CVE-2005-3110 in Linux
Summary
by MITRE
Race condition in ebtables netfilter module (ebtables.c) in Linux 2.6, when running on an SMP system that is operating under a heavy load, might allow remote attackers to cause a denial of service (crash) via a series of packets that cause a value to be modified after it has been read but before it has been locked.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/10/2019
The vulnerability described in CVE-2005-3110 represents a critical race condition within the ebtables netfilter module of the Linux kernel version 2.6, specifically affecting systems operating in symmetric multiprocessing environments under significant load conditions. This flaw exists in the ebtables.c file where the module handles packet filtering and forwarding operations, creating a scenario where concurrent access to shared data structures can lead to system instability. The race condition occurs when multiple processor cores attempt to modify a value that has already been read but not yet protected by appropriate locking mechanisms, fundamentally compromising the integrity of the packet filtering operations.
The technical implementation of this vulnerability exploits the inherent timing issues present in concurrent system operations, particularly when multiple threads or processors access the same memory locations simultaneously. In an SMP environment, the ebtables module fails to properly synchronize access to critical data structures during packet processing, allowing attackers to craft specific sequences of network packets that trigger the race condition. This manipulation causes the kernel to access memory locations that have been modified by other processes while still being in an inconsistent state, leading to unpredictable behavior and ultimately system crashes. The vulnerability is particularly dangerous because it can be triggered remotely through network traffic without requiring local access or authentication.
The operational impact of this vulnerability extends beyond simple denial of service, as it can result in complete system crashes and potential data loss within network infrastructure devices. Systems running ebtables in high-traffic environments, such as routers, firewalls, and network switches, become particularly susceptible to exploitation. The vulnerability demonstrates a fundamental flaw in kernel-level synchronization primitives, where the lack of proper locking mechanisms during concurrent packet processing creates a window of opportunity for attackers to destabilize the entire system. This type of vulnerability directly impacts the availability and reliability of network services, potentially affecting large-scale network operations and enterprise infrastructure that depend on consistent packet filtering capabilities.
Mitigation strategies for this vulnerability must address both immediate system protection and long-term architectural improvements. The primary solution involves applying the appropriate kernel security patches that implement proper locking mechanisms and synchronization protocols within the ebtables module. Organizations should prioritize updating their Linux systems to versions that contain the fixed ebtables implementation, ensuring that all network filtering operations include appropriate mutex locks and atomic operations to prevent concurrent access violations. Additionally, implementing network monitoring and intrusion detection systems can help identify potential exploitation attempts, while reducing system load through proper resource management and traffic shaping can minimize the window of opportunity for attackers. This vulnerability aligns with CWE-362, which specifically addresses race conditions in concurrent programming, and represents a classic example of how improper synchronization can lead to system instability and denial of service conditions that affect the core networking infrastructure.