Attack code released for critical Windows flaw

Security researchers have developed attack code that exploits a dangerous flaw in Windows' multicasting protocol.

In what may be the first step toward a major security problem, security researchers have released attack code that will crash Windows machines that are susceptible to a recently patched bug in the operating system.

The code is not available to the general public. It was released Thursday to security professionals who use Immunity's Canvas computer security testing software. It causes the Windows system to crash but does not let the attacker run malicious software on the victim's system.

"It reliably crashes Windows machines," said Dave Aitel, Immunity's chief technology officer, in an e-mail interview. "In fact, it blue-screened our print server by accident -- this is a broadcast attack, after all."

That's the biggest concern for security experts who worry that a more dangerous attack may soon follow as researchers dig further into the vulnerability. The bug is particularly troublesome for two reasons. First, it affects a widely used Windows component that is turned on by default. Worse, no user interaction is required to trigger the flaw, meaning that it could be exploited in a self-copying worm attack.

Microsoft patched the flaw in its MS08-001 update, released last week, but it takes time for enterprise users to test and install Microsoft's patches.

The flaw lies in the way Windows processes networking traffic that uses IGMP (Internet Group Management Protocol) and the MLD (Multicast Listener Discovery) protocol, which are used to send data to many systems at the same time. The protocols are used by a range of applications including messaging, Web conferencing and software distribution products.

For a worm attack to work, the attacker would have to send specially crafted packets to a victim's machine, which could then allow the attacker to run unauthorized code on the PC. The worm could then spread from computer to computer within a LAN, but would generally be stopped from travelling to another network by a firewall.

A reliable exploit could be combined with malicious botnet software, giving attackers a way to widen the size of their networks of infected computers. The flaw is rated critical for Windows XP and Vista systems, according to Microsoft.

After patching the flaw, Microsoft published some technical research indicating that it would be hard for an attacker to exploit this vulnerability.

But Aitel believes that Microsoft may have overestimated how difficult it would be to create reliable attack code. Because it could spread so quickly through a network, a reliable exploit "is going to be worth the effort," Aitel said. "You can be assured lots of smart people are working on it."

Part of the problem is that IT staff may not be aware of how widely these multicasting protocols are used within their companies, said Russ Cooper, a senior network consultant with Verizon Business. "I am extremely worried that this becomes a problem simply because people are unaware of what they're already allowing," he said.

If one machine were infected within a network subnet, its attempt to attack other machines might not even be noticeable, he added. "It may look like a large file transfer."

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Robert McMillan

IDG News Service
Show Comments

Cool Tech

Breitling Superocean Heritage Chronographe 44

Learn more >

SanDisk MicroSDXC™ for Nintendo® Switch™

Learn more >

Toys for Boys

Family Friendly

Panasonic 4K UHD Blu-Ray Player and Full HD Recorder with Netflix - UBT1GL-K

Learn more >

Stocking Stuffer

Razer DeathAdder Expert Ergonomic Gaming Mouse

Learn more >

Christmas Gift Guide

Click for more ›

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

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.

Ben Ramsden

Sharp PN-40TC1 Huddle Board

Brainstorming, innovation, problem solving, and negotiation have all become much more productive and valuable if people can easily collaborate in real time with minimal friction.

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

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?