Memos From The Digital Darkroom

USB flash drives are very handy for transferring data from one computer to another. In fact, I use one as a “sneaker-net” in my office because sometimes it’s easier to transfer data with a USB drive than with my network.

However, these simple little devices can cause big problems because they are an extremely efficient tool for spreading computer viruses.

A Virus in the Lab

A couple of weeks ago I was preparing computers in a digital lab for a Photoshop class I was teaching. Part of that preparation included copying student practice files to each system. My preferred method for doing this is to load a folder of files onto a flash drive and plug it into each system to carry out the transfer. In this case the USB drive had only one folder with 12 image files on it.

Everything was fine until I got the the 10th computer and noticed two new files (n0qls.exe and autorun.inf) had mysteriously appeared on the root directory of the drive. This led me to believe that the previous computer placed the virus on my flash drive. This made sense because it was the only Windows system being used for that class. As you probably know, the Windows operating system is a major target for a wide variety of computer viruses.

When I got back to my office I did a quick search and found that n0qls.exe is a well known trojan horse virus that can be used to modify or delete files on an infected Windows system. Like many other viruses, it can be spread by USB flash drives.

A Simple Virus Delivery System

When you think about controlling the spread of computer viruses, risky websites and contaminated email attachments are usually the main suspects. Few people consider the ubiquitous flash drive that so many of us carry everywhere we go. However, using these devices to deliver a virus payload isn’t new.

A few years ago I was having a conversation with a friend who was an IT person at a secure government installation. The topic of USB drives came up and he told me the management at his facility had circulated a memo on the topic of these drives. The memo stated that if an employee  found a USB flash drive in the parking lot, or anywhere on the premises, they were to call security immediately. That’s because a hacker knows that the first thing someone does with a found flash drive is stick it into a computer to see what’s on it and maybe find out who owns it.

Take Appropriate Precautions

Even if you use Macs, you may still be part of the problem. In my case above, I began my process with a very clean USB drive, because I had formatted it before placing my folder onto it. However, it only took a few minutes for the drive to become contaminated and ready to infect the next Windows system I plugged the drive into. So no matter which OS platform you use, it’s best to take a few precautions when working with a flash drive.

If you use a Windows machine regularly, you should be familiar with the drill:

• Make sure that your virus protection software is up-to-date and running.
• If your anti-virus software runs automatically, it may not find a virus on the USB drive if the drive isn’t plugged into the system during the scan. Because of that you may need to manually scan the drive with your virus software.
• If you even suspect your flash drive is contaminated, scan it with your anti-virus software and take appropriate action.

Even if you don’t regularly use a Windows computer, you should be taking precautions with your flash drive, especially is it’s being used on a Windows machines. Because most Mac users don’t employ virus software, it may be difficult to scan the drive for viruses. In this case, because the data on a flash drive is often disposable, the best way to insure cleanliness is to format the drive on a regular basis to remove everything from it. Just be sure to format it so that it can still be used on Macs and PCs.

When formatting a drive for use on both platforms, follow these guidelines:

• When formatting on a PC, choose FAT32 (also known as MS-DOS format) as the formatting option.
• When formatting on a Mac, choose the MS-DOS FAT option in the Erase section of the Disk Utility program.

I used to take my USB flash drives for granted, never checking them for unwanted programs. Now I’m much more careful when using my drives on other people’s computers. By the way - in the future I plan to transfer student files from a CD so that I won’t be responsible for inadvertently spreading a virus.