I think it's because it's smells like arbitrary-but-plausible sounding additions to a domain name, picked until they hit one domain that wasn't taken yet. Even

I think it's because it's smells like arbitrary-but-plausible sounding additions to a domain name, picked until they hit one domain that wasn't taken yet. Even worse would have been if they had used dashes equifax-security-2017.com. (plausible for those without the experience of "suspicious impression", of course)