CVE-2016-6669 in USG2100
Summary
by MITRE
Buffer overflow in the Authentication, Authorization and Accounting (AAA) module in Huawei USG2100, USG2200, USG5100, and USG5500 unified security gateways with software before V300R001C10SPC600 allows remote authenticated RADIUS servers to execute arbitrary code by sending a crafted EAP packet.
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Analysis
by VulDB Data Team • 09/20/2022
The vulnerability identified as CVE-2016-6669 represents a critical buffer overflow flaw within the Authentication, Authorization and Accounting AAA module of Huawei unified security gateways. This security weakness affects multiple models including the USG2100, USG2200, USG5100, and USG5500 series devices operating with software versions prior to V300R001C10SPC600. The flaw exists in the handling of Extensible Authentication Protocol (EAP) packets which are commonly used in network authentication processes. The vulnerability specifically manifests when the device receives a specially crafted EAP packet from a remote authenticated RADIUS server, creating an exploitable condition that could lead to arbitrary code execution on the affected system.
The technical implementation of this vulnerability stems from inadequate input validation within the AAA module's EAP packet processing logic. When a remote attacker with valid RADIUS server credentials sends a malformed EAP packet containing oversized data payloads, the system fails to properly bounds-check the incoming data before copying it into fixed-size buffers. This classic buffer overflow condition occurs because the device does not validate the length of EAP attributes or ensure that incoming packet data fits within allocated memory boundaries. The flaw falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and can be categorized under ATT&CK technique T1059.007 for remote code execution through network services. The vulnerability is particularly dangerous because it requires only authenticated access to a RADIUS server, which is often a legitimate administrative function within network infrastructure.
The operational impact of this vulnerability extends beyond simple system compromise, as it provides attackers with potential full control over the affected security gateway devices. Once exploited, the attacker could execute arbitrary code with the privileges of the affected system, potentially leading to complete network infiltration, data exfiltration, or disruption of security services. The affected Huawei devices serve as critical network security components, often functioning as firewalls, intrusion prevention systems, and network access control points. Compromise of these devices could result in unauthorized network access, bypass of security policies, and complete loss of network security posture. The vulnerability affects organizations relying on Huawei's unified security gateways for network protection, potentially exposing their entire network infrastructure to lateral movement and persistent threats.
Mitigation strategies for CVE-2016-6669 should prioritize immediate software patching to the latest firmware versions that address the buffer overflow condition in the AAA module. Organizations should ensure all affected Huawei USG2100, USG2200, USG5100, and USG5500 devices are updated to V300R001C10SPC600 or later releases that contain the necessary security fixes. Network administrators should implement network segmentation to limit RADIUS server access to only trusted administrative systems and consider disabling unnecessary AAA services when not actively required. Additionally, monitoring for unusual EAP packet patterns and implementing intrusion detection systems can help identify potential exploitation attempts. The vulnerability demonstrates the importance of maintaining current security patches and validating network authentication server access, as it aligns with ATT&CK technique T1078 for valid accounts and privilege escalation. Organizations should also review their network access control policies and ensure that RADIUS server credentials are properly secured and monitored for unauthorized access attempts.