Plug computers are a serious threat, though the need for physical access and relatively easy discovery mean that it's not going to be that common. Pentest teams

Plug computers are a serious threat, though the need for physical access and relatively easy discovery mean that it's not going to be that common. Pentest teams are currently using them, which means malicious users are too. I'd definitely be worried about those POE injectors for conference room phones and other uses. Most of them already look like a cheap black box, have two ethernet ports and power and aren't out of place. Practically though, I'd be much more concerned about penetrations in official clients. You can get most of the same functionality out of an employees mobile device and have the added advantage of more deniability. Client malware is so common that most is not assumed to be a targeted attack, whereas finding an unauthorized plug computer will raise alarm bells quickly. Never the less, it's yet another strong argument for implementing 802.1x.