DDoS on WordPress using the search feature

This fairly low tech DDoS can easily take down an under resourced WordPress website, what you will see in your logs is something like:

/?s=SwCGbtyTPFbgIy 19:02:40
/?s=rNiwiuFckGegR 19:02:49
/?s=SwCGbtyTPFbgIy 19:02:53
/?s=SwCGbtyTPFbgIy 19:02:56
/?s=SwCGbtyTPFbgIy 19:03:01
/?s=mYwyTaXVqvlW 19:03:12
/?s=SwCGbtyTPFbgIy 19:03:18
/?s=mYwyTaXVqvlW 19:03:22