oss-sec mailing list archives

Re: BadUSB discussion


From: Rich Felker <dalias () libc org>
Date: Fri, 8 Aug 2014 17:55:00 -0400

On Fri, Aug 08, 2014 at 01:36:36PM +0100, John Haxby wrote:
On 08/08/14 12:20, Dan Carpenter wrote:
The attack looks like someone who says, "Can you copy some files from
my USB flash drive which?" (not knowing it is infected) and then there
is a popup, "This newly inserted USB device is trying to type commands,
is that ok?  y/N?".

That's all very well, but:

One of the attacks involves a USB stick that acts as three separate
devices -- two thumb drives and a keyboard. When the device is first
plugged into a computer and is detected by the OS, it acts as a regular
storage device. However, when the computer is restarted and the device
detects that it's talking to the BIOS, it switches on the hidden storage
device and also emulates the keyboard, Nohl said.

Acting as a keyboard, the device sends the necessary button presses
to bring up the boot menu and boots a minimal Linux system from the
hidden thumb drive. The Linux system then infects the bootloader of the
computer's hard disk drive, essentially acting like a boot virus, he said.

This sounds like an argument for password-protecting your BIOS and
bootloader if anything, and disabling boot from any device except the
primary hdd except when installing.

Rich


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