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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Origin HTTP header not set to null after following cross-origin redirect"
href="https://bugs.webkit.org/show_bug.cgi?id=144817">144817</a>
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<th>Summary</th>
<td>Origin HTTP header not set to null after following cross-origin redirect
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<th>Classification</th>
<td>Unclassified
</td>
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<th>Product</th>
<td>WebKit
</td>
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<th>Version</th>
<td>528+ (Nightly build)
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<th>Hardware</th>
<td>Unspecified
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>Normal
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<th>Priority</th>
<td>P2
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<th>Component</th>
<td>Page Loading
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<th>Assignee</th>
<td>webkit-unassigned@lists.webkit.org
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<th>Reporter</th>
<td>hillbrad@fb.com
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<pre>The HTTP Origin header, described by <a href="https://tools.ietf.org/html/rfc6454">https://tools.ietf.org/html/rfc6454</a>, allows a server to determine a user agent's view of where a request originated from.
RFC6454 allows this header to be multi-valued on redirects, but CORS (<a href="http://w3.org/TR/cors">http://w3.org/TR/cors</a>) implicitly requires it to be single-valued (because it specifies an exact string match comparison).
All major user agents implement single-valued behavior, and because of this must set the header to 'null' when a redirect crosses same-origin boundaries. If the value of the original Origin is preserved after a 3xx redirect, it may result in a confused deputy vulnerability that allows bypass of CSRF protections.
For example, the issue described at the following post is enabled by this incorrect behavior:
<a href="http://sakurity.com/blog/2015/03/05/RECONNECT.html">http://sakurity.com/blog/2015/03/05/RECONNECT.html</a>
Test cases are available at the following URLs:
<a href="https://www.webappsec-test.info/~bhill2/OriginRedir/test.php?redircode=302">https://www.webappsec-test.info/~bhill2/OriginRedir/test.php?redircode=302</a>
<a href="https://www.webappsec-test.info/~bhill2/OriginRedir/test.php?redircode=303">https://www.webappsec-test.info/~bhill2/OriginRedir/test.php?redircode=303</a>
<a href="https://www.webappsec-test.info/~bhill2/OriginRedir/test.php?redircode=307">https://www.webappsec-test.info/~bhill2/OriginRedir/test.php?redircode=307</a>
<a href="https://www.webappsec-test.info/~bhill2/OriginRedir/test.php?redircode=308">https://www.webappsec-test.info/~bhill2/OriginRedir/test.php?redircode=308</a>
WebKit is vulnerable by not setting Origin to null on cross-origin redirects on any 3xx status code which preserves the GET/POST payload.
A similar issue was reported to Blink for status code 308, and has since been patched, see:
<a href="https://code.google.com/p/chromium/issues/detail?id=465517">https://code.google.com/p/chromium/issues/detail?id=465517</a></pre>
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