At least 74 countries impacted in 'biggest ever' cyber attack

He said his company had seen the attack coming, and was now helping local clients defend themselves against the attack.

(AP Photo/Alastair Grant, File).

In Russia, where a wide array of systems came under attack, officials said services had been restored or the virus contained.

Patrick Ward, 47, a sales director at Purbeck Ice Cream, from Dorset in England, poses for photographs after giving media interviews after his heart operation scheduled today was cancelled because of a cyberattack, outside St Bartholomew's Hospital in London, Friday, May 12, 2017.

Russian Federation appeared to be the hardest hit, according to security experts, with the country's Interior Ministry confirming it was struck.

Organizations around the world were digging out this weekend from what experts are calling one of the biggest cyberattacks ever.

In the wake of the attack, Microsoft said it had taken the "highly unusual step" of releasing a patch for computers running older operating systems including Windows XP, Windows 8 and Windows Server 2003.

One of the first and worst attacks was aimed at Britain's National Health Service.

While hospitals were not the target of the WannaCry ransomware strain Friday, they were among the most infected as they often lack budgets to defend their online systems, and once their networks are down, thousands of patients lives may be put at risk.

The attack appeared to encrypt data on infected computers and demand payment, usually via the digital currency bitcoin, to release it.

But the ransomware virus proved so malicious that Microsoft had to issue another patch for all Windows OS-based computers dating back as far as 14 years.

A researcher for Avast says the cybersecurity company has now detected 100,000 incidents involving the ransomware over the past day.

Security experts said it appeared to be caused by a self-replicating piece of software that enters companies when employees click on email attachments, then spreads quickly as employees share documents.

Kaspersky Lab said its team has confirmed additional infections in additional countries, including Ukraine and India.

Private security firms identified the ransomware as a new variant of "WannaCry" that had the ability to automatically spread across large networks by exploiting a known bug in Microsoft's Windows operating system.

It remained unclear how many organizations had already lost control of their data to the malicious software - and researchers warned that copycat attacks could follow.

The Windows vulnerability was made public last month, when a group known as the Shadow Brokers released a trove of alleged NSA hacking tools into the public, included those used to hack into systems. Microsoft has issued a patch against this as early as March.

Leading global shipper FedEx Corp said it was one of the companies whose Microsoft Corp Windows system was infected with the malware that security firms said was delivered via spam emails.

Kaspersky researcher Costin Raiu cited 45,000 attacks in 74 countries as of yesterday evening.

Hospitals in areas across Britain found themselves without access to their computers or phone systems. Some hospitals diverted ambulances and canceled surgeries as a result of the attack, which blocked doctors' access to patients' files. There were no reported problems in Scotland or Wales.

"Both staff and patients were frankly pretty appalled that somebody, whoever they are, for commercial gain or otherwise, would attack a health care organization", he said.

"It's an worldwide attack and a number of countries and organisations have been affected", she said.

Spain's Telefonica was among the companies hit.

Microsoft updated security tools Friday to stop the ransomware that has wreaked havoc across the world.

"Today, it happened to 10,000 computers", Eisen said.