Introduction
The FireShell CTF is a Brazilian event in jeopardy style. The proposal is to test participants’ hacking skills in a challenging yet fun environment.
I participated with the team IrisCS and scored 1807 points landing us in 52nd Place. We completed 4 challenges.
Against the Perfect Discord Inquisitor 1
Information: 19 Solves, 495 Points.
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You're on a journey and come to the Tavern of a Kingdom Enemy, you need to get information of a secret organization for the next quest. Be careful about the Inquisitor! He can ban you from this world.
TL;DR find the flag
Link to Challenge: https://discord.gg/fHHyU6g
See the Youtube Video below for my writeup.
Miscrypto Alphabet
Information: 446 Points
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points: 446
description: Help us to recover the alphabet.
As we can see from the image, we have a square for each letter of the alphabet as well as an interesting bar on the top of the image.
The solution here is to create a matrix/system of equations for each of the pictured words. In total, we will get 26 equations to solve.
For example, A is Apple. So, we will do 1A+2P+1L+E=453.
If we complete this calculation all the way through and solve (I used an online calculator after writing out my equations) we get the flag.
Flag:
F#{y0u-ar4-gr34t-w1th-z3!}
Welcome Challenge
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Welcome to FireShell CTF 2020.
Follow us in our social networks:
Facebook Instagram Linkedin Telegram Twitter
On the Twitter Page, we find this image:
I scanned the QR Code with my phone and got the flag.
Flag:
F#{Fr4ç01S3_d’4ub1gNé}
Simple Encryption
117 Solves - 261 Points
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I found this small program on my computer and an encrypted file. Can you help me decrypt the file?
For this challenge, you can use the binary to map the alphabet to a special encrypted alphabet. Afterwards, apply the same
decryption to the encrypted file.
After doing so, your file will look like this:
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_______ _____ _______ _____ _______
|______ | | | | |_____] | |______
______| __|__ | | | | |_____ |______
_______ __ _ _______ ______ __ __ _____ _______ _____ ______
|______ | \ | | |_____/ \_/ |_____] | | | |_____/
|______ | \_| |_____ | \_ | | | |_____| | \_
Congratulations!
I hope you liked this small challenge.
The flag you are looking for is F#{S1mpl3_encr1pt10n_f0und_0n_g1thub!}
Flag:
F#{S1mpl3_encr1pt10n_f0und_0n_g1thub!}
Conclusion
Overall, the CTF was very enterainting and had several interesting challenges I had never seen before. I was able to cheese
a harder challenge and that ended up netting us several points. However, I feel like it was a massive oversight that we had
to break Discord TOS in order to solve it (using a selfbot).