Online shoppers and internet bank customers are being warned to change their passwords to reduce the risk of falling victim to the online bug that can allow hackers to snatch credit card and bank details.
The Heartbleed bug has been dubbed the biggest internet security threat the world has ever seen.
The virus, which has been around since 2012, allows hackers to steal valuable data, such as passwords or credit card numbers, through holes in a firm’s website security.
t is virtually impossible for firms to check if any information has been taken this way and there are fears that hackers could hold on to stolen data for months before exploiting it.
A report in British Newspaper Daily Mail says that Heartbleed has affected half a million websites across the world.
Other firms are rushing to seal holes in their servers after hacking groups were revealed to be scanning the internet for vulnerable websites.
Many affected internet companies say they have fixed the problem.
But security experts still warn people to change their passwords to be doubly safe.
This is especially vital if a website they frequently use announces it has been affected by the Heartbleed bug and has recently fixed the flaw.
In these circumstances you should change your password again, even if you have already changed it.
Use a mixture of upper and lower case letters, numbers and characters.
Avoid using the same password on different websites or ones that are easy to guess — such as your surname or your children’s names.