Home CTF Crypto Write-up | The Cyber Grabs CTF 0x02.

Crypto Write-up | The Cyber Grabs CTF 0x02.

by Nihal Umar

The Cyber Grabs CTF

Wa4m_up

Welcome to The Cyber Grabs CTF buddy :)
Flag format: cybergrabs{}
Author: Odin

Solution:

Challenge file: @[email protected]@@[email protected][email protected]@[email protected][email protected]@@[email protected]@[email protected]@[email protected][email protected][email protected]@[email protected]@[email protected]@[email protected][email protected]@[email protected]@[email protected]@@@[email protected][email protected]@@[email protected]@[email protected]@[email protected][email protected][email protected][email protected]@@[email protected][email protected][email protected][email protected][email protected][email protected]@[email protected][email protected][email protected]@@@[email protected]@[email protected][email protected][email protected][email protected]@[email protected]@[email protected]@@@@@[email protected]@@@@[email protected]@[email protected]@@[email protected][email protected][email protected][email protected]@[email protected][email protected]@@[email protected]@[email protected]@[email protected][email protected][email protected][email protected][email protected][email protected][email protected]@@@@[email protected][email protected][email protected][email protected]@[email protected][email protected]@[email protected][email protected][email protected]@@[email protected]@[email protected][email protected][email protected]@@[email protected][email protected][email protected][email protected]@[email protected][email protected][email protected]@@[email protected]$

When you look at the challenge file. You will See there is same pattern follow of Encoding @ and $ So just replace @ -> 0 and $ -> 1 will give you.

0110001101111001011000100110010101110010011001110111001001100001011000100111001101111011011100010111010101101001011101000011001101011111011001110011000000110000011001000101111101110111001101000111001001101101011101010111000001011111011010010111001101101110001001110111010001011111011010010111010001111101

and after just use any binary decoder you will get the flag.

cybergrabs{quit3_g00d_w4rmup_isn’t_it}

Easiest One

Listen the audio carefully.
Flag format: cybergrabs{}
Author: Nihal

Solution:

You will get .wav file in this challenge. After listening it. You will get to know that it’s in Morse code. So, use this online tool to decode it.

https://morsecode.world/international/decoder/audio-decoder-adaptive.html

cybergrabs{1S TH1S A M0RS3 C0D3?}

Something feasy

Key to unlock anything is already with you.
Flag format: cybergrabs{}
Author: Odin

Solution:

Challenge file:
Cipher =>  O|k.Wa{.]{|k.Wa{.[}kj.Ma||kmz.Ekw.4.P*-PP(---*(*-*(/P(((+h(N-$P$(PPhPh-P-PNh-(P*(/PoP--&-(Pj(N-*NhPo-+(&P-P&P--PP(-&(/-*P+Nl

In this challenge first you got the file. It has Encrypted text and as its description says Key to unlock anything is already with you.

So if u apply Xor decryption on it you with the key as key you can get the decrypted text like this:

Are You Sure You Used Correct Key : ^$#^^&###$&$#$&!^&&&%f&@#*^*&^^f^f#^#^@f#&^$&!^a^##(#&^d&@#[email protected]^a#%&(^#^(^##^^&#(&!#$^%@b

Hint: Remember your keyboard is your true friend & ot will help you two times in this journey.

So if you look at the keyboard you will get that it was alphanumberic Characters you have to replace them by digits.

s = "^$#^^&###$&$#$&!^&&&%f&@#*^*&^^f^f#^#^@f#&^$&!^a^##(#&^d&@#[email protected]^a#%&(^#^(^##^^&#(&!#$^%@b"
l = len(s)


i = 0

while i<l:
    if(s[i] == '!'):
        print("1" , end='')
    elif(s[i] == '@'):
        print("2", end='')
    elif(s[i] == '#'):
        print("3", end='')
    elif(s[i] == '$'):
        print("4", end='')
    elif(s[i] == '%'):
        print("5", end='')
    elif(s[i] == '^'):
        print("6", end='')
    elif(s[i] == '&'):
        print("7", end='')
    elif(s[i] == '*'):
        print("8", end='')
    elif(s[i] == '('):
        print("9", end='')
    elif(s[i] == ')'):
        print("0", end='')
    else:
        print(s[i], end='')

    i = i+1

Script by Odin.

After Running this script you will get the hex value:

643667333474347167775f723868766f6f36362f3764716a6339376d72342f6a35796369633667397134652b

After Decode it online you will get the another Encoded Cipher.

d6g34t4qgw_r8hvoo66/7dqjc97mr4/j5ycic6g9q4e+

Now if you remeber the hint we need keyboard once again so basically it was a Keyboard Shift Cipher after Decoding it you will get:

`cybergrabs{fin4llyy0ucam3ou7fr0mth3k3yboard}`

Seperate each Word By _ and you have your final flag.

cybergrabs{fin4lly_y0u_cam3_ou7_fr0m_th3_k3yboard}

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