CVE-2003-0552 in Linux
Summary
by MITRE
Linux 2.4.x allows remote attackers to spoof the bridge Forwarding table via forged packets whose source addresses are the same as the target.
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Analysis
by VulDB Data Team • 06/29/2021
The vulnerability described in CVE-2003-0552 represents a significant security flaw in the Linux 2.4.x kernel networking stack that specifically affects bridge forwarding table management. This issue arises from improper handling of network packets within the bridging functionality that connects multiple network segments. The vulnerability enables remote attackers to manipulate the bridge forwarding table by crafting and transmitting forged packets that contain source addresses matching the target network segments. This fundamental flaw in the kernel's packet processing logic creates a pathway for malicious actors to compromise network integrity and potentially gain unauthorized access to bridged network segments.
The technical implementation of this vulnerability stems from the kernel's insufficient validation mechanisms when processing bridge forwarding table entries. In Linux 2.4.x systems, when packets are received on a bridge interface, the kernel maintains a forwarding table that maps MAC addresses to specific ports for efficient packet forwarding. The flaw occurs because the kernel does not adequately verify the legitimacy of source MAC addresses when updating this forwarding table, allowing attackers to inject forged packets with malicious source addresses that match legitimate network targets. This weakness is particularly dangerous because it operates at the network layer where the kernel makes critical forwarding decisions based on the information provided in these packets.
The operational impact of this vulnerability extends beyond simple network disruption to potentially enable more sophisticated attacks within bridged network environments. Attackers can leverage this vulnerability to perform man-in-the-middle attacks, redirect network traffic through unauthorized paths, or even facilitate network reconnaissance activities that would otherwise be difficult to achieve. The ability to spoof the bridge forwarding table means that malicious actors can effectively manipulate how network traffic flows through the bridged infrastructure, potentially leading to data interception, network segmentation bypasses, or complete network compromise. This vulnerability is particularly concerning in enterprise environments where multiple network segments are interconnected through Linux-based bridges.
Mitigation strategies for CVE-2003-0552 require both immediate patching and network-level defensive measures. The most effective solution involves upgrading to Linux kernel versions that contain the appropriate fixes for this vulnerability, which were released as part of the standard kernel security updates. Network administrators should also implement additional security controls such as implementing proper access control lists, configuring network segmentation, and deploying intrusion detection systems to monitor for suspicious packet patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-284 access control weaknesses and can be mapped to ATT&CK techniques related to network sniffing and man-in-the-middle attacks, emphasizing the need for comprehensive network security measures beyond simple patch management.
This vulnerability demonstrates the critical importance of proper input validation and state management in kernel-level network code, particularly within bridging and forwarding functionalities. The flaw highlights how seemingly simple packet processing logic can create significant security implications when proper validation mechanisms are absent. Organizations should consider implementing network monitoring solutions that can detect anomalous forwarding table updates and establish robust patch management processes to ensure timely deployment of security fixes. The vulnerability also underscores the need for continuous security assessment of network infrastructure components, particularly those handling critical forwarding decisions in bridged network environments.