CVE-2018-5330 in P-660HW
Summary
by MITRE
ZyXEL P-660HW v3 devices allow remote attackers to cause a denial of service (router unreachable/unresponsive) via a flood of fragmented UDP packets.
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Analysis
by VulDB Data Team • 02/02/2023
The vulnerability identified as CVE-2018-5330 affects ZyXEL P-660HW v3 routers, representing a significant denial of service weakness that can be exploited remotely by attackers. This issue stems from the device's inadequate handling of fragmented UDP packets, which creates a pathway for malicious actors to disrupt network services and render the router completely unresponsive. The vulnerability specifically targets the router's packet processing mechanisms, where the device fails to properly manage fragmented UDP traffic, leading to system instability and complete service disruption.
The technical flaw manifests in the router's failure to implement proper packet reassembly and validation procedures for fragmented UDP datagrams. When the device receives a flood of fragmented UDP packets, its processing capabilities become overwhelmed, causing the routing engine to become unresponsive and ultimately resulting in a complete denial of service condition. This behavior aligns with CWE-400, which categorizes the vulnerability as an uncontrolled resource consumption issue, where the device's resources are exhausted through malicious packet flooding. The attack vector requires only remote access to the network, making it particularly dangerous as it can be exploited from outside the local network perimeter.
The operational impact of this vulnerability extends beyond simple service disruption, as it can effectively cut off network connectivity for all devices relying on the affected router. Network administrators may experience complete loss of management access and internet connectivity, forcing them to physically intervene to restore services. The vulnerability's exploitation can occur without authentication requirements, making it accessible to any attacker with network access to the device's interface. This characteristic places the vulnerability in the ATT&CK framework under the T1498 technique for Network Denial of Service, where adversaries leverage network infrastructure to disrupt service availability. The impact is particularly severe in enterprise and residential environments where the router serves as the primary gateway for network communication.
Mitigation strategies for CVE-2018-5330 should focus on implementing network-level protections and firmware updates where available. Network administrators should consider deploying ingress filtering and rate limiting mechanisms to prevent excessive fragmented UDP traffic from reaching the affected device. The implementation of firewall rules that restrict UDP packet fragmentation or limit the rate of incoming UDP packets can provide temporary protection while permanent solutions are developed. Additionally, organizations should prioritize firmware updates from ZyXEL if available, as this vulnerability likely represents a known issue that manufacturers have addressed in subsequent releases. The vulnerability highlights the importance of network segmentation and monitoring to detect unusual traffic patterns that may indicate exploitation attempts, particularly in environments where network devices lack proper resource management and traffic filtering capabilities.