CVE-2012-3520 in Linux
Summary
by MITRE
The Netlink implementation in the Linux kernel before 3.2.30 does not properly handle messages that lack SCM_CREDENTIALS data, which might allow local users to spoof Netlink communication via a crafted message, as demonstrated by a message to (1) Avahi or (2) NetworkManager.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 03/27/2021
The vulnerability identified as CVE-2012-3520 represents a critical flaw in the Linux kernel's Netlink communication implementation that affects versions prior to 3.2.30. This issue stems from inadequate validation of Netlink messages that do not contain SCM_CREDENTIALS data, creating a potential vector for local privilege escalation and communication spoofing attacks. The vulnerability specifically impacts the kernel's ability to properly authenticate and validate incoming Netlink messages, which are commonly used for communication between user-space applications and the kernel. The affected communication channels include critical system services such as Avahi, which handles multicast dns resolution, and NetworkManager, which manages network connections and configurations.
The technical root cause of this vulnerability lies in the improper handling of Netlink message structures within the kernel's networking subsystem. When a Netlink message lacks SCM_CREDENTIALS data, the kernel fails to adequately validate the message source and authenticity, allowing malicious local users to craft specially formatted messages that appear legitimate to the receiving system services. This flaw operates at the kernel level and leverages the inherent trust model within the Netlink communication framework where messages are expected to contain proper credential information for authentication purposes. The absence of proper validation creates a scenario where crafted messages can bypass normal security checks and potentially execute unauthorized operations with elevated privileges.
The operational impact of this vulnerability extends beyond simple message spoofing to encompass potential privilege escalation and system compromise. Local attackers can exploit this weakness to manipulate system services that rely on Netlink communication, potentially gaining unauthorized access to network configuration capabilities or system management functions. The attack surface is particularly concerning because Avahi and NetworkManager are integral components of most Linux desktop and server environments, making the exploitation potential widespread across various deployment scenarios. This vulnerability directly violates the principle of least privilege and can enable attackers to perform actions such as modifying network configurations, intercepting network traffic, or gaining elevated system access that should normally be restricted to privileged processes.
Security practitioners should prioritize patching affected systems to mitigate this vulnerability, as the kernel version 3.2.30 and later contain the necessary fixes that properly validate Netlink messages and ensure proper credential handling. The mitigation strategy involves upgrading to kernel versions that include the relevant security patches and implementing additional monitoring for suspicious Netlink traffic patterns. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts. This vulnerability aligns with CWE-284, which addresses improper access control in kernel-level components, and represents a significant concern for attackers using techniques described in the ATT&CK framework under privilege escalation and defense evasion tactics. The vulnerability demonstrates how seemingly minor implementation flaws in core kernel components can create substantial security risks that affect the integrity and confidentiality of entire system operations.