What is the point of these bots endlessly trying utterly random HTTP requests?

I can't be the only one seeing this kind of garbage in my server logs:

"GET /!?asdas1230ds0a=da90sue21qh HTTP/1.1"
"GET /HotelInformation/HotelInformation.aspx?asdas1230ds0a=da90sue21qh HTTP/1.1"
"GET /++?asdas1230ds0a=da90sue21qh HTTP/1.1"
"GET /.cancel?asdas1230ds0a=da90sue21qh HTTP/1.1"
"GET /.specialSubmit?asdas1230ds0a=da90sue21qh HTTP/1.1"
"GET /img.youtube.com?asdas1230ds0a=da90sue21qh HTTP/1.1"
"GET /.droppable/?asdas1230ds0a=da90sue21qh HTTP/1.1"
"POST /.droppable/ HTTP/1.1"
"GET /_isMasked/?iqi_localization_country=x27f&vst=x27f&gitlab=x27f&1111ef1ee11b=x27f&ocxlaarct7tk=x27f&gad_source=x27f&landcode=x27f&confirmPrivacyStatement=x27f&26=x27f&frm_action=x27f…"

This is just a tiny sampling of endless junk that has been going on for at least the past 2 weeks. The last example is abbreviated, it goes on like that, with exactly 100 of those random query parameters that always have the same value “x27f.” It are several bots, which according to an IP locator service come from different countries, mostly the UK and Hong Kong. However, doing a WHOIS on each of the IP addresses reveals that many of them are hosted by Contabo GmbH, a cheap VPS hosting service in Germany.

Something similar has happened years ago, and then the junk also came from Contabo-hosted addresses. The pattern was similar, but each request then looked like the last example shown above, using a ridiculous number of query parameters with different field names but all the same value “z3re”. I filed an abuse report back then, and the junk stopped for a while, but it has been sporadically returning, and now it is back in a slightly different incarnation, but it still makes no sense at all. NONE.

Often these bots will still perform requests with a ridiculous number of parameters (usually 100), but more often they look like the above: a random string with the same damn query string appended to it. I really mean the same damn string for at least 2 weeks straight, which in the above case was obviously produced by someone bashing their keyboard: “asdas1230ds0a” and “da90sue21qh”. The same bot will keep on doing requests with the same base path like “.specialSubmit” or “London” for a whole day, and then might switch to another string for the next day, if I haven't kicked its ass with an iptables DROP in the meantime. The choice of these strings generally makes no sense. Lately they have also started using random characters next to city names and domains or just random words. Most of the time, the strings don't look like anything a real web app would ever use. It is all totally random. The mind boggles.

I really don't understand what is being tried to achieve with this. It is as if they are trying to brute force the internet in the hopes of finding an exploit, but the chances of this strategy producing anything fruitful is negligibly small, especially when not even varying the query parameters. Also, they do only 1 request about every 10 minutes, maybe to try to stay under the radar of suspicious activity detectors (not mine, obviously). At such slow rate, a Monte Carlo approach is just pointless.

I truly cannot grok what could be going in in the mind of whatever crackpot implemented this piece of junk and then decided to pump Kilowatts into a server farm to unleash this nonsense across the internet. If I see this in my logs, then it probably means they do these requests non-stop on whole IP ranges or a list of domains obtained from wherever. All that electricity is wasted on total nonsense. They had better spent the effort on mining crypto. It must take a very special kind of mental deficiency to believe this strategy will yield any return on investment.

Luckily the incomprehensible act of always using the same strings in the request, makes it easy to ban these bots. The set of IP addresses they work from is also pretty stable, so firing up the firewall is a good option as well.