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I Can Crack Your App With Just A Shell (And How To Stop Me)

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Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#61

Post by mindslight »

rikthevik wrote: post #35
TheAmazingIdiot wrote: post #31

Earlier quoted context omitted.

No. Effective means of protection are when you "roach motel" the data. The first rule of software engineering is you never let the shareware stuff do it all. Test version should not save? Rip it out. Shouldn't print? Remove printing. Chop it out wholesale. If you do an unlocking scheme, then make it subtle. Take a hint from Unix development: dont tell the user that the code worked or not. Just take the code or whatev…

There was a rumour going around the EE department that if you tried to crack Eagle or use a keygen'ed license, the software would slowly start corrupting the circuits you were working on. After a month it would tell you that you had pirated the software, but not before you'd created a fair number of non-working PCBs. Devious! I'm not sure if this is true or not, but it kept us all on the straight and narrow. :)

From what I remember, the copy protection on Eagle was conceptually simple and seemingly effective. Basically it put the license ID into all saved files. Updates to the software would include an updated blacklist which prevented loading of files from old pirated versions. Crackers wouldn't bother with fixing the load functionality as everything would work fine for the current iteration.

There were of course ways to work around it (load then save with the same version under the free license, or export the entire design as text using a ULP and then import in the new version). But on the whole, it struck me as frustrating the process just enough to encourage users who would possibly pay, to pay. (I wonder if Cadsoft made even more from unlocking design files. "You are having trouble opening that design because your fly-by-night consultant used a pirated version of Eagle. We'll happily unlock it for the cost of a deluxe license.")

Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#62

Post by nfriedly »

btn wrote: post #60
phillco wrote: post #53

Earlier quoted context omitted.

Brilliant, but be careful about this. There was an article here years ago about an indie game developer who put tons of different piracy checks all throughout his game. He was pretty clever, and made it so that several didn't activate until partway through the levels — that way the crackers might miss them. Also, he didn't show any "pirated copy detected!" messages, which would have made the checks trivial to find. I…

A similar (but much simpler) anti-piracy feature was built into Command & Conquer: Red Alert 2. The game would appear to operate normally, and let you start playing; however, after 30 seconds, all of your buildings would explode and you'd instantly lose.

That one was a bitch - sometimes it'd happen to my legally bought and paid for copy of the game.

Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#63

Post by mml »

I recall Intellij Idea IDE had some pretty decent protection. They used an "encrypting" class loader (of the xor variety), and also encrypted all their resource files. I have a lot of respect for the lengths they went to, though i'm not sure how much it benefitted them really.

Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#64

Post by bermanoid »

The great danger in the fight against piracy is that it's so damn interesting. You can spend months playing cat and mouse with the people trying to crack your schemes, ratcheting up the complexity to insane levels, and every time you come up with a new scheme and get it working you'll feel like a million bucks because you Won(tm).

But the people on the other side feel the same way, there are more of them, and in reality, they're not actually hurting your business as badly as your delusions tell you they are - none of them were ever going to buy your shit anyway.

Add features, improve your design, fix bugs, or tweak your shitty description and screen shots in the app store (which, in my experience, will affect sales for most apps more than the first three factors put together). Literally any time that you devote to copy protection is wasted, unless you're Angry Birds (and even then I'm not sure) you're not reaching anywhere near a high enough percentage of the people that would happily pay for your product to worry about the ones that would rather just take it.

Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#65

Post by huhtenberg »

pygy_ wrote: post #44
eps wrote: post #29

Earlier quoted context omitted.

Fravia materials are great, but they are outdated. Techniques are still valid, but the users have changed. Perhaps Mac users are still naive and ignorant when it comes to running random stuff on their machines, but on the Windows side anti-virus companies were fairly successful in educating people on this matter. Scaremongering works :) So signed executable + few simple validity checks + a couple of well-hidden timeb…

Subtly crippling the app may not be the wisest move, unless you make it obvious that it happens because the crack has been detected. Otherwise, the pirates will get the impression that your program is buggy and will look at alternatives rather than opening their wallet. And still... Even if you announce that the crack has been discovered before crippling, you may upset them and send them to your rivals anyway. ==> Po…

As someone who has been down this path I can offer a couple of comments.

1. Crashing or crippling the program indeed has an obvious negative PR side-effect. However it can be mitigated by inducing a very exotic crash, something like "Division by zero" or better yet - "Illegal Instruction", which would clearly point at mangled code being at fault. Also stick a thread titled "Illegal Instruction" in Support forums, explain why it happens and this will be the first hit in Google for a respective search.

2. While the trialware model is the way, it does not automatically mean it has to be an annoying nagware. What worked for one of my projects was to allow multiple consecutive trials. First was one month, next was two weeks, third and all subsequent trials were a few days long. These periods were configured on the licensing server, and the program did real-time license retrieval. So for me to be able to experiment with this model and get meaningful statistics, I had to ensure that the program at the other end of the licensing sessions is authentic. From that followed a need to safeguard parts of its code from modification and I ended up doing pretty much what eps described.

