"The latest count is over 200,000 victims in at least 150 countries".
Cisco Systems rose 2.8 percent, making it the leading gainer in the Dow Jones Industrial Average, which was up more than 100 points in afternoon trading, as investors focused more on opportunities the attack presented rather than the risk it posed to corporations.
"Using outdated versions of Windows that are no longer supported raises a lot of questions", said Christopher Dore, a lawyer specializing in digital privacy law at Edelson PC.
"We should expect similar attacks regularly in the coming days and weeks", said Giullaume Poupard, head of French government cyber security agency ANSSI.
The "WannaCry" ransomware used did not specifically target the NHS, and Fedex and Spain's main telecoms operator are among those effected. Microsoft says payment does not guarantee unlocking.
While there appears to have been some success in halting the impact of WannaCry, the vulnerability remains, and if those new variations get traction, we'll see additional waves of computer attacks. Europol, the European Union law-enforcement agency, has advised people to be wary of clicking on links in or downloading attachments from any emails from senders they do not recognise.
The effects could be turned off if the software looks up a specific domain name and finds it exists; the "inadvertent hero" who stopped the spread of the virus in its tracks simply registered the domain, thus triggering the "kill switch".
The anonymous specialist, known only as MalwareTech, issued a warning that hackers could upgrade the virus to remove the kill switch.
He believes that state-sponsored cyberespionage groups could also take advantage of the SMB flaw to plant stealthy backdoors on computers while defenders are busy dealing with the much more visible ransomware attack.
Once opened, the malware can install itself on a system without the user's knowledge.
Naturally, this starts at the doorstep of Microsoft, which sells the Windows operating system and which has been criticized for years for its security shortcomings.
The shocker in the United Kingdom was that so many machines at the National Health Service were running on Windows XP. XP!
Healthcare organizations should take immediate steps to patch Microsoft vulnerabilities causing the spread of WannaCry. Although Microsoft released patch in March fixing the flaw, the patch has been applied inconsistently, leaving many organizations and individuals vulnerable. Many banks in Europe said they had stepped up efforts to prevent attackers getting through.
The safest way to protect yourself is to avoid clicking links from unknown sources. It also says to block pop-ups adverts, which will stop most potentially risky pop-up windows with harmful links appearing on your screen.
But I want to reassure the public that investigators are working round the clock to secure evidence and have begun to forensically analyse a number of infected computers. If the ransomware has just blocked access to your web browser, it may be possible to regain control by accessing your computer's task manager and shutting down the program.
"Backing up important data is the single most effective way of combating ransomware infection". You may have to download safety software on to an uninfected computer, then try to transfer it to the affected computer via a CD-Rom or USB stick.