I think our LAN has been compromised, I don’t know why or how but since two weeks ago several computers (15 out of 25) randomly restart or shut down with no previous notice. In one of the servers we saw a pop-up window saying “HELLO” in chinese. It may sound funny but I’m very worried :(.
Windows update is up to date, we have Fortigate 90E with all services activated, we have McAfee in all clients… I installed Malwarebytes to see if it find something but no luck. We didn’t find anything in the firewall logs.
I need advice on what to do, any help would be highly appreciated.