Security researchers demonstrated a way to hack directly into the computer that controls monitor to see the pixels displayed on the monitor as well as manipulate the pixels in order to display different images. Attackers can change the status-alert light on the control interface of a power plant from Green to Red, which could trick someone into shutting down the power plant. The researchers say they discovered the hack by reverse-engineering a Dell U2410 monitor, though it was not an easy process, as it took over two years.
Source: https://thehackernews.com/2016/08/computer-monitor-hack.html