When I sshed into my server today, it said I had mail. I checked /var/mail/{myuser} and got a mail from caddy. The title was “SECURITY information for {hostname}”. The message was this.

caddy : user NOT in sudoers ; PWD=/ ; USER=root ; COMMAND=/usr/bin/tee /usr/local/share/ca-certificates/Caddy_Local_Authority_-_2025_ECC_Root_31435960950297150297199787413716908247066220.crt

I’m still learning this self-hosting thing, I know enough to set stuff up but I still know barely anything about security, and the message looks kinda scary, so I would like to know what it means, thanks in advance. Note that I was messing around with Caddy and stuff yesterday, so maybe that has something to do with it, but I’m not sure.

  • rtxn@lemmy.worldEnglish
    64·
    7 days ago

    I can’t believe it. The incident has actually been reported!

    I don’t use Caddy, but it seems like it tried to generate and write a TLS certificate into /usr/local, but didn’t have the necessary permissions. Basically it tried to use sudo tee ... to write a file. Is Caddy running in a container? If it is, you might need to create a volume at /usr/local/share/ca-certificates. If not in a container, you’ll need to grant the caddy user write permissions in that directory.

    But to answer your question directly, it’s not a cause for concern. You’re not getting hacked, it’s just a configuration error.

        • sugar_in_your_tea@sh.itjust.worksEnglish
          1·
          5 days ago

          Don’t require elevated permissions. Either grant the user it runs as permission to that dir, or instruct it to use a different dir that it has access to. Services should have the least permissions possible.

            • sugar_in_your_tea@sh.itjust.worksEnglish
              1·
              5 days ago

              what better option is there than to limit scope of execution by doing pinhole actions with sudo?

              For binding privileged ports like 80 and 443, use CAP_NET_BIND_SERVICE. For access to protected directories, adjust permissions.

              At no point should sudo be necessary, that’s how you get security vulnerabilities.

                • sugar_in_your_tea@sh.itjust.worksEnglish
                  2·
                  5 days ago

                  If the caddy service account has write access to the config and certs, isn’t that a weaker security posture than having them owned by root?

                  I’m much less worried about an attacker messing w/ my certs (that’s a pretty sophisticated attack) and more worried about privilege escalation where the attacker gets root access. Caddy is intended to be externally facing, so it’ll be getting the brunt of the attacks (like this one that attacks HTTP 1.1). If someone is able to find an exploit to allow remote code execution, being able to run commands with sudo is a pretty big deal.

                  That’s a big part of why I run my services in containers, and also why I’m switching from Docker to Podman. Docker runs everything as root by default, and it’s a pain to run things as non-root. Podman runs everything as an underprivileged user by default, which forces the admin to configure it properly. If an attacker is able to break out of Docker, it’ll have root access to the system, whereas if an attacker breaks out of Podman, they’ll just have whatever that user’s permission is.

                  If I’m going to expose something to the internet, I want to make sure it’s properly configured to reduce the chances of getting a rootkit or something.