The hacker or hackers gained access to the data by getting into the HSIN account of a federal employee or contractor, McDavid said.

And some quick details on the sophisitcation of the hack:

McDavid said he did not know of other successful hacks into the platform. He called the tactics used to gain access to the user account “very sophisticated.” However, he said the amount of data accessed was relatively minor and that officials have been able to map exactly what files were accessed.

Any bets on whether or not this was really just a simple password or social engineering hack?