NewScientist -- PACEMAKERS are supposed to protect people from heart attacks. But to do that they have to provide digital as well as biological security. Earlier this year, a team led by William Maisel at Harvard Medical School demonstrated how a commercial radio transmitter could be used to modify wireless communications from a pacemaker (New Scientist, 22 March, p 23). Doctors normally use these signals to monitor and adjust the implanted device, but a malicious hacker could reprogram the pacemaker to give its wearer damaging shocks, or run down its batteries. Such irresponsible attacks might seem inconceivable, but Tamara Denning, a computer scientist at the University of Washington in Seattle, points out that in 2007 hackers posted flashing images to the Epilepsy Foundation’s website, apparently with the aim of triggering attacks in people with photosensitive epilepsy.