A hoax email warning people that their PCs may contain a virus called sulfnbk.exe - that will be triggered on 1 June - seems to be propagating as a result of mass hysteria.
The email, which was originally written in Portugese and was reported to be doing the rounds in Brazil last month, has now been translated and appears to be appearing throughout the UK, advising people to delete a harmless Microsoft Windows utility - called sulfnbk.exe - from their hard disks.
Antivirus experts were quick to point out that the email does not contain a worm, and is being passed around simply by well-meaning people alarmed at its contents.
"This is social engineering on a grand scale," said Symantec spokesperson Lucy Bunker.
"Whereas email worms mass mail themselves and cause destruction, this hoax message simply asks you to mass mail it yourself, and then delete the information on your computer. In essence, you're doing the work of a destructive virus yourself."
The hoax message indicates that the virus was found on every PC in somebody's office, and that it was not detectable with virus software.
In fact, the file is on every PC that has Windows installed, and is not detected by antivirus software because it is not - and does not normally contain - a virus.
"The file that people are being asked to delete is a legitimate file that is part of the Windows operating system," said Bunker.
"We are working with Microsoft to find out what people should do if they have deleted this file; it is a useful file and you shouldn't delete it."
Sulfnbk.exe is a Microsoft Windows utility that is used to restore long file names, according to Symantec, and deleting it could cause that feature to cease working properly.
Bunker said that Symantec received a handful of enquiries about the e-mail message yesterday, and more today - probably triggered by the warning that the virus would activate on 1 June.
There are several easy clues to detect bogus virus warnings, according to Bunker.
"Anything that has lots of capital letters saying things like VIRUS WARNING should be treated with scepticism," she said.
Also, phrases warning that a supposed virus will absolutely destroy everything on a hard disk should be taken with a pinch of salt, as should those suggesting there is no known fix.
"Hoax emails also often attribute information to MSN, AOL, Microsoft, CNN to give them credibility," Bunker added, "but these companies don't usually issue virus warnings".