--

In other words ensuring integrity of the program is needed for more than just fighting pirates. Pirates are not a big deal, let 'em steal and crack. It's the legit customers that this protection ultimately benefits.

Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#66

Post by asnyder »

coderdude wrote: post #59
phillco wrote: post #53

Earlier quoted context omitted.

Brilliant, but be careful about this. There was an article here years ago about an indie game developer who put tons of different piracy checks all throughout his game. He was pretty clever, and made it so that several didn't activate until partway through the levels — that way the crackers might miss them. Also, he didn't show any "pirated copy detected!" messages, which would have made the checks trivial to find. I…

I mentioned this game in another comment on this page, but Spyro: Year of the Dragon used this technique and it worked very well for them. It could be that this is because it was on a console and not on the PC, but who knows. The goal for them was to simply keep the crackers at bay for as long as possible to keep the sales high during the initial release of the game. The developers stated that once the game is cracke…

I remember playing Spyro, good memories. I think there's a new one out, maybe I'll check it out for old time sake. Thanks for the positive nostalgia

Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#67

Post by EGreg »

daeken wrote: post #57
EGreg wrote: post #41

I personally like the idea of an application "unlocking" itself every time based on a hash of its binary. You would have to find all the places these hashes are computed -- if you missed even one place, you wouldn't be able to unlock the app. Of course, such an app could still be cracked -- as could any app... because all you have to do is 1) purchase a legitimate copy and enter a fake name 2) take a snapshot of a wo…

> The only way to really prevent cracking of apps that run locally is either challenge-response dongles ... This doesn't really work. If you have all of the functionality running on your machine but the dongle is there to authenticate, it can be cracked by ripping out the code that does the challenges. The proper way to secure an app using a dongle is to move some key piece of functionality out to hardware instead.

good point! You need some functionality though where the response can't just be memoized by the crack. What could it be?

Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#68

Post by daeken »

EGreg wrote: post #67
daeken wrote: post #57

Earlier quoted context omitted.

> The only way to really prevent cracking of apps that run locally is either challenge-response dongles ... This doesn't really work. If you have all of the functionality running on your machine but the dongle is there to authenticate, it can be cracked by ripping out the code that does the challenges. The proper way to secure an app using a dongle is to move some key piece of functionality out to hardware instead.

good point! You need some functionality though where the response can't just be memoized by the crack. What could it be?

Depends on the application, really. I can give you an example of where I've personally considered using this (ended up going with an alternative, however): my startup's product is a hotel front desk system and we have to encrypt room keys to work in the locks; pushing the crypto off onto an external device would make it considerably more difficult to pirate the software, as you'd have to reverse the algorithm and reimplement it in software. In the end, it didn't make sense for us, but it would've been pretty solid, as the odds of you having two identical cards is monumentally slim (and would only even be possible every couple of years).

Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#69

Post by Confusion »

moopark wrote: post #47

The fact that most simple copy protection can be broken by someone that knows a bit of assembly shouldn't surprise anyone writing applications, and this post is just self-congratulatory silliness that doesn't actually help someone that wants to protect their software. It wouldn't be any more responsible/ethical/useful of me to post a "I Can Crack Your Non-Mac App With Just A Copy Of IDA Pro and HexRays" tutorial. I c…

  The fact that most simple copy protection can be broken by
  someone that knows a bit of assembly shouldn't surprise
  anyone writing applications,
But it does, which is the point of the author.

  this post is just self-congratulatory silliness
You know, some people just like to write up something they did that they think is pretty interesting. People will keep inventing the wheel over and over again and still be proud of their wheel. This kind of derogatory remarks are uncalled for. You have no idea about the thoughts or feelings of the author and have no reason to think ugly things.

If I were to respond to your comment in the same way, I would say that you were just displaying your superiority complex over someone learning the ropes. Or perhaps bitterness and jealousy over the attention this article gets, while your more advanced knowledge does not get the attention it deserves. Or ... whatever. I can come up with a number of epithets to attribute to you based on that little bit of text, all equally uncalled for.

Re: I Can Crack Your App With Just A Shell (And How To Stop Me)

#70

Post by dangero »

The App Store doesn't need high levels of security on your apps. No matter how much you obfuscate, it only takes one smart person to crack it and then your app is on all the bit torrent sites.

People will buy from the App Store because they want the protection it provides and the convenience. They know when they download your app from the app store that it's not a virus, the install will be one click simple, and Apple has hand reviewed and approved the app.

I think the Mac App Store protection is designed to be just enough to stop Average Joe from copying it onto a usb stick and giving it to his friend. In the end that's really what you want.

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