But millions of individuals and smaller businesses still had such systems.
Computers booting up to start the workweek might continue the spread of "WannaCry", a ransomware attack where hackers lock down a computer and threaten to delete all its data unless a ransom is paid.
Following on from the news that the NHS and organisations in 150 countries around the world have been affected by a cyber attack, there have been fresh fears that the ransomware virus could spread even further when people return to work on Monday.
This is a CJ CGV screen in Seoul that has been crippled by WannaCry ransomware on May 15, 2017. Among those hit were Russia's Interior Ministry and companies including Spain's Telefonica and FedEx Corp.in the U.S.
Meanwhile, new versions of the ransomware have reportedly surfaced, including one without the kill switch exploited by a 22-year-old computer security researcher to shut the attack down.
It's worth noting, though, that in general home users should not be affected by this particular piece of ransomware. Now on Monday, a security risk management expert told CNBC that even Apple is vulnerable to similar cyber-attacks.
"You are dealing with a criminal", he said. This particular program, called WannaCry, asks for about $300, though the price increases over time.
"I still expect another to pop up and be fully operational", Kalember said. The system appears to be manual, which doesn't scale to the incredible number of computers infected.
Experts say the attackers might get more than $1 billion from the scam, although as of Saturday, only $33,000 was deposited into several Bitcoin accounts associated with the ransomware.
The ransomware worm that took the world by storm over the weekend, WannaCry, has brought to light the fact that many companies outside of the United States may not be properly insured to deal with the financial damage caused by the attack.
"The numbers are still going up", Wainwright said. And they're blaming the USA government for stockpiling cyber weapons.
Microsoft today took the "highly unusual step" of releasing a public patch for older Windows versions that are otherwise only eligible for custom support - Windows XP, Windows 8 and Windows Server 2003 - to fix the vulnerability being exploited by the widespread ransomware attack targeting institutions around the world. He said it was too early to say who was behind the onslaught and what their motivation was, aside from the obvious demand for money. Install Microsoft's patch. 3.
Microsoft distributed a patch two months ago that could have forestalled much of the attack, but in many organizations it was likely lost among the blizzard of updates and patches that large corporations and governments strain to manage.