One in five social media users has been negatively affected by information revealed on these networks, and more than one in ten have even had accounts hijacked, a survey by Barracuda Networks has found.

The survey of “hundreds” of users of Facebook, Twitter, LinkedIn, Google+ and MySapce from 20 countries over a recent two week period found a population remarkably sanguine about taking take the rough with the smooth.

Nintety-one percent said they had received spam, 54.3 phishing attempts, and 23.3 percent malware. A not implausible 13 percent said they had had their accounts hijacked while 20 percent believed they had suffered negative consequences as a result of personal data that appeared on these sites.

Paradoxically, the services remain hugely popular despite 40 percent of users feeling insecure while using Facebook and 28 percent while on Twitter.

“The fact that nine out of 10 users already have been attacked proves that attackers are taking over social networks and users are living in fear,” concluded Barracuda Networks’ CSO, Dr. Paul Judge.

“Living in fear” is perhaps an exaggeration. Perhaps ‘living happily with risk’ might be a better description of the results from what is at best a small snapshot.

Unquestionably, these networks are now being targeted by criminals keen to exploit the trust levels many people seem to take for granted while using them which has prompted providers to build in ever more elaborate security and filtering.

Facebook recently announced a deal to build in Websense web link scanning technology, while companies such as F-Secure have also offered client-side apps that do a similar job.

The same security layers can be applied to Twitter accounts, timely given that the network has suffered a number of account hijacking attacks this year aided by poor user password habits.

Predictably, LinkedIn was the most accepted social network for business use with only 1 in 5 reporting that it was blocked at work; Facebook’s figure was 31 percent.