CVE-2019-2107
CVE-2019-2107 - looks scary. Still remember Stagefright and PNG bugs vulns .... With CVE-2019-2107 the decoder/codec runs under mediacodec user and with properly "crafted" video (with tiles enabled - ps_pps->i1_tiles_enabled_flag) you can possibly do RCE. The codec affected is HVEC (a.k.a H.265 and MPEG-H Part 2) #exploit #rce #android #stagefright #cve
LineageOS (Android):
02-11 20:18:48.238 260 260 D FFmpegExtractor: ffmpeg detected media content as 'video/hevc' with confidence 0.08
02-11 20:18:48.239 260 260 I FFMPEG : [hevc @ 0xb348f000] Invalid tile widths.
02-11 20:18:48.239 260 260 I FFMPEG : [hevc @ 0xb348f000] PPS id out of range: 0
02-11 20:18:48.240 260 260 I FFMPEG : [hevc @ 0xb348f000] Invalid tile widths.
02-11 20:18:48.240 260 260 I FFMPEG : [hevc @ 0xb348f000] PPS id out of range: 0
02-11 20:18:48.240 260 260 I FFMPEG : [hevc @ 0xb348f000] Error parsing NAL unit #5.
02-11 20:18:48.240 260 260 I FFMPEG : [hevc @ 0xb348f000] Invalid tile widths.
mplayer (laptop)
id: 0
[hevc @ 0x7f0bf58a7560]Decoding VPS
[hevc @ 0x7f0bf58a7560]Main profile bitstream
[hevc @ 0x7f0bf58a7560]Decoding SPS
[hevc @ 0x7f0bf58a7560]Main profile bitstream
[hevc @ 0x7f0bf58a7560]Decoding VUI
[hevc @ 0x7f0bf58a7560]Decoding PPS
[hevc @ 0x7f0bf58a7560]Invalid tile widths.
[hevc @ 0x7f0bf58a7560]Decoding SEI
[hevc @ 0x7f0bf58a7560]Skipped PREFIX SEI 5
[hevc @ 0x7f0bf58a7560]PPS id out of range: 0
[hevc @ 0x7f0bf58a7560]Error parsing NAL unit #5.
Error while decoding frame!
This stops it when the tile width is bigger than allowed: https://gitlab.freedesktop.org/gstreamer/meson-ports/ffmpeg/blob/ebf648d490448d511b5fe970d76040169e65ef74/libavcodec/hevc_ps.c#L1526
So the check are there.
On stock/google Andoird I think it will use libhevc, not ffmpeg, when using VideoPlayer.
https://www.droidviews.com/enjoy-hevc-h-265-video-playback-on-android/
I have the google codec:
OMX.google.hevc.decoder
I am wondering however why it does not crash ....
Attaching the video (videopoc.mp4) that should trigger this condition:
if (value >= ps_sps->i2_pic_wd_in_ctb - start)
+ {
+ return IHEVCD_INVALID_HEADER;
+ }
Maybe somebody have more luck.
Whoooo hooo .... made it :)
Proof of concept is in hevc-crash-poc.mp4, other videos are for non andoird players.
Hvec-"fright" is possible. You can own the mobile by viewing a video with payload. In my example I didn't include real payload.
07-13 21:50:59.000 3351 3351 I /system/bin/tombstoned: received crash request for pid 24089
07-13 21:50:59.006 24089 24089 F DEBUG : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
07-13 21:50:59.006 24089 24089 F DEBUG : Build fingerprint: 'samsung/hero2ltexx/hero2lte:8.0.0/R16NW/G935FXXS4ESC3:user/release-keys'
07-13 21:50:59.006 24089 24089 F DEBUG : Revision: '9'
07-13 21:50:59.006 24089 24089 F DEBUG : ABI: 'arm64'
07-13 21:50:59.006 24089 24089 F DEBUG : pid: 24089, tid: 24089, name: media.extractor >>> mediaextractor <<<
07-13 21:50:59.006 24089 24089 F DEBUG : signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x7ccb800050
07-13 21:50:59.009 24089 24089 F DEBUG : x0 00000000ffffff36 x1 0000000000000000 x2 00000000000000f0 x3 0000000000000001
07-13 21:50:59.009 24089 24089 F DEBUG : x4 0000000000000001 x5 0000007ccb5df1b8 x6 0000007cc927363e x7 0000007cc8e7bd04
07-13 21:50:59.009 24089 24089 F DEBUG : x8 0000000000004170 x9 0000000000004160 x10 00000000ffffffff x11 0000007ccb7fbef0
07-13 21:50:59.010 24089 24089 F DEBUG : x12 0000007ccb5d3ce0 x13 000000000000001e x14 0000000000000003 x15 0000000000000001
07-13 21:50:59.010 24089 24089 F DEBUG : x16 0000007cc99f5f50 x17 0000007ccb88885c x18 0000007ccb566225 x19 0000007ccb562020
07-13 21:50:59.010 24089 24089 F DEBUG : x20 0000007ccb4f18a0 x21 0000007ccb468c6c x22 0000000000000000 x23 0000000000000006
07-13 21:50:59.010 24089 24089 F DEBUG : x24 000000000000001e x25 0000000000000094 x26 0000000000004160 x27 0000000000000001
07-13 21:50:59.010 24089 24089 F DEBUG : x28 0000007ccb55e750 x29 0000007fd6d39d90 x30 0000007cc99c4438
07-13 21:50:59.010 24089 24089 F DEBUG : sp 0000007fd6d39d20 pc 0000007cc99c44c4 pstate 0000000080000000
07-13 21:50:59.013 24089 24089 F DEBUG :
--
If you want to bring it further to get RCE (Remote Command Execution)
I would start with getting LineageOS rom with debug build (if you don't have a rooted target phone, disassembly gives you headaches, should be much easier to work with), possibly changing memory allocator to jemalloc (to target newer mobiles) You could set it in your BoardConfig:
device/samsung/msm8226-common/BoardConfigCommon.mk
# Memory
#MALLOC_IMPL := dlmalloc
MALLOC_IMPL := jemalloc
I found that my Samsung mobile was using jemalloc, not sure about older/newer Mobile. Hopefully the same.
Some more info about jemallc/dlmalloc: https://blog.nsogroup.com/a-tale-of-two-mallocs-on-android-libc-allocators-part-1-dlmalloc/
Here I removed the checks from libavcodec.so
Test on LineageOS 7.1.2 on Samsung S3 Neo+
As we can see the mediaplayer has crashed/went away ... with unhandled events (MediaPlayer: mediaplayer went away with unhandled events). Not sure why it does not crash natively. To goal would be here to take the execution flow. Good luck!
02-25 16:44:15.008 2954 2954 I art : Explicit concurrent mark sweep GC freed 4988(521KB) AllocSpace objects, 1(40KB) LOS objects, 25% free, 6MB/8MB, paused 484us total 43.471ms
02-25 16:44:15.011 2954 2954 I art : Starting a blocking GC Explicit
02-25 16:44:15.046 2954 2954 I art : Explicit concurrent mark sweep GC freed 435(17KB) AllocSpace objects, 0(0B) LOS objects, 24% free, 6MB/8MB, paused 523us total 34.700ms
02-25 16:44:15.083 2954 2954 W MediaPlayer: mediaplayer went away with unhandled events