CVE-2016-8796 in USG9520
Summary
by MITRE
Huawei USG9520 V300R001C01, USG9560 V300R001C01, and USG9580 V300R001C01 allow unauthenticated attackers to send abnormal DHCP request packets to the affected products to trigger a DoS condition.
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Analysis
by VulDB Data Team • 11/24/2022
The vulnerability identified as CVE-2016-8796 affects Huawei USG9520, USG9560, and USG9580 firewall models running specific firmware versions. This issue represents a denial of service weakness that can be exploited by unauthenticated attackers without requiring any prior authentication credentials or privileged access to the network infrastructure. The affected devices are part of Huawei's Unified Security Gateway product line, which serves as enterprise-grade firewall solutions protecting network perimeters against various cyber threats.
The technical flaw resides in the DHCP processing functionality of these firewall devices where abnormal DHCP request packets can be crafted and sent to exploit a lack of proper input validation and sanitization. When these malformed packets are received, the devices fail to properly handle the unexpected data structures, leading to system instability and subsequent service disruption. The vulnerability specifically targets the DHCP client or server implementation within the firewall's network stack, where insufficient error handling mechanisms allow malformed packets to cause system crashes or restarts. This weakness aligns with CWE-129, which describes improper validation of input boundaries, and CWE-400, which covers resource exhaustion vulnerabilities that can lead to denial of service conditions.
The operational impact of this vulnerability is significant for organizations relying on these firewall models for network security. An unauthenticated attacker can remotely trigger a denial of service condition that disrupts network connectivity and potentially affects business operations. The DoS condition can cause complete network outages or partial service degradation, depending on how the firewall's DHCP functionality is utilized within the network architecture. Since these devices are typically deployed at network perimeters and may serve as primary gateways for network access, the disruption can cascade across multiple network segments and affect numerous connected systems. The vulnerability can be exploited from any location on the network where the attacker has access to send packets to the affected firewall interfaces, making it particularly dangerous in environments where network segmentation is not properly implemented.
Organizations should implement immediate mitigations including network segmentation to limit access to affected firewall interfaces, deployment of access control lists to filter DHCP traffic, and monitoring of network traffic for anomalous DHCP packet patterns. The most effective long-term solution involves applying the official Huawei security patches and firmware updates released to address this vulnerability. Network administrators should also consider implementing intrusion detection systems to monitor for potential exploitation attempts and establish incident response procedures for handling DoS events. According to ATT&CK framework, this vulnerability maps to T1499.004 which covers network denial of service, and T1595.001 which involves network infrastructure manipulation. Organizations should also consider implementing redundant firewall configurations to maintain network availability during patching operations and ensure proper network monitoring to detect exploitation attempts before they cause significant disruption. The vulnerability demonstrates the critical importance of input validation in network infrastructure devices and highlights the need for comprehensive security testing of network protocols in enterprise-grade security appliances.