Make a good and a bad version of the executable.

• Make a malicious and benign version of the code.
  • Make arrays B and C right after A,
    • B is just for ease of identification
    • C will be a copy of A in one executable, but different in another.

    • 
      unsigned char A[201] {"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" };
      
      unsigned char B[201] {"bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"};
      
      unsigned char C[201] {"cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc"};

  • Add a function Check()

    • bool Check(){
         bool good {true};
      
         int i = 0;
         while (i < 200) {
            ++i;
            if (A[i] != C[i]) {
               good = false;
            }
         }
      
         return good;
      } 

  • Change main to be

    • if (Check()) {
          cout << "Something GOOD" << endl;
      } else {
          cout << "Something BAD" << endl;
      }

• Using bless, copy
  • The code from A to C in both myappA and myappB
  • I needed two versions of bless to do this .
• Convince yourself that the code has the same md5sum, but it does different things..