UPD: The monitor belongs to the company 3Stars and is located on Serpukhov Square, at the entrance to the tunnel.
According to Sostav.ru , they managed to get a comment from 3Stars commercial director Viktor Laptev: “Yesterday night a hacker attack was carried out on a computer directly connected with this screen. As a result of the attack, one of the commercial clips was replaced with a clip of indecent content. We were promptly informed about this, and the screen was turned off as soon as possible. We have filed an application with the police, and is now being checked. I have no doubt that this is not just mindless hooliganism, but an action aimed specifically at our company. ”