CVE-2017-9542 in DIR-615 Wireless N 300 Router
Summary
by MITRE
D-Link DIR-615 Wireless N 300 Router allows authentication bypass via a modified POST request to login.cgi. This issue occurs because it fails to validate the password field. Successful exploitation of this issue allows an attacker to take control of the affected device.
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Analysis
by VulDB Data Team • 10/16/2019
The CVE-2017-9542 vulnerability affects D-Link DIR-615 Wireless N 300 routers and represents a critical authentication bypass flaw that stems from insufficient input validation within the web interface authentication mechanism. This vulnerability resides in the login.cgi script which processes user authentication requests, specifically failing to properly validate the password field in POST requests. The flaw allows an attacker to bypass the normal authentication process by crafting a modified POST request that either omits or manipulates the password field, thereby gaining unauthorized administrative access to the router's management interface. This represents a fundamental failure in the router's security architecture where the system assumes valid authentication credentials without proper verification of the password field, creating a pathway for unauthorized access to the device's administrative functions.
The technical implementation of this vulnerability demonstrates a classic authentication weakness that aligns with CWE-287, which addresses improper authentication issues in software systems. The vulnerability operates at the application layer of the network stack, specifically within the web server component that handles HTTP requests for the router's administrative interface. When a user attempts to authenticate, the login.cgi script should validate both the username and password against the stored credentials in the device's memory or configuration files. However, due to the flawed validation logic, the system accepts requests where the password field is either empty, contains invalid data, or is completely absent from the POST request, allowing unauthorized users to gain administrative privileges without proper authentication.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass complete device compromise and potential network infiltration. Once an attacker successfully bypasses authentication, they gain full administrative control over the router, enabling them to modify network configurations, change administrator passwords, enable or disable network services, and potentially redirect traffic through malicious proxies. This access level allows for advanced persistent threat activities including network reconnaissance, man-in-the-middle attacks, and the establishment of persistent backdoors within the local network. The vulnerability affects the router's core security functions and compromises the integrity of the entire network infrastructure that relies on the device for routing and access control.
Security professionals should recognize this vulnerability as a prime example of how insufficient input validation can create severe security implications within embedded network devices. The flaw demonstrates the importance of proper authentication mechanisms and input sanitization in network appliances, particularly those with web-based management interfaces. Organizations should implement immediate mitigations including firmware updates from D-Link, network segmentation to isolate affected devices, and monitoring for unauthorized access attempts. The vulnerability also highlights the need for proper security testing of embedded systems, particularly those with web interfaces, and aligns with ATT&CK technique T1078 for valid accounts and T1046 for network service scanning. Additionally, this vulnerability exemplifies the broader category of insecure direct object references and improper authentication that frequently appear in IoT and networking equipment, emphasizing the critical need for robust security practices in device firmware development and deployment.