Source: Security Fix
"Cyber crooks are providing cheap, instant access to detailed consumer databases, offering identity thieves the ability to find missing data as they compile dossiers on targeted individuals." "It's unclear how these sites are obtaining this kind of information. It may be that they're relying on insiders at companies with access to this data. Alternatively, perhaps the services are making use of using stolen credentials needed to access sensitive online databases. More likely, it is a mixture of both."