The study - conducted in concert with Breach Security, the virtualisation and security firm's US partner - found that the planting of malware and overt changes remain the most common outcome of web attacks, accounting for 28%.

Leakage of sensitive data, meanwhile, came a close second at 26%  - up from 19% in H1 2008 - and 'disinformation' came a distant third at 19%, mainly due to the hacking of celebrity online identities, said the company.

On the attack vector front, injection remains the number one attack methodology, accounting for nearly one-fifth of all security breaches, with authentication abuse at 11% tracking in second place.

Cross Site Request Forgery, meanwhile, rose to number five with 5% of the reported attacks, said the study.

Commenting on the the Web Hacking Incidents Database (WHID) 2009 Bi-Annual Report, Nick Garlick, managing director of Nebulas Solutions Group said: "The report's findings clearly show that social networking sites are being targeted."

"We've seen and heard anecdotal evidence that web 2.0 applications are being attacked more frequently and more aggressively, but the scale of these findings show very clearly that organisations must now look very closely at their security policies and procedures around web 2.0," he said.

"Many companies still don't fully comprehend the security risks that social networking sites and user-generated content can represent, so this report is a wake-up call for them and highlights the need to address these issues as a key priority," he added.