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<header>
  <title>Malicious Stanzas</title>
  <abstract>This document defines an XMPP protocol extension for flagging malicious stanzas within Jabber/XMPP.</abstract>
  &LEGALNOTICE;
  <number>0076</number>
  <status>Active</status>
  <type>Humorous</type>
  <sig>Standards</sig>
  <dependencies>
    <spec>XMPP Core</spec>
    <spec>RFC 3514</spec>
  </dependencies>
  <supersedes/>
  <supersededby/>
  <shortname>evil</shortname>
  &stpeter;
  &hildjj;
  <revision>
    <version>1.0</version>
    <date>2003-04-01</date>
    <initials>psa</initials>
    <remark><p>April Fools!</p></remark>
  </revision>
</header>
<section1 topic='Introduction'>
  <p>&rfc3514;, published just today (2003-04-01), defines a mechanism for specifying the "evil bit" in IPv4 in order to determine if a packet was sent with malicious intent. In Section 5 ("Related Work") of that RFC, reference is made to complementary mechanisms for other forms of evil such as IPv6 support and the application/evil MIME type. Because the &XSF; desires to maintain compliance with protocols developed by core Internet standards bodies, the current document defines a complementary mechanism for Jabber support of evil.</p>
</section1>
<section1 topic='Requirements and Approach'>
  <p>There are three basic Jabber stanza types that may be sent within XML streams:</p>
  <ul>
    <li>&lt;message/&gt; -- a "push" medium for sending information to other entities.</li>
    <li>&lt;presence/&gt; -- a "broadcast" medium for publishing information to entities that have subscribed to an entity's availability status.</li>
    <li>&lt;iq/&gt; -- a "request-response" medium for executing basic but structured transactions with other entities.</li>
  </ul>
  <p>Any one of the foregoing data elements can be used with malicious intent. Therefore a generalized mechanism is needed. Because XML namespaces are used within Jabber to properly scope data, this document proposes a new namespace ('http://jabber.org/protocol/evil') to implement the desired functionality.</p>
</section1>
<section1 topic='Use Cases'>
  <section2 topic='Evil Messages'>
    <p>If a Jabber entity sends an evil message, it MUST include an appropriately namespaced extension in the message stanza:</p> 
    <example caption='Jabber Entity Sends Evil Message'><![CDATA[
<message 
    from='iago@shakespeare.lit/pda'
    to='emilia@shakespeare.lit/cell'>
  <body>
      I told him what I thought, and told no more
      Than what he found himself was apt and true.
  </body>
  <evil xmlns='http://jabber.org/protocol/evil'/>
</message>
    ]]></example>
  </section2>
  <section2 topic='Evil Presence'>
    <p>If a Jabber entity sends evil presence information, it MUST include an appropriately namespaced extension in the presence stanza:</p> 
    <example caption='Jabber Entity Sends Evil Presence'><![CDATA[
<presence from='iago@shakespeare.lit/pda'>
  <show>dnd</show>
  <status>Fomenting dissension</status>
  <evil xmlns='http://jabber.org/protocol/evil'/>
</presence>
    ]]></example>
  </section2>
  <section2 topic='Evil IQs'>
    <p>If a Jabber entity provides evil information in an IQ exchange, it MUST include an appropriately namespaced extension in the IQ stanza:</p> 
    <example caption='Jabber Entity Sends Evil Message'><![CDATA[
<iq 
    from='iago@shakespeare.lit/pda'
    to='emilia@shakespeare.lit/cell'
    id='evil1'>
  <query xmlns='jabber:iq:version'>
    <name>Stabber</name>
    <version>666</version>
    <os>FiendOS</os>
  </query>
  <evil xmlns='http://jabber.org/protocol/evil'/>
</iq>
    ]]></example>
  </section2>
</section1>
<section1 topic='Security Considerations'>
  <p>Because the 'http://jabber.org/protocol/evil' namespace flags an XML stanza as malicious, it is critically important that an entity appropriately process an XML stanza that contains the evil extension. Mission-critical applications SHOULD ignore any stanzas tagged with the evil extension. Evil servers MAY pass through evil stanzas unmodified. Really evil servers MAY silently delete the evil extension. Jabber entities that are evil to the core SHOULD support channel-level evil as defined in RFC 3514, since this document defines per-stanza evil only.</p>
</section1>
<section1 topic='IANA Considerations'>
  <p>This document requires no interaction with &IANA;.</p> 
</section1>
<section1 topic='XMPP Registrar Considerations'>
  <p>The &REGISTRAR; shall register the 'http://jabber.org/protocol/evil' namespace as a result of this document.</p>
</section1>
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