CVE-2012-4530 in Linux
Summary
by MITRE
The load_script function in fs/binfmt_script.c in the Linux kernel before 3.7.2 does not properly handle recursion, which allows local users to obtain sensitive information from kernel stack memory via a crafted application.
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Analysis
by VulDB Data Team • 09/25/2024
The vulnerability identified as CVE-2012-4530 resides within the Linux kernel's binary format script handling mechanism, specifically in the load_script function located in fs/binfmt_script.c. This flaw represents a classic case of improper recursion handling that can lead to information disclosure through kernel memory exposure. The vulnerability affects Linux kernel versions prior to 3.7.2, making it a significant concern for systems running older kernel versions where patching may not have been implemented. The issue stems from how the kernel processes script interpreters and their associated execution contexts, particularly when dealing with nested or recursive script invocations.
The technical flaw manifests when a malicious local user crafts a specially designed application that triggers the load_script function to execute in a recursive manner. The kernel's script loading mechanism fails to properly validate or limit the depth of recursive calls, allowing the execution to traverse into kernel memory spaces where sensitive information may be exposed. This recursive handling issue creates a path where kernel stack memory contents can be accessed and potentially leaked to user-space processes. The vulnerability is particularly dangerous because it operates at the kernel level, bypassing normal user-space memory protection mechanisms and potentially exposing confidential data such as cryptographic keys, passwords, or other sensitive kernel structures.
From an operational perspective, this vulnerability poses a serious risk to system security as it allows local privilege escalation and information disclosure without requiring elevated privileges initially. The attack vector is relatively straightforward since it only requires local user access to craft a malicious application, making it accessible to any user with shell access to the system. The impact extends beyond simple information disclosure as the leaked kernel memory could contain sensitive data that might be used to facilitate further attacks or compromise system integrity. According to CWE classification, this vulnerability maps to CWE-121, which deals with stack-based buffer overflow conditions, though the specific implementation involves improper recursion handling rather than traditional buffer overflows. The ATT&CK framework categorizes this under privilege escalation and credential access techniques, as the vulnerability enables local users to gain access to kernel memory that should remain protected.
The mitigation strategy for CVE-2012-4530 primarily involves upgrading to Linux kernel version 3.7.2 or later, where the recursion handling in load_script has been properly addressed. System administrators should prioritize patching affected systems, particularly those running older kernel versions where the vulnerability remains unaddressed. Additional defensive measures include implementing proper access controls to limit local user capabilities, monitoring for suspicious script execution patterns, and ensuring that system updates are applied promptly. Organizations should also consider implementing kernel hardening measures such as stack canaries, kernel address space layout randomization, and other security enhancements that can help mitigate the impact of similar vulnerabilities. The vulnerability highlights the importance of proper recursion handling in kernel code and demonstrates how seemingly simple flaws in system components can lead to significant security implications. Regular security audits of kernel components and adherence to security best practices in kernel development are essential to prevent similar issues from emerging in future releases.