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Text File | 1996-05-18 | 16.9 KB | 307 lines

HOW TO CRACK, A TUTORIAL - LESSON 1 by +ORC (the old red cracker) -> How to crack, an approach LESSON 1 How to crack, tools and tricks of the trade LESSON 2 How to crack, hands on, paper protections LESSON 3 (1-2) How to crack, hands on, time limits LESSON 4 How to crack, hands on, disk-CDrom access LESSON 5 How to crack, funny tricks LESSON 6 (1-2) How to crack, intuition and luck LESSON 7 How to crack windows, an approach LESSON 8 How to crack windows, tools of the trade LESSON 9 How to crack, advanced cracking LESSON A (1-2) How to crack, zen-cracking LESSON B How to crack, cracking as an art LESSON C How to crack INDEX LESSON 1 - HOW TO CRACK, AN APPROACH The best way to learn cracking (i.e. understanding, broadly individuating, locating exactly and eliminating or suspending or deferring one or more protection schemes inside a software application you do not possess the source code of) is to begin your tampering experiments using OLDER applications which have OLDER protection schemes. In this way you 'll quickly grasp the base techniques of the trade. Do not forget that the evolution of the protection schemes has not been a one way road... strictly speaking it's not even an evolution: you'll eventually find some very clever new tricks, but most of the time you 'll unearth only various trite repetitions of past (and well known) tricks. This is no wonder: the REAL knowledge of the "commercial" programmers themselves (the "protectionists") is often very limited indeed: they are inclined to use the old methods (albeit somehow changed, sometimes even improved) instead of conceiving new methods. This typical "commercial" degeneration happens every time people act for money instead of doing things for the sake of it or for pleasure. This "commercial" trend is blindly encouraged by the stupid, money-oriented society we are coerced to live in. So I'll begin the "hands on" part (-> starting from lesson 3), using as examples, some "old" applications and some "old" tricks. We'll be able to come later over to the newest protection schemes in order to understand them, and you 'll learn how to defeat this kind of junk too. I'll also explain WHERE you can find a lot of programs to crack for next to no money at all, and HOW 'grossomodo', you should proceed in your work. The applications you'll use to learn with can be divided into: 1 - Password crippled applications (the easiest to crack) 2 - applications crippled on how many times, or how many days, you use them (fairly easy to crack) 3 - applications crippled on which date you use them before (easy to crack) 4 - applications that have some functions present but disabled (sometimes easy, sometimes difficoult) 5 - applications crippled on Disk access (protections schemes that are now defined as "obsolete") and apps crippled on CD-ROM presence (more or less the same methodes, but - somehow- not defined as "obsolete") (vey easy to crack) 6 - CRYPTOGRAFED ADDS ON (i.e. one of the previous protection schemes, but with some scrambled or self modifying code (XORring and SHRLing codes) (fairly easy to crack) 7 - None of the above (sometimes difficoult to crack) WHERE TO GET THE STUFF The recent widespread appearance of "Demo"-CDROM on magazine covers is a treasure for all crackers! Obviously even if they are cheap, you should never buy such magazines immediately on their release, coz after a short time you 'll get all the copies that remain unsold for next to free. The demos on CD-ROMs will permit you to gather quickly a lot of applications -old and new- that have somehow been crippled (at times with interesting schemes). Truly a wonderful world of cracking possibilities! Gee! For next to no money you can secure on one CDROM the whole of LOTUS applications (or Microsoft or Wordperfect, or you name them) on "trial for 30 days" or "try it 20 times" editions. You'll really enjoy to crack them and to use them subsequently for ever and ever (and/or graciously donate them on the Web to the poor lamers that have no money and no brain). GAMES are definitely not to be frowned upon! They are extraordinarily interesting from a cracker prospective coz they are often "overprotected". With this I mean that they possess protection schemes of a relatively HIGH level hidden inside files that are not very large. Now, see, it is much more easy, and simple to track down and eliminate protection schemes inside a single 35.000 bytes long executable file than to locate them inside a collection of many lengthy DLLs and overlaids that could have swollen as long as 2.000.000 bytes each. The lazy bunch of "modern" programmers relies systematically for protection schemes on this "hide the sting in the wide desert" logic. As a matter of fact they are no longer able to program in assembler: they bank more and more on overbloated "fatty" monstrosities like Visual Basic, Delphy or Visual C++. (But do not worry... I'll nevertheless teach you how to crack -and quickly- those huge apps too). There is another reason for employing games instead of applications as study material: often EXACTLY THE SAME protection schemes that you find in a simple (and short) shareware game will be used -without much improving- a little later in order to "protect" some huge and extremely expensive graphic application. For this reason in