W3C home > Mailing lists > Public > public-dap-commits@w3.org > April 2011

2009/dap/policy-reqs Note-src.html,NONE,1.1 Note.html,NONE,1.1

From: Frederick Hirsch via cvs-syncmail <cvsmail@w3.org>
Date: Fri, 15 Apr 2011 15:27:51 +0000
To: public-dap-commits@w3.org
Message-Id: <E1QAkw3-0003wO-Pw@lionel-hutz.w3.org>
Update of /sources/public/2009/dap/policy-reqs
In directory hutz:/tmp/cvs-serv15132

Added Files:
	Note-src.html Note.html 
Log Message:
policy requirements note

--- NEW FILE: Note.html ---
<!DOCTYPE html PUBLIC '-//W3C//DTD HTML 4.01 Transitional//EN' 'http://www.w3.org/TR/html4/loose.dtd'>
<html lang="en" dir="ltr">
<head>
    <title>Device API Access Control Use Cases and Requirements</title>
    <meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<style type="text/css">
.story {
    margin: 1em 0em 0em;
    padding:    1em;
    border: 2px solid #cfd9f6;
    background: #e2f0ff;
}

.story::before {
    content:    "Story";
    display:    block;
    width:  150px;
    margin: -1.5em 0 0.5em 0;
    font-weight:    bold;
    border: 1px solid #cfd9f6;
    background: #fff;
    padding:    3px 1em;
}
</style>
        
<!--     <script src='../ReSpec.js/js/respec.js' class='remove'></script> -->
    
    
  <link href="http://www.w3.org/StyleSheets/TR/W3C-NOTE" rel="stylesheet" type="text/css" charset="utf-8"></head><body style="display: inherit; "><div class="head"><p><a href="http://www.w3.org/"><img width="72" height="48" src="http://www.w3.org/Icons/w3c_home" alt="W3C"></a></p><h1 class="title" id="title">Device API Access Control Use Cases and Requirements</h1><h2 id="w3c-note-17-march-2011">W3C Note 17 March 2011</h2><dl><dt>This version:</dt><dd><a href="http://www.w3.org/TR/2011/NOTE-dap-policy-reqs-20110317/">http://www.w3.org/TR/2011/NOTE-dap-policy-reqs-20110317/</a></dd><dt>Latest published version:</dt><dd><a href="http://www.w3.org/TR/dap-policy-reqs/">http://www.w3.org/TR/dap-policy-reqs/</a></dd><dt>Latest editor's draft:</dt><dd><a href="http://dev.w3.org/2009/dap/policy-reqs/">http://dev.w3.org/2009/dap/policy-reqs/</a></dd><dt>Previous version:</dt><dd><a href="http://www.w3.org/TR/2011/NOTE-dap-policy-reqs-20110118/">http://www.w3.org/TR/2011/NOTE-dap-policy-reqs-20110118/</a></dd><dt>Editors:</dt><dd><span>Laura Arribas</span>, <a href="http://vodafone.com/">Vodafone</a></dd>
<dd><span>Frederick Hirsch</span>, <a href="http://www.nokia.com/">Nokia</a></dd>
<dd><span>Dominique Hazaël-Massieux</span>, W3C</dd>
</dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2011 <a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p><hr></div>
    <div id="abstract" class="introductory section"><h2>Abstract</h2>
      With the emergence of numerous new APIs in Web browsers and
      runtime engines, the need to control which Web sites and
      applications can make use of these APIs increases. This document
      describes use cases and requirements for controlling access to
      these APIs.    
    </div><div id="sotd" class="introductory section"><h2>Status of This Document</h2><p><em>This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at http://www.w3.org/TR/.</em></p>
      This document is not normative.  The Working Group expects to evolve
      this document further and will eventually publish a stable
      version as a Working Group Note. This version is an update of
      the previous version of his note, modified to present the material
      using  "user
      stories" and associating requirements with those use cases. This
      version also adds informative references and is revised to not
      assume a specific mechanism to meet the requirements.
    <p>This document was published by the <a href="http://www.w3.org/2009/dap/">Device APIs and Policy Working Group</a> as a Note. If you wish to make comments regarding this document, please send them to <a href="mailto:public-device-apis@w3.org">public-device-apis@w3.org</a> (<a href="mailto:public-device-apis-request@w3.org?subject=subscribe">subscribe</a>, <a href="http://lists.w3.org/Archives/Public/public-device-apis/">archives</a>). All feedback is welcome.</p><p>Publication as a Note does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.</p><p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent Policy</a>. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/43696/status" rel="disclosure">public list of any patent disclosures</a> made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of the W3C Patent Policy</a>.</p></div><div id="toc" class="section"><h2 class="introductory">Table of Contents</h2><ul class="toc"><li class="tocline"><a href="#introduction" class="tocxref"><span class="secno">1. </span>Introduction</a><ul class="toc"><li class="tocline"><a href="#defs" class="tocxref"><span class="secno">1.1 </span>Definition</a></li></ul></li><li class="tocline"><a href="#interactions" class="tocxref"><span class="secno">2. </span>Access Control Interactions</a><ul class="toc"><li class="tocline"><a href="#userconsent" class="tocxref"><span class="secno">2.1 </span>Granular User Consent</a><ul class="toc"><li class="tocline"><a href="#userconsent-story-1" class="tocxref"><span class="secno">2.1.1 </span>User Story: Unknown restaurant Web site</a></li><li class="tocline"><a href="#userconsent-story-2" class="tocxref"><span class="secno">2.1.2 </span>User Story: Widget of unknown source using the camera</a></li><li class="tocline"><a href="#userconsent-rqmts" class="tocxref"><span class="secno">2.1.3 </span>Requirements</a></li></ul></li><li class="tocline"><a href="#grouped-permissions" class="tocxref"><span class="secno">2.2 </span>Grouped permissions</a><ul class="toc"><li class="tocline"><a href="#grouped-permissions-story1" class="tocxref"><span class="secno">2.2.1 </span>User Story: Web application for email</a></li><li class="tocline"><a href="#grouped-permissions-rqmts" class="tocxref"><span class="secno">2.2.2 </span>Requirements</a></li></ul></li><li class="tocline"><a href="#delegated-authority-case" class="tocxref"><span class="secno">2.3 </span>Delegated Authority</a><ul class="toc"><li class="tocline"><a href="#delegated-authority-story1" class="tocxref"><span class="secno">2.3.1 </span>User Story: Enterprise-level ban on geolocation</a><ul class="toc"><li class="tocline"><a href="#delgated-authority-story1-rqmts" class="tocxref"><span class="secno">2.3.1.1 </span>Requirements</a></li></ul></li><li class="tocline"><a href="#delegated-authority-story2" class="tocxref"><span class="secno">2.3.2 </span>User Story: Third-party protection against malware</a><ul class="toc"><li class="tocline"><a href="#delgated-authority-story2-rqmts" class="tocxref"><span class="secno">2.3.2.1 </span>Requirements</a></li></ul></li><li class="tocline"><a href="#delegated-authority-story2a" class="tocxref"><span class="secno">2.3.3 </span>User Story: Transfering remembered choices to another device</a><ul class="toc"><li class="tocline"><a href="#delgated-authority-story3-rqmts" class="tocxref"><span class="secno">2.3.3.1 </span>Requirements</a></li></ul></li><li class="tocline"><a href="#delegated-authority-story3" class="tocxref"><span class="secno">2.3.4 </span>User Story: Operator-enforced usage limitations</a><ul class="toc"><li class="tocline"><a href="#delegated-authority-case-rqmts" class="tocxref"><span class="secno">2.3.4.1 </span>Requirements</a></li></ul></li></ul></li></ul></li><li class="tocline"><a href="#threats" class="tocxref"><span class="secno">A. </span>Security and Privacy Threats</a><ul class="toc"><li class="tocline"><a href="#premium-rate-abuse" class="tocxref"><span class="secno">A.1 </span>Premium Rate Abuse</a></li><li class="tocline"><a href="#privacy-breach" class="tocxref"><span class="secno">A.2 </span>Privacy Breach</a></li><li class="tocline"><a href="#integrity-breach" class="tocxref"><span class="secno">A.3 </span>Integrity Breach</a></li><li class="tocline"><a href="#phishing" class="tocxref"><span class="secno">A.4 </span>Phishing</a></li></ul></li><li class="tocline"><a href="#acknowledgements" class="tocxref"><span class="secno">B. </span>Acknowledgements</a></li><li class="tocline"><a href="#references" class="tocxref"><span class="secno">C. </span>References</a><ul class="toc"><li class="tocline"><a href="#normative-references" class="tocxref"><span class="secno">C.1 </span>Normative references</a></li><li class="tocline"><a href="#informative-references" class="tocxref"><span class="secno">C.2 </span>Informative references</a></li></ul></li></ul></div> <!-- abstract -->

