Three London hospitals continue to restore computer systems three weeks after being infected with a relatively old worm.
Around 5,000 PCs at St Bartholomew's, the Royal London Hospital and The London Chest Hospital were hit in mid-November by an infection of Mytob , a worm that e-mails itself to other PCs and can be used to put other malicious software on a machine, which could put confidential personal data at risk.
About 97 percent of those PCs are now clear of Mytob, according to a statement issued Friday. The remaining PCs, which are located in non-clinical areas, should soon come back online.
As a precaution, all of the PCs were shut down after the infection was discovered. The infection affected computers used to admit patients, and the hospitals diverted emergency patients to other facilities for a short time.
The PCs did have antivirus software made by McAfee installed. McAfee, which received a sample of the Mytob strain infecting the hospital's PCs, said its up-to-date products do have the have the right signature to detect the worm.
It remains unclear how the PCs were infected. Mytob, official called W32/[email protected], was discovered in early 2005, and most security products can detect it. If left on the system, in a worst case scenario, hackers could exploit the worm to gain control over infected networks and computers. A spokesman for the hospitals said on Monday an investigation is ongoing.