CVE-2005-4723 in DI-624
Summary
by MITRE
D-Link DI-524 Wireless Router, DI-624 Wireless Router, and DI-784 allow remote attackers to cause a denial of service (device reboot) via a series of crafted fragmented UDP packets, possibly involving a missing fragment.
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Analysis
by VulDB Data Team • 12/04/2024
The vulnerability identified as CVE-2005-4723 affects several D-Link wireless router models including the DI-524, DI-624, and DI-784 series devices. This represents a denial of service flaw that can be exploited remotely by sending specially crafted fragmented UDP packets to the affected routers. The vulnerability specifically targets the router's handling of fragmented network traffic, creating a condition where the device becomes unstable and eventually reboots. This type of vulnerability falls under the category of network protocol implementation flaws that can be exploited to disrupt service availability. The issue demonstrates a critical weakness in how these routers process incoming fragmented packets, particularly when dealing with missing or incomplete fragments during the reassembly process.
The technical root cause of this vulnerability lies in the improper handling of IP fragment reassembly within the router's network stack implementation. When the router receives UDP packets that are fragmented across multiple IP packets, it fails to properly validate or handle the reassembly process when fragments are missing or arrive out of order. This flaw is classified as a buffer over-read or improper input validation issue according to CWE standards, specifically mapping to CWE-129 Input Validation and CWE-125 Out-of-bounds Read. The router's firmware does not adequately check fragment boundaries or validate the integrity of the reassembled packet data, allowing malicious actors to craft packets that trigger memory access violations or unexpected state transitions in the network processing components. The missing fragment condition creates a scenario where the router's packet reassembly logic encounters an unexpected state that causes the system to crash and reboot.
The operational impact of this vulnerability is significant as it allows remote attackers to perform denial of service attacks against network infrastructure without requiring authentication or physical access to the devices. This creates a serious security risk for organizations relying on these routers for network connectivity, as unauthorized parties can remotely disrupt network services and potentially cause extended outages. The vulnerability affects both wired and wireless network operations since the issue occurs at the network layer processing level. The attack vector is particularly concerning because it requires minimal technical expertise to execute and can be automated, making it a popular choice for attackers seeking to disrupt network availability. From an attack chain perspective, this vulnerability aligns with ATT&CK technique T1498-Network Denial of Service, where adversaries target network infrastructure to cause service disruption and maintain operational impact.
Mitigation strategies for this vulnerability should include immediate firmware updates from D-Link to address the packet reassembly logic flaws in affected devices. Network administrators should implement firewall rules to limit or block fragmented UDP traffic where possible, though this approach may impact legitimate network operations. The implementation of intrusion detection systems that can identify and block malformed fragmented packet patterns provides an additional layer of protection. Organizations should also consider network segmentation to limit the impact of such attacks and implement monitoring solutions that can detect unusual reboot patterns or network disruption events. Regular vulnerability assessments and network traffic analysis should be conducted to identify similar weaknesses in other network infrastructure components. The vulnerability highlights the importance of robust input validation and proper error handling in network device firmware, particularly in the critical packet processing paths that handle fragmented network traffic.