I am currently researching IoT security and am trying to find out about how a single device with poor password security on a network could be utilised to gain access to the other components of said network. Let's assume that it's an embedded device running some kind of Linux distribution. I'm trying to write about the implications of poor password security for IoT devices, and why you should care even if it's a mundane device that controls no private data.
When you gain administrator/root access to a device with poor security you have a feet in a network, the first thing you need to do is to backdoor the device in order to get a persistent access to the device. Then, you can easily create a SSH tunnel between your attacking box and your target, forward multiple or all ports through the tunnel. At this point you are able to work (play) with the rest of the network.
In few words, you create a pivoting point.