HACKING LESSON 18

Finalizing the patch-

In order to finalize the patch and make an executable running file we need to perform the following steps –
Repeat all the steps that we perform earlier but this time we have to change the instruction instead of flags.

1). Keep on pressing F8 until you reach the following instruction “CMP EAX, -1” followed by “JNZ Short 0040109A”.

Double click on “JNZ Short 0040109A”, a window will open. Remember, here we need to perform the jump in order to bypass the barrier so change JNZ to JMP, and click on assemble, rest remains the same.

2). Keep on pressing F8 until you reach the following instruction “JNZ SHORT 004010B4” followed by “JMP SHORT 004010F7”.

Double click on “JNZ Short 004010B4”, a window will open. Here also we need to perform the jump in order to bypass the barrier so change JNZ to JMP, and click on assemble, rest remains the same.

3).Keep on pressing F8 until you reach the following instruction “JL SHORT 004010F7”.

Double click on “JL Short 004010F7”, a window will open. Remember, here we do not need to jump because it will jump directly to the barrier so we need to skip this instruction. Change “JL Short 004010F7” to NOP, click on assemble, rest remains the same.

4).Keep on pressing F8 until you again reach the following instruction “JL SHORT 004010F7”.

Repeat step number 3.

Now all the four patches have been applied, next we need to save these patches and create an executable file.

1).Select the code from where you started applying patches i.e. from the opcode “00401073” to “004010D0”.

2).Right click on the selection and select copy to executable > selection.

3).A new window will open, again right click inside the window and select save file. Make sure it is saved as an executable file.

4). Now click on the new file.

The file is cracked.