The downturn in spam has led to a rise in "rogue direct marketing" on social networks.

Speaking to SC Magazine at the Infosecurity Europe conference in London, Wieland Alge, general manager EMEA at Barracuda Networks, said a combination of bringing down botnets, arrests and spam traps had led to a decline in traditional spam. However, this has led to a rise by three times in spam on social networks.

He said: “We monitor mass attacks on social networks closely on Twitter and Facebook and both are in a critical state. Only one per cent of Twitter messages and 1.6 per cent on Facebook are bad, but the sheer amount of messages makes it [worrying].

“On Facebook, if one in 200 messages is spam, you will read it and click on the links. The rogue direct marketers are terrible spellers, but the click rate is massive due to the small amount of text. They use automated clients and the success rate is massive.”

Barracuda Networks' chief research officer, Dr Paul Judge, said attacks have gone up significantly over the past two years and attackers are now using Facebook's new implementations and APIs and creating fake pages to attract 'likes'.

“If one person likes a page, they can be tagged in a photo with 50 other people. They have 5,000 friends so 250,000 people can be reached from one photo; that is why it is so efficient,” he said.

“The photo has a comment and a description that says 'look at this girl' or 'remember this night' and there will be a malicious link for apparently more pictures. It is a confidence thing and it is part of Facebook; fake accounts account for one per cent of all profiles, while ten to 30 per cent are not real people.”

Judge also said that Twitter continues to have fake accounts with huge amounts of malicious tweets sent, while new social networks such as Pinterest and Foursquare have not had such a level of spam interest as yet.