Antivirus firm finds USB drives and other removable media spread the most prolific forms of malware last month.


April 2, 2008
By Andy Patrizio: More stories by this author:
The latest trick from malware (define) writers is a retro form of virus propagation. For some time now, e-mail has been the standard form of delivery and spreading of malicious code by getting users to click on malicious links. But in the pre-Internet days, viruses typically spread from one computer to another via the floppy disks people used to share data and applications.

That old method is coming back, with a modern twist. Now the bad guys are targeting USB storage devices, most notably USB thumb drives, by taking advantage of the nature of the drive and a major weakness in Windows.

When a removable media like a thumb drive or CD-ROM are placed in a computer's USB port or optical drive, respectively, a program can be automatically executed through the autorun.inf file. Windows' AutoRun facility is programmed to seek this file and execute whatever instructions are in it.

In the case of an application install CD, the installer starts up the installation process. In the case of INF/Autorun, it installs malware on the user's system, such as a Trojan, rootkit (define) or keystroke logger.