CVE-2012-6543 in Linux
Summary
by MITRE
The l2tp_ip6_getname function in net/l2tp/l2tp_ip6.c in the Linux kernel before 3.6 does not initialize a certain structure member, 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 • 01/01/2022
The vulnerability identified as CVE-2012-6543 resides within the Linux kernel's Layer 2 Tunneling Protocol implementation for IPv6 addressing. This flaw specifically affects the l2tp_ip6_getname function located in the net/l2tp/l2tp_ip6.c source file, which is part of the kernel's network subsystem responsible for handling L2TPv6 tunneling operations. The issue manifests when the function fails to properly initialize a critical structure member during its execution, creating a potential information disclosure vulnerability that can be exploited by local attackers.
The technical nature of this vulnerability stems from improper memory initialization within the kernel's L2TPv6 implementation. When the l2tp_ip6_getname function processes network requests, it does not initialize all members of a structure before returning data to user-space applications. This incomplete initialization leaves residual data from kernel stack memory accessible to the calling application, effectively allowing local users to read uninitialized memory contents that may contain sensitive information such as kernel pointers, stack contents, or other confidential data structures. The vulnerability is classified as a information exposure issue that violates fundamental security principles of memory isolation and data sanitization.
From an operational perspective, this vulnerability represents a significant risk to systems running affected Linux kernel versions prior to 3.6. Local attackers who can execute arbitrary code on the system can leverage this flaw to extract sensitive kernel memory contents, potentially revealing information that could aid in more sophisticated attacks. The impact extends beyond simple information disclosure, as the leaked memory contents might contain cryptographic keys, session identifiers, or other data that could be used to escalate privileges or conduct further exploitation attempts. This vulnerability is particularly concerning in environments where local access is possible, as it provides attackers with a means to gather intelligence about the kernel state and configuration.
The vulnerability maps to CWE-1287, which specifically addresses improper initialization of structure members in kernel code, and aligns with ATT&CK technique T1005 for data from local system. The flaw demonstrates poor coding practices in kernel space where memory safety mechanisms are not properly enforced. Organizations should immediately apply the kernel patch released in version 3.6, which addresses this issue by ensuring proper initialization of all structure members within the l2tp_ip6_getname function. Additionally, system administrators should implement monitoring for suspicious local activity and consider restricting local user access to minimize potential exploitation vectors. The remediation process should include comprehensive kernel updates across all affected systems, followed by verification that the patched version properly initializes all memory structures to prevent similar issues in the future.