UID

Aadhaar ‘breach’: Everything you need to know (Hindustan Times)

“The crux of the matter, as reported by Tribune newspaper and corroborated by BuzzFeed News, is that there exists a portal on the Aadhaar website which gives anyone who has the login credentials access to the Aadhaar database. UIDAI says the portal is intended for government officials for addressing grievances such as rectifying spelling mistakes in a person’s name.
But somewhere in the chain, according to media reports, rogue agents have started to sell access to this portal to just anyone.”

It looks like a government employee was selling username/password(s) to access the government database at a fairly low level. It should be pretty easy to figure out who abused their position.