CVE-2005-4215 in Cable Modem
Summary
by MITRE
Motorola SB5100E Cable Modem allows remote attackers to cause a denial of service (device crash) via an IP packet with the same source and destination IPs and ports, and with the SYN flag set (aka LAND).
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Analysis
by VulDB Data Team • 07/27/2017
The vulnerability identified as CVE-2005-4215 represents a classic denial of service flaw affecting Motorola SB5100E Cable Modem devices. This issue manifests when the modem receives an IP packet that contains identical source and destination IP addresses and port numbers, with the SYN flag activated. The specific packet structure creates a condition where the device's network stack becomes overwhelmed and eventually crashes, rendering the modem inoperable and disrupting internet connectivity for affected users. This vulnerability falls under the category of malformed packet exploitation, where the attacker crafts packets that exploit implementation flaws in network protocol handling rather than targeting application-level weaknesses.
The technical root cause of this vulnerability lies in the modem's insufficient validation of incoming IP packets, particularly those with anomalous source and destination address combinations. When the device processes a LAND attack packet, it essentially attempts to establish a connection with itself, creating a loop in the network stack processing that consumes excessive resources and ultimately leads to system instability. This flaw demonstrates a critical weakness in the modem's packet filtering and validation mechanisms, which should normally reject such malformed packets before they can impact system operations. The vulnerability is categorized as a denial of service condition where the attacker can remotely trigger device failure without requiring authentication or specialized access privileges.
The operational impact of this vulnerability extends beyond simple service disruption, as it affects the reliability and availability of internet connectivity for users relying on the affected modem. Network administrators and service providers may experience increased support tickets, device failures, and potential revenue loss due to service interruptions. The remote nature of the attack means that adversaries can exploit this vulnerability from anywhere on the internet without requiring physical access to the device or knowledge of network credentials. This makes the vulnerability particularly dangerous in environments where modems are deployed without adequate network segmentation or monitoring controls. The LAND attack pattern has been documented in various network security contexts and represents a well-known exploitation technique that has affected numerous network devices throughout the history of internet protocols.
Mitigation strategies for this vulnerability should focus on implementing proper network filtering and packet validation mechanisms at the network perimeter. Network administrators should deploy ingress and egress filtering to block packets with identical source and destination addresses, which effectively prevents LAND attacks from reaching affected devices. The implementation of stateful packet inspection and proper firewall rules can significantly reduce the attack surface by dropping malformed packets before they reach vulnerable network endpoints. Additionally, regular firmware updates and patches should be applied to modem devices to address known vulnerabilities, while network monitoring systems should be configured to detect and alert on unusual packet patterns that may indicate exploitation attempts. This vulnerability aligns with CWE-129, which addresses improper validation of input data, and represents a typical example of how basic protocol implementation flaws can create significant security risks. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of such attacks across their network infrastructure.