ctf_aria

write up ctf by ariafatah

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Project maintained by ariafatah0711 Hosted on GitHub Pages — Theme by mattgraham

soal

I wonder what this really is… enc ‘‘.join([chr((ord(flag[i]) « 8) + ord(flag[i + 1])) for i in range(0, len(flag), 2)])

hint

• You may find some decoders online

solve

wget https://mercury.picoctf.net/static/e47483f88b12f2ab0c46315afc12f64d/enc

cat enc
# 灩捯䍔䙻ㄶ形楴獟楮獴㌴摟潦弸彥ㄴㅡて㝽 

with tool web

• disini kita bisa lihat bahwa teks enc tersebut seperti menggunakan UTF-16 (big-endian)
• disini saya akan mencoba dengan tool utf-16 to hex
  • https://www.coderstool.com/utf16-encoding-decoding

    \u7069\u636f\u4354\u467b\u3136\u5f62\u6974\u735f\u696e\u7374\u3334\u645f\u6f66\u5f38\u5f65\u3134\u3161\u3066\u377d
    

• lalu convert ke ascii menggunakan tool hex to ascii
  • https://www.rapidtables.com/convert/number/hex-to-ascii.html

    picoCTF{16_bits_inst34d_of_8_e141a0f7}
    

with python3

ipython3

enc = open("enc").read()
print enc
# 灩捯䍔䙻ㄶ形楴獟楮獴㌴摟潦弸彥ㄴㅡて㝽

for i in enc:
    print(hex(ord(i)))
# 0xe7
# 0x81
# ...

for i in enc:
    print(hex(ord(i)).lstrip("0x"))
# 7069
# 636f
# 4354

for i in enc:
    print(hex(ord(i)).lstrip("0x"),end="")
# 7069636f4354467b31365f626974735f696e73743334645f6f665f385f65313431613066377d

import codecs
codecs.decode('7069636f4354467b31365f626974735f696e73743334645f6f665f385f65313431613066377d', 'hex')
# b'picoCTF{16_bits_inst34d_of_8_e141a0f7}'

flag

picoCTF{16_bits_inst34d_of_8_e141a0f7}