Generally a popup will appear if there is an update available but you can also force the computer to check for updates.
Still, he said, the greatest burden should fall on the government. And WannaCry threatens to create even more havoc on Monday when people return to work.
Prime Minister Malcolm Turnbull's cyber security adviser, Alastair MacGibbon, said on Sunday there had been one confirmed incident in Australia, but warned it was likely more computer systems would eventually be hit.
Called "WannaCry", the fast-spreading malware is the first ever detected to combine both a worm - which enables it to burrow into an entire network from a single infected computer - and a ransomware, demanding US$300 (€275, RM1,298) in the virtual currency Bitcoin to unlock systems. Experts say the attackers have made just over $51,000.
Becky Pinkard, from Digital Shadows, a UK-based cyber-security firm, told AFP news agency that it would be easy for the initial attackers or "copy-cat authors" to change the virus code so it is hard to guard against.
The culprits used a digital code believed to have been developed by the US NSA - and subsequently leaked as part of a document dump, according to researchers at the Moscow-based computer security firm Kaspersky Lab.
It was among a large number of hacking tools and other files that a group known as the Shadow Brokers released on the internet.
"The attack targeted machines that use older software (Windows XP, Windows 2003, Windows 8) and US companies tend to adopt modern systems on a more regular basis", said Kevin O'Brien, chief executive officer of GreatHorn, a Boston-based security company.
Writing in blog, Brad Smith said: "An equivalent scenario with conventional weapons would be the USA military having some of its Tomahawk missiles stolen".
Smith said the crisis is a "wake-up call", and that Microsoft has been "working around the clock" to assist affected customers, including those on older versions of Windows that are no longer supported.
Once inside a network the virus can then spread to other connected computers.
How can I protect my computer from the ransomware virus?
The NHS was among hundreds of organisations affected around the world, with 47 trusts hit.
A ULHT statement said: "Due to the ongoing issues relating to the cyber attack on the NHS on Friday, we will be cancelling all routine activity in our hospitals on Monday 15 May".
French carmaker Renault was forced to stop production at sites in France, Slovenia and Romania, while FedEx said it was "implementing remediation steps as quickly as possible".
The political fallout from the attack escalated over the weekend as both Labour and the Lib Dems blamed the crisis in the health service on the government's failure to upgrade hospital computers.