Adam Furmanek

Hacking C# from the inside - how to do anything in NET

There's no such thing as 'impossible' in .NET. Learn to hijack methods, execute raw machine code, and even catch a StackOverflowException.

Hacking C# from the inside - how to do anything in NET
#1about 6 minutes

Avoiding dynamic dispatch with static method invocation

Bypass polymorphism by generating intermediate language (IL) with the `call` instruction instead of `callvirt` to invoke a specific base class method.

#2about 4 minutes

How to await async void methods in C#

Implement a custom `TaskScheduler` and `SynchronizationContext` to enable awaiting `async void` methods and properly handle their exceptions.

#3about 14 minutes

Running raw machine code from a C# byte array

Explore two methods for executing machine code: using the `Marshall` API for managed delegates or by manually overwriting a method's body with a CPU jump instruction.

#4about 4 minutes

Hijacking methods by modifying metadata or machine code

Explore two techniques for method hijacking: either by overwriting the function pointer in the method descriptor or by injecting a jump instruction into the method's machine code.

#5about 6 minutes

Use case: Running an application on a different desktop

Apply method hijacking to the `CreateProcess` API by intercepting a constructor to specify a target desktop, a feature not exposed by the standard .NET API.

#6about 2 minutes

Use case: Handling unhandled exceptions on a thread

Prevent application crashes by hijacking the `Thread` constructor to automatically wrap the thread's starting logic in a try-catch block.

#7about 4 minutes

Handling the uncatchable StackOverflowException

Catch a `StackOverflowException` by using a WinAPI vectored exception handler to save and restore CPU registers, allowing the application to continue safely.

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