MVC 5 : Is using Attribute on Async action make it Synchronous?

I've create an attribute called Log, which is Synchronous ( you cannot create async attributes in MVC 5 ), is it making my action synchronous ( Sync over Async antipattern )? Here is the code:

[Log]
[HttpGet]
public async Task<HttpResponseMessage> Get()
{ 
    // ...
}