    

    <div id="introduction" class="informative section">
      <!--OddPage--><h2><span class="secno">1. </span>Introduction</h2><p><em>This section is non-normative.</em></p>
      <p>
        Various groups have been defining APIs designed to enable
        Web sites and applications access to device resources, including geolocation [<cite><a class="bibref" rel="biblioentry" href="#bib-GEOLOCATION-API">GEOLOCATION-API</a></cite>], personal information such as calendar and contacts [<cite><a class="bibref" rel="biblioentry" href="#bib-CONTACTS-API">CONTACTS-API</a></cite>],
        system information [<cite><a class="bibref" rel="biblioentry" href="#bib-SYSINFOAPI">SYSINFOAPI</a></cite>] such as network information, etc. Much of this information is sensitive and can be misused.</p>

      <p>This document outlines "user story" use cases 
      for security and access 
      control for device APIs and derives requirements from these
      cases. Although security and access control is related to
      privacy, this document does not discuss privacy specifically as
      there is another document specific to privacy [<cite><a class="bibref" rel="biblioentry" href="#bib-DAP-PRIVACY-REQS">DAP-PRIVACY-REQS</a></cite>].
      </p> 

      <div id="defs" class="section">
	<h3><span class="secno">1.1 </span>Definition</h3>
        <p>A <dfn id="dfn-non-safe-api">non-safe API</dfn> is an API that shares sensitive
        user information or makes a commitment for the user to a
        third-party (e.g. paying a fee).</p> 
      </div>
    </div>  <!-- introduction -->
    <div id="interactions" class="informative section">
      <!--OddPage--><h2><span class="secno">2. </span>Access Control Interactions</h2><p><em>This section is non-normative.</em></p>
      <p>Three main types of interactions have been identified for
      controlling access to non-safe APIS:</p> 
      <ul>
        <li>based on granular user consent, for every first call of a sensitive API,</li>
        <li>based on user consent for a set of APIs at once, packaged into a single interaction (e.g. at “installation” time),</li>
        <li>or delegated by the user to a third party that sets new default interactions for APIs based on the requesting script.</li>
      </ul>

      <p>These interactions can be relevant both for a Web site accessed through a browser, or an installable Web application (e.g. a widget [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>]) accessed through a dedicated runtime engine.</p>

    <div id="userconsent" class="section">
      <h3><span class="secno">2.1 </span>Granular User Consent</h3>
      <div id="userconsent-story-1" class="section">
        <h4><span class="secno">2.1.1 </span>User Story: Unknown restaurant Web site</h4>
	<div class="story">
	<p>Alice uses her browser to get more information on a restaurant her friends have told her about. The Web site of the restaurant offers to give her indications on how to come from where she stands to their location, as well as to send automatically a SMS to reserve a table for lunch.</p>
	<p>Alice follows a link to the direction page, and her browser
	asks her unintrusively to confirm she wants to share her current
	location with the map service provider embedded in the Web
	restaurant site. After considering issues related to sharing this
	information, she decides to share her current location. Upon consenting to sharing her location through the browser, she gets detailed directions to the restaurant.</p>
	<p>Her browser then displays a non-modal prompt asking if she wants to send an SMS to make a reservation at the restaurant. She is not interested and simply ignores the prompt.</p>
	</div>
	<h4 id="analysis">Analysis</h4>

	<p>Access to non-safe APIs from web pages or applications with
	which the user has no pre-established relationship must only be
	granted after explicit user consent, and that consent needs to be
	granted for each non-safe API separately. Note that it isn't
	obvious whether this consent is truly informed, or that the user
	understands all the issues involved. This is discussed further
	elsewhere [<cite><a class="bibref" rel="biblioentry" href="#bib-DAP-PRIVACY-REQS">DAP-PRIVACY-REQS</a></cite>].</p> 

	<p>The user may need to gather more information before making a decision on granting access to a given API: e.g. reading the site privacy policy or getting more information on what the collected data will be used for. To make it possible for the user to make an informed decision, the user consent interactions need to be non-blocking.</p>

	</div>
      <div id="userconsent-story-2" class="section">
	<h4><span class="secno">2.1.2 </span>User Story: Widget of unknown source using the camera</h4>
	<div class="story">
	<p>Bob receives from Alice a mobile widget that she says is used to create a crowd-sourced view of their city. While Bob trusts Alice, he is not sure how trustable that particular widget is.</p>
	<p>He runs it in his widget runtime engine in untrusted mode; the widget is only able to take pictures when Bob explicitly press the shutter button of the phone; the geolocation of the pictures is only sent along with the pictures when Bob agrees to it.</p>
	</div>
	<h4 id="analysis-1">Analysis</h4>

        <p>
          An un-trusted widget (e.g.. unsigned widget or widget signed by an
          unknown or untrusted authority) should be treated in the
          same manner as an unknown web site, since the risks
          are the same.</p>


	<p>To make it easier for the user to understand what he is
    granting access to, the access control interactions need to be as
    integrated as possible as a part of the task specific workflow,
    thus not necessarily appearing as a permission dialog. Relying on
    the user pressing the shutter button to take a picture is more
    effective than asking him if he agrees with sharing a picture.</p> 

