Microsoft Internet Explorer 8 MSHTML Ptls5::LsFindSpanVisualBoundaries Memory Corruption
Posted on 23 November 2016
Throughout November, I plan to release details on vulnerabilities I found in web-browsers which I've not released before. This is the fifteenth 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/20161121001.html. Follow me on http://twitter.com/berendjanwever for daily browser bugs. MSIE8 MSHTML Ptls5::LsFindSpanVisualBoundaries memory corruption ================================================================ (The fix and CVE number for this bug are unknown) Synopsis -------- A specially crafted web-page can cause an unknown type of memory corruption in Microsoft Internet Explorer 8. This vulnerability can cause the `Ptls5::LsFindSpanVisualBoundaries` method (or other methods called by it) to access arbitrary memory. 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. JavaScript is not necessarily required to trigger the issue. Description ----------- The memory corruption causes the `Ptls5::LsFindSpanVisualBoundaries` method to access data at seemingly random addresses. However, these addresses appear to always be in the same range as valid heap addresses, even if they are often not DWORD aligned. The reason for the memory corruption is not immediately obvious. Time-line --------- * July 2014: This vulnerability was found through fuzzing. * November 2016: Details of this issue are released. Cheers, SkyLined Repro.html <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <body> <button> <pre> <x> <sub> <ruby> <img height="1"/> </ruby> </sub> </x> </pre> </button> </body> </html>
