern taxonomy under privilege escalation and information disclosure categories. The vulnerability affects systems running powerpc architecture specifically, making it relevant to embedded systems, network appliances, and specialized computing platforms that utilize powerpc processors.
Mitigation strategies for this vulnerability include immediate patching to kernel versions 2.6.16.21 and 2.6.17 or later where the access_ok checks have been properly implemented. System administrators should also consider implementing additional monitoring for unusual memory access patterns and signal handling activities. The vulnerability demonstrates the importance of comprehensive input validation in kernel code and highlights the necessity of thorough security reviews for memory management functions. Organizations should ensure their powerpc-based systems are updated promptly and maintain regular kernel security assessments to prevent similar vulnerabilities from being exploited in their environments.