Understanding the Risks Associated with USB Memory Sticks

Since their introduction the USB memory stick has been hailed by those fed up with the shortcomings of the floppy. Their small physical size, satisfactory speed and ever-increasing storage capacity makes them the most convenient device to use for transferring files from one place to another. However, these very features can introduce new security risks and amplify risks that already existed with floppy disks. The primary risks associated with USB memory sticks can be identified as:

• Virus Transmissions - Data sharing opens up an avenue for viruses to propagate
• Corruption of data - Corruption can occur if the drive is not unmounted cleanly
• Loss of data - All media is susceptible to data loss
• Loss of media - The device is physically small and can easily be misplaced
• Loss of confidentiality – Data on the lost physical media can be obtained by others

Virus Transmissions

Whenever files are transferred between two machines there is a risk that viral code or some other malware will be transmitted, and USB memory sticks are no exception. Some USB memory sticks include a physical switch that can put the drive in read-only mode. When transferring files to an untrusted machine a drive in read-only mode will prevent any data (including viruses) to be written to the device. If files need to be transferred from an untrusted machine, the only countermeasure is to immediately scan the memory stick before copying files from it.


Corruption of Data

If the drive is physically lost or uncleanly unmounted, then data loss can occur. Physical loss is covered in the next section and corruption can usually be prevented. USB memory sticks differ from other types of removable media, such as CD and DVD-ROMs because the computer usually has no way of knowing when USB memory sticks are going to be removed. Users of USB memory sticks usually need to alert the computer that they intend to remove the device, otherwise the computer will be unable to perform the necessary clean-up functions required to disconnect the device, especially if files from the device are currently open. The OS will attempt to handle unexpected disconnects as best it can, so often no corruption will occur. However, it is still advisable to research the preferred method for unmounting the device according to the OS documentation.