I got hacked: My Hetzner server started mining Monero

>>jakels+(OP)
> I also enabled UFW (which I should have done ages ago)

I disrecommend UFW.

firewalld is a much better pick in current year and will not grow unmaintainable the way UFW rules can.

    firewall-cmd --persistent --set-default-zone=block
    firewall-cmd --persistent --zone=block --add-service=ssh
    firewall-cmd --persistent --zone=block --add-service=https
    firewall-cmd --persistent --zone=block --add-port=80/tcp
    firewall-cmd --reload

Configuration is backed by xml files in /etc/firewalld and /usr/lib/firewalld instead of the brittle pile of sticks that is the ufw rules files. Use the nftables backend unless you have your own reasons for needing legacy iptables.

Specifically for docker it is a very common gotcha that the container runtime can and will bypass firewall rules and open ports anyway. Depending on your configuration, those firewall rules in OP may not actually do anything to prevent docker from opening incoming ports.

Newer versions of firewalld gives an easy way to configure this via StrictForwardPorts=yes in /etc/firewalld/firewalld.conf.

>>3np+pm
If you can, do not expose ports like this 8080:8080, but do this "192.168.0.1:8080:8080" so its bound to a private IP. Then use any old method expose only what you want to the world.

In my own use I have 10.0.10.11 on the vm that I host docker stuff. It doesn't even have its own public IP meaning I could actually expose to 0.0.0.0 if I wanted to but things might change in the future so it's a precaution. That IP is only accessible via wireguard and by the other machines that share the same subnet so reverse proxying with caddy on a public IP is super easy.

>>dizhn+u41
Yup the regular "8080:8080" bind resulted in a ransom note in my database on day 1. Bound it to localhost only now.

>>zwnow+g91
I had the same experience (postgres/postgres on default port). It took me a few days to find out, because the affected database was periodically re-built from another source. I just noticed that for some periods the queries failed until the next rebuild.

>>andix+hr1
Yea plenty of bots scouting the internet for these kinda vulnerabilities, good learning experience, wont happen again :D

zlacker