binary

Binary

Level: Easy

Points: 397

Author: Justin Applegate

Description:

Can you reverse the compiled code to get the flag?

[binary]

Writeup

Opening the main function in Ghidra will return this decompiled code:

undefined8 main(void)

{
  bool bVar1;
  basic_ostream *pbVar2;
  basic_string<char,std::char_traits<char>,std::allocator<char>> local_48 [47];
  allocator local_19 [9];
  
  std::operator<<((basic_ostream *)std::cout,"Flag> ");
  std::allocator<char>::allocator();
                    /* try { // try from 00102303 to 00102307 has its CatchHandler @ 001023af */
  std::__cxx11::basic_string<char,std::char_traits<char>,std::allocator<char>>::
  basic_string<std::allocator<char>>(local_48,"",local_19);
  std::allocator<char>::~allocator((allocator<char> *)local_19);
                    /* try { // try from 00102325 to 0010239b has its CatchHandler @ 001023c9 */
  std::getline<char,std::char_traits<char>,std::allocator<char>>
            ((basic_istream *)std::cin,(basic_string *)local_48);
  bVar1 = std::operator==((basic_string *)local_48,"ctf{just_0p3n_th1s_1n_n0t3p4d}");
  if (bVar1 == false) {
    pbVar2 = std::operator<<((basic_ostream *)std::cout,"Wrong :(");
    std::basic_ostream<char,std::char_traits<char>>::operator<<
              ((basic_ostream<char,std::char_traits<char>> *)pbVar2,
               std::endl<char,std::char_traits<char>>);
  }
  else {
    pbVar2 = std::operator<<((basic_ostream *)std::cout,"Correct!");
    std::basic_ostream<char,std::char_traits<char>>::operator<<
              ((basic_ostream<char,std::char_traits<char>> *)pbVar2,
               std::endl<char,std::char_traits<char>>);
  }
  std::__cxx11::basic_string<char,std::char_traits<char>,std::allocator<char>>::~basic_string
            (local_48);
  return 0;
}

The flag can be seen in plaintext in the code. In addition, using the Linux command strings or opening the file in any editor will show the flag in the text.

The source code can be found in binary.cpp.

Flag - ctf{just_0p3n_th1s_1n_n0t3p4d}