Quoting the article that exposed this breach on ZDNet, "Localblox, a Bellevue, Wash.-based firm, says it 'automatically crawls, discovers, extracts, indexes, maps and augments data in a variety of formats from the web and from exchange networks.' Since its founding in 2010, the company has focused its collection on publicly accessible data sources, like social networks Facebook, Twitter, and LinkedIn, and real estate site Zillow to name a few, to produce profiles.
But earlier this year, the company left a massive store of profile data on a public but unlisted Amazon S3 storage bucket without a password, allowing anyone to download its contents.
The bucket, labeled 'lbdumps,' contained a file that unpacked to a single file over 1.2 terabytes in size. The file listed 48 million individual records, scraped from public profiles, consolidated, then stitched together."