Google captcha issue

Fri Jun 19 16:15:07 UTC 2020

We run a smaller ISP of about 7.5k customers and the other day we got an email (excerpt below) from one of Google's automated tools.

We are seeing automated scraping of Google Web Search from a large
number of your IPs.  Automated scraping violates our /robots.txt file
and also our Terms of Service.  We request that you terminate this
traffic immediately.  Failure to do so may cause your network to be
blocked by our abuse systems.

To allow you to identify the traffic, we are providing a list of
your IPs they used today (Source field), as well as the most common
destination (Google) IP and port and a timestamp of a recent request
(in UTC) to aid in your identification.  Note that this list may not
be exhaustive, and we request that you terminate all such traffic, not
just traffic from IPs in this list.

All of the destination ports are either 80 or 443, so they at least appear to be legit web traffic on the surface. They are obviously spoofed IP address as there are network addresses in the list and the IP belongs to a router that doesn't appear to be compromised in any way. The initial letter included 700+ IP addresses from our network.

It's now affecting our customers as they are now getting Captcha's for every couple of Google searches that they perform.

Does anyone know of a good way to track the perpetrator(s) down and/or know of a way to mitigate this?

-- 
Christopher Tyler
Senior Network Engineer
MTCRE/MTCNA/MTCTCE/MTCWE

Total Highspeed Internet Solutions
1091 W. Kathryn Street
Nixa, MO 65714
(417) 851-1107 x. 9002
www.totalhighspeed.com