subjack
Subdomain Takeover tool written in Go
.... You can use scanio.sh which is kind of a PoC script to mass-locate vulnerable subdomains using results from Rapid7's Project Sonar. This script parses and greps through the dump for desired CNAME records and makes a large list of subdomains to check with subjack if they're vulnerable to Hostile Subdomain Takeover. Of course, this isn't the only method to get a large amount of data to test.