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Information disclosure (mouse tracking) vulnerability in Microsoft Internet Explorer versions 6-10

Summary: Unprivileged attackers can track your system-wide mouse
movements from any IE page, even when the page is unfocused or
Package: Microsoft Internet Explorer
Affected: Tested on versions 6–10

A security vulnerability in Internet Explorer, versions 6–10, allows
your mouse cursor to be tracked anywhere on the screen, even if the
Internet Explorer window is inactive, unfocused or minimised. The
vulnerability is notable because it compromises the security of
virtual keyboards and virtual keypads.

As a user of Internet Explorer, your mouse movements can be recorded
by an attacker even if you are security conscious and you never
install any untoward software. An attacker can get access to your
mouse movements simply by buying a display ad slot on any webpage you
visit. This is not restricted to lowbrow porn and file-sharing sites.
Through today’s ad exchanges, any site from YouTube to the New York
Times is a possible attack vector. Indeed, the vulnerability is
already being exploited by at least two display ad analytics companies
across billions of webpage impressions each month. As long as the page
with the exploitative advertiser’s ad stays open—even if you push the
page to a background tab or, indeed, even if you minimise Internet
Explorer—your mouse cursor can be tracked across your entire display.

Details of the vulnerability
Internet Explorer’s event model populates the global Event object with
some attributes relating to mouse events, even in situations where it
should not. Combined with the ability to trigger events manually using
the fireEvent() method, this allows JavaScript in any webpage (or in
any iframe within any webpage) to poll for the position of the mouse
cursor anywhere on the screen and at any time—even when the tab
containing the page is not active, or when the Internet Explorer
window is unfocused or minimized. The fireEvent() method also exposes
the status of the control, shift and alt keys.

Affected properties of the Event object are altKey, altLeft, clientX,
clientY, ctrlKey, ctrlLeft, offsetX, offsetY, screenX, screenY,
shiftKey, shiftLeft, x and y.

<!DOCTYPE html>
  <meta charset="utf-8" />
  <title>Exploit Demo</title>
  <script type="text/javascript">
    window.attachEvent("onload", function() {
      var detector = document.getElementById("detector");
      detector.attachEvent("onmousemove", function (e) {
        detector.innerHTML = e.screenX + ", " + e.screenY;
      setInterval(function () {
      }, 100);
  <div id="detector"></div>

A demonstration of the security vulnerability may be seen here:

The implications for virtual keyboards and virtual keypads
We have created a game to illustrate how easily this security
vulnerability in Internet Explorer may be exploited to compromise the
security of virtual keyboards and virtual keypads. The game may be
found at http://iedataleak.spider.io/