UCLA Health (at the University of California) was breached after a cyber attack and data was stolen from around 4.500.000 people registered on the website. 
The University said Friday that a network containing personal and medical information was breached by unknown hackers, who managed to steal names, addresses, social security numbers as well as medical data – such as status, medications, tests and test results.
However, the University stated that “there is none evidence” that the data has been intercepted, although “they cannot rule it out with certainty.”
The health system operates in four Los Angeles Los Angeles hospitals in California and at the time they announced they are working with the FBI and external IT specialists to identify the causes of the infringement that happened in October last year. The breach was discovered in 5 May of 2015.
It is not known who or who are behind the attack, but James Atkinson, president of the UCLA hospital system, told the LA Times that it was "from a highly sophisticated team and likely to be offshore.”
UCLA Health confirmed that the data was not encrypted, which means that the data could be used directly by malicious users.
