CVE-2010-3876 in Linux
Summary
by MITRE
net/packet/af_packet.c in the Linux kernel before 2.6.37-rc2 does not properly initialize certain structure members, which allows local users to obtain potentially sensitive information from kernel stack memory by leveraging the CAP_NET_RAW capability to read copies of the applicable structures.
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Analysis
by VulDB Data Team • 10/07/2021
The vulnerability described in CVE-2010-3876 resides within the Linux kernel's packet socket implementation, specifically in the net/packet/af_packet.c file. This flaw represents a classic information disclosure vulnerability that affects systems running Linux kernel versions prior to 2.6.37-rc2. The issue manifests when certain structure members within the packet socket subsystem are not properly initialized during kernel operations, creating potential pathways for unauthorized information extraction.
The technical flaw occurs in the af_packet.c implementation where kernel structures used for packet socket operations contain uninitialized memory regions. When processes with the CAP_NET_RAW capability attempt to read from packet socket structures, they can inadvertently access uninitialized portions of kernel memory that may contain sensitive data from previous operations. This uninitialized memory could include remnants of passwords, cryptographic keys, network credentials, or other confidential information that was previously stored in those memory locations. The vulnerability is particularly concerning because it leverages existing privileges through the CAP_NET_RAW capability, making it accessible to users who already possess network administration permissions.
From an operational impact perspective, this vulnerability creates a significant risk for systems where local users have access to the CAP_NET_RAW capability, which is typically granted to network administrators and privileged services. The exposure of kernel stack memory can potentially reveal sensitive information that could be exploited by attackers to escalate privileges or conduct further reconnaissance. The vulnerability affects the confidentiality aspect of the CIA triad and can be classified under CWE-248, which deals with exposure of uninitialized variables. Attackers could potentially use this information to construct more sophisticated attacks against the system.
The attack vector requires local access with the CAP_NET_RAW capability, making it a privilege escalation vulnerability that can be exploited by users who already have elevated permissions. This aligns with ATT&CK technique T1068, which involves privilege escalation through the exploitation of system vulnerabilities. The vulnerability demonstrates the importance of proper memory initialization in kernel code and highlights the potential for information disclosure even within privileged execution contexts. Systems affected by this vulnerability should implement immediate patching to upgrade to Linux kernel version 2.6.37-rc2 or later, which contains the necessary fixes to properly initialize the affected structure members and prevent access to uninitialized kernel memory regions.
Organizations should also consider implementing additional monitoring for unusual packet socket activity and ensure that the CAP_NET_RAW capability is granted only to absolutely necessary processes and users. The vulnerability underscores the critical need for thorough code review processes in kernel development, particularly focusing on memory management and initialization practices that can lead to information disclosure vulnerabilities. Security teams should prioritize patch management for this specific vulnerability as it represents a straightforward but potentially dangerous exposure that can be exploited by malicious users with existing network privileges.