How do I defeat Copy Protection?

@DrWatson

Published in 

Hacking Tutorials

 · 5 years ago

How do I defeat Copy Protection?

There are two common methods of defeating copy protection. The first is to use a program that removes copy protection. Popular programs that do this are CopyIIPC from Central Point Software and CopyWrite from Quaid Software.
The second method involves patching the copy protected program. For popular software, you may be able to locate a ready made patch. You can them apply the patch using any hex editor, such as debug or the Peter Norton's DiskEdit. If you cannot, you must patch the software yourself.
Writing a patch requires a debugger, such as Soft-Ice or Sourcer. It also requires some knowledge of assembly language. Load the protected program under the debugger and watch for it to check the protection mechanism. When it does, change that portion of the code. The code can be changed from JE (Jump on Equal) or JNE (Jump On Not Equal) to JMP (Jump Unconditionally).
Or the code may simply be replaced with NOP (No Operation) instructions

The flags-faking approach

Well, i decided to write this little essay for everyone (especially newbies) who does not like to spend a lot of time trying to decypher lines and lines of (meaningless?) code inside too many protection schemes.

For example, have u ever found a serial number protected program which u were not able to crack? I bet you have! You change a lot of bytes, and yet it still sayd "Unregistered" and the "only for registered users" options were still disabled.

On the other hand, did the following ever happen to you? A crippled program with some options disabled and u DO NOT FIGURE how to enable them? Well, go to the nearest tobacconist, buy a cool box of Marlboro Lights (or the red ones, if you prefer), choose a rainy day (the best for cracking purposes), sit in front of your PC and load this essay in your favourite text-editor (i use old, good dos EDIT). By the way, i hope you'll be able to read it, coz i dunno if the +HCU will really be interested on this piece of text.... in fact it doesn't describe any new protection scheme, it describes merely a different approach on cracking a lot of programs.

Ok, let's start!

I will take as example a program called "HyperCam" v1.19, sort of an AVI recorder of what happens on your screen... really good, especially if u want to create an animated "cracking essay" for your new brand cool target :-)

To get it go to www.hyperionics.com - HYPERCAM.ZIP - 251819 bytes (i'm not really sure of the ZIP name, i found it on a CD. But I believe it should be right)

Well, it's nothing new from the point of view of the protection scheme, as I said... the only thing to notice is that it uses a very very nasty key creation algorithm, maybe not understandable by most newbie-crackers. Also, it stores the registration infos in a file called HYPERCAM.LIC, so it needs quite a lot of work to crack it.

Ok, but this time we don't want to crack it with the usual "BMSG xxxx WM_COMMAND" no?

We want to try something new! Light your cigarettes, fire your SoftICE and install a good disassembler (i use now WDasm 8 < - thanx a lot to Frog's Print for cracking it! very good work!).

The "protection" consist, basically, in the following scheme:

1) It displays a nag screen at the beginning
2) It adds a boring "HyperCam Unregistered" to all your nice AVI creations

So, let's begin examining the "Unregistered Hypercam" add-on to the AVIs, i.e. the nagstring:

Since we want to crack it without really "registering" it, we have to take care of the flags that the program controls in order to know if it's registered or not.

Usually, a program will store in a location a "00" if unregistered (=FALSE) and a "01" if it's registered (=TRUE)... that's most of the times NOT a protectionist choice, that's the overbloated programming language doing it whithout ever letting them to know that this happens :-)

We have to find this "holy" location. How? In this way:

1) Load up WDasm and disassemble HYPERCAM.EXE, save the *.alf. (be sure to use the cracked one by FrogPrint!! If you use the demo one u will not be able to examine the textfile at leisure inside your wordprocessor!)
2) Search the nagstring it adds to all your AVIs: "Unregistered Hypercam" YEAH!!!! FOUND IT! Examine this piece of code: (don't care about my comments now, yu'll look at them after)

 
* Referenced by a Jump at Address :00401464(C) 
| 
:0040151C A1C0A34300           mov eax, [0043A3C0]  *** < Now is "0" 
:00401521 85C0                 test eax, eax            < If "0" 
:00401523 740F                 je 00401534          *** < You suck! 
:00401525 8B0D045E4300         mov ecx, [00435E04]      < Checks again 
:0040152B A1C0504300           mov eax, [004350C0]      < with another flag 
:00401530 3BC8                 cmp ecx, eax         *** < Final Check 
:00401532 7418                 je 0040154C              < Equal? BRAVO=!! 

