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I’m greatly surprised how Lemmy and the fediverse society has responded with this. The bug was found yesterday, maybe? And I’ve read about it three, four times (in different servers); a temporal solution was published in hours and it’s already patched on the repo.
Another victory for Open Source and the Fediverse in general.
This is what happens when the people running a platform actually care about it and it's users
More importantly the issue was tracked and resolved publicly.
The issue of trust in corporate spaces gets used to bury these things, this is a good model on how to restore it in the open.
Security is crazy hard and having perfect security is impossible. Kudos to the dev team for resolving this so quickly.
It makes me think I should see about contributing. I'm not an expert in security flaws or pen testing, but having an extra set of eyes checking for vulnerabilities doesn't hurt.
Plus, in my experience, the vulnerabilities to watch out for are code that the developers didn't write. Updating packages usually isn't a problem until it's discovered a major version update is necessary looks at Spring angrily
Looks like they posted some more updates scene I check this morning:
u/spez did it!
Paid someone to do it, that man can't code.
So what happened:
Am I right?
I'm old-school developer/programmer and it seems that web is peace of sheet. Basic security stuff violated:
Am I right? Correct me if I'm wrong.
Again, web is peace of sheet. This would never happen in desktop/server application. Any of the bullet points above would prevent this from happening. Even if the previous bullet point failed to do its job. Am I too naïve? Maybe.
Marek.
User provided content (post using custom emojis) caused havoc when processing (doesn’t matter if on server or on client). This is lack of sanitization of user-provided-data.
100%. Always act as though user provided content is malicious.
JavaScript (TypeScript) has access to cookies (and thus JWT). This should be handled by web browser, not JS.
Uh... what? JavaScript is a client-side language (unless you're using NodeJS, which Lemmy is not). Which means JavaScript runs in the browser. And that JavaScript has access to cookies, that's just a basic part of how web browsers work. Lemmy can't do anything to prevent that.
How the attacker got those JWTs? JavaScript sent them to him? Web browser sent them to him when requesting resources form his server? This is lack of site isolation, one web page should not have access to other domains, requesting data form them or sending data to them.
Again, Lemmy can't do anything about that. Once there's a vulnerability that allows an attacker to inject arbitrary JS into the site, Lemmy can't do anything to prevent that JS from making requests.
Then, if they want to administer something, they should log-in using separate username + password into separate log-in form and display completely different web page
On the backend you'd still have a single system which kind of defeats the purpose. Unless you're proposing a completely independent backend? Because that would be a massive PITA to build and would drastically increase the system's complexity and reduce maintainability.
And that JavaScript has access to cookies, that’s just a basic part of how web browsers work. Lemmy can’t do anything to prevent that.
Yes and No. Cookies could be accessed by JS on the client. BUT. When the cookie is sent by the server with additional HttpOnly header, then the cookie cannot be accessed from JS. Look at Lemmy GitHub issue, they discuss exactly this. Lemmy server absolutely has power to prevent this.
Again, Lemmy can’t do anything about that. Once there’s a vulnerability that allows an attacker to inject arbitrary JS into the site, Lemmy can’t do anything to prevent that JS from making requests.
I believe they can. But I'm not sure about this one. The server could send a response preventing the web browser to request content from other domains. Banks are using this. There was an attack years ago when attacker created a web page with i-frame in it. The i-frame was full screen to confuse the victim it is actually using the Banks site and not the attacker site. The bank web site was inside the inner i-frame, the code in the outer frame then had access to sensitive data in the inner frame. I believe there are HTTP response headers that instruct the web browser to not allow this. But I'm not sure I remember how exactly this works.
completely independent backend
Yes, it would be more costly, but more secure. It is trade-off, which one is more important to you? In case of chat/blog/forum app such as Lemmy I prefer cheap, in case of my Bank website I prefer secure.
Oh I forgot another line of defense / basic security mitigation. If a server produces an access token (such as JWT or any other old school cookie / session ID), pair it with an IP address. So in case of cookie theft, the attacker cannot use this cookie from his computer (IP address). If the IP changes (mobile / WiFi / ADSL / whatever), the legitimate user should log-in again, now storing two auth cookies. In case of another IP change, no problemo, one of the stored cookies will work. Of course limit validity of the cookie in time (lets, say, keep it valid only for a day or for a week or so).
I'm sorry you want a mobile user to login every time their IP address changes? Why bother to keep them authenticated at all, just make them login for every web request. /s
This would never happen in desktop/server application
MOVEit would suggest otherwise.
If lenny-ui is already using a JSX based library (InfernoJS), why not use it? I can't believe they construct HTML manually like that without a hint of escaping or stripping. Sure, many markdown renderers tell you to just slap it in __html or dangerouslySetInnerHtml but there are many that just parse the MD and let you render it with JSX!
I also can't believe there's no CSP that stopped this. Sure, it's a pain in the ass to configure with a nonce but this is literally the kind of thing it's made to block!