Yes, that's standard practice. Even hobbyists like me do it.
Also, any good hacker would be sure to leave behind multiple access paths. But maybe a professional hacker would refrain from dumping stuff, because that alerts the target. So the dump implies that they're not very professional.
It all depends on the goal right? In this case it seems the goal was to harm the company because they didn't pay ransom. Not to perform long term espionage.
Also, any good hacker would be sure to leave behind multiple access paths. But maybe a professional hacker would refrain from dumping stuff, because that alerts the target. So the dump implies that they're not very professional.