        <p>Prompts should be eliminated whenever possible. Many prompts do not provide  any meaningful security because:</p> 
          <ul>
            <li>they don't provide the user with the information
            needed to make an 
            informed security decision;</li>
            <li>with modal prompts, the user is inclined simply to
            dismiss the prompt and permit the operation 
            just because that's what's needed for the application to
            continue.</li>
          </ul>

        <p>
          If prompts are shown and dismissed as a matter of routine,
          then the user is 
          less inclined to take any security decision seriously, which further
          undermines the effectiveness of a user-driven access control system.
          </p>

</div>
      <div id="userconsent-rqmts" class="section">
        <h4><span class="secno">2.1.3 </span>Requirements</h4>
          <ul>
	    <li>Non-safe APIs <em class="rfc2119" title="must not">must not</em> require the usage of blocking user consent interactions (e.g. modal dialogs) while the application is running (although modal dialogs may be required for security prompts provided during application
            installation or invocation).</li>
	    <li>As a result, non-safe APIs <em class="rfc2119" title="must">must</em> use asynchronous calls for operations that require user consent.</li>
	    <li>Non-safe APIs <em class="rfc2119" title="should">should</em> permit to get user consent in interactions that are well-integrated in the workflow of the underlying operation.</li>
	    <li>In an untrusted context, user consent for a given non-safe
	    API <em class="rfc2119" title="should not">should not</em> imply consent for another non-safe API.</li> 
	    <li>when a non-safe API expose multiple non-safe operations, the API <em class="rfc2119" title="must">must</em> describe the granularity of user consent if that granularity is not part of the user workflow; the parameters to which this granularity can be applied include:<ul>
		<li>separate consent for each operation, or grouped for the whole API,</li>
		<li>persistent for each call in a given session,</li>
		<li>persistent for each call over a period of time spanning
		multiple sessions.</li>
		</ul>
	      </li>
	    </ul>
      </div>
    </div> <!-- userconsent -->
    <div id="grouped-permissions" class="section">
      <h3><span class="secno">2.2 </span>Grouped permissions</h3>
      <div id="grouped-permissions-story1" class="section">
        <h4><span class="secno">2.2.1 </span>User Story: Web application for email</h4>
	<div class="story">
	<p>Alice uses a Web application as her email client, and considers it trustable.</p>
	<p>Her service provider offers to use a set of advanced features that requires access to off-line storage, addressbook integration, access to a dedicated storage space on her device, and interactions through the microphone.</p>
	<p>Rather than being prompted every so often to grant permission to use these features, Alice is offered to approve all these accesses in a batch, as part of an installation procedure that identifies these extra-permissions.</p>
	<p>Alice follows that procedure and is no longer prompted for these permissions for this application; she still gets prompted when her email client asks for her geolocation since that permission was not part of the batch approval.</p>
	</div>

	<h4 id="analysis-2">Analysis</h4>

	<p>Once a user has established a certain level of trust with a service provider, she is more likely to want to approve permissions as a batch rather than having to respond to prompt every so often that might slow down her work, or might make her miss an additional feature of the application.</p>

	<p>Similarly, the user can be offered to validate a set of permissions in a batch when installing a widget, where the permissions can be identified through the <code>feature</code> element [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>].</p>

	<p>To that end, the various permissions that are bound to APIs need to identified.</p>

	<p>To establish trust, a few basic parameters may be used, among which:</p>
	<ul>
	  <li><dfn id="dfn-identity">identity</dfn>&nbsp;— ensuring that the privileges are granted to the application from the trusted provider itself, to avoid phishing attacks;</li>
	  <li><dfn id="dfn-reputation">reputation</dfn>&nbsp;— if others have reviewed positively an application, the user is more likely to trust it; reputation is itself linked to identity, either as a way to identify the source of the recommandation (e.g. approval from a network operator), or as a way to identify the aggregator of recommendations;</li>
	  <li><dfn id="dfn-context">context</dfn>&nbsp;— a user is more likely to trust an application that requests permissions that make sense to her use of the said application.</li>
	</ul>

        <p>
          Identity and reputation may be established in different ways; one of the most common being
          through a validated signature on the widget or application package,
          with a corresponding verification of the trust chain to a trusted root.
        </p>


      </div>
      <div id="grouped-permissions-rqmts" class="section">
        <h4><span class="secno">2.2.2 </span>Requirements</h4>
	<ul>
	  <li>Non-safe APIs <em class="rfc2119" title="should">should</em> define an identifier for the various permissions they require.</li>
	  <li>The security framework <em class="rfc2119" title="should">should</em> refer to these API permissions identifiers to allow grouping them in a single user consent operation.</li>
          <li>when identity is checked through the use of signature in
          conjunction with PKI mechanisms, the security framework <em class="rfc2119" title="must">must</em>
          require the verification of the signature, and <em class="rfc2119" title="must">must</em> require
          validation of the certificate chain to a known trust
          root. Certificate revocation <em class="rfc2119" title="should">should</em> be considered.</li> 

	</ul>
      </div>
    </div>
    <div id="delegated-authority-case" class="section">
      <h3><span class="secno">2.3 </span>Delegated Authority</h3>
        <p>Delegated authority use case refers to the use of
        explicit and interoperable policy definitions to control the use of
        an extensive set of APIs, safe and unsafe.  Such rules may be used
        in the context of a trusted widget or of well-identified web site, with clients that  support it.</p>
      <div id="delegated-authority-story1" class="section">
        <h4><span class="secno">2.3.1 </span>User Story: Enterprise-level ban on geolocation</h4>
	<div class="story">
	  <p>Bob manages the fleet of phones and laptops for ACMEcash, a cash transportation company: all the drivers have been equipped with a phone and a laptop they can use to interact with their intranet.</p>
	  <p>To keep the whereabouts of their employees as hidden as possible for security reasons, Bob wants to restrict all the devices distributed to employees so that they cannot use the geolocation API, except when connecting to the company intranet.</p>
	  <p>Bob creates a policy matching these rules, and deploys it to the phones and laptops.</p>
	  <p>When ACMEcash gets renamed ACMEbucks, Bob updates this policy to reflect the new domain name of the intranet.</p>

