Reporting / validating suspicious resellers

Where do I report a suspicious reseller or validate that they are legitimate?

Searching Google for TurboTax Deluxe 2017 (https://www.google.com/search?q=turbotax+deluxe+2017&tbm=shop) brings up a vendor ($28.00 from eCrater - wagykatherine, https://www.ecrater.com/p/29149657/turbotax-deluxe-for-tax-year-2017-federal). When ordered from the vendor, a download link to a file sharing website was provided. Link was like https://www.mediafire.com/file/.../TurboTax_Deluxe_2017_MAC-1.zip. I intentionally gave only part of the link.

Another vendor that comes up on Google is https://store.taxprosdeal.com/. Where do I verify these vendors who prominently distribute TurboTax software, but some are supposedly not authorized?