Message-ID: <4649E93F.7070108@alighieri.org>
Date: Tue, 15 May 2007 19:09:19 +0200
From: Davide Del Vecchio <dante@...ghieri.org>
To: full-disclosure@...ts.grok.org.uk, bugtraq@...urityfocus.com
Subject: Retrieving "deleted" sms/mms from Nokia phone (Symbian S60)

Hello list,

During some research, I found an intersting "feature"
on my Nokia mobile phone; I was able to retrieve any
apparently deleted sms/mms.
Letting aside some paranoid thoughts about WHY this
sms are not deleted, I think that, while this represents
an high risk for our privacy, this discover could give some
hint into mobile phone forensics and anti-forensics field.

First, I would like to tell you that I tested this on
my Nokia N-gage and on a Nokia 6600 but I am quiete sure
that this procedure works on every Nokia Symbian S60
(maybe other vendors). So I strongly incite you to test
it on your mobile phone and share the results.


Tested products:

Nokia N-gage, firmware version: V 4.03 26-11-2003 NEM-4

Nokia 6600

Maybe the whole S60 series.


Procedure:

Download the Nokia PC Suite for your mobile phone and make
a backup on your local hd.
I used PC Suite for Nokia N-Gage Version 1.0.0
http://www.nokia.com/pcsuite

It will create a huge number of ".dat" files in a specified
directory.

Download, install and start Cygwin. This is not required but
suggested, you could use an hexadecimal editor and a bit of
patience but using Cygwin is surely faster.
http://www.cygwin.com


Move into the backup directory.


$ ls -al | less

total 6016
drwx------+ 2 Administrator Nessuno      0 Feb  6 01:35 .
drwx------+ 7 Administrator Nessuno      0 Feb  5 23:00 ..
-rwx------+ 1 Administrator Nessuno   2972 Nov 27  2003 1.dat
-rwx------+ 1 Administrator Nessuno  22913 Nov 27  2003 10.dat
-rwx------+ 1 Administrator Nessuno   1062 Feb 16  2005 100.dat
-rwx------+ 1 Administrator Nessuno   3912 Aug  9  2005 1000.dat
-rwx------+ 1 Administrator Nessuno   2750 Aug 25  2005 1001.dat
-rwx------+ 1 Administrator Nessuno   8741 Dec 15  2005 1002.dat
-rwx------+ 1 Administrator Nessuno   9926 Dec 20  2005 1003.dat
-rwx------+ 1 Administrator Nessuno     63 Dec 30  2005 1004.dat
-rwx------+ 1 Administrator Nessuno  23988 Jan 13  2006 1005.dat
-rwx------+ 1 Administrator Nessuno     18 Jan 23  2006 1006.dat
...
...
etc etc (files created by the nokia pc suite).


Choose a file to examine.

$ ls -al 3102.dat
-rwx------+ 1 Administrator Nessuno 666569 Feb  5 23:59 3102.dat

Use the command "strings" to find printable characters.

$ strings 3102.dat | less

Ciao! Auguro a te ed alla tua fa@...ica Farlonesi
...
...
etc etc



This is part of an sms I deleted and that I don't see on my phone.
So, just grep every file in the directory to find the complete sms:

$ grep -i "Auguro a te ed alla" *

Binary file 1770.dat matches
Binary file 3102.dat matches

The sms has been found in 1770.dat file, let's see what's inside it:

$ strings 1770.dat

Ciao! Auguro a te ed alla tua famiglia un felice anno nuovo! E.
4+393915253350
4+393922378986

Got it! The complete sms, with the phone number of the sender (phone
numbers have been changed).
In earlier versions of Nokia PC Suite it just creates a ".nbu" file and
you can just edit it with an hexadecimal editor.

I mailed the Nokia support and they told me they didn't know about this
bug and would like to know more informations about impacted models but
they don't have any intention to release some kind of patch.
I contacted Symbian too, they told me that Symbian sources are
distributed to mobile phone vendors and so they cannot release any
final-user patch.

This description is also avaiable here:
http://www.alighieri.org/advisories/retrieving_deleted_sms.txt (ENG)
http://www.alighieri.org/advisories/recuperare_sms_cancellati.txt (ITA)

Regards,

Davide Del Vecchio.

-- 
http://www.alighieri.org

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