# A Weird List of Sequences (Misc)
Hi CTF player. If you have any questions about the writeup or challenge. Submit a issue and I will try to help you understand.
Also I might be wrong on some things. Enjoy :)
(P.S Check out my [CTF cheat sheet](https://github.com/flawwan/CTF-Candy))
![alt text](1.png "Chall")
Connecting to the netcat server we get a prompt saying we need to supply a captcha code.
![alt text](2.png "Chall")
Using pwntools and a simple md5 bruteforce script we quickly crack the captcha.
Script available here: [brute.py](brute.py)
After cracking the captcha, we can start the challenge.
![alt text](3.png "Chall")
Okay we have to predict the number sequence 25 times. Doing it by hand is quite hard. Let's use `oeis.org`.
![alt text](4.png "Chall")
Again manually typing all these numbers in to the website is boring. Also there might be a timeout (untested). Automating the process with python is easier and more fun. Let's do that.
### Creating a automatic tool to solve the task
Our goal is to:* Bruteforce the captcha* Parse the given number sequence.* Send the number sequence to oeis.org.* Fetch the next predicted number from the response of oeis.org.* Send the number to the server.* Loop 25 times.* Get the flag
With this python script I used the following libraries:* Pwntools - Connect to challenge server over tcp.* requests - To send GET request to oeis.org* pyquery - Parsing the response of oeis.org to get the next predicted number* hashlib - md5 encode function
Full script available here: [solve.py](solve.py)
Running the script, we get the flag after 25 solved sequences! Cool
![alt text](5.png "Chall")