Hi all,

If you’re just now signing in for the first time in 12+ hours, you may just now be finding out that Lemmy World and other instances where hijacked. The hijackers had the full abilities of hijacked user, mod, and admin accounts. At this time, I am only aware of instance defacing and URL redirections to have been done by the hijackers.

If you were not forced to sign back in this morning, contact your instance admin to verify mitigations were completed on your instance.

How?

This occurred due to an XSS attack in the recently added custom emojis. Instance admins should follow the issue tracker on the LemmyNet GitHub, as well as the Matrix Chat. Post-Incident Activity is still on-going.

Currently, it is likely that just your session cookie was stolen, with instance admins being targeted specifically by checking for navAdmin, an HTML element only instance admins had. I do not believe this to affect users across instances, but I have yet to confirm this.

What happens next?

As I am not the developers or affected instance admins, I cannot make any guarantees. However, here is what you’ll likely see:

  1. Post Incident investigation continues. This will include inspecting code, posts, websites, and more used by the hijackers. An official incident writeup may occur. You should expect the following from that report:
  • Exactly what happened, when.
  • The incident response that occurred from instance admins
  • Information that might have helped resolve the issue sooner
  • Any issues that prevented successful resolution
  • What should have been done differently by admins
  • What should be improved by developers
  • What can be used to identify the next attack
  • What tools are needed to identify that information

  1. A CVE is created. This is an official alert of the issue, and notifies security experts (and enthusiasts), even those not using lemmy, about the issue.

  2. A code security audit is done. This will likely just be casual reviews by technical lemmy users. However, I will be reaching out to the Mozilla Foundation and Cure53 as they recently did an audit of Mastodon. If there is interest in an external audit of lemmy and the costs are affordable, I’ll look into crowdfunding this cost.

    • @graphiteEnglish
      4•1 year ago

      The way the hack was utilized is honest very creative and interesting;

      That’s often the case with exploits.

        • @graphiteEnglish
          0•1 year ago

          Sure. Not sure how that’s relevant though?

          In general, finding an exploit requires looking for little tiny details that could exist in, really, any area of a given system; looking for a bug, and then exploiting that bug by understanding how input data can be used to create a deterministic chain of events.

          This almost always requires thinking outside of the box.

          There are people who are also paid to find these before malicious actors do.

          It’s always going to be creative in some way, at least in the beginning.

          It’s like when people first discover Quake’s fast inverse square root. Sure, the first time around it seems genius. In reality, code like that is actually everywhere, and there is a somewhat trivial aspect to optimizing those kinds of problems.

    • @[email protected]English
      4•1 year ago

      HTML injection / XSS vulnerabilities tend to be a sign of amateur hour to be honest. Made me a bit worried that I’m hitching my reddit escape wagon to the wrong technology. But sounds like this was due to instance-specific customizations rather than the core Lemmy tech, so hopefully we’re still on solid ground.