curious wrote:

I've seen people who try to take their laptops onto a plane as carry-on get
stopped by security at the gate. The security guard asks them to boot up the
laptop, and then they insert some sort of device into the laptop (presumably
into the USB port or something). ...

When did you first see this? I've not struck this before, but it's a
while since I've flown through a US airport.

I have once myself, and a few times seen others having their laptops
"wanded" for explosives. It's much the same process they use for bag
checks: A clean piece of cloth broken out of a sealed envelope is
fitted across the end of a "wand", rubbed over various parts of the
laptop likely to have been contacted by the users hands such as the
"front" (non-hinge) corners of the lid, the wrist-rest area on the
keyboard, the space bar and touch-pad or pointing device buttons (with
bags they tend to focus on the zippers), then they remove the cloth and
put it into some kind of analysis device that presumably "sniffs" in
some way for the likely compounds that are the "chemical fingerprints"
of recent contact with explosives.

... What exactly does this device do, and is
there a possibility of a virus being transmitted from the device into the
computer?

Without knowing more, I couldn't say. That said though, although some
devices that connect to USB do "autorun" under Windows, your typical
"thumb drive" device will not, so I don't believe they can autorun
something off such a device. It is conceivable that something could be
specially manufactured to lie about its device type and "fake" as a CD
drive though, and in that case a default Windows installation would
probably autorun contents off the device ahortly after insertion.


--
Nick FitzGerald