OP can't prove that. The only way is to scrap the server completely and start with a fresh OS image. If OP has no backup and ansible repo (or anything similar) to configure a new home server quickly, then I guess another valuable lesson was learned here.
Especially when it comes to my home network, I would rather be safe than sorry. How would you even begin to investigate a rootkit since it can clean up after itself and basically make itself invisible?
Particularly when it comes to Kinsing attacks, as there seem to been rootkits detected in tandem with it, which is exactly what OP got hit by it seems (although they could only see the coinminer).
My general feeling is that if someone wants to install a hardware rootkit on my extremely boring home servers, it’s highly unlikely that I’ll be able to stop them. I can do best practices (like not exposing things publicly), but ultimately I can’t stop Mossad; on the other hand, I am an unlikely target for anything other than script kiddies and crypto miners.
Sure, but if you already know since before that this specific cryptominer has been found together with rootkits, and you know rootkits aren't as easy to detect, what's your approach to validate if you're infected or not?
Maybe I'm lucky that I can tear down/up my infrastructure relatively easily (thanks NixOS), but I wouldn't take my chances when it's so close to private data.