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Is this mail something I should be concerned about? (sopuli.xyz)

submitted 3 days ago by theselfhoster@sopuli.xyz to c/selfhosted@lemmy.world

9 comments fedilink hide all child comments

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.

all 12 comments

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[–] rtxn@lemmy.world 62 points 3 days ago* (last edited 3 days ago) (1 children)

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.works 1 points 3 days ago (1 children)

Caddy should never run sudo IMO, I think it's also a software bug.

[+] dgdft@lemmy.world 1 points 2 days ago (1 children)

[removed by mod]

[–] sugar_in_your_tea@sh.itjust.works 1 points 2 days ago (1 children)

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.

[+] dgdft@lemmy.world 1 points 2 days ago (1 children)

[removed by mod]

[–] sugar_in_your_tea@sh.itjust.works 1 points 2 days ago (1 children)

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.

[–] some_guy@lemmy.sdf.org 2 points 2 days ago

If you have anything exposed, scripts and bots are testing your server all day, every day. So long as you've got proper security in place, ignore the failed attempts.

[–] jrgd@lemmy.zip 19 points 3 days ago (1 children)

You're likely looking for this docs section for Caddy. The failure is the automated request to populate Caddy's root CA cert to the host system, but obviously failed as it doesn't have root permissions. As the docs state, if you intend to use the local HTTPS functionality of Caddy, you can manually run caddy trust privileged in order to populate the Caddy root CA cert manually. If you intend to disable the local HTTPS functionality (such as if you're running Caddy behind a http reverse proxy), you can ignore the mail message.

[–] theselfhoster@sopuli.xyz 7 points 3 days ago

Thanks for clearing my anxieties :) Sometimes I feel an irrational fear that perhaps someone has broken into my server because of my lack of security knowledge, so having that mail come in was very anxiety inducing.

[–] Tetsuo@jlai.lu 5 points 3 days ago

Yeah I think it's just a false alarm.

I would suggest looking into how sudoers works. I might just be that you asked caddy to do something that required root and forgot to sudo the command ?

Still double check the timestamp and verify that it was when you tinkered. Use "history" to look for previous commands and maybe the timestamp ?

The way I see it something (probably caddy) wanted to check a TLS certificate and had to concatenate all the certificate authorities to check if an adequate CA was there. And it failed to access what looks like a local CA that is autosigned ? Still worth checking your CA has adequate / similar permission as the others.