	</div>
	<h4 id="analysis-3">Analysis</h4>
	<p>In many professional contexts, allowing access to private or sensors data available through connected devices creates an unacceptable risk.</p>
	<p>In these contexts, being able to enforce and update a policy that determines who can make use of these data across devices and platforms can be a decisive aspect of the adoption of a given technology.</p>
	<p>To that end, it should be possible to describe
	platform-independent and declarative policies that determine which
	APIs can be used from what Web site or application.</p> 
      <div id="delgated-authority-story1-rqmts" class="section">
        <h5><span class="secno">2.3.1.1 </span>Requirements</h5>
	<ul>
      <li>The access control policy language <em class="rfc2119" title="must">must</em> be device-independent.</li>
      <li>The access control policy language <em class="rfc2119" title="must">must</em> be declarative.</li>
    </ul>
      </div>
    </div>
    <div id="delegated-authority-story2" class="section">
        <h4><span class="secno">2.3.2 </span>User Story: Third-party protection against malware</h4>
	<div class="story">
	  <p>Alice keeps a lot of her private and sensitive data on her phone. Having heard that her friend Charlie has had troubles with a phishing attempt recently, she would like to use a service to increase her safety.</p>
	  <p>She subscribes to a service operated by ACMEsafe: they define and maintain a set of rules that block access to certain APIs from unknown sites, facilitate access to sites that she has identified as trustable and that can be reliably identified.</p>
	  <p>Both Alice’s browser and widget runtime engine follow the rules expressed in the policy defined by ACMEsafe; these rules are updated on a regular basis on the device, after having verified their proper origin by checking their digital signature.</p>
	</div>
	<h4 id="analysis-4">Analysis</h4>
        <p>The same way anti-virus and malware tools allow users to reduce their risk of being exposed to troubles on their computers, some users may want to choose to delegate authority for access control policy to an external service provider.</p>
        <p>This external service provider determines the
        trustworthiness of 
        specific applications, and specifies an access control
        policy that embodies 
        that advice: blanket rejection for known malware sites, user consent requested for others, and transparent approval for sites that the user has configured as trusted.</p>
	<p>The policy defined by the external
        authority may be updated 
        regularly in 
        response to new information on known threats.
        </p>

	<p>This policy needs to be integrity-protected during various points in its life-cycle.</p>
      <div id="delgated-authority-story2-rqmts" class="section">
        <h5><span class="secno">2.3.2.1 </span>Requirements</h5>
	<ul>
      <li>Integrity protection and source authentication of the access
      control policy <em class="rfc2119" title="must">must</em> be 
      supported, not only in transit but also storage.</li>
    </ul>
      </div>

      </div>
      <div id="delegated-authority-story2a" class="section">
	<h4><span class="secno">2.3.3 </span>User Story: Transfering remembered choices to another device</h4>
	<div class="story">
        <p>Dave has been using advanced features on the Web from his
        phone for quite some time, and has thus accepted and rejected
        permissions from a large number of Web sites on his
        device.</p> 
	<p>But Dave is now looking to the brand new phone released by
	ACMEdev, and would like to migrate his settings to that new phone,
	which also uses a different browser.</p> 
	<p>Dave’s operator offers him to transfer seamlessly these
	settings from one phone to other, and informs him that they can
	also be used on his other connected devices.</p> 
	</div>

	<h4 id="analysis-5">Analysis</h4>
        <p>
Remembering earlier decisions and
maintaining these choices when changing devices either across vendors or
device versions has value to the user. This may also be the case when
wishing to have the same choices on multple devices. It should be
possible to transfer or share a 
representation of user choices across devices at any time.
        </p>
      <div id="delgated-authority-story3-rqmts" class="section">
        <h5><span class="secno">2.3.3.1 </span>Requirements</h5>
	<ul>
      <li>Access control policy <em class="rfc2119" title="must">must</em> be able to record user decisions
        regarding policy configuration at an appropriate level of
        granularity.</li> 
      <li>Access control policy <em class="rfc2119" title="must">must</em> be portable across devices and
        not bound to specific devices.</li>
    </ul>
      </div>

      </div>
      <div id="delegated-authority-story3" class="section">
        <h4><span class="secno">2.3.4 </span>User Story: Operator-enforced usage limitations</h4>
	<div class="story">
	  <p>Dave has found a nice-looking widget for managing SMS and MMS messages, but is not sure if it is safe to install it.</p>
	  <p>He contacts his operator ACMEcom; they indicate that on their devices, only widgets that have been verified by them will be able to send SMS.</p>
	  <p>Dave checks the widget, sees that the only special permission it requires is access to messaging features, and feels confident that he can now install it.</p>
	</div>
	<h4 id="analysis-6">Analysis</h4>
        <p>An initial  access control  configuration may be
              provided by an external 
              authority, together with any other associated device
              configuration (such as 
              root certificates). The configured  policy may
              determine access control policy 
              without reference to the user, or may refer certain
              decisions to the user.</p>
        <p>
          In determining the policy, the policy authority has the
          opportunity to define 
          a policy that supports a specific objective - such as to
          limit access to APIs 
          to only those web applications that are themselves
          distributed or verified by the policy 
          authority (e.g. to control its exposure to the financial
          risk of abuse of device 
          APIs).
        </p>

      <div id="delegated-authority-case-rqmts" class="section">
        <h5><span class="secno">2.3.4.1 </span>Requirements</h5>
          <ul>
            <li>It <em class="rfc2119" title="should">should</em> be possible to update portions of policy independently.</li>
            <li>Access control policies <em class="rfc2119" title="may">may</em> be associated with
            different authorities, including the user.</li> 
          </ul>
        <p class="note">The management of security policies and revocation mechanisms are out of scope of the Device APIs and Policy Working Group charter.</p>
      </div>
      </div>
    </div>
    </div>
      <div id="threats" class="appendix section">
        <!--OddPage--><h2><span class="secno">A. </span>Security and Privacy Threats</h2>
        <p>
          The landscape that is being created 
          is the enablement of
          cross-platform, cross-device, easy to develop, highly functional
          applications based on browser technology. Experience with
          security attacks suggests that the increase of scope and
          power of the Device APIs raises the potential for attacks of
          increasing significance. This section outlines some known threats.
        </p>
        <p>
          Up until now no major malware incident
          has affected the mobile industry, but risks increase as
          adoption and convergence increases. There have been attempts: the
          MMS-spreading Commwarrior virus is probably the most infamous, along
          with the Spyware tool, Flexispy. An additional factor in
          avoiding mobile security issues to date has been the fact that
          mobile platforms have been too fragmented and complex
          to provide an attractive target. Existing modus
          operandi from technology-related attacks can provide indicators
          as to the types of attack and abuse that can be expected on
          widgets and web applications as device APIs are opened up
          and the size of the mobile market increases.
        </p>
        <div id="premium-rate-abuse" class="section">
          <h3><span class="secno">A.1 </span>Premium Rate Abuse</h3>
          <p>A widget that seems benign but is actually spewing out
          SMSs to premium rate numbers without the user’s
          knowledge. This could be modified from an original safe
          widget such as a game. For the malware author, the key
          piece to solve is to dupe the user into thinking that the
          SMS capability is something that is part of the original
          application. Examples of this have been seen in the past,
          created from games and this model could be used for
          ‘dialers’ too (which plagued the desktop world in the
          days of dial-up networking). There have been recent
          warnings about this kind of abuse from security firms. 
          </p>
        </div> <!-- premium rate Abuse -->
        <div id="privacy-breach" class="section">
          <h3><span class="secno">A.2 </span>Privacy Breach</h3>
          <p>An application that gains access to locations, contacts
          and gallery, silently uploading the data in the background
          to a site owned by the attacker. This is something that
          has been a clear goal for attackers already. There have
          been numerous high-profile examples in the past in the
          mobile world. Celebrities such as Paris Hilton, Miley
          Cyrus and Lindsay Lohan have all had private pictures,
          phone numbers and voicemails stolen from devices or
          networks in clear breach of their privacy. There has been
          embarrassment for teachers who had their pictures and
          videos copied by the children in their class and spread
          around school. The most high-profile case in the UK of a
          mobile related privacy breach was that of the News of the
          World's use of voicemail hacking to gain access to private
          information about Royalty. The Royal editor, Clive Goodman
          was jailed for four months and the editor, Andy Coulson
          resigned over this blatant privacy breach. Given the
          appetite for breaching privacy, users need to be safe in
          the knowledge that their personal data will not leak in
          any way. 
          </p>
<p>
Another example is turning on the camera or audio remotely to obtain
audio, video or photo information without permission.
</p>
        </div> <!-- privacy-breach -->
        <div id="integrity-breach" class="section">
          <h3><span class="secno">A.3 </span>Integrity Breach</h3>
          <p>A widget that replaces the voicemail number with a
          premium rate number instead? There are number of reasons
          why an attacker would want to breach the integrity of
          the device. Simply changing the telephone number of the
          voicemail that is stored on the device could be enough
          to make an attacker a lot of money. Users usually have a
          shortcut key to their voicemail and may not notice for a
          long time that anything is wrong. A more sinister use
          could be to plant evidence on a device. Pictures, files
          and even criminal contacts could potentially be
          anonymously planted all without the user's consent or
          knowledge. Proving innocence could suddenly become very
          difficult. 
          There are also a number of reasons why somebody would want to steal
          data. The contents of corporate e-mails would be very
          interesting to a competitor, as would sabotaging data
          stored in spreadsheets and presentations on the target
          phone. 
          </p>
        </div> <!-- integrity-breach -->
        <div id="phishing" class="section">
          <h3><span class="secno">A.4 </span>Phishing</h3>
          <p>
            Widgets contain web content making it is easy to duplicate
            and masquerade as something legitimate… perhaps a bank? 
          </p>
          <p> 
            In January 2010, Google removed a number of applications
            from the Android Market which were supposed to be banking
            applications for a number of different banks worldwide. It
            is unclear whether these applications were intentional
            phishing applications. The removal was based on a breach
            of terms and conditions surrounding copyright. The episode
            however highlighted the phishing potential. Widgets
            contain web content, therefore it is very easy to
            duplicate the look and feel of something that  the user
            trusts and proceed to abuse that trust either by stealing
            credentials or by manipulating money transfers. 
          </p>
          <p>
            These are of course just examples to consider in relation to how we
            would manage the policies for device APIs and are of course not
            exhaustive. Alongside the device-API specific examples
            above, we still 
             need to consider traditional web threats which pose a
            significant risk 
and lots of other types of attack which should be considered in a 
 formal threat model. 
          </p>
        </div> <!-- phishing -->
      </div> <!-- threats -->

