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 NetworkingWindows 7

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

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Cate Bacon

Aruba Instant On AP11D

The strength of the Aruba Instant On AP11D is that the design and feature set support the modern, flexible, and mobile way of working.

Dr Prabigya Shiwakoti

Aruba Instant On AP11D

Aruba backs the AP11D up with a two-year warranty and 24/7 phone support.

Tom Pope

Dynabook Portégé X30L-G

Ultimately this laptop has achieved everything I would hope for in a laptop for work, while fitting that into a form factor and weight that is remarkable.

Tom Sellers

MSI P65

This smart laptop was enjoyable to use and great to work on – creating content was super simple.

Lolita Wang

MSI GT76

It really doesn’t get more “gaming laptop” than this.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?