Many Facebook users are happy to give up access to their personal profile to strangers.
In a random survey of Facebook users, 41 per cent were happy to divulge personal information - such as email address, phone number, and date of birth - by agreeing to accept a complete stranger as a friend.
Sophos, which conducted the survey, warned the behaviour leaves users at a greater risk of identity theft. As well as sending out friends requests, Sophos poked a further 100 random Facebook users. The tactic proved comparatively ineffective with just eight responses, of which only five people revealed personal information.
"While accepting friend requests is unlikely to result directly in theft, it is an enabler, giving cybercriminals many of the building blocks they need to spoof identities to gain access to online user accounts, or potentially, to infiltrate their employers' computer networks," said Graham Cluley, senior technology consultant at Sophos.
The Sophos Facebook ID Probe survey involved creating a fabricated Facebook profile before sending out friend requests to randomly chosen individuals.
It then sent out 200 friends requests which received 87 responses. Of these, 41 per cent of the total sample gave access to personal information. In the majority of these cases, details such as email addresses (72 per cent), date of birth (84 per cent), place of work or education (87 per cent), and current address (78 per cent) were made available to a potential fraudster.
In addition, many users also disclosed the names of their spouses or partners, several included their complete résumés, while one user even divulged his mother's maiden name - information often requested by websites in order to retrieve account details.
"Most people wouldn't give out their details to a stranger in the street, or even respond to a spam email, yet several of the users Freddi contacted went so far as to make him one of their "top friends"... Freddi now has enough information to create phishing emails or malware specifically targeted at individual users or businesses, to guess users' passwords, impersonate them, or even stalk them," Cluley said.
"People need to realise that this is still unsolicited communication, despite it occurring within Facebook, and users must employ the same basic precautions."
As well as the successful friend requests, a number of users unwittingly enabled Freddi to gain access to their profile information simply by sending response messages such as "Who are you?" and "Do I know you?" back to his Facebook inbox.
Users' profiles can be protected from such exposure by adjusting the privacy controls within their Facebook account settings, but these are often ignored.
"It's important to remember that Facebook's privacy features go far beyond those of many competing social networking sites. This is about the human factor - people undoing all that good work through carelessness and being preoccupied with the kudos of having more Facebook friends than their peers," Cluley notes.
"Some businesses may already be considering blocking Facebook for productivity reasons - but equally, other companies will see business benefits in this type of interaction, hence it's important that the site is used sensibly and securely." ®