ctf_aria

write up ctf by ariafatah

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

soal

Can you crack the password to get the flag?
Download the password checker here and you’ll need the encrypted flag and the hash in the same directory too.
There are 100 potential passwords with only 1 being correct. You can find these by examining the password checker script.

hint

• A for loop can help you do many things very quickly.
• The str_xor function does not need to be reverse engineered for this challenge.

solve

wget https://artifacts.picoctf.net/c/20/level4.py
wget https://artifacts.picoctf.net/c/20/level4.flag.txt.enc
wget https://artifacts.picoctf.net/c/20/level4.hash.bin

cat level4.flag.txt.enc
# H
# ...

cat level4.hash.bin
# �ՌG���)BsQP
# ǫ�

python3 level4.py
# Please enter correct password for flag: 158f
# That password is incorrect

## ketika aku lihaht ternyata mirip yang level 3 sebelumnya jadi saya coba lagi seperti sebelumnya

• saya menambahkan loop untuk passwordnya
• namun terdapat perbedaan seperti sebelumnya disini saya mencoba untuk langsung men decrypt tanpa function seperti sebelumnya

  # level_4_pw_check()
  
  # The strings below are 100 possibilities for the correct password.
  #   (Only 1 is correct)
  pos_pw_list = ["158f", "1655", "d21e", "4966", "ed69", "1010", "dded", "844c", "40ab", "a948", "156c", "ab7f", "4a5f", "e38c", "ba12", "f7fd", "d780", "4f4d", "5ba1", "96c5", "55b9", "8a67", "d32b", "aa7a", "514b", "e4e1", "1230", "cd19", "d6dd", "b01f", "fd2f", "7587", "86c2", "d7b8", "55a2", "b77c", "7ffe", "4420", "e0ee", "d8fb", "d748", "b0fe", "2a37", "a638", "52db", "51b7", "5526", "40ed", "5356", "6ad4", "2ddd", "177d", "84ae", "cf88", "97a3", "17ad", "7124", "eff2", "e373", "c974", "7689", "b8b2", "e899", "d042", "47d9", "cca9", "ab2a", "de77", "4654", "9ecb", "ab6e", "bb8e", "b76b", "d661", "63f8", "7095", "567e", "b837", "2b80", "ad4f", "c514", "ffa4", "fc37", "7254", "b48b", "d38b", "a02b", "ec6c", "eacc", "8b70", "b03e", "1b36", "81ff", "77e4", "dbe6", "59d9", "fd6a", "5653", "8b95", "d0e5"]
  
  for i in pos_pw_list:
    decryption = str_xor(flag_enc.decode(), i)
    print(decryption)
  

• dan ketika saya run functionya saya mendapatkan flagnya

  python3 level4.py
  # picoCTF{fl45h_5pr1ng1ng_cf341ff1}
  

flag

picoCTF{fl45h_5pr1ng1ng_cf341ff1}