CVE-2015-7553 in Red Hat
Summary
by MITRE
Race condition in the kernel in Red Hat Enterprise Linux 7, kernel-rt and Red Hat Enterprise MRG 2, when the nfnetlink_log module is loaded, allows local users to cause a denial of service (panic) by creating netlink sockets.
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Analysis
by VulDB Data Team • 11/16/2019
The vulnerability identified as CVE-2015-7553 represents a critical race condition within the Linux kernel's networking subsystem, specifically affecting Red Hat Enterprise Linux 7, kernel-rt, and Red Hat Enterprise MRG 2 environments. This flaw exists within the nfnetlink_log module, which serves as a logging mechanism for netfilter packets and provides a bridge between kernel space and userspace for packet inspection and logging operations. The race condition manifests when multiple threads or processes attempt to interact with the netlink socket interface simultaneously, creating a temporal window where the kernel's internal data structures become inconsistent. This particular vulnerability falls under the CWE-362 category of "Concurrent Execution using Shared Resource with Improper Synchronization" and aligns with ATT&CK technique T1499.004 for network denial of service attacks.
The technical exploitation of this vulnerability occurs when local users leverage the nfnetlink_log module's socket creation functionality to trigger concurrent access patterns that expose the race condition. When multiple processes attempt to create or manipulate netlink sockets simultaneously, the kernel's synchronization mechanisms fail to properly protect shared resources, leading to memory corruption and ultimately a system panic. The vulnerability specifically impacts the kernel's handling of socket reference counting and memory management within the netfilter logging subsystem. The race condition allows attackers to manipulate kernel memory in ways that cause the system to become unstable and eventually crash, resulting in a denial of service condition that can be exploited to disrupt normal system operations and potentially compromise system availability.
The operational impact of CVE-2015-7553 extends beyond simple denial of service, as it represents a fundamental flaw in the kernel's concurrency handling that can lead to complete system instability. Local users with minimal privileges can leverage this vulnerability to cause system panics that require manual intervention and system restarts, potentially disrupting critical business operations in enterprise environments. The vulnerability's exploitation does not require elevated privileges, making it particularly dangerous as it can be triggered by any user with access to the system. Organizations running affected kernel versions are at risk of experiencing unexpected system crashes, which can result in data loss, service interruptions, and potential compliance violations in regulated environments where system uptime is critical.
Mitigation strategies for CVE-2015-7553 primarily focus on applying the appropriate security patches and updates provided by Red Hat. System administrators should immediately deploy the kernel updates that address this specific race condition within the nfnetlink_log module, ensuring that all systems running affected kernel versions receive the necessary patches. Organizations should also consider disabling the nfnetlink_log module if it is not actively required for network monitoring or packet logging purposes, thereby eliminating the attack surface entirely. Additional defensive measures include implementing proper access controls to limit user privileges, monitoring for unusual socket creation patterns, and maintaining robust system logging to detect potential exploitation attempts. The vulnerability demonstrates the importance of proper kernel synchronization mechanisms and highlights the need for thorough testing of concurrent access patterns in kernel subsystems, particularly those handling network packet processing and logging operations that are critical to system security and stability.