Spam Filter Issue

We are being spammed by a bunch of computers that seem to have some virus.   We receive an email with (No Subject) in the subject line and an attachment every 10 minutes.

Its not possible to create a rule specific to (No Subject) .  We cannot create a rule to delete any email with a blank subject.

What is a workaround to delete any emails with no actual subject or (No Subject) in the subject line?

Thanks