      <div class="appendix section" id="acknowledgements">
        <!--OddPage--><h2><span class="secno">B. </span>Acknowledgements</h2>
        <p>
          The editors would like to extend special thanks to Nokia, OMTP
          BONDI, and PhoneGap for providing
          the foundation of the working group's requirements discussion.
        </p>
      </div>
    
  
<div id="respec-err" style="position: fixed; width: 350px; top: 10px; right: 10px; border: 3px double #f00; background: #fff" class="removeOnSave"><ul><li style="color: #c00">There appears to have been a problem fetching the style sheet; status=0</li></ul></div><div id="references" class="appendix section"><!--OddPage--><h2><span class="secno">C. </span>References</h2><div id="normative-references" class="section"><h3><span class="secno">C.1 </span>Normative references</h3><p>No normative references.</p></div><div id="informative-references" class="section"><h3><span class="secno">C.2 </span>Informative references</h3><dl class="bibliography"><dt id="bib-CONTACTS-API">[CONTACTS-API]</dt><dd>R. Tibbett. <a href="http://dev.w3.org/2009/dap/contacts/Overview.html"><cite>Contacts API</cite></a>. 3rd August 2010. W3C Latest Editor's Draft. (Work in progress.) URL: <a href="http://dev.w3.org/2009/dap/contacts/Overview.html">http://dev.w3.org/2009/dap/contacts/Overview.html</a> 
</dd><dt id="bib-DAP-PRIVACY-REQS">[DAP-PRIVACY-REQS]</dt><dd>L. Arribas, P. Byers, M. Hanclik, F Hirsch, D. Rogers. <a href="http://dev.w3.org/2009/dap/privacy-reqs/"><cite>Device API Privacy Requirements</cite></a> 17 June 2010. (Work in progress.) URL: <a href="http://dev.w3.org/2009/dap/privacy-reqs/">http://dev.w3.org/2009/dap/privacy-reqs/</a> 
</dd><dt id="bib-GEOLOCATION-API">[GEOLOCATION-API]</dt><dd>Andrei Popescu. <a href="http://www.w3.org/TR/2008/WD-geolocation-API-20081222"><cite>Geolocation API Specification.</cite></a> 22 December 2008. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/2008/WD-geolocation-API-20081222">http://www.w3.org/TR/2008/WD-geolocation-API-20081222</a> 
</dd><dt id="bib-SYSINFOAPI">[SYSINFOAPI]</dt><dd>Dzung Tran, Max Froumentin, eds. <a href="http://www.w3.org/TR/2010/WD-system-info-api-20100202/"><cite>The System Information API</cite>, 2 February 2010, W3C Working Draft. (Work in Progess.) URL: </a><a href="http://www.w3.org/TR/2010/WD-system-info-api-20100202/">http://www.w3.org/TR/2010/WD-system-info-api-20100202/</a>
</dd><dt id="bib-WIDGETS">[WIDGETS]</dt><dd>Marcos Caceres. <a href="http://www.w3.org/TR/2009/CR-widgets-20091201/"><cite>Widget Packaging and Configuration.</cite></a> 01 December 2009. W3C Candidate Recommendation. (Work in progress.) URL: <a href="http://www.w3.org/TR/2009/CR-widgets-20091201/">http://www.w3.org/TR/2009/CR-widgets-20091201/</a> 
</dd></dl></div></div></body></html>
--- NEW FILE: Note-src.html ---
<!DOCTYPE html>
<html>
  <head>
    <title>Device API Access Control Use Cases and Requirements</title>
    <meta http-equiv='Content-Type' content='text/html;charset=utf-8' />
<style type="text/css">
.story {
    margin: 1em 0em 0em;
    padding:    1em;
    border: 2px solid #cfd9f6;
    background: #e2f0ff;
}

