Flash – Uninitialized Stack Variable MPD Parsing Memory Corruption
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. --- 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. --- Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/37845.zip |