my tutorial we'll often crack games protection schemes, even if we'll later apply what we learn mainly in order to crack the protection schemes of commercial applications, or to crack the access protection routines to remote servers, or BBS, or even ATM (cash dispensers). Here follows an example cracking session, that will show you -I hope- the dos and donts of our art: let's crack together as introductory example a time crippled application. We'll learn later (-> LESSON 4) that all applications that are crippled on time (i.e. "how many times" you use them or "how long" you use them) rely on analogous protection schemes (albeit with a huge palette of small variations): 1- they may have a counter which "clicks" every so often: FIND IT AND DISABLE IT! 2- they may fetch the time_clock interrupts in your machine: INTERCEPT THEM YOURSELF! 3- they may compare a random_seed with a variable: NOOP IT! 4- they may check randomly the date of your other, unrelated, files on the hard disk: find this verification routine and INVERT the JUMPS! I wanted to start with a modern example of this "counter clicks" protection type, just to give you a feeling for cracking, and I have chosen a widely published demo: you should be able to find it pretty easily. In order to show you some of the problems you may encounter we'll crack this example "wrongly" (you'll learn how to crack effectively in the "HANDS ON" lessons). EXAMPLE: ARCADE POOL, Demonstration version, PC Conversion by East Point Software Ltd, (c) Team 17 Software Ltd 1994. This demo has been published by many magazines on their CDRom covers throughout 1995. What follows will be useful even if you do not have our example; nevertheless you should get a copy of this widespread demo in order to better grasp some of the points that follow. This nice demo of a billiard game is time-crippled. It is crippled on how long you use it: i.e., you can only play 2 minutes, afterwards a "nag" reminder of where and how you can buy the real version snaps: protectionist squalor at its best. So, how do you proceed? Where does the beginning begin? Here is what you could (but not necessarily should) do: Get [Soft-ice] and load it in your config.sys. See the TOOLS OF THE TRADE lesson (-> LESSON 2) about this debugger. Version 2.6 of [Soft-Ice] has been cracked by MARQUIS DE SOIREE and can be found on the Web for free. - vecs s (save all the vectors before loading the babe) - start [pooldemo.exe] - vecs c (vector compare, save a printing of all hooked vectors) - enter and leave Soft-ice a few times to understand what's going on and where in [pooldemo.exe] are we roaming around (you should always check MORE THAN ONCE your findings when you snoop around: nothing moves and confuses pointers in a more frenzied way than good old "inactive" DOS). - have a good look at the map of memory usage ("map") - now "snap_save" the main memory regions where [pooldemo.exe] dwells... snapping saves "photographyes" of memory areas. - do not do anything, let just the seconds go by. - "snap_compare" every two or three seconds without moving anything at all on the game board (no mouse_clicking, NOTHING), so that the only changes are (hopefully) the changes caused by the time counters. - snap_compare twice in a second. - snap_compare at second 00:59 and at second 1:01. - snap_compare just before and just after the time limit and the snapping of the nag screen. - Now collect carefully your printed "snaps" data: write clearly on the various sheets the occurrences of the snaps. - now comes the graceful "zen-cracking" moment: Sit down with a dry Martini and Wodka (obviously only russian Wodka will do) and contemplate the printing of the various mutant locations. Feel, perceive, empathize! Look closely at the locations that have changed in the snap compares. Analyse, interpretate, evaluate. - Mmm! Hey! Something fishy is changing there, and there, and there! (you are lucky, few do actually change in this case: only two dozen) - breakpoint on execute at the location that you believe act as a "continuous" counter, i.e. the location that triggers the "a second went by" event when it zeroes. - Now set the occurrence counter of BPX in order to break at the moment where the location "refills" and restarts from the beginning (the equivalent of "one second" went by, let's start anew). Use the occurrence counter in order not to single-step through the program your life long! - IN THIS CASE you 'll quickly locate the refill at location 3DD0. Here follows the "refill" line: xxxx:3DCC C706F1013C00 MOV WORD PTR [01F1], 003C The "3C" byte at xxxx:3DD0 represents a counter_byte... i.e. the program "charges" 3C in this location and then DECs it step by step to 3B, 3A, 39, 38 etc... till 0. When it reaches 0: bingo! Sucker user has lost one second more of his precious two minutes. Now, you would get a first wizard level if you searched further on for the exact point where you get the "nag screen" in order to eliminate the whole witless protection, but you may think you got it already and you remember anyway that the first principle in cracking is the following: "once you can eliminate the effects of a protection, do not look further!" Most of the time this is true: you do not always need to eliminate a "whole" protection scheme (unless you are just studying it for the joy of it). It's normally easier (and quicker) to eliminate the "effects" of