Malware, trojan, virus writers exploit Windows Operating Systems using the AUTORUN.INF file feature from removable drives in order to infect your system with malware, virus, trojans etc. This feature is present with all USB drives, removable drives by default which use windows operating system which tells the system to perform actions when the USB drive or removable drive is inserted in your system.
Malware writers use this feature in their favour by copying a malicious executable in the drive and modifying the AUTORUN.INF file so that Windows opens the malicious file silently as soon as the drive is mounted.
W32/Sality, W32/Virutas and also theworm fall in this category of malware which, in addition to spreading via a vulnerability and network shares, also spreads via USB drives.
There are many tools which are available to take care of this loophole. One of them and a effective one released by Panda is Panda USB Vaccine with a freeware tag.
The free Panda USB Vaccine allows users to vaccinate their PCs / USB in order to disable AutoRun completely so that no program from any USB/CD/DVD drive (regardless of whether they have been previously vaccinated or not) can auto-execute.
Also keep in mind that USB drives that have been vaccinated cannot be reversed without reformatting the drive. And this feature is presently only works on FAT drives not NTFS.”Computer Vaccination” works on NTFS. It is only “USB Drive Vaccination” that works on FAT/FAT32 currently. However keep in mind that the vast mayority of USB drives come preformatted in FAT/FAT32 anyway.