Microsoft Windows - 'LoadUvsTable()' Heap-based Buffer Overflow

# Date: 15-03-2017

# Author: Hossein Lotfi (https://twitter.com/hosselot)

# CVE: CVE-2016-7274



1. Description



An integer overflow error within the "LoadUvsTable()" function of usp10.dll

can be exploited to cause a heap-based buffer overflow. Full analysis is

available at:



http://blogs.flexerasoftware.com/secunia-research/2016/12/microsoft_windows_loaduvstable_heap_based_buffer_overflow_vulnerability.html





2. Proof of Concept



open “C:\Windows\Fonts\phagspa.ttf” in a hex editor and change the value at

offset 0x2051 from 0x00000006 to 0x33333334.





3. Solution:



Microsoft initially tried to fixed the issue in MS16-147, but the fix was

incomplete and the issue remained unpatched til Microsoft March 2017 patch

release:



https://twitter.com/hosselot/status/809059287037251584



It appears MS17-013 finally fixed the vulnerability properly:



https://technet.microsoft.com/en-us/library/security/ms17-013.aspx



@hosselot