Security of USB Ports and Flash Drives: Problems and Solutions

Over the last few years, computers have startedcomputer is as well protected as the corporate one?
shipping with more and more USB connections - it'sToo many times have there been stories about
that little rectangular plug usually found on the backmalware making their way into a corporate setting
(and now front and even sides) of your PC, used tobecause someone brought a USB drive from home
connect all sorts of devices to your computer -that was infected. Since Windows(R) configures
keyboards, mice, scanners, cameras, MP3 players,these drives on the fly, its possible that the anti-virus
and a myriad of others. In fact, it is now impossibleprogram could be by-passed since they may be only
to get a computer without one. One of the mostset to scan previously existing drives, allowing the
popular uses is to connect small thumb drives (alsovirus to gain access to your company network.
known as pen drives or USB drives) in order to backSo what can you do?
up, store, and transport data. In such a fashion,Thankfully, there are quite a few strategies that can
these are quickly becoming the de facto replacementhelp mitigate the risk of USB drives in your
for both write-able CD-ROMS and floppy disks.environment. Naturally, the strength of your solution
Typically, these are either dedicated storage deviceswill need to be tailored to the sensitivity of your
or integrated as part of portable music players (suchdata, the potential for harm, and the potential for
as the ever popular iPod) and can hold anywhereattack. A bank will have much different exposure
from 128 megabytes to 80 gigabytes (enough forfrom this threat than would a cash-only craft's store,
most companies ENTIRE record set).although both should take care to protect their
What, exactly, is the problem with this? A standard,customer's data.
high-speed, easy to use connection for almost everyAlthough it seems everyone jumps to the technical
device sounds like a great advantage for computersolutions first, one of the best ways to combat this
users.problem is through a strong, well enforced policy
Unfortunately, there are some very serious securityregarding USB drives. If possible and applicable, USB
implications associated with USB and its ease of use.drives should be prohibited. This includes everyone
The worst of these deals with letting data get into(even the IT staff and system administrators who
the wrong hands. There are several ways thatare some of the most likely to want to use them,
someone interested in your data might leverage USBbut also the most likely to go to conferences that
to get your sensitive information and take over youroffer them as free gifts!). This means anyone seeing
computer resources. Even worse, as these devicesa USB drive will know instantly that it shouldn't be
grow in capacity, the danger they pose alsothere and can report the incident immediately.
increases.If this isn't possible, their use should be permitted on
The root of the problem stems from the waya use-by-use basis to employees that have been
Microsoft's Windows(R) operating system handlesmade aware of the risk. Any drives of unknown
plug and play devices (which is what USB devicesorigin (from vendors, gifts, etc) should be connected
are). As you may have noticed, whenever you plugto an isolated machine to be scanned for viruses and
anything into a USB port, nine times out of ten,wiped clean before use.
Windows(R) will automagically recognize and configureOnce a good policy has been established, technical
that device for use. If it is a USB drive, it even getsmeasures can be put into place to enforce it. One of
a drive letter. If Windows(R) detects that the devicethe easiest and cheapest of these is to disable the
isn't classified as "removable", it will automatically runuse of USB ports from the BIOS. The BIOS controls
certain files found on that drive. (This is known asmany of the hardware settings of your computer
auto-run and is enabled by default in Windows(R).)and is typically accessed at the very onset of the
While many of the drives on the market today areboot up process - often a black screen with the
considered by Windows(R) as "removable", certainmanufactures logo on it.
USB drive vendors actually configure their drives soUnfortunately, this means that ALL USB devices will
Windows(R) detects them as "permanent", thusbe non-operational. With the spreading use of USB,
making them capable of "auto-running" these files.this solution is impractical on newer machines since
Someone trying to get your information could usethey don't allow for traditionally connected keyboards
one of these devices with a specially craftedand mice, only USB connected.
auto-run program. When it is inserted into aThat leaves a software solution. Growing awareness
computer, Windows(R) will happily launch thisof this problem has seen the introduction of
program without even asking the user and very likelysoftware that allows you to control what kind of
not even letting the user know something isdevices Windows(R) will allow to be connected and
happening.used. For example, keyboards and mice could be o.k.,
This approach can be used in several ways tobut any type of storage would be denied. Ultimately,
compromise your data and computers. An attackerthis is the most flexible technical solution. Even better,
could come to your location posing as a legitimateas these products mature, they are allowing for
customer and manufacture some excuse to be alonecentralized management. This means if John in
with your computer for a few minutes (how manyaccounting gets a scanner to digitize receipts, you
times have you left your computer unattended evencould authorize its use from anywhere on the
for a few minutes to check on something or get anetwork.
print out on a printer?) while they insert one of theFinally, if USB drives are an integral part of your
small devices into the computer. Within a fewbusiness, and the use outweighs the risk, then all
seconds or minutes, hundreds of files could be copieddata should be encrypted on them. This keeps data
to the USB drive (the new term for this is called "podfrom being readable should the drive get stolen or
slurping"). They then unplug the drive and walk out oflost. There are many products out there that make
your business with data they can sell or otherwisethis process simple and mostly transparent, and offer
use.excellent levels of protection.
Another scenario involves an attacker at a tradeThree other strategies can also help mitigate the risk
show offering "free" USB drives -a very popular item.of USB drives if their use is a must in your company.
They might easily distribute hundreds of these if theThese three are not directly related to USB
convention is large enough. Anytime someone insertsconcerns, but are good network security practices in
one of these drives, it quickly goes about its job ofgeneral. First, special care should be taken to ensure
finding sensitive data and emailing or uploading itthat your users only have access to files and
someplace on the internet. Even worse, it could beinformation that is commensurate with their job titles
used to install a virus, worms, or other malware onto- don't let the new hire have access to the
the computer and allow the attacker to connect topresident's files! Second, don't let your users run as
the computer whenever they are ready, potentiallyfull administrators of their own workstations - many
by-passing any forms of firewalls, virus scanners, andviruses and Trojans rely on this for successful
other security measures.attacks. And finally, keep customers away from your
However, this type of threat isn't only limited tocomputers if possible. Keep them behind a counter or
outside attacks. With the size of these drives andout of sight. Using these three strategies help limit
the power of readily available software, a disgruntledthe amount of data accessible by hackers or
employee could easily and very quickly copydisgruntled employees.
thousands of files and walk out the door withoutMany organizations have no need to allow these
raising any suspicions even from the most carefullydevices on all computers and should take steps to
monitored network (Sound far fetched? There haveensure they are not used. Those that do feel a need
been several reported cases of this.).to use these devices should work on training their
Even worse, the danger might not even be directlyusers and taking the appropriate actions to protect
the cause of disgruntled employees or malicioustheir data, both on their computers and while on the
attackers. Many people use these devices to keep aUSB drives.
copy of their files as they travel or take them homeIn fact, each company will likely need to investigate
to work on them after-hours. With the capacity andand adopt a blend of these strategies to meet their
small physical size, a lot of data is kept in a way thatneeds and still protect their data.
can be easily lost or stolen. It's easy to spotUSB drives really do offer a vast improvement over
someone running away with your laptop bag, but iffloppy disks and CD-ROMs. They are fast, portable,
they slip the USB drive into a pocket, they becomeand easily re-writeable, making them ideal for certain
impossible to find. More dangerous is the doubting ofapplications. Unfortunately, the things that make them
theft: was it stolen or did you just happen to lose it?so convenient can also make them very dangerous
This leads to delayed reporting of the loss andand their use must be tempered with knowledge of
potentially greater damage if it was indeed stolen.that danger and the risks weighed against the
Finally, if an employee does use these drives to takebenefits.
work home, is there any guarantee that the home