I once had the (dis)pleasure of working with these Yomani terminals. I got a development unit (with red text "DO NOT PAY" on the side). I plugged it in my home internet which has a public ip with dhcp just to get it quickly online and keep it out of my internal home network. The next day I got a call from my ISP saying I had a compromised machine in my network with malware. I was like WTF?! and they gave me the mac address and it was the Yomani terminal! I promptply unplugged it from the network and started investigating. Indeed, this development unit had a telnet(!) port open and root login without password was possible. So, having a wide open telnet port on a public ip and it's just a matter of minutes until someone uploads a generic arm malware onto it. I returned the terminal to the vendor with explanation but never got a followup. Lesson learned: never attach anything to public internet, even if it looks secure.

I guess Atos Worldline really doesn't like root passwords.