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Morphing Code to Prevent Reverse Engineering?
ptolemu writes "Cringely's latest article discusses a new obfuscation technique currently being researched called PSCP (Program State Code Protection). An informative read that concludes with some interesting insight on the software giants that heavily depend on this kind of technology."
I've done mostly server-side work where:
- the jar files were secure because they were on the server and
- bytecode optimization and jar size was the least of our problems
Obfuscation seems to be useful only for client-side Java applications that contains super-secret valuable algorithms. I mean, who cares if somebody decompiles your code to see how you did sortable JTables or whatever?
The Army reading list
This technique might be interesting for stopping people from stealing your closed source code, but as far as security goes it's pretty much worthless. 99% of the vulnerabilities in MS's code were found before their code was leaked, and if you believe them, even the major exploit found after it was leaked had more to do with bad code than someone finding the existing problem by reading the code.
Don't blame me; I'm never given mod points.
The medical profession deals with viruses by identifying our weaknesses, and exposing them to the viruses (the ultimate "reverse engineering"?). If there were a biological DMCA, developing vaccines would certainly violate it on the illegality of "hacking into the body".
With software, though, people still insist on trying hide and pretend as if there were no viruses out there and that we would be impervious to them.
Can we finally just open all of our code so we can vaccinate it against all these exploits?
This looks vaguely like self-modifying code, like back in the old days of copy protection.
.net runtime engine (or maybe it's loaded and spews bytecode to the runtime), then it can be removed...or the output intercepted. .
The thing I don't understand about the article (and how it describes the PSCP process) is this: how will this make reverse engineering more difficult?
When you're starting to crack something, you work backwards from system calls, library calls, and known behaviors. "Known behaviors" are, well, patterns of code that people (or compilers) use to do things. Anyone good at low-level stuff can probably identify the compiler used to build the code. Likewise, if you think about something enough, you can probably figure out three or four ways to do something, and look for that pattern in the code.
PSCP prevents this...how? By making this process happens as the program runs? How else do you reverse engineer something?
Anyway, it sounds like this thing sits right before the
What am I not getting here?
Just like all the hubbub over proprietary signal encryption to "protect" digital audio streams, all you need here would be the CPU-equivalent of the old Analog Out jack.
Break it down to the Universal Turing Machine and tape analogy. The program code is the tape, and the state of the machine is in the tape-executing device. If the tape were to somehow morph itself dynamically, and yet execute properly by morphing to a well-designed program at the moment it is read for execution, all you have to do is to watch the read/write head of the UTM itself.
If they find ways to monkey around with bytecodes so that they're shifted around between disk and executor, just run it with a special version of the executor. Shouldn't be hard... the standard for what the unencrypted bytecodes are capable of accomplishing are standardized. Execute the code once, and take "notes" of what is being accomplished. Run through a code coverage test suite, even a crude black-box analysis, and you should get an unscrambled bytecode equivalent.
It just doesn't make sense. If obfuscation, i.e. obscurity, is your only security, it is no security at all.
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Cringely has really outdone himself that time. I can't even follow this poorly thought out mess. He seems to totally misunderstand every single concept he touches on.
Compilation to bytecode and an "interpreted language" are NOT THE SAME THING. Both the CLR and a compiled java class are effectively machine code for a machine that doesn't exist. These abstract machines have machine code that reveal *MORE* information to a disassembler/reverse engineer than, say, x86 or PPC assembly, but it is still far, far from being code. This is reaction one that I have. The rest of the article is so confused I don't even know how to respond to it.
When a computer program runs, the computer can follow millions of paths to get the job done. We leverage those millions of paths and transform them into billions of paths instead
Millions of paths implies some sort of jump instruction, whether or not that translates to millions of function calls, i don't know. assume it does. then instead of making millions of function calls, your making billions of function calls. Going from millions to billions is a large step, bigger than just swapping an "m" for a "b" in marketingspeak. So are they planning on passing this performance hit to the legitimate consumer? No thanks, I'll take my Free source code and like it.
So legitimate software is going to take on the functionality that virus software has been using for years? And companies are patenting these techniques as if they are somehow new? Virus writers are the true innovators here. They pioneered the infamous Mutation Engine. I would consider off the shelf software that used those techniques innovative, in fact I find it creepy. Honestly, if the time wasted trying to protect so-called intellectual property was used instead to invent things to simplify our lives, we (as in humanity) would be better off.
Yet, I have no doubt that if someone came up to them and warned them about the dangers of IP theft and showed them this solution, they would bite.
If they really wanted to do maximum damage to their competition they should have just released the source code and hoped their competitors tried to used that as guidance.
There are probably some rare instances when a specialized software technique is developed and you want to keep its implementation specifics secret. I have yet to run into a single instance of this after many years in the industry.
