Unpatched SMB bug crashes Windows 7, researcher says

Microsoft investigating public exploit that locks up Windows 7 and Server 2008 R2 systems

A day after Microsoft plugged more than a dozen holes in its software, a security researcher unveiled a new unpatched bug in Windows 7 and Server 2008 R2 that, when exploited, locks up the system, requiring a total shutdown to regain control.

Microsoft acknowledged that it's investigating the flaw.

Laurent Gaffie posted details of the vulnerabilities, along with proof-of-concept exploit code, to the Full Disclosure security mailing list today, as well as to his personal blog. The attack code, said Gaffie, crashes the kernel in Windows 7 and its server sibling, Windows Server 2008 R2, triggering an infinite loop.

"No BSOD [Blue Screen of Death], you gotta pull the plug," Gaffie said in notes inserted into the exploit code .

Gaffie claimed that the exploit, powered by a vulnerability in the new operating systems' implementation of SMB (Server Message Block), could be successfully launched from within a network from an already compromised computer, or used to attack Windows 7 machines via Internet Explorer (IE) by transmitting a rogue SMB packet to the PC.

Unlike more serious flaws, the Windows 7 SMB bug cannot be used by attackers to hijack a PC, Gaffie confirmed. "No code execution, but a remote kernel crash," he said in an e-mail today.

Gaffie also said that Microsoft's security team has acknowledged the vulnerability, which he first reported to them last weekend, but was told by the company that it wasn't planning to fix the flaw with a security update, instead perhaps correcting it in the first service packs for Windows 7 and Server 2008 R2.

A Microsoft spokesman confirmed that the company is looking into Gaffie's claims. "Microsoft is investigating new public claims of a possible denial-of-service vulnerability in Windows Server Message Block," said the spokesman in an e-mail reply to questions. "Once we re done investigating, we will take appropriate action & [which] may include providing a security update through the monthly release process, an out-of-cycle update or additional guidance to help customers protect themselves."

Gaffie's disclosure came just a day after Microsoft issued November's security updates , which patched 15 vulnerabilities in Windows, Windows Server and Office. None of the 15 affected the final version of Windows 7, which was released to retail Oct. 22, or affected Windows Server 2008 R2.

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 securityNetworkingWindows 7

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

Gregg Keizer

Computerworld (US)
Show Comments

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Walid Mikhael

Brother QL-820NWB Professional Label Printer

It’s easy to set up, it’s compact and quiet when printing and to top if off, the print quality is excellent. This is hands down the best printer I’ve used for printing labels.

Featured Content

Product Launch Showcase

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?