CVE-2006-4143 in FVG318
Summary
by MITRE
Netgear FVG318 running firmware 1.0.40 allows remote attackers to cause a denial of service (router reset) via TCP packets with bad checksums.
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Analysis
by VulDB Data Team • 03/12/2015
The vulnerability identified as CVE-2006-4143 affects Netgear FVG318 routers operating with firmware version 1.0.40, representing a significant security flaw that enables remote attackers to induce a denial of service condition through manipulation of TCP packet checksums. This issue stems from insufficient input validation within the router's network processing stack, specifically targeting the TCP protocol handling mechanisms that govern how incoming packets are validated and processed. The vulnerability manifests when the device receives TCP packets containing corrupted or malformed checksum values, which the router fails to properly handle, leading to system instability and eventual reboot cycles that disrupt network connectivity for legitimate users.
From a technical perspective, this vulnerability operates at the network layer of the OSI model, specifically within the transport layer protocol implementation where TCP checksum validation should occur. The flaw represents a classic case of inadequate error handling and input sanitization, where the router's firmware does not properly validate TCP packet integrity before processing them. When malformed checksums are encountered, the device's TCP stack implementation lacks proper exception handling mechanisms that would allow it to gracefully discard invalid packets or log the anomaly rather than triggering a complete system reset. This behavior aligns with CWE-129, which addresses improper validation of input boundaries, and demonstrates how insufficient validation can lead to system instability and denial of service conditions. The vulnerability also intersects with ATT&CK technique T1499.004, which covers network denial of service attacks through manipulation of network protocols.
The operational impact of this vulnerability extends beyond simple service disruption, as it creates a persistent threat vector that can be exploited by remote attackers without requiring authentication or specialized access privileges. Network administrators and organizations relying on these devices face potential business disruption, as the router will repeatedly reset itself upon receiving malicious packets, potentially causing extended outages that affect all network services dependent on the device. The automated nature of the attack means that even a single malicious packet can trigger continuous resets, making it particularly dangerous in environments where network availability is critical. The vulnerability affects not only individual users but also broader network infrastructure, as the device serves as a gateway for multiple network endpoints, amplifying the potential impact of the denial of service condition.
Mitigation strategies for this vulnerability require immediate firmware updates from Netgear to address the underlying TCP processing flaw, though organizations should also implement network-level protections to prevent malicious packets from reaching the affected devices. Network segmentation and firewall rules can be configured to filter out packets with invalid checksums or suspicious TCP flags, providing an additional layer of defense while awaiting official patches. Organizations should also consider implementing intrusion detection systems that can monitor for unusual reset patterns or network traffic anomalies that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining current firmware versions and conducting regular security assessments of network infrastructure devices, as outdated firmware often contains unpatched vulnerabilities that can be easily exploited by threat actors. Additionally, network administrators should implement monitoring solutions that can detect and alert on repeated router resets, enabling rapid response to potential exploitation attempts and helping to prevent extended service disruptions.