Metadata leak in voice messages

[krille-chan]

Description

Voice message metadata is not stripped. Audio Metadata should be disabled by default, as it is on many other chatting applications(e.g. WhatsApp, Telegram clients), or at least the user should have the option to disable it.

To Reproduce

Send a voice message via FluffyChat, download it and probe it with ffprobe, you will see:

  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2022-08-10T10:19:33.000000Z
    com.android.version: 12
    com.android.manufacturer: OnePlus
    com.android.model: ONEPLUS A6013
  Duration: 00:00:02.93, start: 0.000000, bitrate: 73 kb/s
    Stream #0:0(eng): Audio: aac (LC) (mp4a / 0x6134706D), 22050 Hz, mono, fltp, 64 kb/s (default)
    Metadata:
      creation_time   : 2022-08-10T10:19:33.000000Z
      handler_name    : SoundHandle

Additional information:

• Device: Oneplus 6T
• OS and OS version: LineageOS / Android 12
• Installed version of FluffyChat: 1.5.0
• (Android only) Which store are you using: F-Droid
• (Android only) Are Google Services available: No

[TrivialDem]

Concerning this issue, is a byte manipulation based approach possible ?

I have checked the header of the m4a file format used in audio, and it seems like the concerned field containing all the metadata is (unsurprisingly) the one named meta.
As described by the container, it consists of a 32 bits unsigned number specifying the length, followed by another 32 bits unsigned number called meta, then the actual metadata which is in the range. The first number also counts itself and the meta field.

After personal tests, stripping out the field and modifying the length specified before the moov field didn't work.
However, nulling all of the content of the metadata (except the length field and name field) results in a playable file without any metadata shown by ffprobe.

After searching in the repos, the relevant manipulation probably happen as far as I know around this variable.

Let me know your thoughts on this solution.

[github-actions]

This issue is stale because it has been open for 120 days with no activity.

[github-actions]

This issue was closed because it has been inactive for 14 days since being marked as stale.