now there are several things that shouldn't have happened (e.g.: don't do these things on your main OS, have root access disabled, etc.), but I'll leave that to you experts.
you're underestimating people's capability to make such mistakes. remember silk road? the guy used the same username in two places, and gave his email id(which had his full name) in one of them.
it was late 2000s(he was arrested in 2013, before snowden leaks). and the guy wasn't a "hacker". he created the website where stuff(both legal and illegal) was sold. so, you have to keep that perspective in mind.
Oh yeah i remember that guy i i thought you were talking about someone else. And in my opinion they should just free him he has done more time that he should have to whie other bigger criminals than him with money are running around free . But still it was a very noob mistake of course unless he did it delibretly because he didn't care about anonymity.
Not saying its actually what happened but I would ask how he knew about the data.
Statistically, it should have been a random port scan that got in but since he‘s from the same country, he‘s either professionally or privately connected I assume. He either worked there in IT function, visited as a patient, dated an employee, etc.
So in other words, he‘s not a master hacker but probably stumbled across this. I had this with a webspace provider once were I could see all other customers folders when I used ssh instead of the web interface. I couldnt access them but I got a wiff of how stuff like this happens. 99.9% of their customers are inept at IT stuff so a mistake in ssh would never come up since customers wouldn’t use it and in that one case, they overlook it.
So, this might have been his first hack ever and it probably took a long time til he even understood what he had in his hands. Thats why I dont do stuff like this, I‘m prone to such mistakes as well. Most elaborate scheme imaginable and cc it by mistake to someone I know.
I just was reading Wikipedia and it said he was arrested previously for hacking.
In 2015, when he was still a teenager, a Finnish court found Kivimäki guilty of more than 50,000 aggravated computer break-ins. Among other targets, he attacked large educational institutions in the US, hijacking emails, stealing credit card details and blocking site traffic.
Kivimäki received a two year suspended sentence for those charges.
The main reason I've never done anything illegal online (not counting piracy) is that I'm confident I've been that stupid many times and will be if I do.