One of the most common causes of USB malware transmittal is the Windows AutoRun feature. Typically left on by default, AutoRun scans newly connected devices and prompts the user for an action to take, from opening Office documents to playing video files. During this simple scan malware can infect a computer, turning a feature of convenience into a dangerous liability. And as USB drives are now found anywhere and everywhere computers are used, simply trading data between users can result in easily infected PCs.
Some easy ways to protect yourself include keeping USB devices disconnected until the PC and its anti-virus software have fully booted, making sure on-access malware scanning is enabled and running in the background, or simply disabling AutoRun altogether.