All my tutorials are for educational purposes only.
Some info about the target :
Title : Quake 3 Arena
Protection : CD Check
Click on the images to view the larger version.
Step 1 : Load OllyDbg and open "quake3.exe", which is our target.
Step 2 : Right click the CPU window and Choose "Search for > All referenced Text Strings". (Refer pic below)
Step 3 : Right Click and Choose "Search for Text".
Step 4 : Enter "CD" in the dialog box that popped up and dont forget to check "Case sensitive" and click "OK". (Refer pic below)
Step 6 : Hit "Ctrl+L" until you land in line "Game CD not in drive". Now double click on this line. It will take you to this line which is at the address 0042DFC6.
Code:
0042DFC6 |. 68 80E34B00 PUSH quake3.004BE380 ; ASCII "Game CD not in drive"
Step 6: Observe the following lines, these lines are found above the previous line which we saw.
Code:
0042DFC2 |. 85C0 TEST EAX, EAX
0042DFC4 |. 75 0F JNZ SHORT quake3.0042DFD5
TEST EAX,EAX -> Checks whether EAX is 0 or not.
JNZ -> Jump if Non-Zero ie. Jumps if EAX is 1.
Step 7 : Just modify the JNZ to JMP by double clicking on the line, so that the code looks like the one below.
Code:
0042DFC4 |. 75 0F JMP SHORT quake3.0042DFD5
Step 8 : Right click in the CPU window and select "Copy to Executable > All modifications" and choose "Copy All" in the dialog that pops up.
Step 9 : A dump window appears, right click on it and select "Save file", type a name, eg. quake3cracked.exe.
You can also change the
Code:
0042DFBD E8 AE210100 CALL quake3.00440170
to
Code:
0042DFBD B8 01000000 MOV EAX, 1
this CALL is above the line TEST EAX, EAX. There are a lot of ways to crack ! This is also a good method to crack, cuz it makes the program think that CD has been inserted.
That concludes the tutorial. I hope that you enjoyed it.
