CVE-2012-6542 in Linux
Summary
by MITRE
The llc_ui_getname function in net/llc/af_llc.c in the Linux kernel before 3.6 has an incorrect return value in certain circumstances, which allows local users to obtain sensitive information from kernel stack memory via a crafted application that leverages an uninitialized pointer argument.
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Analysis
by VulDB Data Team • 01/01/2022
The vulnerability identified as CVE-2012-6542 resides within the Linux kernel's implementation of the Logical Link Control protocol stack, specifically in the llc_ui_getname function located at net/llc/af_llc.c. This flaw represents a classic information disclosure vulnerability that arises from improper handling of kernel memory operations. The issue manifests when the function processes certain socket operations, particularly those involving the getname system call, where it fails to properly initialize a pointer argument before using it to retrieve socket address information. This misconfiguration creates a scenario where uninitialized memory values are inadvertently exposed to user-space applications through the socket interface.
The technical exploitation of this vulnerability stems from the function's failure to properly initialize a pointer variable that is subsequently dereferenced during the socket name retrieval process. According to CWE-457, this corresponds to the use of uninitialized variables, which is a well-documented weakness that can lead to information disclosure when uninitialized memory contents are returned to applications. The vulnerability operates at the kernel level, specifically within the LLC (Logical Link Control) subsystem that handles network protocol operations, making it particularly dangerous as it allows local privilege escalation and information gathering from kernel memory spaces. The flaw affects Linux kernel versions prior to 3.6, indicating that this was a long-standing issue that had not been properly addressed in the kernel's network stack implementation.
From an operational perspective, this vulnerability presents a significant risk to systems running affected kernel versions, as local users can leverage the uninitialized pointer to extract sensitive data from kernel memory. The extracted information may include cryptographic keys, passwords, session tokens, or other confidential data that could be stored in the kernel's memory space at the time of the function call. The attack vector is particularly concerning because it requires only local access to the system, meaning that any user with shell access could potentially exploit this weakness to gain unauthorized access to kernel memory contents. This type of vulnerability aligns with ATT&CK technique T1005, which covers data from local system, and demonstrates how seemingly minor implementation flaws in kernel functions can create substantial security risks.
The remediation for CVE-2012-6542 involves updating to Linux kernel version 3.6 or later, where the function properly initializes the pointer argument before use. System administrators should prioritize patching affected systems, particularly those running older kernel versions where this vulnerability remains unaddressed. The fix implemented in the patched kernel version ensures that all pointer arguments are properly initialized before being dereferenced, preventing the exposure of uninitialized memory contents to user-space applications. Organizations should also implement monitoring for any suspicious network activity or unexpected memory access patterns that might indicate exploitation attempts. Given the nature of this vulnerability and its potential impact on system security, regular kernel updates and security audits remain critical components of maintaining secure computing environments, especially in enterprise settings where kernel-level vulnerabilities can compromise entire network infrastructures.