See if you have the patience to scratch the itch; patience is key. Mosquitto bites are so annoying! Except, in this case.. you can become an admin. Connect at: x.x.x.x:1883 using iot:iot Web Portal: http://x.x.x.x
Look at the new Mosquitto server, connecting using the following command
mosquitto_sub -h x.x.x.x -p 1883 -u iot -P iot -t "#"
Grab the text that looks like a flag.
Base64 decode the username and password.
Grab the giant base64 string that looks a lot like an image and look a the file header. Realize it is an image. Turn it into a file.
Try to use it, realize it is an actual OTP and do it all again quickly.
Use the credentials to get the flag.