https://www.vice.com/en_us/article/v7vb43/vulnerabilities-allowed-researchers-to-remotely-lock-and-unlock-doors

If you have worked or still work in an office, you have probably swiped an access card in front of one of those black devices with a light that toggles from red to green, which lets you get into the building. Thanks to a series of vulnerabilities into one of the most popular access control panels in the world, hackers could get into the building too.

Researchers at cybersecurity firm Trellix found eight vulnerabilities in the LNL-4420 panel, made by HID and distributed by Carrier, which allowed them to take full control of the device. This would have allowed them to remotely lock and unlock the doors controlled by the device, allowing them to steal valuable hardware or access sensitive computers inside whatever building that was protected by the access control system.