What is WannaCry ransomware? Malware used to cripple NHS in 2017 cyber attack
MORE than 200,000 victims across 150 countries were infected by malicious software known as WannaCry in May's cyber attack.
The NHS was one of the worst affected victims of the international cyber attack - here's what we know.
What is WannaCry ransomware?
The ransomware program used in the global cyber attack is known as WannaCry or Wanna Decryptor.
It was launched on Friday, May 12, and infected more than 230,000 computers - demanding a ransom to unlock the victim's files.
Hackers demanded payments in the cryptocurrency bitcoin in 28 languages.
The attack was spread by various methods including phishing emails and on systems without up-to-date security patches.
Experts from the National Cyber Security Centre warned the outbreak could continue to infect more systems.
Investigators from around the globe, including the National Crime Agency (NCA), are working to hunt down those responsible for the WannaCry ransomware.
How has WannaCry affected the NHS?
Around 40 NHS trusts were hit in the WannaCry ransomware attack, forcing them to postpone operations and procedures.
Seven hospitals remained on A&E divert two days later, with ambulances taking emergency patients elsewhere, NHS England said.
The full scale of the attack on the NHS only become apparent four days later as people returned to work.
But people were advised to attend any hospital or doctor appointments as normal, unless they were contacted and told not to.
It was later revealed that networks had been left vulnerable because they were still using outdated Windows XP software.
Has the spread of WannaCry been stopped?
An international operation was launched to find the perpetrators behind the attack.
Surfer Marcus Hutchins, 22, from Devon, was hailed an "accidental hero" after he managed to stop the virus in its tracks by triggering a "kill switch".
By this point, it had already brought chaos to the NHS, as well as a number of banks, factories and schools, by demanding $300 in online currency Bitcoin to unlock infected computers.
But in August he was arrested by the FBI accused of creating and distributing another malware virus called Kronos in 29014 and 2015.
Then in March 29 the virus reportedly infected Boeing with WannaCry - raising fears passenger jet software could be hacked.
One of the company's chief engineers is said to have sent out a memo calling for "all hands on deck" after the apparent attack.
Are more WannaCry attacks expected?
Fears of more attacks spread in June as it was revealed the hackers behind the leak of WannaCry ransomware were offering to sell secret NSA cyber weapons for $21,000 month.
The mysterious organisation called the Shadow Brokers released a statement in broken English offering to “dump” secret NSA software on a monthly basis in return for a subscription paid in the virtual currency ZCash.
The Shadow Brokers were behind the leak of tools which were used in the WannaCry attacks, which brought the NHS to its knees.
Although some experts believe the hackers are from North Korea, no-one has been able to discover the true identity of the group’s members.