Microsoft flips 'kill switch' on all DigiNotar certificates

Permanently blocks all SSL certificates issued by Dutch company hacked in June

Microsoft today updated Windows to permanently block all digital certificates issued by a Dutch company that was hacked months ago.

The update -- the second for Windows Vista and Windows 7, but the first for the decade-old Windows XP -- moves all DigiNotar SSL (secure socket layer) certificates to Windows' block list, dubbed the Untrusted Certificate Store. Microsoft's Internet Explorer (IE) uses that list to bar the browser from reaching sites secured with dubious certificates.

Windows XP users will see this update starting today that blocks all SSL certificates issued by DigiNotar.

DigiNotar, a certificate authority (CA) based in the Netherlands, has admitted that its servers were compromised in mid-July. A report made public Monday by a digital forensics firm said that hackers had acquired 531 certificates, including many used by the Dutch government, and that DigiNotar was unaware of the intrusion for approximately a month.

In that forensics report, Fox-IT said that hackers controlled DigiNotar's servers starting June 17, and that during a month-long stretch in July and August, hackers spied on 300,000 Iranians' Gmail accounts.

SSL certificates are used by websites and browsers to identify a site as legitimate; illegally-obtained certificates can be abused to disguise unauthorized domains using "man-in-the-middle" attacks.

The Windows update will be automatically downloaded and installed to machines that have Windows Update's Automatic Update enabled, Microsoft said in a security advisory.

Microsoft's Dutch customers, however, won't see the update for another week.

"At the explicit request of the Dutch government, Microsoft will delay deployment of this update in the Netherlands for one week to give the government time to replace certificates," Dave Forstrom, a director in Microsoft's Trustworthy Computing group, said in a blog post today. "Dutch customers who wish to install the update can do so by manually visiting Windows Update or following the instructions available at www.microsoft.nl once the security update is released worldwide."

The delay for the Dutch was expected. On Monday, the Netherlands' Ministers of Interior and Security and Justice told parliament that Microsoft would issue an update to block all DigiNotar certificates, and that the update would not be immediately pushed to Dutch Windows users.

Google and Mozilla have already updated their browsers to block all DigiNotar certificates. The former shipped a new version of Chrome on Saturday, while the latter updated Firefox 6 and Firefox 3.6 today.

Mozilla has been especially vocal about its disgust with DigiNotar, and has said that the ban of certificates issued by the company is permanent.

"This is not a temporary suspension, it is a complete removal from our trusted root program," said Johnathan Nightingale, director of Firefox engineering, in a blog post last Friday. "Complete revocation of trust is a decision we treat with careful consideration, and employ as a last resort."

Other security experts have said that the bans by Google, Mozilla and now Microsoft amount to a "death sentence" for DigiNotar and its business.

Andrew Storms, director of security operations at nCircle Security, concurred. "Game over, man," he said today.

Apple has been mum during the DigiNotar episode: Its Safari browser relies on a block list in Mac OS X, so -- like Microsoft -- Apple must update its operating system to protect users.

Last March, when a similar attack targeted Comodo, Apple took a month before blocking the stolen certificates, or three weeks longer than Microsoft.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed. His e-mail address is gkeizer@computerworld.com.

See more articles by Gregg Keizer.

Read more about security in Computerworld's Security Topic Center.

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.

Tags MicrosoftGoogleoperating systemssoftwareWindowsMalware and Vulnerabilities

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

Gregg Keizer

Computerworld (US)
Show Comments

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Jack Jeffries

MSI GS75

As the Maserati or BMW of laptops, it would fit perfectly in the hands of a professional needing firepower under the hood, sophistication and class on the surface, and gaming prowess (sports mode if you will) in between.

Taylor Carr

MSI PS63

The MSI PS63 is an amazing laptop and I would definitely consider buying one in the future.

Christopher Low

Brother RJ-4230B

This small mobile printer is exactly what I need for invoicing and other jobs such as sending fellow tradesman details or step-by-step instructions that I can easily print off from my phone or the Web.

Aysha Strobbe

Microsoft Office 365/HP Spectre x360

Microsoft Office continues to make a student’s life that little bit easier by offering reliable, easy to use, time-saving functionality, while continuing to develop new features that further enhance what is already a formidable collection of applications

Michael Hargreaves

Microsoft Office 365/Dell XPS 15 2-in-1

I’d recommend a Dell XPS 15 2-in-1 and the new Windows 10 to anyone who needs to get serious work done (before you kick back on your couch with your favourite Netflix show.)

Maryellen Rose George

Brother PT-P750W

It’s useful for office tasks as well as pragmatic labelling of equipment and storage – just don’t get too excited and label everything in sight!

Featured Content

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?