Enterprises have a hard time coping with the rise of social news websites such as Myspace and Facebook.

Approximately 70 per cent of all enterprises block access to specific internet domains, according to a recent study by analyst firm Gartner.

Half of the companies who use web filtering equipment from Barracuda Networks, meanwhile, block access to either Myspace and/or Facebook, the two most popular online social networks. Barracuda based findings on a sample of 2,400 customers.

In a separate survey by the security vendor, 70 per cent of the respondents cite the prevention of virus and malware infections as the primary reason for restricting employee web surfing. Another 51 per cent mentioned productivity drain as a reason for filtering.

Other reasons for filtering include bandwidth concerns and regulatory requirements to control employee communications, such as privacy legislation or concerns over insider trading.

The risks however can be as much perceived as real. Rather than all-out banning Myspace or Facebook, companies can prevent malware infection much more effectively by scanning web traffic. However, only 20 per cent of the enterprises use such a malware defense, Gartner found.

Companies blocking social websites furthermore only tend to do so when they start noticing a spike in traffic to such services, says Fred Cohen, an independent security analyst. Cohen suggested that the blocks come from a perceived need to control employees.

"Often there is no specific risk [from social websites]," Cohen said. "But companies have the flawed believe that they are in charge."

Filtering web traffic furthermore is not without pitfalls. Many employees perceive the practice as a lack of trust, cautions Peter Firstbrook, a research director covering security for Gartner.

"Considering that most organizations expect employees to work extra during off-hours, they must accommodate workers' needs to conduct home life activities while at work,"

Instead of instating a blanket ban, he suggests that firms monitor traffic and reprimand individuals who exceed fair use.

"Since monitoring Web activity is easy, catching the people that are wasting time on social sites is also easy. It is counterproductive to punish all workers for the potential transgressions of a few."

In the future, Gartner projects an increase level of granularity in the control of web traffic. Employees for instance could be allowed to view Facebook profiles and messages, but would be blocked from editing their profiles.