And he wears a disguise...Anti-virus experts are warning of a worm disguised as a virus warning threatening UK businesses. The W32/dotor.A virus is masquerading as an anti-virus fix for macro viruses and it spreads via an email attachment titled Doctor.exe. The email has the following subject and body text: "Subject: New Tool for Macro virus. Body: This tool allows you to protect you against unknown macro virus. Click on the attached file to run this freeware. Best Regards. Have a nice day." Anti-virus vendor Panda said the virus, thought to have originated from Israel, extends the infected computer's .exe. com. and .sys file names to corrupt these files. A spokesman from Panda said the virus is yet to spread widely in the UK but advised companies to remain vigilant because of Doctor's unusually tempting use of social engineering. Hackers use social engineering to take advantage of end users and their willingness to forward hoax virus alerts and other malware to alert other users.