London, September 1 : Users of social networking websites like Facebook can be tricked into attacking innocent websites without knowing about them, according to a new study.

Researchers from the Foundation for Research and Technology in Heraklion, Greece, have revealed that they created an application called FaceBot for their study.

The programme was used to present a striking photo to users every day, reports New Scientist magazine.

However, each time a user accessed the application, it also downloaded four images from a targeted website - the team''s own - which it presented in hidden frames invisible to the user.

The researchers found that at the peak of FaceBot''s popularity, about 1,000 of its users had significantly increased the data transfer from the test website, straining its web server.

They will present their findings at the Information Security Conference in Taipei, Taiwan, next month. (ANI)