Microsoft Word 2013/2016 - sprmSdyaTop Denial of Service (MS16-099)

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# Application: Microsoft Office Word
# Platforms: Windows, OSX
# Versions: Microsoft Office Word 2013,2016
# Author: Francis Provencher of COSIG
# Website: https://cosig.gouv.qc.ca/en/advisory/
# Twitter: @COSIG_
# Date: August 09, 2016
# CVE: CVE-2016-3316
# COSIG-2016-32

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1) Introduction
2) Report Timeline
3) Technical details
4) POC

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1) Introduction
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Microsoft Word is a word processor developed by Microsoft. It was first released on October 25, 1983[3]
under the name Multi-Tool Word for Xenix systems.[4][5][6] Subsequent versions were later written for several
other platforms including IBM PCs running DOS (1983), Apple Macintosh running Mac OS (1985), AT&T Unix PC (1985),
Atari ST (1988), OS/2 (1989), Microsoft Windows (1989) and SCO Unix (1994). Commercial versions of Word are licensed
as a standalone product or as a component of Microsoft Office, Windows RT or the discontinued Microsoft Works suite.
Microsoft Word Viewer and Office Online are Freeware editions of Word with limited features.

(https://en.wikipedia.org/wiki/Microsoft_Word)

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2) Report Timeline
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2016-05-15: Francis Provencher of COSIG report the vulnerability to MSRC.
2016-06-07: MSRC confirm the vulnerability
2016-08-09: Microsoft fixed the issue (MS16-099).
2016-08-09: Advisory released.

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3) Technical details
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The specific flaw exists within the parsing of invalid operand in “sprmSdyaTop” into a SEPX structure.
An attacker can use this flaw to read outside the allocated buffer, which could allow for the execution of arbitrary code in the context of the current process.
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4) POC
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https://cosig.gouv.qc.ca/wp-content/uploads/2016/08/COSIG-2016-32.doc
https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/40238.zip

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