Laptop and smartphone users have been warned that public wi-fi hotspots may put them at the mercy of cybercriminals.
Hackers can use freely available software to 'read' data sent via public hotspots - which can then be used for identity theft attacks.
Research by security firm Norton found that two-thirds of PC users used public hotspots - and many of those 'hand out' critical information.
More than 40 percent of PC users access personal information such as email (44 percent) and social networking sites (42 percent) via free or unsecured Wi-Fi.
A hacker sitting on the same network can use freely available software to steal passwords and other information.
Many browsers include systems to warn users that pages are not secure - but Norton has also launched Hotspot Privacy, a service which aims to make public wi-fi safer.
Norton Hotspot Privacy enables users to become ‘invisible’ on the network and also encrypts their username, password and other confidential information they may be entering online.
Losing an email password can hand a hacker enough information to break into bank accounts, social network accounts, and just about any aspect of someone's digital life.
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'If one email password is compromised, that can mean a compromise of everything,' says Tom Beale, of security company Vigilante Bespoke.
'If a hacker has access to your email password, they can reset your passwords for Twitter, Facebook - and even access bank details from old emails.
'They might even be able to find a scan of your passport.'
Hijacking or “sniffing” Wi-Fi is easier than ever.
Using free, legal apps or hardware costing less than $100, hackers can gain access to online banking, email and social networking information transmitted via even password-protected Wi-Fi networks.
“Increasingly, public Wi-Fi is a part of everyday life, providing people with a convenient way to connect on the go,” said Dave Cole, vice president, product management, Consumer Business Unit, Symantec Corporation.
“With Norton Hotspot Privacy, consumers are able to take advantage of the convenience of public Wi-Fi, with the confidence of knowing their information is secure and their online activities remain private.”