Flawed Trend Micro anti-virus update cripples PCs

It quarantines critical Windows files, prevents booting of some XP, Vista machines

Anti-virus updates issued by Trend Micro last week crippled Windows XP and Vista PCs when they mistook several critical system files for malware, and blocked access to those files.

Some users have yet to regain control of their PCs, according to e-mail sent to Computerworld.

Two signature updates that Trend Micro released Friday for its most popular consumer security software incorrectly identified up to eight different Windows files as Trojans, then quarantined those files, thinking they were dangerous. The updates were issued to users running Trend Micro's AntiVirus plus AntiSpyware 2008, Internet Security 2008 and Internet Security Pro 2008.

In some cases, quarantining the files prevented the PC from booting.

Trend acknowledged the snafu, but said the buggy updates were out for only a short time. "For a brief period of time late last week primarily some continental European consumers were affected by a Trend Micro pattern-file update with a false positive that could have led to quarantining a few Windows components," said company spokeswoman Andrea Mueller in an e-mail.

When it realized that the updates were flagging innocent files, Trend Micro issued a replacement signature update.

That was too late for some users, however.

"I have spent a lot of hours to fix this issue, also with a long phone call with [Trend Micro] support this afternoon," said Bruno Misonne from Belgium in an e-mail.

Misonne said two PCs, one running Vista and the other XP, were affected by the faulty update. He was able to restore the Vista system, but had been unable to recover the XP machine. "Technical support told me that they are overfilled with cases," he said in a follow-up e-mail. "This bad signature simply removes essential files."

Trend Micro has published a detailed support document] for users whose anti-virus software downloaded and installed the flawed updates. The document includes step-by-step instructions for users who are unable to boot their PCs that requires them to use Windows' Safe Mode to regain control, then asks them to download and run a restore utility that moves the system files out of quarantine and to their proper locations.

This isn't the first time that Trend Micro has pushed a malicious signature update to its customers. In April 2005, the company issued a buggy definition file that locked up Windows XP machines, most of them owned by Japanese users, as the software consumed 100 percent of the processor's cycles.

Last year, an anti-virus signature released by rival Symantec knocked out thousands of Chinese PCs by falsely labeling two Windows .dll files as malware, preventing users from booting their computers.

Join the PC World newsletter!

Error: Please check your email address.

Tags trend microantivirus

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Gregg Keizer

Computerworld
Show Comments

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

Azadeh Williams

HP OfficeJet Pro 8730

A smarter way to print for busy small business owners, combining speedy printing with scanning and copying, making it easier to produce high quality documents and images at a touch of a button.

Andrew Grant

HP OfficeJet Pro 8730

I've had a multifunction printer in the office going on 10 years now. It was a neat bit of kit back in the day -- print, copy, scan, fax -- when printing over WiFi felt a bit like magic. It’s seen better days though and an upgrade’s well overdue. This HP OfficeJet Pro 8730 looks like it ticks all the same boxes: print, copy, scan, and fax. (Really? Does anyone fax anything any more? I guess it's good to know the facility’s there, just in case.) Printing over WiFi is more-or- less standard these days.

Ed Dawson

HP OfficeJet Pro 8730

As a freelance writer who is always on the go, I like my technology to be both efficient and effective so I can do my job well. The HP OfficeJet Pro 8730 Inkjet Printer ticks all the boxes in terms of form factor, performance and user interface.

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Aysha Strobbe

Windows 10 / HP Spectre x360

Ultimately, I think the Windows 10 environment is excellent for me as it caters for so many different uses. The inclusion of the Xbox app is also great for when you need some downtime too!

Mark Escubio

Windows 10 / Lenovo Yoga 910

For me, the Xbox Play Anywhere is a great new feature as it allows you to play your current Xbox games with higher resolutions and better graphics without forking out extra cash for another copy. Although available titles are still scarce, but I’m sure it will grow in time.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?