Implementado BasicAuthenticationAttribute

gistfile1.cs

public class AppBasicAuthenticationAttribute : BasicAuthenticationAttribute 
{
    public override string Realm { get { return "DOMINIO"; }}

    public override bool Authorize(string username, string password)
    {
        var membershipService = IoC.Current.Resolve<IMembershipService>();
        return membershipService.ValidateUser(username, password);
    }
}