Flash – Uninitialized Stack Variable MPD Parsing Memory Corruption

  • 作者： bilou
    日期： 2015-08-19
  • 类别：
    平台：
  • 来源：https://www.exploit-db.com/exploits/37845/
  • Source: https://code.google.com/p/google-security-research/issues/detail?id=316&can=1&q=label%3AProduct-Flash%20modified-after%3A2015%2F8%2F17&sort=id

[Tracking for: https://code.google.com/p/chromium/issues/detail?id=472201]

Credit is to bilou, working with the Chromium Vulnerability Rewards Program.

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VULNERABILITY DETAILS
Loading a weird MPD file can corrupt flash player's memory.

VERSION
Chrome version 41.0.2272.101, Flash 17.0.0.134
Operating System: Win 7 x64 SP1

REPRODUCTION CASE
I'm ripping most of this from scarybeasts' sources. I'm sure he's ok with that =D.

"To reproduce, host the attached SWF and other files on a web server (e.g. localhost) and load it like this:"

"http://localhost/PlayManifest.swf?file=gen.mpd

"To compile the .as file, I had to use special flags to flex:"

"mxmlc -target-player 14.0 -swf-version 25 -static-link-runtime-shared-libraries ./PlayManifest.as"
"(This also requires that you have v14.0 of playerglobals.swc installed. Any newer version should also be fine.)"


On Win7 x64 sp1 with Chrome 32 bit, crash like this:
6AA8B67C | 8B C3| mov eax,ebx |
6AA8B67E | E8 A1 05 00 00 | call pepflashplayer.6AA8BC24|
6AA8B683 | EB A8| jmp pepflashplayer.6AA8B62D |
6AA8B685 | 89 88 D0 00 00 00| mov dword ptr ds:[eax+D0],ecx |// crash here, eax points somewhere in pepflashplayer.dll
6AA8B68B | 8B 88 88 00 00 00| mov ecx,dword ptr ds:[eax+88] |
6AA8B691 | 33 D2| xor edx,edx |
6AA8B693 | 3B CA| cmp ecx,edx |
6AA8B695 | 74 07| je pepflashplayer.6AA8B69E|
6AA8B697 | 39 11| cmp dword ptr ds:[ecx],edx|
6AA8B699 | 0F 95 C1 | setne cl|


At first sight this looks to be an uninitialized stack variable but I might be wrong.
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Proof of Concept:
https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/37845.zip