CVE-2007-2172 in Linux
Summary
by MITRE
A typo in Linux kernel 2.6 before 2.6.21-rc6 and 2.4 before 2.4.35 causes RTA_MAX to be used as an array size instead of RTN_MAX, which leads to an "out of bound access" by the (1) dn_fib_props (dn_fib.c, DECNet) and (2) fib_props (fib_semantics.c, IPv4) functions.
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Analysis
by VulDB Data Team • 07/19/2019
This vulnerability represents a critical integer overflow and out-of-bounds memory access flaw in the Linux kernel's routing table handling mechanisms. The issue stems from a simple but devastating typo in the kernel source code where RTA_MAX is incorrectly used as an array size parameter instead of the intended RTN_MAX constant. This type of error falls under the CWE-129 weakness category, specifically involving improper validation of array indices or buffer bounds. The vulnerability affects both the DECNet implementation through the dn_fib_props function in dn_fib.c and the IPv4 routing table semantics through the fib_props function in fib_semantics.c, demonstrating how a single typo can compromise multiple network protocols within the same kernel subsystem.
The technical exploitation of this vulnerability occurs during routing table processing when the kernel attempts to allocate or access memory arrays based on the incorrect RTA_MAX value. This improper array sizing leads to out-of-bounds memory access patterns that can result in kernel memory corruption, potential privilege escalation, or system instability. The flaw is particularly dangerous because it operates at the kernel level where memory corruption can lead to complete system compromise. According to ATT&CK framework, this vulnerability maps to T1068 - Exploitation for Privilege Escalation and T1590 - Targeted Threat Activity, as it enables attackers to exploit kernel-level memory corruption to gain elevated privileges. The vulnerability's impact is amplified by the fact that routing table operations are fundamental to network functionality and occur frequently in normal system operation.
The operational impact of CVE-2007-2172 extends beyond simple memory corruption to potentially enable remote code execution or denial of service conditions. Systems running affected kernel versions are vulnerable to exploitation through network-based attacks that trigger the routing table processing functions. The vulnerability affects a wide range of Linux systems including servers, routers, and embedded devices that rely on kernel networking capabilities. Organizations with systems running kernel versions prior to 2.6.21-rc6 or 2.4.35 are at significant risk, as this vulnerability can be exploited by attackers with network access to the affected systems. The nature of the flaw means that exploitation does not require special privileges, making it particularly dangerous in multi-user environments where network access might be available to unprivileged users.
Mitigation strategies for this vulnerability center around immediate kernel version upgrades to patched releases. System administrators should prioritize updating to kernel versions 2.6.21-rc6 or later for 2.6 series, and 2.4.35 or later for 2.4 series, which contain the corrected RTA_MAX and RTN_MAX usage. Additionally, network segmentation and firewall rules can help limit exposure by restricting access to routing table modification interfaces. The vulnerability demonstrates the critical importance of thorough code review processes and the potential for seemingly minor typos to create major security issues. Organizations should implement regular kernel patching procedures and maintain awareness of security advisories from kernel maintainers and security vendors. This vulnerability also highlights the necessity of automated testing and static analysis tools to catch such errors during development cycles, as the error would likely be caught by proper code analysis tools that monitor for improper array sizing and memory access patterns.