Researchers exploit Conficker flaw to find infected PCs

Three researchers, including Dan Kaminsky, created a scanner to quickly detect worm on networks

Just days before the Conficker worm is set to contact its controllers for new instructions, security researchers have discovered a flaw in the worm that makes it much easier for users to detect infected PCs.

Tillmann Werner and Felix Leder, members of the Honeynet Project, an all-volunteer organization that monitors Internet threats, have discovered that Conficker-infected PCs return unusual errors when sent specially crafted Remote Procedure Call (RPC) messages, according to preliminary information they have posted on the Web.

There's a growing urgency in the battle against Conficker as Wednesday approaches. PCs infected with Conficker.c, the third version of the worm, will use a new communication scheme starting April 1 to establish a link to the command-and-control servers operated by the hackers. What's troubling to researchers is that they have no clue about what orders the worm's makers will give those machines.

Using their discovery, Werner and Leder, along with Dan Kaminsky, the security researcher who last summer uncovered a critical flaw in the Domain Name System (DNS) software, spent the weekend crafting a scanner that lets users quickly sniff out Windows machines infected with the worm.

"You can literally ask a server if it's infected with Conficker, and it will tell you," Kaminsky said in an entry to his blog Monday.

The scanner, in turn, has been modified and added to enterprise-grade detection systems from companies such as McAfee Inc., nCircle Inc. and Qualys Inc., which plan to release updates today. The free open-source Nmap scanner is also slated to include the new detection capability.

"What Tillmann and Felix found was that Conficker systems react differently to certain RPC parameters," said Wolfgang Kandek, chief technology officer at Qualys. "The difference is very subtle."

Conficker-patched machines answer differently to the special RPC messages because the worm, which exploited a Windows vulnerability that Microsoft Corp. patched last October, uses its own version of the Microsoft patch to effectively close the door behind it. Quashing a bug is a common tactic by malware authors to prevent other criminals from stealing their infected systems.

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 Kaminskyconficker

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

Gregg Keizer

Computerworld
Show Comments

Father’s Day Gift Guide

Brand Post

Bitdefender 2019

Bitdefender’s best-in-class security solutions have been awarded Product of the Year. Get cybersecurity that 500 MILLION users already have and trust!

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

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.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?