Nude Snapchat selfies could hide fraud, warn security experts

It shot to prominence this year as the must-have messaging app, attracting a £1.8billion valuation and rejecting a takeover bid from Facebook. 350million picture messages are sent on Snapchat every day.

But Snapchat's unique selling point - the idea that photo messages sent using the app have a limited lifespan before they expire and cannot be viewed again - has repeatedly landed them in hot water.

The app quickly became notorious as a 'sexting' service, as predominantly young people used the promise of disposable images to send nude or revealing pictures of themselves to each other.

Snapchat has always been quick to distance itself from the practice - in a recent interview, founder Evan Spiegel said the reputation it had attracted 'meant that we had to do a better job teaching people...now, the growth of the service shows that it's about a lot more'.

But the app's reputation has not escaped internet fraudsters and spammers, who are now using the promise of topless pictures to lure unsuspecting users into installing spamware or giving up their personal details.

Internet security researchers at Symantec discovered that at least 30,000 people had fallen for the scam. Typically, spammers send friend requests to users on Snapchat, always with usernames that take the form "[GIRLSNAME]snap_####" - for example, "Pamsnap_1234, Myasnap_5570".

The snaps sent by these accounts usually feature a 'selfie' of a woman topless or in her underwear, with the promise of more revealing pictures if the user adds them on KIK, an instant messaging app.

From there, the user is prompted to install various apps - mostly games - which are laden with adverts. The spammers get paid for every one of these games that is installed. The whole process is automated, using so-called 'porn bots' to entice Snapchat users into downloading spam apps.

These apps will slow down your phone, bombard you with adverts, and could contain viruses or other malware.

Snapchat has also emerged as a platform for fraudsters looking to steal personal data. Using a similar ploy, the 'Secret Admirer' campaign sends users messages telling them they have a beautiful admirer.

If you respond, it will ask you to install various apps and enter your username and password - which they will then have access to.

There is currently no way to report spam within Snapchat itself, but users can log a complaint on the app's website.

The problem is not restricted to Snapchat itself. Several Facebook pages have appeared which claim to have 'Leaked Snapchat pics 18+' or similar.

Security researcher Troy Hunt found that the pages are filled with suggestive images and enticements to click links for more explicit material.

Following these links leads to pages which prompt you to re-enter your Facebook log-in details, letting the spammers gain thousands of usernames and passwords.

The pages then re-direct to other spam sites, offering mobile phone competitions and sweepstakes. Hunt found that one site alone had lured 699 people into giving their details.

The spam Facebook pages also work hard to establish 'credibility' as genuine pages by commenting on current events.

Hunt found an example of one that posted a message of condolence following actor Paul Walker's death in a car crash, and encouraged users to comment with their own tribute - lending authenticity to the spam pages. The page had attracted 106,000 likes in less than two weeks.