Old worm, new outbreak

The Downloadup (also called Conficker or Kido) worm itself is nothing new. It made its first appearance late November 2008, exploiting the MS08-067 vulnerability to spread unhindered in local area networks.
Its purpose was to install rogue security software on infected computers. Late December BitDefender Labs has uncovered a new version of the worm. Called Win32.Worm.Downadup.B the malware comes with a list of new features beside the already present spreading routine, which in fact was improved as well.

First of all, the worm can now use USB sticks to spread. By copying itself in a random folder created inside the RECYCLER directory used by Recycle Bin to store deleted files and creating an autorun.inf file in the root folder of the drive, the worm will automatically get executed when the device is plugged in the computer if the Autorun feature is enabled.

Second of all, the worm patched certain TCP functions to block access to security related websites by filtering every address that contains certain strings. This makes it harder to remove since information about it is hard, nearly impossible, to gather from an infected computer. Additionally it removes all access rights of the user except execute and directory traversal to protect its files.

The worm is also built to avoid antivirus detection by working with rarely used APis in order to avoid virtualization technologies. It is also disabling windows update and certain network traffic optimizing vista features to ease its spreading.

To complete the feature list, Win32.Worm.Downadup.B comes with a domain name generation algorithm similar to the one found in botnets like Rustock. It uses date and time to compose 250 domains every day, which it checks for updates or other files to download and install.

Having a state of the art update system, a good protection scheme and many people that don’t patch their systems, this worm has great potential to become a rival to already established botnets like Storm or Srizbi.

For more technical details please visit the BitDefender description: Win32.Worm.Downadup.Gen

About the author


Razvan Stoica is a journalist turned teacher turned publicist and
technology evangelist. When Bitdefender isn't paying him to bring complex subjects to wide audiences, he enjoys writing fiction, skiing and biking.

Razvan Stoica started off writing for a science monthly and was the chief
editor of a science fiction magazine for a short while before moving on to
the University of Medicine in Bucharest where he lectured on the English
language. Recruited by Bitdefender in 2004 to add zest to the company's
online presence, he has fulfilled a bevy of roles within the company since.

In his current position, he is primarily responsible for the communications and community-building efforts of the Bitdefender research and technology development arm.