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matrix-org / mjolnir

A moderation tool for Matrix
Apache License 2.0
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Mitigate spammers using mass mentions #211

Closed Caspy7 closed 1 month ago

Caspy7 commented 2 years ago

Is your feature request related to a problem? Please describe. A spammer came into a room I manage and sent several messages. Each one started with a URL then the rest was just mentions of everyone in the channel. I don't know if they managed to ping the whole room before I was able to ban them, but there were hundreds.

Describe the solution you'd like Detect the number of user mentions in a message and act on that to prevent abuse from spammers. I don't know the best solution which is why I'm not being explicitly prescriptive. I know we want users to be able to use a "normal" amount of mentions. Perhaps when X number of mentions are detected we prevent the message from posting and inform the user of the limitation. And if they exceed a certain number of mentions in a short period of time we mute them and notify admins/mods.

Additional context I presume the @room function is blocked for most users by default. This prevents casual users from abusing that notification, but if a spammer can automate the process described above they can achieve the same ends.

TheTimeWalker commented 2 years ago

You're 36 minutes too late :) https://github.com/matrix-org/mjolnir/pull/210