Here we see that if the TEXT EAX,EAX fails at :401521 it will jump to 
401534 Hmmm..... maybe DS:43A3C0 is the holy location where our flag 
is stored? YES!!!! 

* Referenced by a Jump at Address :00401523(C) 
| 
:00401534 8B1534A14300         mov edx, [0043A134]      < not equal ? 
:0040153A 6A15                 push 00000015            < NISBA! (italian) 

* Possible StringData Ref from Data Obj ->"Unregistered HyperCam" 
                               | 
:0040153C 68D0504300         push 004350D0              < the Unregistered 
:00401541 6A00               push 00000000              < string is added 
:00401543 6A00               push 00000000              < to your AVIs 
:00401545 52                 push edx 

(lines tagged with a "***" will be the targets of our crack)

We found something interesting nah? Well, fire your ice (eh... i mean Winice!), run the program and set a BPX which let us return the debugger after doing something.... for example, i often use KERNEL!HMEMCPY and choose an option in which i can enter some strings.... but it's only an example, you could do it in a lot of other ways.... Well,

 
:BPX KERNEL!HMEMCPY 

/

listCTRL-D and select now an option in which you can enter some text (for example, the "License" option). After entering, you will land in Winice again

 
:S 22f:0 lffffffff A1 C0 A3 43 00 85 C0 74 0F 8B 

 
:BPX 22F:1EF91C 

Well, now we know where the flag is... can we suppose that it controls the initial nagscreen as well? yes of course! :)

Remove all the BPXs, set a new BPM DS:43A3C0 and restart the program!

Now we can see what happens to that "flag" location since the beginning... You will land in softice 2 times, and after the 2nd time the nagscreen will appear. So, what does this mean? Easy: the first time softice pops up inside a piece of code which resets the flags, the second time (our target) when the programs checks it. But look:

 
2nd popup: 

:00404958 8BCD               mov ecx, ebp 
:0040495A E83C610200         call 0042AA9B 
:0040495F 39BD48010000       cmp [ebp+00000148], edi < you will land here 
:00404965 750D               jne 00404974            < if not equal jump 
:00404967 6AFF               push FFFFFFFF           < if not..... 
:00404969 57                 push edi                < after some calls 
:0040496A 688B000000         push 0000008B           < the nag pops up! 
:0040496F E886270200         call 004270FA 

as u have noticed, EBP+148 is our "flag" location : 43A3C0 !!!

We are finished now!

 
Change .CMP [EBP+148],EDI with .MOVE BYTE PTR [EBP+148],1  < move always 1 
    .JNE 404974             .JMP 404974                 < in our flag 

Back to 401530, change also the JE 40154C to JMP 40154C to fool completely the protection scheme.

Note that you have to change all of these, 'coz only removing the nag or the string doesn't work. You can check this yourself examining the code....

Ah.... a little side effects of this kind of approach *MAY BE* that the program still say it isn't registered... even if all the options are now cracked and enabled and even if the nag screens has been removed.

This is what happens in HyperCam... but could happen in other programs too ('bcoz obviously you don't register them normally, whit this approach you don't enter any name/serial, you only fool the program to *THINK* it's registered...). But who cares? The main thing is to have a fully working version nah?

Well, i hope this little piece of txt could help you... it is often easier and faster to handle (read crack) the flags than trying to bypass the "real" number check or whatever the protection scheme does... also you can apply this approach to nearly every kind of protection... the main steps you should follow are:

1) Search references to the nag/unregisteecc. things in the code
2) Correctly identify the flags
3) BPM their locations and examine the code which refers to them.
4) Modify them to let the program think it's registedeprotected.

CIAO!

by [>Xoanon