Decompiling Programs

[royjacob]

I'm not sure if its possible, but does anyone know how to decompile EXE programs

To answer your question, yes, you can decompile EXE's but unfortunately I do not have a link to any decompilers.

There were several topics on this so if you do a search, you should find a topic with a link to a decompiler.

[oetje]

It's easy to decompile a VB3 program, and sometimes you will have luck with a VB4 program. But, there aren't any real decompilers for VB5/VB6.

[parksie]

Unfortunately, up come the ethical issues again, which, for the sake of not being called a useless poster, I won't go into here.

Unless its a VB3 Deco. they are usually called DisAssemblers because they usually decompile into ASM.(AKA Assembler)

[parksie]

Some programs attempt to reproduce the original source code, but usually the functions and variables end up with really weird names.

[dimava]

I know that microsoft has one for its personal use, and I'm sure that bill gates can un scrabel it using a hex editor

One of the 1999 issues had some adds for a vb5 decompiler. As stated by others, the decompiled code can be a real hassle to get to grips with.

Had to do this for another dialect of basic, and it took a couple of weeks to determine what the variables actually represented.

e.g

decompile code

dvara = dvarb - today()

It took a while, (and numerouse debug breaks) to work out that dvara was a transaction date and dvarb was an Invoice date. The variable naming conventions might be due to the compiled code holding memory locations.

[dimava]

do you know what month? becuase I have all the one's from 1999 I think

We have a company subscribe, this should be easy but no one's got around to writing our xref app for the journal yet. Do you know if the CD that you can subscribe to holds all the relevant source code from the members site?

[Cromas]

There is a VB5/VB6 decompiler out there. Yes, decompiler, not dissasembler. Unfortunately, I no longer have the link for it. It's also rather pricey, around $295 I believe.

Also, VB does not include variable names when it compiles programs. It does, however, include the function names, contrary to a previous post.

Variable names turn out to be memory addresses I believe, such as #M2840, #M2850, etc., etc. I haven't decompiled anything since VB3 so that may be a little out of date.

As a general rule of thumb, you always want to use an EXE compressor (such as ASPack, http://www.aspack.com) on any VB apps you distribute, as they contain information that could be used by a hacker, such as the paths to the source code on your hard drive. Also, using an EXE compressor eliminates the possibility of decompilation more than 90% of the time.

Another great EXE compressor that is also an EXE packager is Fusion (www.bit-arts.com). Not only does it compress EXE files, it builds dependencies into them. Imagine having a program that doesn't need MSVBVMx0.DLL Unfortunately, if you don't build EVERY dependency into the program, and a user without the dependency you omitted runs the program, it crashes, instead of the nice 'DLL Hell' dialog.

Aight, I'm done babbling now.

[lomac]

Originally posted by parksie
Unfortunately, up come the ethical issues again, which, for the sake of not being called a useless poster, I won't go into here.

[parksie]

Huh? And I thought that was a useless post when I first wrote it .

How much does this VBPJ cost?

[Steve Stunning]

"Huh? And I thought that was a useless post when I first wrote it "


Naw, Many people have asked about this in the past. I would not mind being able to "take a look" at how some others have written their software. But I sure hate the thought of knowning that someone can do the same to mine!!

I have seen sites that have "shareware key generators" for programs. I was thinking that they probably have a decompiler or dissasembler and were able to figure out how a valid key is created in the original software.

Got caught up fixing a friggin ThinkPad.

Cromas

If you had actually taken the time to read my post, and analysis what it stated, before posted without your brain in gear you would note that l mentioned another dialect of basic. Ergo l was not claiming this was visual basic, and was only pointing out some of the problems with decompiling.

Some people should actually read and fully understand a post before making comments on it.

[Pentax]

Have I understood it right, that it's possible to get the sourcecode from an exe compiled from VB6, but you can protect it against this?
And that you can make an exe with all the neccessery information, which you can distribute without dll-files?
Or have I just messed it up?
Pentax

[Steve Stunning]

I saw something in the part about changing a value inside the program that would stop "some" of the programs.. But any experienced hack would know how to get around it.

Anyone know of a program that is capable of altering the exe and stopping the code from being broken down?

[da_silvy]

does visual basic source safe do anything?

[Cromas]

SourceSafe is a team project-management application, it will not prevent your programs from hacking.

Read my previous post about how to protect from de(compilation/assembly).

[V(ery) Basic]

Why would a hacker bother with a VB app?

All the apps which are worthwhile hacking are C++, nobody would really waste their time decompiling a VB app, becuase C++ apps are far more mainstream and all the hackers out there would prefer hacking Word or Excel than 'My Database Manager 5: Deluxe Edition'.

I agree that you should try to make the app as error-proof as possible, but is it really worth going through all of that trouble just to account for something that 99.999999999999999% of the time won't happen?

[Steve Stunning]

<All the apps which are worthwhile hacking are C++, nobody would really waste their time decompiling a VB app, becuase C++ apps are far more mainstream and all the hackers out there would prefer hacking Word or Excel than 'My Database Manager 5: Deluxe Edition'. >

Well, Not all programs are written in C++. I am sure there are several shareware programs in VB. The hackers would love to take credit for knowing how to generate the authors "Shareware Key". I use shareware keys in my programs and I have downloaded other shareware programs that use them as well.

I have visited the hack sites that provide several Key Generators for many popular programs like WinZip, Thumbs Plus, and more. I figure, they must have figured out a way to take a look...

Just my thoughts on the subject.

Ok only ever done decompiles for an old R83 Basic system. The software company had gone up in smoke, and the client needed some quick mods made while we developed a replacement system. No source code, so got a decompiler and hack the code

You shouldn't do this to software...but...the company no longer existed, and we couldn't contact them...and the changes were due to government legislation.

Haven't had to do this to vb yet, the only client that came close had a half written commission system, which we just replaced. But there is always the possibility, though what Cromas mentioned about the memory locations is frightening............

[Kc0bfv]

There are programs that are worth cracking that are written in VB.

Also, I think that the guys that crack shareware use hex editors and programs that decompile to ASM. From what I've seen, most of these guys aren't in High School either, and they've had college experience in ASM, etc. I've heard it's not that hard to learn, so if you want to make simple program corrections or serial number cracks, maybe that's what you should look into.

[Cromas]

Decompile to ASM = Disassemble. Cracking you don't actually take apart the EXE, but you look at the taken apart EXE. Confused? hehe. Basically you watch the x86 assembly code WHILE the program is running, determine where the code involving the serial key is, and eh...fix it up.

[da_silvy]

it all sounds like a lot of trouble, just to chnage the serial code@

If you compile your program in P-Code it can be decompiled by most vb decompilers on the web..Even in vb5 and vb6.

[Kc0bfv]

Chromas that's exactly what I meant, kinda. What is that program, cold ice? soft ice? my friend had it for a while but didn't need it so he uninstalled it.

Magadass - where do I find a decompiler for p-code?

[Cromas]

There are lots of them out there, look for anything called an EXE Debugger. Soft-ICE is definately the most popular.

[LauPro]

Dutch/Netherlands


Ik vind het niet goed dat een vb programma kan worden 'gedecompiled'.

Als iemand mijn programma's onder zijn naam gaat aanbieden op het internet dan ga ik programmeren met een ander programma!

Laurens


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