All it takes is one wrong click by computer users, and hackers can gain a foothold in their cyber lives and those of many others.

Successful phishing attempts to trick users into clicking on bogus links or e-mail attachments led to intrusions in April into both the National University of Singapore and Nanyang Technological University's networks, as disclosed last Friday.

The same phishing method is believed to have caused the initial WannaCry infection in computers before the ransomware spread to hundreds of thousands of machines in 150 countries at the past weekend - for financial gains.

Singapore was not spared as digital signages in some malls broke down, and computers tied to some 500 Internet accounts were believed to be infected - although the fallout overseas was far worse. The virus disrupted hospitals in the United Kingdom and Indonesia, government agencies in China and Russia, railway operations in Germany and car production facilities in France.

The rapid succession of attacks that hit Singapore - albeit for different reasons - is a timely reminder for every organisation and individual to be vigilant.

The breaches at the universities were believed to be a roundabout way to access government-related data. Experts said the universities are involved in projects for the defence, foreign affairs and transport sectors. Experts also said such attacks require considerable resources and are typically state-sponsored.

Although no classified information or personal data was stolen, it is not time to let down one's guard or Singapore may end up paying a huge price.

Not only must organisations constantly update their security software and have adequate cyber defences, they must also continue to educate their employees on the dangers of indiscriminately clicking on links. Employees are probably the weakest link. In today's hyper-connected world, every individual plays a part to keep all networks safe.