Law enforcement agencies may be able to track down the ransomware hackers behind Friday's global hit through computer currency Bitcoin, the UN's cyber-security expert says.
Neil Walsh, the UN's head of global cyber-crime, said while ransomware attacks have been occurring for some time, he has never seen an attack on such a large scale before.
He added that those behind the hit will likely be feeling nervous by the global attention.
Walsh said the UN has been warning for a number of years that ransomware is one of the biggest threats to businesses.
He warned it is now a wake-up call for all governments and law enforcement agencies to work together to prevent further crippling attacks.
Speaking from his office in Vienna, Walsh said there are a lot of investigative opportunities around Bitcoin to track down the ransomware hackers.
Bitcoin is a virtual currency created in 2009 by an unknown person using the alias Satoshi Nakamoto and is being increasingly used to move criminal proceeds.
The United Nations Office on Drugs and Crime (UNODC) teaches investigators and prosecutors around the world how to track a Bitcoin transaction online, even if people are trying to hide it or anonymise it.
Walsh said: "When you demand a ransom, you have to get that money back. If you can't cash that value or turn it into something, then it doesn't do anything for your criminal business model.
"In the past month alone we have trained investigators and prosecutors in over 40 countries on how to investigate Bitcoin transactions and how to link those transactions to find an individual or entity.
"So, that is the risk (for the hackers) if they start to get payments coming back. It gives us opportunities to investigate and identify."
He added that due to the notoriety of the cyber-hit, those responsible will be feeling nervous about being identified.
Walsh said: "If I was the person or persons who had sent this and you hit over 100 countries and you hit big players - the US, Russia, China, the UK - I'd be nervous.
"You can rest assured that global law enforcement effort will be looking at identifying the origin of this."