To reproduce, host the attached files appropriately and:

http://localhost/LoadMP4.swf?file=crash4000368.flv

If there is no crash at first, refresh the page a few times.

With a debugger attached to 64-bit Flash in Chrome Linux, the crash manifests like this:

=> 0x00007f7789d081bb <__memmove_ssse3_back+443>:	movaps %xmm1,-0x10(%rdi)

rdi            0x7f7778d69200

7f777894b000-7f7778d69000 rw-p 00000000 00:00 0 
7f7778d69000-7f7778d88000 ---p 00000000 00:00 0 

This looks very like a heap-based buffer overflow that just happens to have walked off the end of the committed heap.

Also, this bug bears disturbing similarities to CVE-2015-3043, see for example: https://www.fireeye.com/blog/threat-research/2015/04/probable_apt28_useo.html


This bug is subject to a 90 day disclosure deadline. If 90 days elapse
without a broadly available patch, then the bug report will automatically
become visible to the public.

 

LoadMP4.as 1.0 KB Download

crash4000368.flv 8.4 MB Download

LoadMP4.swf 1.0 KB Download