CVE-2016-4951 in Linux
Summary
by MITRE • 01/25/2023
The tipc_nl_publ_dump function in net/tipc/socket.c in the Linux kernel through 4.6 does not verify socket existence, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact via a dumpit operation.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2016-4951 resides within the Linux kernel's TIPC (Transparent Inter-Process Communication) subsystem, specifically in the tipc_nl_publ_dump function located in net/tipc/socket.c. This flaw represents a critical security issue that affects Linux kernel versions through 4.6, where the function fails to properly validate socket existence before proceeding with dump operations. The TIPC protocol is designed to provide high-performance communication between processes in distributed systems, making this vulnerability particularly concerning for environments relying on kernel-level messaging capabilities. The vulnerability stems from inadequate input validation and resource management within the kernel's network subsystem, creating a pathway for malicious local users to exploit the system's communication infrastructure.
The technical implementation of this vulnerability manifests as a NULL pointer dereference condition that occurs when the tipc_nl_publ_dump function attempts to process dumpit operations without first verifying that the target socket exists. This type of flaw falls under CWE-476, which specifically addresses NULL pointer dereference vulnerabilities in software systems. When a local user crafts a malicious dumpit operation, the function proceeds to access memory locations that have not been properly initialized or validated, resulting in system crashes and potential denial of service conditions. The kernel's failure to implement proper socket validation creates an exploitable condition where arbitrary memory access can occur, leading to unpredictable system behavior and complete system instability.
The operational impact of CVE-2016-4951 extends beyond simple denial of service scenarios, as it can potentially enable local privilege escalation or arbitrary code execution depending on the system configuration and attack vector. This vulnerability is particularly dangerous in multi-user environments where local users might attempt to exploit the system to gain elevated privileges or disrupt system operations. The attack surface is limited to local users with access to the system, but the potential for system-wide disruption makes this a significant concern for security administrators. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving privilege escalation and denial of service, specifically targeting the kernel's network communication mechanisms. The vulnerability can be exploited through local system calls or network operations that trigger the TIPC dump functionality, making it accessible to any user with sufficient privileges to interact with the kernel's network interfaces.
Mitigation strategies for this vulnerability require immediate kernel updates to versions that contain the appropriate patches addressing the socket validation issue in the TIPC subsystem. System administrators should prioritize applying security updates from their respective Linux distributions, as the fix typically involves implementing proper socket existence checks before proceeding with dump operations. Additionally, implementing kernel hardening measures such as disabling unnecessary network protocols, restricting local user privileges, and monitoring for suspicious network operations can help reduce the attack surface. Organizations should also consider implementing intrusion detection systems that can identify anomalous dumpit operations or other network communication patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and resource management in kernel space operations, emphasizing the need for comprehensive security testing and code review processes to prevent similar issues in other kernel subsystems.