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How are people discovering random subdomains on my server? (lemmy.blahaj.zone)
submitted 10 months ago by to c/selfhosted@lemmy.world
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I generated 16 character (upper/lower) subdomain and set up a virtual host for it in Apache, and within an hour was seeing vulnerability scans.

How are folks digging this up? What's the strategy to avoid this?

I am serving it all with a single wildcard SSL cert, if that's relevant.

Thanks

Edit:

  • I am using a single wildcard cert, with no subdomains attached/embedded/however those work
  • I don’t have any subdomains registered with DNS.
  • I attempted dig axfr example.com @ns1.example.com returned zone transfer DENIED

Edit 2: I'm left wondering, is there an apache endpoint that returns all configured virtual hosts?

Edit 3: I'm going to go through this hardening guide and try against with a new random subdomain https://www.tecmint.com/apache-security-tips/

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[–] 16 points 10 months ago

A long time ago, I turned a PC in my basement into a web server. No DNS. Just a static IP address. Within 15 minutes, the logs showed it was getting scanned.

SSL encrypts traffic in-transit. You need to set up auth/access control. Even better, stick it behind a Web Application Firewall.

Or set up a tunnel. Cloudflare offers a free one: https://developers.cloudflare.com/cloudflare-one/networks/connectors/cloudflare-tunnel/

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