[Security Advisory] Multiple Smartphones SMS Sender Obfuscation via WAP Push SI

Discovered by: Michael Mueller a.k.a. c0rnholio
Contact: c0rnholio on domain netcologne.de
Vendor Status: not contacted
Fixes / Workarounds: none known
Discovery Date: June, 2008
Public Disclosure: 11.09.2009

Description:

WAP Push SI (Service Indication) is a special service SMS which allows operators
or everyone else to provide an easy way for alerting the smartphone user about new
services or online resources. (see specification WAP-167 for further details)
Some Smartphones fail to properly display the originator of this kind of message
which leads to a sender obfuscation.

Impact:

This attack can be used in combination with social engineering to mislead the recipient
to access the resource specified in the WAP Push SI message (usually an online resource).

In addition this attack can be used to send spam and hate SMS.

Sample Screenshot:

Tested Devices:

The following devices have been tested and found vulnerable for this kind of attack:
It is very likely that other devices and vendors are also vulnerable to this attack.

– Blackberry (Tested on BB 8800, Firmware: 4.5.0.37)
The BlackBerry fails to report the correct originating number and display the number
of the SMS service center as originator of the message

– Windows Mobile (Tested on WM5, WM6, WM6.1, WM6.5)
A Windows Mobile driven device fails to properly display the originating number and
displays whatever information is defined in the X-WAP-Initiator-URI field.

– Sony Ericsson W890i, W810i
The Sony Ericsson W890i and W810i device fails to properly display the correct
originating number and displays a default string instead.

– Motorola RazrV3
The Motorola RazrV3 device fails to properly display the correct originating number
and displays a default string instead.

Proof of Concept:

The following PDU can be sent to an affected device:

UDH: 05 04 0b 84 23 f0
Message:
dc 06 11 ae af 82 b4 83 b1 45 76 69 6c 20 48 34 78 30 72 00 02 05 6a 00 45 c6 0c 03
77 77 77 2e 73 69 6c 65 6e 74 73 65 72 76 69 63 65 73 2e 64 65 2f 61 64 76 30 33 2d
32 30 30 39 2e 68 74 6d 6c 00 01 03 67 6f 74 20 72 30 30 74 3f 00 01 01

The above PDU will display as follows (example on Windows Mobile target):

Sender: Evil H4x0r
Subject: got r00t?
Message: http://www.silentservices.de/adv03-2009.html

Use pduspy to send it. In addition HushSMS Version 1.0 will be available soon for
Windows Mobile devices for further tests.