Category / tools

by ReWolf

Reverse engineering Mortal Kombat GRA file format (part 1)

Disclaimer: This post is aimed at retro-gaming preservation and code-archeology. All product names, trademarks and registered trademarks are property of their respective owners.

GRA files are used by the PC DOS version of Mortal Kombat 1 and 2 (available on GOG) to store all kinds of graphics. There are two different types of GRA files:

  • compressed static images or animations – this is a well-defined self-contained file format that can be easily converted to the PNG/APNG/GIF, the only obstacle is compression which has to be reverse-engineered first. I’ll refer to it as cGRA and cover that format today.
  • not compressed sprites/fonts/graphic objects/UI elements – this format is kind of a mess, it just contains encoded pixel data without any metadata. All necessary information has to be scavenged from the Mortal Kombat executable (sprites offsets, width, height, palette). I’ll refer to it as uGRA and cover that format in part 2 of this blog post (still have to figure out a few things).

Continue reading →

by ReWolf

GoGoGadget – kernel exploitation helper class

The aim of this class is to facilitate building kernel shell-codes and ROP chains (at least before RFG kicks in sometime next year) by providing easy access to some of the available kernel information leaks. Under the hood I am using well known NtQuerySystemInformation with following classes: SystemExtendedHandleInformation, SystemModuleInformation. This piece of code came to live as a part of an exploit that I was developing some time ago, but I can’t release it yet. Therefore I decided to publish it as a separate project, so everyone (or just future me) can reuse it for their own purposes. Code is written in C++ and should compile with Visual Studio 2015, for now it only supports x64 platform and some of the functionality is limited to Windows 10 (obtaining EPROCESS address of some of the system processes). I advise compiling Release build, since Debug is very slow due to extensive use of STL

GitHub: https://github.com/rwfpl/rewolf-gogogadget

Continue reading →

by ReWolf

wow64ext v1.0.0.8

New version of wow64ext library is available for download:
http://rewolf.pl/stuff/rewolf.wow64ext.v1.0.0.8.zip
or if someone prefer github:
https://github.com/rwfpl/rewolf-wow64ext

Changelog

  • Fixed elusive bug that appears only on AMD cpus
  • Removed VS CRT dependencies – dll size shrank to 9kB (previously 41kB)
  • Added sanity checks, so x64 switch won’t run on x86 OS

Continue reading →

by ReWolf

Terminus Project launch.

terminus_logo_blog

I would like to announce launch of my new web-based tool: Terminus Project. It’s automatically generated diff of Windows structures with nice (I hope!) presentation layer. Currently it contains only data gathered from NTDLL PDBs (281 dlls at the moment of writing this post), but it can be easily extended with other libraries. Idea behind this project was derived from my old research on PEB structure (link), which is still quite popular (comparing to the other posts on this blog). There are a few things that should be improved (for example, better support for structures with unions), but I decided to publish it now, so it won’t stay on my HDD for the next few months.

Continue reading →

by ReWolf

wow64ext v1.0.0.7

New version of wow64ext library is available for download:
http://rewolf.pl/stuff/rewolf.wow64ext.v1.0.0.7.zip

Changelog

  • All 64bit APIs are now properly setting last Win32 error, thanks goes to Dreg (http://www.fr33project.org/) who implemented this feature.

This is actually unexpected benefit from hosting wow64ext on github (google code is dead, long live github), so if some of you want to add something to this library do not hesitate to do pull requests. I can’t promise that I’ll accept everything, but at least you may try :) Here is the address:
https://github.com/rwfpl/rewolf-wow64ext

by ReWolf

Java VM Operand Stack Viewer

Recently I’ve got asked about this quite an old unpublished project that I actually forgot about and I decided to finally do something with it. I’ve mentioned it once in this post: http://blog.rewolf.pl/blog/?p=856 and I’ve shared below screen-shot with an annotation that it will be published soon as a part of dirtyJOE:

java_debug

One and a half year passed and I did nothing regarding this integration. Even more, at some point I came to the conclusion that this project does not fit for dirtyJOE as it’s rather Proof of Concept than a proper solution to the problem (no matter if the proper solution even exists). I’m still not sure if I don’t change my mind and eventually make it a part of the dirtyJOE, but I’m 100% sure that JVM Operand Stack Viewer deserves a release. An open source release with the full description of the method used to obtain JVM operand stack.

