Recap of the Lemmy XSS incident & steps for mitigation - LemmyWorld > Wayfarers' Haven approach
Recap of the Lemmy XSS incident & steps for mitigation - Lemmy.world
https://lemmy.world/post/1293336
# UPDATE: The latest RC version of Lemmy-ui (0.18.2-rc.2) contains fixes for the issue, but if you believe you were vulnerable, you should still rotate your JWT secret after upgrading! Read below for instructions. Removing custom emoji is no longer necessary after upgrading. Original post follows: ---- This post is intended as a central place that admins can reference regarding the XSS incident from this morning. ### What happened? A couple of the bigger Lemmy instances had several user accounts compromised through stolen authentication cookies. Some of these cookies belonged to admins, these admin cookies were used to deface instances. Only users that opened pages with malicious content during the incident were vulnerable. The malicious content was possible due to a bug with rendering custom emojis. Stolen cookies gave attackers access to all private messages and e-mail addresses of affected users. ### Am I vulnerable? If your instance has ANY custom emojis, you are vulnerable. Note that it appears only local custom emojis are affected, so federated content with custom emojis from other instances should be safe. ### I had custom emojis on my instance, what should I do? This should be enough to mitigate now: 1. Remove custom emoji DELETE FROM custom_emoji_keyword; DELETE FROM custom_emoji; 2. Rotate your JWT secret (invalidates all current login sessions) -- back up your secret first, just in case SELECT * FROM secret; -- generate a new secret UPDATE secret SET jwt_secret = gen_random_uuid(); 3. Restart Lemmy server If you need help with any of this, you can reach out to me on Matrix (@sunaurus:matrix.org) or on Discord (@sunaurus) ### Legal If your instance was affected, you may have some legal obligations. Please check this comment for more info: https://lemmy.world/comment/1064402 [https://lemmy.world/comment/1064402] ##### More context: https://github.com/LemmyNet/lemmy-ui/issues/1895 [https://github.com/LemmyNet/lemmy-ui/issues/1895] https://github.com/LemmyNet/lemmy-ui/pull/1897 [https://github.com/LemmyNet/lemmy-ui/pull/1897]
You can read the breakdown of the XSS incident at Lemmy.world.
This won't be an issue for Wayfarers' Haven because we don't actually have any custom emoji.
My main account was indeed also the admin account for the server. If I had seen that script, that would have made this server vulnerable to the attack - I may have and we just missed it out of sheer luck. That and the backup account have both been moved to alternate accounts - I'm now following security best practices by separating out admin and every day use users.
The only practical change here is that I now have to log in as a separate user to approve applications and if I feel like changing the sidebar. I'll live. :)