Add Warning Labels to Matrix/Synapse

[Mikaela]

Description

URL of affected page: https://privacyguides.org/software/real-time-communication/#federated

This is practically privacytools/privacytools.io#2424 from where I am hoping for a warning label to be applied onto Element/Matrix.

• Per-room profiles leak in user-directory (problem for people coming from Discord and examples listed in issue comments): User Directory leaks Per-room Nicknames and Avatars matrix-org/synapse#5677
• Media redactions are never actually removed (direct links keep working): When we redact events, any mxc content they refer to should be redacted too (SYN-216) matrix-org/synapse#1263
• Reactions in private rooms aren't encrypted: https://github.com/matrix-org/matrix-doc/issues/2678

[Flam3z]

I think an update from the developers should be needed as they have not responded to their issues in a while just so we can see what their current stance/progress on the said issues are.

[xanoni]

@Mikaela Thank you for reopening. Let's make sure we get to an answer this time. Kind of strange that the previous issue was closed and archived, so I couldn't even add comments to it. But let's assume for now that there is no bad intent.

On topic:
I agree that Matrix indeed needs several warning labels related to Ephemeral / disappearing messages. My understanding is that in most common server/room setups, this feature simply can't be assumed to be existent. However, the most dangerous part is that the user could think that messages are actually being deleted when they are not.

Non-exhaustive list of learnings that were non-obvious to me when I first started using Matrix:

1. By default Synapse just sets something like a "hidden=true" flag when the user deletes messages, the messages are not actually removed from the database, but stored together with the "reason"
2. Even if you run your own home server, you don't know if other admins in the federation are also deleting messages from their drives
3. Due to the prevalence of bridges (and the fact that they are not always obvious/visible to the user), messages are forwarded to other networks (e.g., IRC, Discord, ...) where they are definitely NOT deleted
4. Matrix makes it appear as if message deletion was supported in bridged rooms, but people connected to the native network will still see your messages ... non-technical users might not understand that Matrix can't delete their messages from Libera.chat or from Freenode

(I understand that ephemeral messages are never 100% secure, but at least an attempt should be made ...... or if not possible, the user should be warned.)

[jonaharagon]

Kind of strange that the previous issue was closed and archived

I can't speak to why it was closed initially having not been resolved as I haven't been involved with the PrivacyTools side of things in quite a while, but that repo was archived because there are currently no active maintainers, the entire PrivacyTools team has moved to this project. Just an FYI.

[Flam3z]

Has matrix given a reason as to why those messages are still stored onto the server?

[Mikaela]

Has matrix given a reason as to why those messages are still stored onto the server?

Assuming you mean media files, they say that multiple messages may point to the same media repo address and thus it's difficult to know when all messages pointing to the file are removed. That especially affects encrypted messages. This can be found from comemnts of matrix-org/synapse#1263.

If you mean the servers storing removed messages for 7 days in general, that is for server administrators in case someone was abusive and redacting messages to remove proof of it. They are also planning to make those visible to room moderators. matrix-org/matrix-spec-proposals#2815

[Mikaela]

Self-assigning as an issue I care about and may be PRing by myself so it will be visible in /issues, please feel free to send a PR on this regardless should I not have done that at the time.

[dngray]

Done in #192