java self-contained application packaging cracking

[Chuck954]

I have an app that uses a JAR file for security. It used to open up javaw.exe. Working on cracking a newer version and it looks like it uses a self-contained application packaging. That's what I think this is. If it just used javaw.exe I could attach a java debugger.

The program now uses DLL files to access the JAR file. Anyone know of a way to attach a java debugger to something like this? Any suggestions?

I've decrypted the JAR file but it but it'd be nice to be able to manipulate the data in real time.

[chants]

It sounds unclear that this new version has anything to do with Java. After all a JAR is just a ZIP archive with a special Metadata folder and Metadata files. If DLLs are being used and Javas executables are not running, then it would been to be reversed like any native code app.

[zen]

I ran into something like this when cracking CISCAT Pro, it was a "install4j" package as the app itself - so instead of having and installer that deploys the software, the software that run is each time is an installer package that decrypts to a temp directory (which is why my current crack is a race condition in powershell (but works great)). (it did use a dll file in the process as well)

Anyway if that is what happened in your case then it might help to know that these things (Exe4j for example) bundle the actual java code in a pack200 format, and then for some mysterious-to-me reason they xor it all with x88. You said you already decrypted the jar so maybe this isn't your issue... ? If you have a jar and the program is just java, then it seems you should be able to set your manifest Main-Class and run it.

edit: i just realized these posts are years old. oh well, maybe someone else working on a java package will see this and find use.

[sendersu]

anyone knows how to attach to running java app and debug it on bytecode level? (similar as dnSpy it's super magic over .net assemblies)