.story::before {
    content:    "Story";
    display:    block;
    width:  150px;
    margin: -1.5em 0 0.5em 0;
    font-weight:    bold;
    border: 1px solid #cfd9f6;
    background: #fff;
    padding:    3px 1em;
}
</style>
        <script src='http://dev.w3.org/2009/dap/ReSpec.js/js/respec.js' class='remove'></script>
<!--     <script src='../ReSpec.js/js/respec.js' class='remove'></script> -->
    <script class='remove'>
      var respecConfig = {
      specStatus: "NOTE",
      shortName:            "dap-policy-reqs",
      editors: [
        {
          name:       "Laura Arribas",
          company:    "Vodafone",
          companyURL: "http://vodafone.com/" },
        {
          name:       "Frederick Hirsch",
          company:    "Nokia",
          companyURL: "http://www.nokia.com/" },
        {
           name: "Dominique Hazaël-Massieux", 
           company: "W3C"
        }
      ],
      publishDate:  "2011-03-17",
      previousPublishDate:  "2011-01-18",
      previousMaturity: "NOTE",
      edDraftURI:           "http://dev.w3.org/2009/dap/policy-reqs/",
      // lcEnd: "2009-08-05",
      noRecTrack:   true, 
      };
    </script>
    <script src='../common/config.js' class='remove'></script>
  </head>
  <body>
    <section id='abstract'>
      With the emergence of numerous new APIs in Web browsers and
      runtime engines, the need to control which Web sites and
      applications can make use of these APIs increases. This document
      describes use cases and requirements for controlling access to
      these APIs.    
    </section> <!-- abstract -->

    <section id='sotd'>
      This document is not normative.  The Working Group expects to evolve
      this document further and will eventually publish a stable
      version as a Working Group Note. This version is an update of
      the previous version of his note, modified to present the material
      using  "user
      stories" and associating requirements with those use cases. This
      version also adds informative references and is revised to not
      assume a specific mechanism to meet the requirements.
    </section>

    <section id='introduction' class='informative'>
      <h2>Introduction</h2>
      <p>
        Various groups have been defining APIs designed to enable
        Web sites and applications access to device resources, including geolocation [[GEOLOCATION-API]], personal information such as calendar and contacts [[CONTACTS-API]],
        system information [[SYSINFOAPI]] such as network information, etc. Much of this information is sensitive and can be misused.</p>

      <p>This document outlines "user story" use cases 
      for security and access 
      control for device APIs and derives requirements from these
      cases. Although security and access control is related to
      privacy, this document does not discuss privacy specifically as
      there is another document specific to privacy [[DAP-PRIVACY-REQS]].
      </p> 

      <section id="defs">
	<h2>Definition</h2>
        <p>A <dfn>non-safe API</dfn> is an API that shares sensitive
        user information or makes a commitment for the user to a
        third-party (e.g. paying a fee).</p> 
      </section>
    </section>  <!-- introduction -->
    <section id="interactions" class="informative">
      <h2>Access Control Interactions</h2>
      <p>Three main types of interactions have been identified for
      controlling access to non-safe APIS:</p> 
      <ul>
        <li>based on granular user consent, for every first call of a sensitive API,</li>
        <li>based on user consent for a set of APIs at once, packaged into a single interaction (e.g. at “installation” time),</li>
        <li>or delegated by the user to a third party that sets new default interactions for APIs based on the requesting script.</li>
      </ul>

      <p>These interactions can be relevant both for a Web site accessed through a browser, or an installable Web application (e.g. a widget [[WIDGETS]]) accessed through a dedicated runtime engine.</p>

    <section id='userconsent'>
      <h3>Granular User Consent</h3>
      <section id='userconsent-story-1'>
        <h4>User Story: Unknown restaurant Web site</h4>
	<div class="story">
	<p>Alice uses her browser to get more information on a restaurant her friends have told her about. The Web site of the restaurant offers to give her indications on how to come from where she stands to their location, as well as to send automatically a SMS to reserve a table for lunch.</p>
	<p>Alice follows a link to the direction page, and her browser
	asks her unintrusively to confirm she wants to share her current
	location with the map service provider embedded in the Web
	restaurant site. After considering issues related to sharing this
	information, she decides to share her current location. Upon consenting to sharing her location through the browser, she gets detailed directions to the restaurant.</p>
	<p>Her browser then displays a non-modal prompt asking if she wants to send an SMS to make a reservation at the restaurant. She is not interested and simply ignores the prompt.</p>
	</div>
	<h4>Analysis</h4>

	<p>Access to non-safe APIs from web pages or applications with
	which the user has no pre-established relationship must only be
	granted after explicit user consent, and that consent needs to be
	granted for each non-safe API separately. Note that it isn't
	obvious whether this consent is truly informed, or that the user
	understands all the issues involved. This is discussed further
	elsewhere [[DAP-PRIVACY-REQS]].</p> 

	<p>The user may need to gather more information before making a decision on granting access to a given API: e.g. reading the site privacy policy or getting more information on what the collected data will be used for. To make it possible for the user to make an informed decision, the user consent interactions need to be non-blocking.</p>

	</section>
      <section id="userconsent-story-2">
	<h4>User Story: Widget of unknown source using the camera</h4>
	<div class="story">
	<p>Bob receives from Alice a mobile widget that she says is used to create a crowd-sourced view of their city. While Bob trusts Alice, he is not sure how trustable that particular widget is.</p>
	<p>He runs it in his widget runtime engine in untrusted mode; the widget is only able to take pictures when Bob explicitly press the shutter button of the phone; the geolocation of the pictures is only sent along with the pictures when Bob agrees to it.</p>
	</div>
	<h4>Analysis</h4>

        <p>
          An un-trusted widget (e.g.. unsigned widget or widget signed by an
          unknown or untrusted authority) should be treated in the
          same manner as an unknown web site, since the risks
          are the same.</p>


	<p>To make it easier for the user to understand what he is
    granting access to, the access control interactions need to be as
    integrated as possible as a part of the task specific workflow,
    thus not necessarily appearing as a permission dialog. Relying on
    the user pressing the shutter button to take a picture is more
    effective than asking him if he agrees with sharing a picture.</p> 

        <p>Prompts should be eliminated whenever possible. Many prompts do not provide  any meaningful security because:</p> 
          <ul>
            <li>they don't provide the user with the information
            needed to make an 
            informed security decision;</li>
            <li>with modal prompts, the user is inclined simply to
            dismiss the prompt and permit the operation 
            just because that's what's needed for the application to
            continue.</li>
          </ul>

        <p>
          If prompts are shown and dismissed as a matter of routine,
          then the user is 
          less inclined to take any security decision seriously, which further
          undermines the effectiveness of a user-driven access control system.
          </p>

</section>
      <section id='userconsent-rqmts'>
        <h4>Requirements</h4>
          <ul>
	    <li>Non-safe APIs MUST NOT require the usage of blocking user consent interactions (e.g. modal dialogs) while the application is running (although modal dialogs may be required for security prompts provided during application
            installation or invocation).</li>
	    <li>As a result, non-safe APIs MUST use asynchronous calls for operations that require user consent.</li>
	    <li>Non-safe APIs SHOULD permit to get user consent in interactions that are well-integrated in the workflow of the underlying operation.</li>
	    <li>In an untrusted context, user consent for a given non-safe
	    API SHOULD NOT imply consent for another non-safe API.</li> 
	    <li>when a non-safe API expose multiple non-safe operations, the API MUST describe the granularity of user consent if that granularity is not part of the user workflow; the parameters to which this granularity can be applied include:<ul>
		<li>separate consent for each operation, or grouped for the whole API,</li>
		<li>persistent for each call in a given session,</li>
		<li>persistent for each call over a period of time spanning
		multiple sessions.</li>
		</ul>
	      </li>
	    </ul>
      </section>
    </section> <!-- userconsent -->
    <section id='grouped-permissions'>
      <h3>Grouped permissions</h3>
      <section id='grouped-permissions-story1'>
        <h4>User Story: Web application for email</h4>
	<div class="story">
	<p>Alice uses a Web application as her email client, and considers it trustable.</p>
	<p>Her service provider offers to use a set of advanced features that requires access to off-line storage, addressbook integration, access to a dedicated storage space on her device, and interactions through the microphone.</p>
	<p>Rather than being prompted every so often to grant permission to use these features, Alice is offered to approve all these accesses in a batch, as part of an installation procedure that identifies these extra-permissions.</p>
	<p>Alice follows that procedure and is no longer prompted for these permissions for this application; she still gets prompted when her email client asks for her geolocation since that permission was not part of the batch approval.</p>
	</div>

