Shadowfall

Over the last several months, RSA Research embarked on a cross-organizational effort against RIG Exploit Kit (RIG EK or just plain RIG), which led to insight into the operational infrastructure (and possibly the entire ecosystem), as well as significant discoveries related to domain shadowing. Domain shadowing is “a technique in which attackers steal domain account credentials from their owners for the purpose of creating subdomains directed at malicious servers”.

https://blogs.rsa.com/shadowfall/