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!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection

Tags NetworkingsecurityWindows 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

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

George Khoury

Sharp PN-40TC1 Huddle Board

The biggest perks for me would be that it comes with easy to use and comprehensive programs that make the collaboration process a whole lot more intuitive and organic

David Coyle

Brother PocketJet PJ-773 A4 Portable Thermal Printer

I rate the printer as a 5 out of 5 stars as it has been able to fit seamlessly into my busy and mobile lifestyle.

Kurt Hegetschweiler

Brother PocketJet PJ-773 A4 Portable Thermal Printer

It’s perfect for mobile workers. Just take it out — it’s small enough to sit anywhere — turn it on, load a sheet of paper, and start printing.

Matthew Stivala

HP OfficeJet 250 Mobile Printer

The HP OfficeJet 250 Mobile Printer is a great device that fits perfectly into my fast paced and mobile lifestyle. My first impression of the printer itself was how incredibly compact and sleek the device was.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?