	<h4>Analysis</h4>

	<p>Once a user has established a certain level of trust with a service provider, she is more likely to want to approve permissions as a batch rather than having to respond to prompt every so often that might slow down her work, or might make her miss an additional feature of the application.</p>

	<p>Similarly, the user can be offered to validate a set of permissions in a batch when installing a widget, where the permissions can be identified through the <code>feature</code> element [[WIDGETS]].</p>

	<p>To that end, the various permissions that are bound to APIs need to identified.</p>

	<p>To establish trust, a few basic parameters may be used, among which:</p>
	<ul>
	  <li><dfn>identity</dfn> — ensuring that the privileges are granted to the application from the trusted provider itself, to avoid phishing attacks;</li>
	  <li><dfn>reputation</dfn> — if others have reviewed positively an application, the user is more likely to trust it; reputation is itself linked to identity, either as a way to identify the source of the recommandation (e.g. approval from a network operator), or as a way to identify the aggregator of recommendations;</li>
	  <li><dfn>context</dfn> — a user is more likely to trust an application that requests permissions that make sense to her use of the said application.</li>
	</ul>

        <p>
          Identity and reputation may be established in different ways; one of the most common being
          through a validated signature on the widget or application package,
          with a corresponding verification of the trust chain to a trusted root.
        </p>


      </section>
      <section id='grouped-permissions-rqmts'>
        <h4>Requirements</h4>
	<ul>
	  <li>Non-safe APIs SHOULD define an identifier for the various permissions they require.</li>
	  <li>The security framework SHOULD refer to these API permissions identifiers to allow grouping them in a single user consent operation.</li>
          <li>when identity is checked through the use of signature in
          conjunction with PKI mechanisms, the security framework MUST
          require the verification of the signature, and MUST require
          validation of the certificate chain to a known trust
          root. Certificate revocation SHOULD be considered.</li> 

	</ul>
      </section>
    </section>
    <section id='delegated-authority-case'>
      <h3>Delegated Authority</h3>
        <p>Delegated authority use case refers to the use of
        explicit and interoperable policy definitions to control the use of
        an extensive set of APIs, safe and unsafe.  Such rules may be used
        in the context of a trusted widget or of well-identified web site, with clients that  support it.</p>
      <section id='delegated-authority-story1'>
        <h4>User Story: Enterprise-level ban on geolocation</h4>
	<div class="story">
	  <p>Bob manages the fleet of phones and laptops for ACMEcash, a cash transportation company: all the drivers have been equipped with a phone and a laptop they can use to interact with their intranet.</p>
	  <p>To keep the whereabouts of their employees as hidden as possible for security reasons, Bob wants to restrict all the devices distributed to employees so that they cannot use the geolocation API, except when connecting to the company intranet.</p>
	  <p>Bob creates a policy matching these rules, and deploys it to the phones and laptops.</p>
	  <p>When ACMEcash gets renamed ACMEbucks, Bob updates this policy to reflect the new domain name of the intranet.</p>

	</div>
	<h4>Analysis</h4>
	<p>In many professional contexts, allowing access to private or sensors data available through connected devices creates an unacceptable risk.</p>
	<p>In these contexts, being able to enforce and update a policy that determines who can make use of these data across devices and platforms can be a decisive aspect of the adoption of a given technology.</p>
	<p>To that end, it should be possible to describe
	platform-independent and declarative policies that determine which
	APIs can be used from what Web site or application.</p> 
      <section id='delgated-authority-story1-rqmts'>
        <h4>Requirements</h4>
	<ul>
      <li>The access control policy language MUST be device-independent.</li>
      <li>The access control policy language MUST be declarative.</li>
    </ul>
      </section>
    </section>
    <section id='delegated-authority-story2'>
        <h4>User Story: Third-party protection against malware</h4>
	<div class="story">
	  <p>Alice keeps a lot of her private and sensitive data on her phone. Having heard that her friend Charlie has had troubles with a phishing attempt recently, she would like to use a service to increase her safety.</p>
	  <p>She subscribes to a service operated by ACMEsafe: they define and maintain a set of rules that block access to certain APIs from unknown sites, facilitate access to sites that she has identified as trustable and that can be reliably identified.</p>
	  <p>Both Alice’s browser and widget runtime engine follow the rules expressed in the policy defined by ACMEsafe; these rules are updated on a regular basis on the device, after having verified their proper origin by checking their digital signature.</p>
	</div>
	<h4>Analysis</h4>
        <p>The same way anti-virus and malware tools allow users to reduce their risk of being exposed to troubles on their computers, some users may want to choose to delegate authority for access control policy to an external service provider.</p>
        <p>This external service provider determines the
        trustworthiness of 
        specific applications, and specifies an access control
        policy that embodies 
        that advice: blanket rejection for known malware sites, user consent requested for others, and transparent approval for sites that the user has configured as trusted.</p>
	<p>The policy defined by the external
        authority may be updated 
        regularly in 
        response to new information on known threats.
        </p>

	<p>This policy needs to be integrity-protected during various points in its life-cycle.</p>
      <section id='delgated-authority-story2-rqmts'>
        <h4>Requirements</h4>
	<ul>
      <li>Integrity protection and source authentication of the access
      control policy MUST be 
      supported, not only in transit but also storage.</li>
    </ul>
      </section>

      </section>
      <section id="delegated-authority-story2a">
	<h4>User Story: Transfering remembered choices to another device</h4>
	<div class="story">
        <p>Dave has been using advanced features on the Web from his
        phone for quite some time, and has thus accepted and rejected
        permissions from a large number of Web sites on his
        device.</p> 
	<p>But Dave is now looking to the brand new phone released by
	ACMEdev, and would like to migrate his settings to that new phone,
	which also uses a different browser.</p> 
	<p>Dave’s operator offers him to transfer seamlessly these
	settings from one phone to other, and informs him that they can
	also be used on his other connected devices.</p> 
	</div>

