Grandstream GRP Default Login Scanner

The Grandstream GRP series is a line of IP phones designed for business communication, widely deployed in offices, call centers, and enterprises. These devices offer VoIP integration, call handling, and mobile connectivity, making them essential for efficient communication management. IT administrators rely on them for their affordability and ease of deployment within existing network infrastructure.

The vulnerability arises from the use of default login credentials, such as 'admin' and 'admin', which are often left unchanged after initial setup. This oversight occurs due to rushed deployments or lack of security awareness, leaving the device management interface exposed to unauthorized access.

Specifically, the scanner targets the HTTP POST request to the '/cgi-bin/login' endpoint of Grandstream GRP devices. It attempts authentication using known default username and password combinations. If successful, it indicates that the device has not been properly secured against basic credential-based attacks.

If exploited, an attacker gains full administrative access to the device, allowing them to modify call routing, intercept communications, deploy malware, or pivot to other network resources. This can lead to data breaches, service disruption, and compromise of the entire business communication system.