Dozens of countries hit by 'unprecedented' cyber attack
Dozens of countries have been hit by an "unprecedented' cyber attack at a multitude of hospitals, companies and government agencies.
The extortion attack, which locked up computers and held users' files for ransom, is believed to be the biggest of its kind ever recorded, disrupting services in nations as diverse as the US, Russia, Ukraine, Spain and India.
Europol, the European Union's police agency, said the onslaught was at "an unprecedented level and will require a complex international investigation to identify the culprits".
The ransomware appeared to exploit a vulnerability in Microsoft Windows that was purportedly identified by the US National Security Agency (NSA) for its own intelligence-gathering purposes and was later leaked to the internet.
It was not yet known who perpetrated Friday's attacks. Two security firms - Kaspersky Lab and Avast - said they had identified the malicious software behind the attack in over 70 countries, although both said the attack had hit Russia the hardest.
The Russian Interior Ministry, which runs the country's police, confirmed it was among those that fell victim to the "ransomware", which typically flashes a message demanding a payment to release the user's own data.
Spokeswoman Irina Volk was quoted by the Interfax news agency as saying the problem had been "localised" and that no information was compromised.
A spokesman for the Russian Health Ministry, Nikita Odintsov, said on Twitter that the cyber attacks on his ministry were "effectively repelled".
Russia's central bank said it had seen no incidents "compromising the data resources of bank institutions," state news agency Tass reported. The national railway system said although it was attacked, rail operations were unaffected.
Security experts said the attack appeared to be caused by a self-replicating piece of software that enters companies and organisations when employees click on email attachments, then spreads quickly internally from computer to computer when employees share documents.
The security holes it exploits were disclosed several weeks ago by TheShadowBrokers, a mysterious group that has published what it says are hacking tools used by the NSA as part of its intelligence-gathering.
Shortly after that disclosure, Microsoft announced that it had already issued software "patches" or fixes for those holes - but many users have not yet installed the fixes or are using older versions of Windows.
In the US, FedEx reported that its Windows computers were "experiencing interference" from malware, but would not say if it had been hit by ransomware.
Elsewhere in Europe, the attack hit companies including Spain's Telefonica, a global broadband and telecommunications company.
Germany's national railway said that departure and arrival display screens at its train stations were affected, but there was no impact on actual train services.
Deutsche Bahn said it deployed extra staff to busy stations to provide customer information, and recommended that passengers check its website or app for information on their connections.