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Comment by nodesocket | Hacker News Reader

Can you answer the following for us?

    Is ssh only allowed by public key? (in /etc/ssh/sshd_config => PasswordAuthentication no)
    Is Apache or NGINX running on the server?
    Is PHP/Ruby/Node/Python running apps?
    What ports are open in iptables (iptables -L)
    What does /var/log/auth.log say?

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Thank you for responding.

We searched the whole system for authorized_keys files and found one created in a /var/lib/redis/ of a staging container (with no firewall) on this host. We then came across the redis vulnerability https://kevinchen.co/blog/postmortem-server-compromised/ . A junior dev had spawned this container without help from dev-ops and hence left ports open.

What doesn't make sense to us is how this daemon (yam) was running under a statd username when the container doesn't have such a user, but the host does? Are LXC containers able to run daemons on the host?

Well, it is always possible that attacker broke out of the container, as the container is still running under the same kernel, only its process(es) are chrooted + namespaced. Containerized "root" supposedly has its' privileges cut down, but if the kernel is exploitable...

> What doesn't make sense to us is how this daemon (yam) was running under a statd username when the container doesn't have such a user, but the host does? Are LXC containers able to run daemons on the host?

This is because usernames don't exist, as far as the kernel's concerned. ps is resolving the process's UID to the corresponding name for the outside context, not the one inside the container.

This makes sense, we can rest easy knowing they didn't break out of the container. Thanks!

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