WATCH: Cybersecurity expert explains what made Friday's "ransomware" attack so massive.
UPDATE 12:33 p.m.: Microsoft offered a free tech fix for those hit by the massive extortion cyber attack. The company announced that it will make security fixes available for free for older Windows systems, which are still used by millions of individuals and smaller businesses.
In Russia, where a wide array of systems came under attack, officials said services had been restored or the virus contained.
UPDATE March 12, 12:30 p.m.: Friday's cyberattack hit almost 20 percent of UK's 248 public health trusts, according to Britain's home secretary.
Speaking Saturday after an emergency government meeting in London, Home Secretary Amber Rudd said 48 out of 248 NHS organizations were affected by the largest-ever cyberextortion attack, though "most of them are back to the normal course of business."
Some hospitals were forced to cancel or delay treatment for patients, even those with serious aliments like cancer.
UPDATE: Malware company Avast has reported computers in 99 different countries have been affected by the "WannaCry" "ransomware" that crippled hospitals across Britain Friday. Russia, Ukraine and Taiwan are the countries that have been hit the hardest, according to Avast.
The malware reached an especially large amount of PCs (Windows 8) around the world through the "unique ... timing and orchestration of the attack" early Friday, VP of IBM Security Caleb Barlow told Circa. A patch for the "ransomware" vulnerability was released in March; affected PCs had not applied the patch.
Barlow told Circa, "At this stage, [WannaCry] is probably not something consumers need to worry about." To that end, Symantec released a blog explaining the malware's deadly trick: It can spread within corporate networks by itself.
A massive cyber attack crippled computer systems at hospitals across Britain on Friday leading to appointment cancellations, downed phone lines, and turned away patients, the Associated Press reported.
Britain's National Health Service said hospitals were hit by an apparent "ransomware" attack, though there was no immediate evidence that patient data had been accessed.
Screenshots of the apparent attack read, "Ooops, your files have been encrypted!"
NHS Digital, which oversees hospital cyber security, said the attack employed the Wanna Decryptor variant of malware, which infects and paralyzes computers while the attackers demand a ransom.
Attackers requested $300 worth of Bitcoin as ransom.
NHS Digital said the attack "was not specifically targeted at the NHS and is affecting organizations from across a range of sectors." It said 16 NHS organizations had reported being hit.