CVE-2021-20150 in AC2600 TEW-827DRU
Summary
by MITRE • 12/31/2021
Trendnet AC2600 TEW-827DRU version 2.08B01 improperly discloses information via redirection from the setup wizard. Authentication can be bypassed and a user may view information as Admin by manually browsing to the setup wizard and forcing it to redirect to the desired page.
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Analysis
by VulDB Data Team • 01/05/2022
The vulnerability identified as CVE-2021-20150 affects Trendnet AC2600 TEW-827DRU routers running firmware version 2.08B01, presenting a critical security flaw in the device's web interface authentication mechanism. This issue stems from improper handling of redirection sequences within the setup wizard component, creating a pathway for unauthorized users to bypass the standard authentication process and gain administrative privileges. The vulnerability manifests when an attacker manually navigates to specific URLs within the router's web interface, forcing the setup wizard to redirect to administrative pages without proper authentication checks. This misconfiguration allows malicious actors to access sensitive configuration data, system settings, and administrative functions that should normally be restricted to authenticated administrators.
The technical implementation of this vulnerability involves a flaw in the router's web server response handling during setup wizard operations. When the setup wizard processes certain URL requests, it fails to properly validate the authentication status of the requesting user before proceeding with redirection to administrative interfaces. This creates a condition where any user, whether authenticated or not, can manipulate the browser to access administrative functions by directly navigating to specific endpoints that should only be accessible after successful authentication. The flaw operates at the application layer of the network stack, specifically within the web interface component that manages the initial configuration process. According to CWE classification, this represents a weakness in the authentication mechanism where insufficient validation of user credentials leads to unauthorized access, specifically categorized under CWE-287 which addresses improper authentication scenarios.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with complete administrative control over the affected router. Once exploited, an attacker can modify network settings, configure firewall rules, change administrator passwords, access network traffic, and potentially use the device as a pivot point for attacks against other systems within the local network. The vulnerability enables a wide range of malicious activities that align with multiple tactics outlined in the MITRE ATT&CK framework, particularly covering privilege escalation and defense evasion techniques. An attacker could leverage this vulnerability to establish persistent access, modify routing tables, disable security features, or even deploy malware through the compromised device. The impact extends beyond simple information disclosure, as the attacker gains the ability to manipulate the entire network infrastructure, potentially leading to data breaches, man-in-the-middle attacks, or unauthorized network access.
Mitigation strategies for CVE-2021-20150 should prioritize immediate firmware updates from Trendnet, as the vendor has likely released patches addressing this specific authentication bypass vulnerability. Organizations should also implement network segmentation to limit exposure of such devices to untrusted networks, enforce strong authentication practices for administrative access, and monitor network traffic for suspicious activities related to the affected router models. Network administrators should consider disabling unnecessary web interfaces and services, implementing proper access controls, and regularly auditing device configurations. The vulnerability highlights the importance of proper input validation and authentication flow management in embedded web applications, emphasizing the need for security testing during the development lifecycle. Additionally, organizations should maintain up-to-date vulnerability management processes to identify and remediate similar issues across their entire network infrastructure, particularly in IoT and networking devices that may be susceptible to similar authentication bypass scenarios.