Is it bad to have an empty attribute? (C#)

I have created an attribute which will define which properties have "special" data. My Attribute looks something like this:

[AttributeUsage(AttributeTargets.Property)]
    public class TestAttribute : Attribute
    {
    }

I don't need anything in the body of the class because all it's doing is identifying the properties. Is this bad practice? If so, what are better alternatives?

Thanks in advance!