If you are a lemmy.world user, log out and log back in to clear cookies!

Last night, lemmy.world was compromised via an XSS vulnerability with custom emoji. Using this vulnerability, attackers took control of an admin account. The site redirected to mp4 files when logged in, and porn sites when not logged in. The issue was resolved by lemmy.world admins soon after it started, but the attacker regained control of the compromised admin account around ten minutes after resolution, redirecting users to the same mp4 files and sites. Soon after that, the site became inaccessable. The issue is currently resolved, and lemmy dev team has been notified of this vulnerability. sh.itjust.works will not be affected, as we do not have any custom emojis. If you own an instance with custom emojis, it is advised to remove these emojis and clear your cookies.

The following is the original post:

PSA: DO NOT ATTEMPT TO ACCESS LEMMY.WORLD, THERE MIGHT BE MALWARE

Lemmy.world member here. I created this account after .world started redirecting me to porn sites and odd mp4 files. We might want to defederate to limit the potential impact. Also, SJW might be affected by the same vulnerabilities as .world, so maybe the admins here should look at that.

Edit: Situation seems to have stabilized. Some site icons aren’t loading, but otherwise everything seems stable. Read Edit2

Edit2: HOLY SHIT ITS BACK Read Edit3

Edit3: lemmy.world is now down as of 10:56 PM CST (USA) Read Edit4

Edit4: lemmy.world is now up, but serving an error as of 11:03 CST (USA) See a screenshot of this error. I also got logged out, hopefully it doesn’t mean they just wiped the databases lol.

Edit5: Edit4 still applies, but I can now access lemmy.world via Memmy on my phone. Wefwef (Voyager now) does not work, however. Timestamp: 11:34 PM CST (USA)

Edit6: lemmy.world restored. Compromised admin account said something in a weird post. I’m going to bed now, my brain is play-dough rn. Will update you guys tomorrow morning.

  • Mic_Check_One_Two@reddthat.comEnglish
    4·
    1 year ago

    Seems like there’s an active cookie-scraping attack going on. Lots of compromised accounts are going around different instances posting links with drive-by JavaScript. The JS tries to grab your current login token, which would give hackers access to your current login session.

    They don’t need your password because they’re just grabbing that cookie that your browser gets when you check the “Keep me logged in” checkbox on login. That’s what allows you to verify your account across multiple sessions, and it allows them to do the exact same thing. They can simply send that authorized token, and “log in” as you. This would (likely) work across instances, because if they grab your cookie then it will give them access to whatever instance your account is logged in on.

    So Lemmy.world will likely need to be completely defederated (to stop any compromised accounts from posting on other instances) and your specific instance will likely need to deauthorize all current login tokens (which will forcibly log everyone on your instance out) to stop any local accounts that got hit.