The attack appeared to exploit a vulnerability purportedly identified for use by the U.S. National Security Agency and later leaked to the internet.
The unprecedented attack plunged the health service into chaos, forcing hospitals to cancel and delay treatment.
The Shadow Brokers released Eternal Blue as part of a trove of hacking tools that they said belonged to the USA spy agency.
"Like many other companies, FedEx is experiencing interference with some of our Windows-based systems caused by malware", said a spokesperson in a statement. "We are implementing remediation steps as quickly as possible", it said in a statement. "We regret any inconvenience to our customers".
The Department of Homeland Security has received no confirmed reports from US -based hospitals, power plants, water systems or other entities considered to be critical infrastructure that they've been affected by a massive cyberattack that disrupted Britain's health system and other computers worldwide, an agency official told Recode.
Hospitals in areas across Britain found themselves without access to their computers or phone systems. Many canceled all routine procedures and asked patients not to come to the hospital unless it was an emergency. When he tried to access patient files on a computer, he couldn't find them - even though he knew they were there.
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The Spaniard also dismissed the suggestion he had a stronger chance against Djokovic given the Serbian's slow start to the year. The world number eight missed the Barcelona Open late last month due to the recurring problem.
Most of the affected hospitals were in England, but several facilities in Scotland also reported being hit. Several individual health service trusts in England reported severe problems.
"The key question" to consider is how an attack such as Friday's could originate "from a noncritical system such as email" and then spread to other systems, said Awais Rashid, a professor of software engineering at Lancaster University.
Britain's national health service fell victim, its hospitals forced to close wards and emergency rooms and turn away patients.
With at least 25 hospitals and health trusts hit in the attack, NHS Digital said there was no evidence patient data has been compromised.
"It's an global attack and a number of countries and organizations have been affected", she said.
"The investigation is at an early stage, but we believe the malware variant is Wanna Decryptor", the NHS says, referring to software that is being blamed for a number of ransom attacks in Europe Friday.
United Kingdom interior minister Rudd says health system has recovered from cyber attack
The hacking tool, a new variant of "WannaCry" ransomware, is believed to have been developed by the US National Security Agency. Elsewhere in Europe, the attack hit companies including Spain's Telefonica, a global broadband and telecommunications company.
The ransomware attack is at "unprecedented level and requires worldwide investigation", Europol, the European Union's law enforcement agency, said on Twitter.
Doctors reported seeing computers go down "one by one" as the "ransomware" took hold on Friday, locking machines and demanding money to release the data.
Authorities in Britain have been braced for cyber attacks in the run-up to the vote, as happened during last year's US election and on the eve of the French vote.
It demands payment in three days or the price is doubled, and if none is received in seven days the files will be deleted, the screen message claims.
NHS Digital said the attack "was not specifically targeted at the NHS and is affecting organizations from across a range of sectors".
Only a small number of USA -headquartered organizations were hit because the hackers appear to have begun the campaign by targeting organizations in Europe, said Vikram Thakur, research manager with security software maker Symantec.
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It increased, as 69 investors sold WYNN shares while 123 reduced holdings. 52 funds opened positions while 125 raised stakes. It fall, as 34 investors sold TESARO Inc shares while 64 reduced holdings. 76 funds opened positions while 94 raised stakes.
Telecommunications company Telefonica was among many targets in Spain, though it said the attack was limited to some computers on an internal network and had not affected clients or services.
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