	<h4>Analysis</h4>
        <p>
Remembering earlier decisions and
maintaining these choices when changing devices either across vendors or
device versions has value to the user. This may also be the case when
wishing to have the same choices on multple devices. It should be
possible to transfer or share a 
representation of user choices across devices at any time.
        </p>
      <section id='delgated-authority-story3-rqmts'>
        <h4>Requirements</h4>
	<ul>
      <li>Access control policy MUST be able to record user decisions
        regarding policy configuration at an appropriate level of
        granularity.</li> 
      <li>Access control policy MUST be portable across devices and
        not bound to specific devices.</li>
    </ul>
      </section>

      </section>
      <section id='delegated-authority-story3'>
        <h4>User Story: Operator-enforced usage limitations</h4>
	<div class="story">
	  <p>Dave has found a nice-looking widget for managing SMS and MMS messages, but is not sure if it is safe to install it.</p>
	  <p>He contacts his operator ACMEcom; they indicate that on their devices, only widgets that have been verified by them will be able to send SMS.</p>
	  <p>Dave checks the widget, sees that the only special permission it requires is access to messaging features, and feels confident that he can now install it.</p>
	</div>
	<h4>Analysis</h4>
        <p>An initial  access control  configuration may be
              provided by an external 
              authority, together with any other associated device
              configuration (such as 
              root certificates). The configured  policy may
              determine access control policy 
              without reference to the user, or may refer certain
              decisions to the user.</p>
        <p>
          In determining the policy, the policy authority has the
          opportunity to define 
          a policy that supports a specific objective - such as to
          limit access to APIs 
          to only those web applications that are themselves
          distributed or verified by the policy 
          authority (e.g. to control its exposure to the financial
          risk of abuse of device 
          APIs).
        </p>

      <section id='delegated-authority-case-rqmts'>
        <h4>Requirements</h4>
          <ul>
            <li>It SHOULD be possible to update portions of policy independently.</li>
            <li>Access control policies MAY be associated with
            different authorities, including the user.</li> 
          </ul>
        <p class="note">The management of security policies and revocation mechanisms are out of scope of the Device APIs and Policy Working Group charter.</p>
      </section>
      </section>
    </section>
    </section>
      <section id="threats" class='appendix'>
        <h3>Security and Privacy Threats</h3>
        <p>
          The landscape that is being created 
          is the enablement of
          cross-platform, cross-device, easy to develop, highly functional
          applications based on browser technology. Experience with
          security attacks suggests that the increase of scope and
          power of the Device APIs raises the potential for attacks of
          increasing significance. This section outlines some known threats.
        </p>
        <p>
          Up until now no major malware incident
          has affected the mobile industry, but risks increase as
          adoption and convergence increases. There have been attempts: the
          MMS-spreading Commwarrior virus is probably the most infamous, along
          with the Spyware tool, Flexispy. An additional factor in
          avoiding mobile security issues to date has been the fact that
          mobile platforms have been too fragmented and complex
          to provide an attractive target. Existing modus
          operandi from technology-related attacks can provide indicators
          as to the types of attack and abuse that can be expected on
          widgets and web applications as device APIs are opened up
          and the size of the mobile market increases.
        </p>
        <section id="premium-rate-abuse">
          <h2>Premium Rate Abuse</h2>
          <p>A widget that seems benign but is actually spewing out
          SMSs to premium rate numbers without the user’s
          knowledge. This could be modified from an original safe
          widget such as a game. For the malware author, the key
          piece to solve is to dupe the user into thinking that the
          SMS capability is something that is part of the original
          application. Examples of this have been seen in the past,
          created from games and this model could be used for
          ‘dialers’ too (which plagued the desktop world in the
          days of dial-up networking). There have been recent
          warnings about this kind of abuse from security firms. 
          </p>
        </section> <!-- premium rate Abuse -->
        <section id="privacy-breach">
          <h3>Privacy Breach</h3>
          <p>An application that gains access to locations, contacts
          and gallery, silently uploading the data in the background
          to a site owned by the attacker. This is something that
          has been a clear goal for attackers already. There have
          been numerous high-profile examples in the past in the
          mobile world. Celebrities such as Paris Hilton, Miley
          Cyrus and Lindsay Lohan have all had private pictures,
          phone numbers and voicemails stolen from devices or
          networks in clear breach of their privacy. There has been
          embarrassment for teachers who had their pictures and
          videos copied by the children in their class and spread
          around school. The most high-profile case in the UK of a
          mobile related privacy breach was that of the News of the
          World's use of voicemail hacking to gain access to private
          information about Royalty. The Royal editor, Clive Goodman
          was jailed for four months and the editor, Andy Coulson
          resigned over this blatant privacy breach. Given the
          appetite for breaching privacy, users need to be safe in
          the knowledge that their personal data will not leak in
          any way. 
          </p>
<p>
Another example is turning on the camera or audio remotely to obtain
audio, video or photo information without permission.
</p>
        </section> <!-- privacy-breach -->
        <section id="integrity-breach">
          <h3>Integrity Breach</h3>
          <p>A widget that replaces the voicemail number with a
          premium rate number instead? There are number of reasons
          why an attacker would want to breach the integrity of
          the device. Simply changing the telephone number of the
          voicemail that is stored on the device could be enough
          to make an attacker a lot of money. Users usually have a
          shortcut key to their voicemail and may not notice for a
          long time that anything is wrong. A more sinister use
          could be to plant evidence on a device. Pictures, files
          and even criminal contacts could potentially be
          anonymously planted all without the user's consent or
          knowledge. Proving innocence could suddenly become very
          difficult. 
          There are also a number of reasons why somebody would want to steal
          data. The contents of corporate e-mails would be very
          interesting to a competitor, as would sabotaging data
          stored in spreadsheets and presentations on the target
          phone. 
          </p>
        </section> <!-- integrity-breach -->
        <section id="phishing">
          <h3>Phishing</h3>
          <p>
            Widgets contain web content making it is easy to duplicate
            and masquerade as something legitimate… perhaps a bank? 
          </p>
          <p> 
            In January 2010, Google removed a number of applications
            from the Android Market which were supposed to be banking
            applications for a number of different banks worldwide. It
            is unclear whether these applications were intentional
            phishing applications. The removal was based on a breach
            of terms and conditions surrounding copyright. The episode
            however highlighted the phishing potential. Widgets
            contain web content, therefore it is very easy to
            duplicate the look and feel of something that  the user
            trusts and proceed to abuse that trust either by stealing
            credentials or by manipulating money transfers. 
          </p>
          <p>
            These are of course just examples to consider in relation to how we
            would manage the policies for device APIs and are of course not
            exhaustive. Alongside the device-API specific examples
            above, we still 
             need to consider traditional web threats which pose a
            significant risk 
and lots of other types of attack which should be considered in a 
 formal threat model. 
          </p>
        </section> <!-- phishing -->
      </section> <!-- threats -->

      <section class='appendix'>
        <h2>Acknowledgements</h2>
        <p>
          The editors would like to extend special thanks to Nokia, OMTP
          BONDI, and PhoneGap for providing
          the foundation of the working group's requirements discussion.
        </p>
      </section>
    </body>
  </html>
Received on Friday, 15 April 2011 15:27:56 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 15 April 2011 15:27:56 GMT