Sure, you can reverse engineer it. But is it worth the effort?
Most of the time it's not even worth reverse engineering unencrypted code, because it's really hard. There are open source projects that go undone because people don't want to expend the effort.
The trick is not to make it impossible, but to make it hard enough that it isn't done. That level is different for different projects, but it's always finite.
There is nothing new under the sun. These Java and .NET obfuscators are just the same old anti-SoftICE sections, which were just the same old Amiga/Atari copylocks, which were just the same Spectrum/C64 turboloaders, and so on.
Every single one of these is broken. Almost all good programmers are capable of deciphering the standardised, retail-boxed algorithm used for the obfuscation, and can easily un-obfuscate it. Are all the Java variables named "a"? Diddums! You don't have a Java decompiler with the option to ignore that simple tweak.
All that matters is:
1) How important is the code behind the obfuscation?
2) How much time and effort is the reverse engineer willing to spend?
If you use a company's retail-box obfuscator, anyone with the "'Brand X obfuscator' deobfuscator v1.0" can get straight at your code. It's a technological arms race, nothing more.
Does my bum look big in this?
I don't love microsoft, but I think this article makes several claims without backing them up or offering any explanation as to their merits. Such as:
And "You can write a program in C# or Visual Basic.NET." while factually accurate, ignores Delphi.NET, C++ managed code using the CRL, and other implementations of the CRL (COBOL, etc).
I think the basic premise of the article, where if someone is using your objects it is obviously a bad thing/security breach, is flawed. If you need to secure your objects, SECURE them! Seal them, see who is calling you, etc.
Lastly, As shown by previous posts, Obfuscation is not the end-all panacea to security. In my opinion, it's barely a detour. Otherwise, Open Source literally could not be secure.
If you blog it...
You're a asuming that there is a Microsoft way to look at code and that every MS developer is a robot brain washed to think that way. MS hire very capable and brilliant people, you couldn't tell the difference between a bunch of NT kernel hackers and a bunch of Linux kernel hackers, both groups are extremely knowledgeable and manufacture high quallity code.
MS has the biggest industrial infrastructure in the world of quallity assurance. Every developer should go trhough an internship in Redmond to see this.
Large software *is* complex, period. Given a finite amount of talent and time, bugs are depedent of the size of the project, it really don't make a difference whether you're code is open source or not.
How many people do you think actually look at open source code to look for bugs?
Moral: if MS releases buggy, exploitalbe and potentially unsafe code is *not* because they are sloppy or because propietary code is inherently worse than open source, is because large software is complex and takes a lot of time to do it right.
If it changes how it executes every time, it sounds like it would be a fantastic way to introduce unreproducable bugs.
I'm sure this would make QA testing a nightmare.
"He's lost in a 'floyd hole"
tmp is less clear, but it certainly would have local scope, and only exists because of shortcomings in the implementation language (like not having a primitive operation for swapping the values of two variables without introducing a temporary variable), but no real significance in the problem domain.
These variable names are perfectly acceptable and clear - unless you abuse them, of course, but you can abuse all nameing schemes. Nothing stops you from calling a global integer m_pszHelloKitty.
Hungarian notation on the other hand is problematic because a) it is just a non-functional workaround for the weak typing in C and C++ (and their habit to make type errors crash your program in random unrelated places, or just corrupt your data) and b) there aren't actually enough rules, and if there were, nobody could remember them all. "iSomeInteger" and "sSomeString" are pretty common, but if you happen to use more interesting types, or even a whole C++ class hierarchy, it just doesn't work anymore. The only use of Hungarian Notation is to make clueless middle managers happy, similar to a long-winded format for mandatory comments preceding any trivial function or multi-page e-mail disclaimers. Source code is readable when you can actually read it out loud and people would understand whats going on, not if you encrypt redundant information in variable names.
Programming can be fun again. Film at 11.
Of course, if you don't know what the type of a variable is you can also just look at the type declaration.
Unless you're using something like BASIC where variables just suddenly appear out of the ether I really can't see how Hungarian notation is necessary. Especially in an age where we have advanced editors with split windows, and powerful search tools like glimpse, cscope, and ctags.
Besides, why should I trust some agglutinated letters on a variable name when I can do the same thing the compiler will do and look at the type declaration and be totally _sure_ of the type of the variable? What if some doofus changed the type of the variable in the declaration but was too lazy to update all the instances of Hungarian notation? Hungarian notation can only lead to a code maintainence nightmare!
--
"I'm too old to use Emacs." -- Rod MacDonald
The problem with Hungarian, of course, is that it lies.
It's like the comments. They tell you what the programmer *meant* to do, not what he or she did.
Similarly, Hungarian notation tells you the *intended* scope, type, etc, but the compiler may have a very different view of things.
Eloi, Eloi, lema sabachtani?
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