Category: Reversing

April update of unpackers

kao

Molebox VS unpacker

This is a quite big update for Molebox VS unpacker. It fixes most of the bugs I'm aware of:

  • Supports Molebox GPL version
  • Removes "anti-hacking" protection
  • Supports BOX files in sub-directories
  • Shows embedded command-line
  • Main executable will be named {yourfile}_unpacked.exe
  • Fix calculation of SizeOfImage in edge cases
  • Fix decryption in edge cases

It's still not perfect and will fail in some situations - but I didn't want to postpone the release any longer. Please let me know if it crashes for you and I'll try to fix the problem. 🙂
Read More →

March update of unpackers

kao

Enigma VirtualBox unpacker

  • Unpacker will refuse to run if there is not enough space in TMP folder and/or in working directory
  • PE header size was calculated incorrectly in some cases
  • TLS directory was not detected correctly for some files

Setting TMP folder to a RAM drive was a good idea in 1990s. Now it's year 2019 and you can't manage virtual memory better than Windows already do. But some people apparently still try, so I added checks to stop them from shooting themselves in the foot.

Molebox VS unpacker

  • Added support for a very old version on Molebox VS, as reported by death

The fix was actually implemented a long time ago, I just didn't make the announcement.

Unity3D protection in Moonton games, part 2

kao

I wrote about Moonton game protection in November 2018. It was a pretty boring protection, so I quickly forgot about that. In January 2019 Moonton devs decided to change their protection. I'm not sure if it's a coincidence or not - but here's the update anyway.

This analysis covers:

specifically versions from 1.3.37 upto 1.3.47 (latest at the time of writing). All other games that I mentioned in my previous post haven't been updated, or are still using the old protection mechanism.

Read More →

Unity3D protection in “AU2” dance games

kao

Today's story is about dancing games. Specifically, about

These games employ some tricks in the APK file structure as well as modified libmono.so. I will go through each of the protection mechanisms step-by-step and explain how it works. In the end, you will have all the necessary information to implement your own decryption tool that can decrypt AU2 protected DLL files.

Read More →

Unity3D/Mono protections, part 4

kao

This part is more about my own failure than about Unity3D or Mono. I enjoy looking at Android game cheats and how they manage to exploit every single bug in Mono engine used by Unity3D. And then I make equally stupid bug in my fixer tool. How embarrassing! 😳

Well, not really. I don't pretend to be perfect. I make mistakes just like everyone else and I have no problem admitting them. And hope that somebody else will learn from my mistakes, too.

So, today we'll look at the Vietnamese app that has a funny way to encrypt DLLs:

First, I'll show how the main module is encrypted in the original app. Then I'll analyze a modded version of the app on which my fixer tool failed miserably. Finally, I'll provide a fixed version for my tool.

Read More →

Unity3D protection in Moonton games

kao

This is Part 3 of the series about tricks in PE file format used by Unity3D-based games and cheats.

In Part 1 I analyzed some basic tricks used by Android game modders and ways how to defeat them. In Part 2 I covered more tricks used by modding teams and traced their origins to obscure Chinese Android games.

This part will cover tricks used by game developer Moonton in their games:

All games use modified versions of libmono.so containing few tricks that nobody else uses. Different versions of libraries have slightly different ways of implementing these tricks, most of my analysis is based on Mobile Legends: Bang Bang v1.3.25.3323.

Read More →

Unity3D, Mono and invalid PE files, part 2

kao

In the first part of the series I explained how some cheat authors try to protect their work against other cheaters. It was a quick introduction to Unity3D and bugs in Mono that cheat authors exploit.

Last week someone emailed me another example of a game cheat. My tool from the previous article failed to fix invalid metadata, so I decided to look at it again.

Cheats by BlackMod.net

The cheat I received was made by Mod4U from BlackMod.net team. It appears that Mod4U is one of the most active members of the team, judging by number of the releases. His/her cheats use invalid PE file tricks and are encrypted, as you'll see later in the article.

After looking at different mods from other team members, I've confirmed that Rito, Aurora and Legend also are using invalid PE files for hiding their work. But none of their cheats encrypt Assembly-CSharp.dll.

So, let's look at the cheats and see what new tricks BlackMod team members have found!
Read More →

Why morons shouldn’t be writing about security, part 4

kao

Yesterday I read an article on ZDNet called "Researcher finds simple way of backdooring Windows PCs and nobody notices for ten months" and it made my laugh hysterically.

Why? Because it's a bloody nonsense from start to end.

Let's just look at the main claim in the article.

... in cases where a hacker has a foothold on a system --via either malware or by brute-forcing an account with a weak password-- the hacker can give admin permissions to a compromised low-level account, and gain a permanent backdoor with full SYSTEM access on a Windows PC.

What. The. Fuck.
Read More →