HexBrain

Unikrn · Report #255978

Non-Cloudflare IPs allowed to access origin servers

Validstatus
mediumseverity
$50bounty
14upvotes
7 Feb 2018disclosed

How it was found

Summary: Non-Cloudflare IPs allowed to access origin servers

Description: Your origin servers are not blocking access from non-Cloudflare servers. This way crawlers can find your origin servers' IPs by checking random IPs until they found your origin server(s).

What makes this especially easy are tools like censys.io (which can find your origin servers).

One of the origin server IPs I found is ███████ but there were quite a few others, too.

This attack vector can be extremely bad because with the IP found out an attacker could attack the servers by DDoS or other attacks without being stopped by CloudFlare.]

This report was disclosed publicly on HackerOne and belongs to its author and the program. See the original