Continue reading →

by ReWolf

Reverse engineering Might and Magic III compression

I’m not quite sure how I ended up deep inside DOSBox debugger, going through 16bit assembly and recovering decompression routine used to handle MM3.CC file, but it was definitely fun. I got the game from one of the recent humble bundles and somehow (this is the part that I’m missing) I’ve found Jeff Ludwig’s page. I’ve read about his approach to modding Might and Magic III and problems related to compressed/encrypted MM3.CC data file. One of the phrases sounded like an invitation:

“It turns out that this algorithm has been a particularly tough nut to crack, and no one has come up with a viable way of decrypting the data.”

I recommend reading the whole story as his method of dealing with this problem is also great. In this post I’ll describe how I’ve handled it, in the end there will be link to the open source utility that can not only decompress, but also compress valid MM3.CC file.

Continue reading →

by ReWolf

dirtyJOE v1.7 (c529)

New version of dirtyJOE is available for download at http://dirty-joe.com. The main new feature is Java 8 class files support, as there were some minor changes to the file format that were breaking dirtyJOE. You can find full changelog below:

  • Java 8 support:
    • Added support for new constant pool types:
      • CONSTANT_MethodHandle
      • CONSTANT_MethodType
      • CONSTANT_InvokeDynamic
    • Added viewer for BootstrapMethod attribute
    • Added support for invokedynamic opcode
  • Added viewer for StackMap attribute
  • Added Copy and Copy all to the exception table list in Code Editor
  • Added /opcodes command line switch to start Opcodes Help only
  • Added demangling of Signature attribute
  • Opcodes Help window can now be stuck to the main application window or to Code Editor window
  • Added some more keyboard shortcuts

PS: It seems that dirtyJOE became a thing on Brazilian Minecraft modding scene (in the last few months over 50% of downloads were from Brazil). Greetings to You guys, if You have any special Minecraft related feature requests just send me a message and I’ll see what can I do for You :)

by ReWolf

wow64ext v1.0.0.6

New version of wow64ext library is available for download:
http://rewolf.pl/stuff/rewolf.wow64ext.v1.0.0.6.zip

Changelog

  • Bugfix for improperly aligned stack. It was aligned to 8, and it was failing when some x64 SSE code was executed as it needs 0x10 alignment. Thanks goes to Vlad, who pointed it out in some recent comment under previous release: http://blog.rewolf.pl/blog/?p=1097#comment-51893. This bug was present since the first version of the library, thankfully now it’s gone.
by ReWolf

wow64ext v1.0.0.5

New version of wow64ext library is available for download:
http://rewolf.pl/stuff/rewolf.wow64ext.v1.0.0.5.zip

Changelog

  • Added VirtualProtectEx64
  • Bugfix for ReadProcessMemory64 / WriteProcessMemory64 – lpNumberOfBytesRead / lpNumberOfBytesWritten is declared as SIZE_T pointer. SIZE_T on x64 platforms is 64bit value, but wow64ext library is 32bit, so SIZE_T will be 32bit. Passing this pointer directly to the x64 version of NtReadVirtualMemory / NtWriteVirtualMemory would lead to a buffer overflow. To keep backward compatibility, I’ve introduced intermediate DWORD64 value that is used internally by ReadProcessMemory64 / WriteProcessMemory64, result is cropped to 32bit value, but it shouldn’t be a problem most cases.
    Link to described fix:
    https://code.google.com/p/rewolf-wow64ext/source/detail?r=474542f2eb4fc29fd1dde4cd852c419bd6ad1ea0#