Authentication Bypass in WDR201A WiFi Extender Web Interface

Executive Summary

[{'type': 'paragraph', 'content': 'The vulnerability in the WiFi Extender WDR201A (HW V2.1, FW LFMZX28040922V1.02) is an authentication bypass in its web management interface. The login page does not properly enforce session validation, which means attackers can bypass the login process by directly accessing restricted web application endpoints through forced browsing without needing valid authentication cookies.'}, {'type': 'paragraph', 'content': "This allows attackers to gain full administrative access to the device's web interface without logging in."}] [2]

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Impact Analysis

[{'type': 'paragraph', 'content': "This vulnerability allows an attacker to bypass authentication and gain full administrative access to the WiFi extender's management interface. With this access, the attacker can perform actions such as changing device settings, updating firmware, and potentially compromising the network the device is connected to."}, {'type': 'paragraph', 'content': 'Such unauthorized control can lead to network disruption, unauthorized data access, or the device being used as a foothold for further attacks within the network.'}] [2]

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by attempting to access restricted web management interface endpoints of the WiFi Extender WDR201A without authentication cookies, effectively performing forced browsing to bypass the login page.'}, {'type': 'paragraph', 'content': "One practical approach is to send HTTP requests directly to admin or restricted URLs on the device's web interface and observe if access is granted without proper authentication."}, {'type': 'paragraph', 'content': 'Additionally, testing for the presence of hardcoded credentials or unauthorized access can be done by inspecting the web interface source code or by attempting to log in using known default credentials.'}, {'type': 'paragraph', 'content': "Commands that can be used include curl or wget to send HTTP requests to the device's management URLs, for example:"}, {'type': 'list_item', 'content': 'curl -I http://<device-ip>/admin or other restricted endpoints to check for HTTP status codes indicating access without authentication.'}, {'type': 'list_item', 'content': 'curl http://<device-ip>/admin -b "" to simulate requests without cookies and see if access is granted.'}, {'type': 'list_item', 'content': 'Inspecting the web page source code using a browser or curl to look for hardcoded credentials or SSI directives.'}] [2]

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Mitigation Strategies

[{'type': 'paragraph', 'content': "Immediate mitigation steps include restricting access to the device's web management interface by network segmentation or firewall rules to prevent unauthorized forced browsing."}, {'type': 'paragraph', 'content': 'Disabling remote management or limiting it to trusted IP addresses can reduce exposure.'}, {'type': 'paragraph', 'content': 'If possible, update the device firmware to a version that addresses the authentication bypass vulnerability.'}, {'type': 'paragraph', 'content': 'Change any default or hardcoded credentials if the device allows it, and monitor the device for any unauthorized access attempts.'}, {'type': 'paragraph', 'content': 'Physically securing the device to prevent UART interface access is also recommended to avoid firmware extraction and further compromise.'}] [2]

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