Magazine CD risks computer virus

A computer magazine has put its 31,000 readers at risk from a computer virus by inadvertently including it in software on a cover-mounted free CD.

The virus could conceivably corrupt important files of any system that it infected, an expert warned yesterday, though it was more likely just to slow the machine down.

The rogue program was accidentally included in a digital film clip given away with this month's edition of Mac User, which reached newsagents yesterday.

The magazine is now asking readers and newsagents to destroy the discs, known as CD-Roms, because there is no way of erasing the virus from them, and offering a free replacement.

The process of recalling the flawed discs and pressing a full set of "clean" ones could cost up to pounds 60,000.

"We want people to destroy them because the last thing that we want is lots of infected discs lying about the place," said Stuart Price, the magazine's editor.

He added: "It's not the best week I've had in my life as an editor."

The virus, called MBDF A, can only affect Apple Macintosh computers. It cannot affect PCs running Microsoft's Windows or other operating systems, which use a different computer language.

The virus was attached to a video clip of a tour of MTV's UK studios which was provided by a third party to the magazine. Copying the clip to a computer and running it would activate the virus, which would begin to make copies of itself.

"MBDF A isn't malicious; it doesn't damage data," said Megan Skinner, associate editor of Virus Bulletin. "But it could make the system slow down so much that the user would think it had crashed, and if you turned it off while it was writing itself, you could corrupt your system."

Mr Price admitted that Mac User had failed to carry out the normal procedure of checking all contents of the cover disc for viruses.

"I don't think it was malicious on the part of the people who sent it," he said. "I've known them for years." The virus - first identified in 1992 - would be caught and destroyed by most anti-virus software. The magazine is offering a free anti virus program at its Internet site.

The dangers of viruses on CD-Roms were first pointed out by the Independent in December 1994, when four instances of viruses on the discs - which resemble music CDs, but hold software - were discovered. Since then the problem has been found in a number of instances.

The worst case of a virus spread by CD-Rom was inadvertently perpetrated last year by Microsoft.

It sent a CD-Rom containing important programming information about Windows to a number of software companies.

The information was sent as documents written in Microsoft's Word word- processing program.

But some documents contained a "macro virus", so that when the information was read on a computer, the virus - known as "Concept" - would copy itself to any other document written on that the system. This only happens in Version 6 of Microsoft Word - but this is one of the most common word-processing programs, which is used on both PCs and Apple Macintoshes around the world.

Luckily, Concept has no malicious effect. But computer virus experts think that it is now the most common in the world. In Britain, it is thought to affect one in every four companies.

Virus experts reckon that the rapid spread of Concept, which was discovered last August, is due to the fact that word-processing documents can now be sent as "attachments" to internal electronic mail in large companies.

If somebody sends a document which is affected with the virus to someone else, the recipient's machine will be infected when they open the document to read it.

So far, four other "Word viruses" have also been discovered, though none seems to deliberately destroy data. The worst is one called Wazzu, which could swap words at random inside a document, corrupting the contents.