.NET Reactor v7.5.9.1 (Aggressive Settings + Custom Anti-Tamper)

Hey everyone,

I put together a small challenge for anyone interested in reversing .NET protections. This one is packed using .NET Reactor v7.5.9.1 with some pretty aggressive settings, along with a bit of custom anti-tamper logic on top.

Your goal is to unpack the application and recover a clean, working assembly.

1. Protections Enabled
   NecroBit
   String Encryption
   Obfuscation
   Anti ILDASM
   Hide Method Calls
   Code Virtualization
   Anti Tampering
   Anti Debug
   Merge Enums
   Control Flow Obfuscation (Level 9)
   

2. Additional Protections

   Custom runtime anti-debug

   Anti-injection checks

   Integrity verification

   A background watchdog thread

🎯 Objectives
1. Primary: Unpack the application and produce a clean assembly that runs without errors
2. Bonus: Recover the correct password (completely optional)

File Information

Submitter Visual Studio

Submitted 04/13/2026

Category UnPackMe (.NET)

View File

Does .NET Reactor 7.5.9.1 exist in the world? Seems the latest is 7.5 : https://www.eziriz.com/reactor_download.htm

12 hours ago, CreateAndInject said:

Does .NET Reactor 7.5.9.1 exist in the world? Seems the latest is 7.5 : https://www.eziriz.com/reactor_download.htm

Sure does.

1 hour ago, Visual Studio said:

Sure does.

Hello, could you please share the installation package?

please...thank you

13 minutes ago, cjhrb said:

Hello, could you please share the installation package?

please...thank you

I am sorry, I can't as its not public yet. Don't want anything coming back on me.

14 minutes ago, Visual Studio said:

I am sorry, I can't as its not public yet. Don't want anything coming back on me.

ok , I am so sorry to bather you.

thank you .

4 hours ago, Visual Studio said:

Sure does.

How do you get it?

Took a quick look, didn’t dive too deep yet.

Already managed to expose part of the check (PBKDF2 → AES → "UNPACKED"), so it’s not as opaque as it first looks.

This kind of protection layer is also something I’ve been dealing with in my own work:
https://forum.tuts4you.com/topic/46002-continuation-fork-krypton-net-reactor-devirtualizer/#comment-229109

No full unpack yet, just a quick peek for now.

3 hours ago, dawwinci said:

Took a quick look, didn’t dive too deep yet.

Already managed to expose part of the check (PBKDF2 → AES → "UNPACKED"), so it’s not as opaque as it first looks.

This kind of protection layer is also something I’ve been dealing with in my own work:
https://forum.tuts4you.com/topic/46002-continuation-fork-krypton-net-reactor-devirtualizer/#comment-229109

No full unpack yet, just a quick peek for now.

Well done :)

I can create some more challenges for you if you'd like, I also have Intellilock

along with a bit of custom anti-tamper logic on top

@Visual Studio How do you add custom anti-tamper? Can we add custom anti-tamper on .net reactor 7.5?

Edited yesterday at 07:51 AM1 day by CreateAndInject

3 hours ago, CreateAndInject said:

@Visual Studio How do you add custom anti-tamper? Can we add custom anti-tamper on .net reactor 7.5?

If its not on the build you're using, I am assuming its coming in the near future.

34 minutes ago, Visual Studio said:

If its not on the build you're using, I am assuming its coming in the near future.

What do you mean? Can you show some screenshot how do you add custom anti-tamper?
The difference I can see is: The anti-tamper method is called by EntryPoint in your target, but it's called by <Module>::.cctor in standard .NET Reactor.

18 hours ago, Visual Studio said:

Well done :)

I can create some more challenges for you if you'd like, I also have Intellilock

Okey, it would be nice to share more similar challenges, this one was really interesting.

7.5.9.1 NOT EXIST.

https://www.eziriz.com/reactor_history.htm