So obvious but I’m checking my unused domains to make sure they have no nameservers configured
The root of this vulnerability occurs when a managed DNS provider allows someone to add a domain to their account without any verification of ownership of the domain name itself. This is actually an incredibly common flow and is used in cloud services such as AWS, Google Cloud, Rackspace and of course, Digital Ocean. The issue occurs when a domain name is used with one of these cloud services and the zone is later deleted without also changing the domain’s nameservers. This means that the domain is still fully set up for use in the cloud service but has no account with a zone file to control it. In many cloud providers this means that anyone can create a DNS zone for that domain and take full control over the domain. This allows an attacker to take full control over the domain to set up a website, issue SSL/TLS certificates, host email, etc. Worse yet, after combining the results from the various providers affected by this problem over 120,000 domains were vulnerable (likely many more).
The Orphaned Internet – Taking Over 120K Domains via a DNS Vulnerability in AWS, Google Cloud, Rackspace and Digital Ocean | The Hacker Blog : https://thehackerblog.com/the-orphaned-internet-taking-over-120k-domains-via-a-dns-vulnerability-in-aws-google-cloud-rackspace-and-digital-ocean/index.html