I am trying to learn Frida on an Il2cpp based Unity app based on arm.

I am trouble setting the custom string param on function invoke. I can access the function’s param but I can’t replace the string param with a new value.

Please suggest what can I do here.

I can access the method using

“`

const AssemblyCSharpfirstpass = Il2Cpp.domain.assembly("Assembly-CSharp-firstpass").image; const NameSpaceNameClassName = AssemblyCSharpfirstpass.class( "NameSpaceName.ClassName" ); const MethodName = NameSpaceNameClassName.method("MethodName"); 

“`

This method accept all the params as string but when I try to change the param and invoke the method, I get different errors based on what all I try

“`

MethodName.implementation = function ( this: Il2Cpp.Object | Il2Cpp.Class, param_1: string,

) {

// this works, as I don’t change any value, just pass the existing value this.method<void>(“MethodName”).invoke( param_1 as unknown as Il2Cpp.Parameter.Type, );

// when I try this, I get, il2cpp: couldn't invoke method MethodName using incorrect parameter types this.method<void>(“MethodName”).invoke( “changed_param_string” as unknown as Il2Cpp.Parameter.Type, );

// when I try this, I get the error Error: access violation accessing 0x80e64498 const modifiedContentType = “NewContentType”; // Replace with your desired value const modifiedContentTypePtr = Memory.allocUtf8String(modifiedContentType); const modifiedContentTypeStr = modifiedContentTypePtr.readUtf8String(); this.method<void>(“MethodName”).invoke( modifiedContentTypeStr as unknown as Il2Cpp.Parameter.Type, );

});

“`

“`

// when I try this, I get, Error: unable to intercept function at 0x7fdd0e38; please file a bug Interceptor.attach(MethodName, { onEnter: function (args) { const modifiedArg = replacementValue; args[0] = Memory.allocUtf8String(modifiedArg); }, });

“`

Thanks