Microsoft correctly predicts reliable exploits just 27% of the time

Exploitability index ratings useless, experts argue; Microsoft disagrees

Microsoft's monthly predictions about whether hackers will create reliable exploit code for its bugs were right only about a quarter of the time in the first half of 2009, the company acknowledged Monday.

"That's not as good as a coin toss," said Andrew Storms, director of security operations at nCircle Network Security. "So what's the point?"

In October 2008, Microsoft added an "Exploitability Index" to the security bulletins it issues each month. The index rates bugs on a scale from 1 to 3, with 1 indicating that consistently-successful exploit code was likely in the next 30 days, and 3 meaning that working exploit code was unlikely during that same period.

The idea was to give customers more information to decide which vulnerabilities should be patched first. Before the introduction of the index, Microsoft only offered impact ratings -- "critical," "important," "moderate" and "low" -- as an aid for users puzzled by which flaws should be fixed immediately and which could be set aside for the moment.

But in the first half of this year, Microsoft correctly predicted exploits just slightly more than one out of every four times.

"Forty-one vulnerabilities were assigned an Exploitability Index rating of 1, meaning that they were considered the most likely to be exploited within 30 days of the associated security bulletin's release," Microsoft stated in its bi-annual security intelligence report , which it published Monday. "Of these, 11 were, in fact, exploited within 30 days."

That means Microsoft got it right about 27% of the time.

Microsoft also tallied its predictions by security bulletins -- in many cases a single bulletin included patches for multiple vulnerabilities -- to come up with a better batting average. "Sixteen bulletins received a severity rating of Critical," it said in its report. "Of these, 11 were assigned an Exploitability Index rating of 1. Five of these 11 bulletins addressed vulnerabilities that were publicly exploited within 30 days, for an aggregate false positive rate of 55%."

The company defended its poor showing -- even on a bulletin-by-bulletin level it accurately predicted exploitability only 45% of the time -- by saying it was playing it safe. "The higher false positive rate for Critical security bulletins can be attributed to the conservative approach used during the assessment process to ensure the highest degree of customer protection for the most severe class of issues," said Microsoft.

"There's some validity to that," agreed Storms. "They're going to err on the side of caution, if only to prevent people saying 'I told you so' if an exploit appears later."

Join the Good Gear Guide newsletter!

Error: Please check your email address.

Tags Microsoftsecurity

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 (US)
Show Comments

Essentials

Lexar® JumpDrive® S57 USB 3.0 flash drive

Learn more >

Microsoft L5V-00027 Sculpt Ergonomic Keyboard Desktop

Learn more >

Mobile

Lexar® JumpDrive® S45 USB 3.0 flash drive 

Learn more >

Exec

Lexar® Professional 1800x microSDHC™/microSDXC™ UHS-II cards 

Learn more >

Lexar® JumpDrive® C20c USB Type-C flash drive 

Learn more >

HD Pan/Tilt Wi-Fi Camera with Night Vision NC450

Learn more >

Audio-Technica ATH-ANC70 Noise Cancelling Headphones

Learn more >

Budget

Back To Business Guide

Click for more ›

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

Michael Hargreaves

Windows 10 for Business / Dell XPS

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

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

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.

Kathy Cassidy

STYLISTIC Q702

First impression on unpacking the Q702 test unit was the solid feel and clean, minimalist styling.

Anthony Grifoni

STYLISTIC Q572

For work use, Microsoft Word and Excel programs pre-installed on the device are adequate for preparing short documents.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?