CVE-2005-3272 in Linux
Summary
by MITRE
Linux kernel before 2.6.12 allows remote attackers to poison the bridge forwarding table using frames that have already been dropped by filtering, which can cause the bridge to forward spoofed packets.
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Analysis
by VulDB Data Team • 06/19/2019
The vulnerability described in CVE-2005-3272 represents a significant flaw in the Linux kernel's network bridge implementation that existed prior to version 2.6.12. This issue resides within the bridge forwarding table management mechanism, which is responsible for maintaining information about network devices and their forwarding capabilities within a bridged network environment. The vulnerability specifically affects the interaction between packet filtering and forwarding table updates, creating a potential pathway for malicious actors to manipulate network traffic flow through carefully crafted frame manipulation techniques.
The technical root cause of this vulnerability stems from a race condition or logic flaw in how the kernel processes bridge packets that have already been filtered and dropped by access control lists or other filtering mechanisms. When a network frame passes through the bridge component and is dropped due to filtering rules, the system should not update the forwarding table with information about that frame. However, in affected kernel versions, the bridge implementation fails to properly account for previously dropped frames, allowing these frames to influence the forwarding table state. This creates a scenario where spoofed or maliciously crafted frames can be used to insert false entries into the bridge's forwarding table, effectively enabling attackers to manipulate how packets are forwarded through the network bridge.
The operational impact of this vulnerability extends beyond simple network disruption to potentially enable sophisticated man-in-the-middle attacks and network traffic manipulation. An attacker who can successfully poison the bridge forwarding table can redirect legitimate traffic to unintended destinations, create network partitions, or even establish unauthorized communication paths. The vulnerability is particularly dangerous in environments where network bridges are used for security isolation between different network segments, as it allows attackers to bypass network segmentation controls. This issue can be exploited remotely, meaning that an attacker does not need physical access to the network infrastructure to carry out the attack, making it particularly concerning for distributed network environments.
This vulnerability aligns with several cybersecurity frameworks and threat models, including CWE-129 which addresses improper handling of input boundaries in network components, and relates to ATT&CK technique T1071.004 for application layer protocol traffic shaping. The flaw demonstrates the importance of proper state management in network security components and highlights the need for robust input validation and filtering mechanisms. Organizations implementing network bridges or using Linux-based systems for network infrastructure should prioritize updating to kernel versions 2.6.12 or later to remediate this vulnerability. Additionally, network administrators should implement monitoring solutions to detect anomalous forwarding table behavior and consider implementing additional network segmentation controls as defense-in-depth measures. The vulnerability also underscores the critical importance of maintaining up-to-date kernel versions and following security best practices for network infrastructure management, particularly in environments where network security is paramount.