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วันพุธที่ 4 พฤศจิกายน พ.ศ. 2558

School CTF 2015: Cipollino, little onion (Admin) Write-up

Description:
Do you like containers as we do?
Solution: 

1. Rename an extension from jpg to rar.



2. Get a QRCode.



3. Decode QRCode in https://zxing.org/w/decode.jspx, get a c++ code.


4. Compile and run in http://www.tutorialspoint.com/compile_cpp_online.php


5. Replace ", " to space and replace "0x" to space, get a hex and decode it got a base64.

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

B64'YSA9ICc3MCA3NiA2NSA3MSA5NSA3MSA0OCA2OCA5NSA2OCA2NSA3NyA3OCA5NSA2NiA4MiA0OCA5NSA4NSA5NSA4MiA5NSA4MyA0OCA5NSA2NyA0OCA0OCA3NiA5NSA2OCA2OSA2NyA4MiA4OSA4MCA4NCA3OSA4MicKCm1hcz1bXQoKbWFzPWEuc3BsaXQoJyAnKQoKZm9yIGkgaW4gcmFuZ2UobGVuKG1hcykpOgoJYj1pbnQobWFzW2ldKQoJYz1oZXgoYikKCXByaW50KGMsIGVuZD0nICcpCgpwcmludCgnJyk='

6. Base64 Decode and get python code and run it.

a = '70 76 65 71 95 71 48 68 95 68 65 77 78 95 66 82 48 95 85 95 82 95 83 48 95 67 48 48 76 95 68 69 67 82 89 80 84 79 82'

mas=[]

mas=a.split(' ')

for i in range(len(mas)):
b=int(mas[i])
c=hex(b)
print(c, end=' ')

print('')

7. Result from python code.

0x46 0x4c 0x41 0x47 0x5f 0x47 0x30 0x44 0x5f 0x44 0x41 0x4d 0x4e 0x5f 0x42 0x52 0x30 0x5f 0x55 0x5f 0x52 0x5f 0x53 0x30 0x5f 0x43 0x30 0x30 0x4c 0x5f 0x44 0x45 0x43 0x52 0x59 0x50 0x54 0x4f 0x52

8. HEX Decoding.

464c41475f4730445f44414d4e5f4252305f555f525f53305f4330304c5f444543525950544f52

Flag: FLAG_G0D_DAMN_BR0_U_R_S0_C00L_DECRYPTOR

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