a given protection scheme. Unfortunately this is not true in this case. Here you believe that you have already found the way: you got the counter that charges the reverse clock that triggers the particular protection scheme of [pooldemo.exe]. Now you may think that if you could modify the refill_value... say changing "3C" to "EE" (Yeah, the maximum would be FF... but it's always good practice to avoid such extreme values when cracking) you should get four times more playtime for your game... more than enough in order to make the protection scheme useless. So you change location xxxx:3DD0 from "3C" to "EE". To work on bytes you should use a good Hexeditor like PSEDIT (Parity solutions, [Psedit.exe], brilliant shareware: see the "tool of the trade" section) but you could also work with simpler debuggers like [debug] or [symdeb] (-> see lesson 2). If you do, remember to work on a "dead" copy of your crippled [*.exe] file, i.e.: ren POOLDEMO.EXE POOLDEMO.DED symdeb POOLDEMO.DED -s (cs+0000):0 Lffff C7 06 F1 01 C3 <- this string corresponds to the refill line). cs:3E85 <- symdeb gives you two locations as answer cs:3EEA -e cs:3E85+4 EE <- refill changed from C3 to EE -w ren POOLDEMO.DED POOLDEMO.EXE Now you run your tampered pooldemo. You think you cracked it, you glee with satisfaction... but loo! Nothing at all has changed, everything's as lame as before, you still have only 2 minutes playtime. How disappointing: how comez it did'nt work? Well, for a start you have not been attentive enough! The search in debug gave you TWO locations, you moron, and not just the one you just tampered with. Check and you 'll see that the second location (cs:3EEA) is a MIRROR/CONTROL location (more on this later). Some times there exist "double" locations... coz at times it's quicker to use a double routine than to use a branching if or switch structure... some times the second locations do mirror the first ones and correct them on the fly if need be. So you need to modify this too... you act as said above but this time you enter in debug a -e cs:3EEA+4 EE before writing back the dead file and then renaming it to exe and then running it... and loo! Hoow sloow! THERE YOU ARE! Your crippled POOLDEMO.EXE is now (sort of) unprotected: You think that you can now play the stupid game up to 12 minutes real time, even if the protection scheme (and the counter) "believes" that it is playing only two minutes. So you begin to play, and the seconds look veeery sloow, and everything seems OK, but -alas- NO! At screen second 28 you get the irritating "two minutes are over" nag screen! Obviously you were dead wrong: the program "knows" the time directly from the timer... you only modified the stupid counter ON THE SCREEN. So it's back to cracking, and now you are angry, and forget the quiet ways of the zen-analyse and begin the heavy cracking you should reserve -if ever- for really complicated schemes. You now start to check the hooked vectors (you did your routinely VECS_save before loading pooldemo in [Soft-ice] and your VECS_compare afterwards) and you see some findings that you believe interesting: vecs c 08 1EFD:84C6 0CD1:17AC <- the clock 09 1EFD:85EC 136A:069C <- the keyboard 22 0BCE:02B1 0BCE:017E <- the terminate That's more like it -you think. Smack at the beginning: the first hooked vector does it! It's good old interrupt_08: the timer_clicker! Some basics for those of you that do not know anything: INT_08 controls indirectly the INT_1C timer interrupt. The 8253 clock chip generates an IRQ_0 hardware interrupt at a rate of 18.2 interrupts per second. This gives control to the ISR (Interrupt Service Routine) that the INT_08 points to... and this should be at 0CD1:17AC, but has been hooked here, by pooldemo, to 1EFD:84C6. One of the actions taken by the INT_08 ISR within the BIOS is to issue a software interrupt call to INT_1C, just in case any software modules within the system have established an intercept. If no intercepts have been established, the default contents of the INT_1C vector point to an iret instruction within the BIOS, so that a null action results. (Iret retrieves the three words of stack information which were automatically saved when the interrupt call began, and uses them to restore execution control to the appropriate point). Normally a protectionist would intercept INT_1C, coz at every ISR from INT_08 the CPU would fetch the contents of the corrisponding interrupt vector and make an interrupt style call to the code at that address (which should contain the iret at address F000:9876 but can contain any trick they could think of). So -you think- the protectionist hooked here INT_08 directly (a pretty infrequently used protection scheme by the way): What now? A rather drastic misure would be, in such circumstances, to disable the IRQ_0 level timer interrupt, which is controlled by bit 0 of the mask register, at address I/O 0021h. The controllers have IMRs (Interrupt Mask Registers) which can be used to hide or mask specific interrupts. The IMR of the first controller is located at port address 21h, while the IMR of the second controller is located at port 0a1h. When bit 0 within the mask register is set to 1, no further interrupts will be recognized for this IRQ level. This unfortunately won't work here, but it's an interesting technique per se, so you better learn it anyway, just in case you should need it elsewhere: