Enable unsafe code with dnlib

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Hello ! I am coding an obfuscator using C# and dnlib. At some point i need to inject unsafe code in the executable but this should end up in an app crash, if you don't "declare" it . Is there a way to declare(with or without dnlib) that a selected module will contain unsafe code ?
Thanks!!

What I have tried:

Tried to find how to declare that a module will contain unsafe code using dnlib. I couldn't find anything in the docs.

Posted 16-Jun-17 2:20am

xXxRevolutionxXx

Updated 22-Jun-17 1:11am

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2 solutions

Solution 1

I can't speak for dnlib but the standard compiler marks unsafe modules with the [System.Security.UnverifiableCodeAttribute()]

The simplest detection would be something like

private void SafeOrUnsafe(Assembly asm) {
  foreach (Module m in asm.GetModules(true)) {
    Debug.Print("{0} Unsafe : {1}", m.Name, m.IsDefined(typeof(System.Security.UnverifiableCodeAttribute), true));
  }
}

Alan.

Posted 16-Jun-17 8:21am

Alan N

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xXxRevolutionxXx · Accepted Answer · 2017-06-22T01:11:00

After some more digging, i found out that you can mark a module as unsafe with dnlib with the following code:

C#

ModuleDefMD module = ModuleDefMD.Load("theModuleYouWantToMarkAsUnsafe.exe");

module.CustomAttributes.Add(new CustomAttribute(new MemberRefUser(module, ".ctor", MethodSig.CreateInstance(module.CorLibTypes.Void), module.CorLibTypes.GetTypeRef("System.Security", "UnverifiableCodeAttribute"))));

I thank very much @Alan for pointing out what attribute is needed for the job !