These been going on for some while, however don't recall having this many in such a short time (15 minutes & 7 minutes). More than 2,200 requests from each.
All ate 403's
One from a Hungarian Colo and the other from Peer 1.
Both used blank UA's.
Both appear to be using the same software, as requests were duplicated on the two IP's.
69.90.47.167 - - [09/Aug/2014:03:41:58 -0600] "GET /0_admin/modules/Wochenkarte/frontend/index.php?x_admindir=http://www.google.com/humans.txt? HTTP/1.0" 403 794 "-" "-"
87.229.73.60 - - [08/Aug/2014:22:47:10 -0600] "GET /0_admin/modules/Wochenkarte/frontend/index.php?x_admindir=http://www.google.com/humans.txt? HTTP/1.0" 403 794 "-" "-"