I'm not sure about less targetted bots, but I gave a friend an account on my media server without locking off shell access (which she had no need for), and it turns out that she used the same password as she used for every other service. Something got hold of those (that something must have run on her machine while she was on my network as it was not an externally connectable service) found the account with that user+pass and got in.

I noticed PDQ because of a sudden and fairly constant flow of upstream data that was unusual from that machine, and finding the account & processes involved was easy. As well as installing something to run SSH scans (presumably for further propagation) and running what looked like a crypto-miner, it seemed to be forwarding HTTP(S) requests in a manner that suggested the machine had become part of a “residential proxy” network or similar. Maybe if it hadn't been so greedy I wouldn't have noticed so soon (it hadn't been able to, or hand't tried to, cover its traces, so I found the time of installation very easily as the account otherwise had no SSH activity).

Luckily there were no open root escalation attacks at the time (at least that it knew about) so I only needed to pave that account to get rid of everything, but combined with one of the LPE attacks that have been around over the years it could have caused me much more of a headache.

- Steal application credentials if posix perms or database privs are weak, attempt privilege escalation, install rootkit RATs Remote Access Trojans for persistence and hiding processes.

- Install Proxies, DDoS Agents, Bitcoin mining, proxy to SMTP servers, etc...

- If anything looks interesting on their console they will log in and poke around. The order of these events depends on the sophistication of the bot script. Most are very simple.

If you the target look like you have money they may install ransomware and encrypt some of your files. Now I want to watch the Beekeeper again as corny as it was, also a fun movie.

The most common things I observe:-

- Installing a cryptominer or persistence tool

- Sending spam (smtp)

- Using pre-obtained credentials to log into various ecommerce/social media sites

Anonymizing network proxy.