If one device on our network is hacked, are the others at risk?
Often, yes. An attacker who controls one machine uses it to look around and move on: scanning for other hosts, trying the passwords stored on the first machine and connecting over administration protocols such as SMB, RDP or SSH. On a flat network, where every computer can reach every server, nothing slows this down. Three free measures limit how far they get: segment the network so that workstations cannot reach servers they do not need, take local administrator rights away from everyday accounts, and use a different password for every system. NetSenX flags the scanning and the new host-to-host sessions this movement creates, on every plan, Free included. It does not see what the attacker does inside the first machine before anything touches the network.