A Spanish companies called telefonica spread a virus called ransomware to the NHS systems. This caused the files of each patient that were data of the NHS to be encrypted and a ransom had to be paid to retrieve the information and files. Patients appointments had to be cancelled due to this.
The attack made was huge, it was global it affected places such as Russia, Ukraine, Taiwan and other countries.
The Spanish Companies basically wanted to rob users of their money. Which is why the ransom was around $300 dollars, and if they did not pay they would hack their bitcoin account and take the money themselves
Patients regular procedures had to be cancelled, and emergency patients had to be diverted to other hospitals. The normal procedures such as x-ray scanning has to be shut down and x-rays are a very important part of accident and emergencies. Patients with more severe problems had an even worse impact of the ransomware. A patient with breast cancer in London was half way through her chemotherapy infusion when the attack happened.
The attack could have been prevented by many simple procedures such as updating your security software to the latest one to prevent these kind of viruses.
link to actual news article http://www.bbc.co.uk/news/uk-39916778