AngstromCTF_2018: slots

Category: Misc Points: 90 Description:

defund is building a casino empire. Break his slot machine, which is running at web.angstromctf.com:3002. Note: connect with netcat or an equivalent tool.

Write-up

This challenge is a mere teaser on one of Python's quirks with integers, that it could be NaN or not a number. If it is not a number, it simply cannot be used to check if it's below 0, above money or 1000000000. As such, we can break this challenge with just one bet.

$ nc web.angstromctf.com 3002
Welcome to Fruit Slots!
We've given you $10.00 on the house.
Once you're a high roller, we'll give you a flag.
You have $10.00.
Enter your bet: NaN
🍐 : 🍈 : 🍈
🍉 : 🍇 : 🍒 ◀
🍒 : 🍌 : 🍒
You lost everything.
Wow, you're a high roller!
A flag: actf{fruity}

Therefore, the flag is actf{fruity}.