Comment on Windows RDP lets you log in using revoked passwords. Microsoft is OK with that. - Ars Technica
taladar@sh.itjust.works 3 days ago
So if I understand that correctly that cache is never updated again after it is initially created? Wouldn’t that lead to a lot of issues when the online account has its password changed in terms of the new password not working too? Something seems to be missing from this article.
Gibibit@lemmy.world 3 days ago
That is addressed in the article
wizardbeard@lemmy.dbzer0.com 3 days ago
I’m not exactly calling bullshit, but I’ve worked almost the entire last decade in IT in a Windows environment that has a decent amount of RDP use and has grown from ~2000-4000 employees during that time.
We’ve never encountered this as described.
From what I can tell, this “exploit” is just the standard NT password caching functionality that Windows has had for literal decades. Windows caches the last valid password used to log in, so if you lose your connection to your identity provider (AD or Entra) you can still log in with the last password confirmed to be valid.
In AD environments, this is what allows you to log into your laptop at home before you connect to VPN. You can’t hit your work AD before you’re on the work network. It also causes some fun because if you changed your password at work but didn’t lock and unlock your computer with the new one, it might still have your old one cached for the login screen but need the new one for VPN. This was a fairly common support call (I’m out of direct user support now so I can’t easily see if it still is).
Any situation where an old password would be valid indefinitely and a new one not recognized would require the machine to not be able to reach AD or Entra, but also to still be reachable by RDP… indefinitely. That’s definitely not impossible, but it’s one hell of an edge case to use the term “indefinitely” for.
It’s annoying that there aren’t separate settings from “local logins with AD as the IDP” and “remote logins with RDP”, but this feature is pretty damn critical for remote workers to be able to function and it is an intentional design choice as Microsoft states. Any potential workaround for a theoretical lack of this functionality is worse than the current state.
There’s no nefariousness here or lack of due dilligence. Labeling it as some horribly dangerous security hole with the amount of vagueness this article has is just misleading and clickbaity.
IllNess@infosec.pub 3 days ago
Would something like this happen if AD and Entra is in a remote office, the machine has a networking issue that prevents non local connections?
wizardbeard@lemmy.dbzer0.com 3 days ago
Yep. If the network is local only and can’t reach Azure (for Entra) or the Domain Controller (for AD) that we’re saying is at another physical location, then there’s no way for the machine to see the new password. It will continue to accept the old cached password until that network issue is resolved.
But that’s always been the case. It’s how Windows NT and forward work. In that scenario, you could only reach the machine over RDP if you were on another machine on that isolated network.
taladar@sh.itjust.works 3 days ago
Yeah, but “some cases” is extremely vague. If it is indeed cached indefinitely under all circumstances I would expect changed passwords to never work at all.
SL3wvmnas@discuss.tchncs.de 3 days ago
In typical MS fashion this might be very hard to debug with the hundreds of interacting components./s
In all seriousness they reviewed their internal docs not even the code (likely because it’s extremely complex) and said fixing this would brake existing functionality. I think “some cases” is doing heavy lifting for “we know many cases, but won’t tell the bad guys out there”.
SL3wvmnas@discuss.tchncs.de 3 days ago
Year of the Linux (Server|Desktop). Seriously. If you are in IT pls look into this (and hide your RDP server behind some VPN. No not MS RDP Gateway.)
the_crotch@sh.itjust.works 3 days ago
Anyone who isn’t doing this already is dumb. Same goes for exposing ssh publicly. I don’t care that you’re using a cert to log in, if there’s a 0 day in the openssh server you’re boned
maxwellfire@lemmy.world 3 days ago
If there’s a 0 day in the VPN software then I’m also probably boned. The chances of that seem on par with the likelihood of an openssh vulnerability? I feel like vpns are useful to secure services without good authentication, but their use in front of an openssh server had never made much sense to me.