bits ctf

baby rev

• check the type of file
• try to use ghidra and see the main function
• main function led to my funciton
• 
• we see the chars and see we got the flag

  solve.py

  a = """(((param_1[4] == 'C') && (param_1[0xd] == 'm')) && (param_1[0x13] == 'r')) &&
     (((param_1[3] == 'S' && (param_1[10] == 'l')) &&
     ((param_1[2] == 'T' && ((param_1[0xe] == 'e' && (param_1[0x11] == '0')))))))) &&
     ((param_1[0x16] == '}' &&
     (((param_1[7] == '{' && (param_1[5] == 'T')) && (param_1[0xf] == '_')))))) &&
     (((param_1[1] == 'I' && (param_1[0x15] == 'v')) &&
     (((param_1[8] == 'w' && ((param_1[0xb] == 'c' && (param_1[6] == 'F')))) &&
     (param_1[0x14] == '3')))))) &&
     ((((param_1[9] == '3' && (param_1[0xc] == '0')) && (param_1[0x10] == 't')) &&
     (param_1[0x12] == '_')))
  """
  a = a.replace("(", "")
  a = a.replace(")", "")
  a = a.split("&&")
  ans = [0 for i in range(23)]
  indices = []
  for i in a:
    i = i.strip()
    s = i.find("[")
    e = i.find("]")
    index = i[s+1:e]
    if index.startswith("0x"):
        index = int(index, 16)
    index = int(index)
    indices.append(index)
    f = i.find("'")
    l = len(i)-1
    string = i[f+1:l]
    ans[index] = string
    print(index, string)
  print(ans)
  ans = "".join(str(e) for e in ans)
  print(ans)
  

• which gives the flag
•