Azure's Weakest Link – Five Full Cross-Tenant Compromises

(binarysecurity.no)

182 points | by swq115 6 hours ago

11 comments

  • unddoch 49 minutes ago
    If anyone from Microsoft security reads this, could you please do something about login.microsoftonline.com/XXX/v2.0/adminconsent?

    The callback you're redirecting the user to at the end of that flow is forgeable if an attacker knows an azure tenant ID of a different customer, and putting a "Never use the tenant ID value of the tenant parameter to authenticate or authorize users" warning in the docs is only helpful as long as a way to authenticate users exists.

  • meekins 3 hours ago
    When it comes to the amount of cross-tenant leaks Azure looks to be way ahead the competition. Makes me wonder why enterprises still flock there.
    • xmcp123 3 hours ago
      Same reason as it was in 2002. “No one ever got fired for buying Microsoft.”
      • sandeepkd 11 minutes ago
        It pretty much applies to everything, going along the tide is always easier
      • Betelbuddy 2 hours ago
        Lets get our Cloud...from the same guys who have been unable to provide a freeze screen feature in Teams for 10 years..should be a firing offense...
    • traceroute66 3 hours ago
      > Makes me wonder why enterprises still flock there

      Well, when you're already paying Microsoft $/user/month for Intune, Teams&co. you might as well use Azure too.

      Only one vendor relationship to manage, and I suspect you probably have to spend far less money than you do with AWS to get some personal attention.

      • waz0wski 51 minutes ago
        > one vendor relationship to manage

        Anyone that's had to deal with Microsoft will tell you this means nothing

        If you can even get attention from someone, you'll be bounced between teams and people who barely know the products they are "supporting"

        Don't get me started on the Azure and O365 management portals

        The only worse support experience I've had was with Oracle where it could take days just to get the boilerplate "send us your logs" response on a Sev1 issue, despite the logs already being provided in the initial ticket

        In both cases, this is while at F100 companies with millions of dollars of licensed software and premium support contracts

        • traceroute66 26 minutes ago
          > Anyone that's had to deal with Microsoft will tell you this means nothing...

          In relation to everything you said in your post, let's just say "trust me, I know".

          But you missed the point I was making.

          The GP said "Makes me wonder why enterprises still flock there".

          And anyone who's had to deal with enterprise procurement knows if you've got a vendor on the list then its easier to deal with that one than push for multiple.

          And then there's the whole budgeting thing. If management can see you're already buying every single employee in the org a Teams license, then getting extra budget for some Azure toys will probably be an easier sell then "yeah, I know we're paying Microsoft a lot of money, but can we have some AWS too". Since in their eyes Azure and Teams licenses is the same thing, "money for Microsoft".

          Sadly the tech desk experience in enterprises tends to fall low down the list, if it is considered at all.

          Sure, in theory, if you've got a good CTO to fight your corner then YMMV, but not everyone does.

      • jeffrallen 1 hour ago
        Must be convenient to get all your security bugs from one vendor...
    • magicalhippo 1 hour ago
      For us a big part is that they have data centers in our country. It makes for improved latency and also makes a lot of our customers sleep better (justifiably so or not).

      Amazon doesn't and regardless nobody feels comfortable using Google, who knows when they'll discontinue a product we would rely on.

      So not a lot left to choose from.

    • toomuchtodo 1 hour ago
      Their sales folks are very good with C level folks, from the meetings I've sat in on. They will give you substantial credits and hands on support to build for you, depending on vertical and predicted future spend, especially if you're already at another cloud provider they're trying to pull you from.
      • Betelbuddy 1 hour ago
        AI Agents are salivating at that level of incompetence....
        • toomuchtodo 1 hour ago
          If there is no cost for poor decisions, nothing will be learned. Incentives drive outcomes.
    • jon128 1 hour ago
      Feels. AKA stupidity, ultimately.
  • giovanni_or2 43 minutes ago
    This guy must be the nightmare of Azure developers, kudos for the incredible work on finding these vulnerabilities!
  • albert_e 3 hours ago
    maybe we should tag submissions with dates now?

    [2026-10-02]

    beginning of curent month feels like two years ago when multiple vulns drop daily

  • mapotofu 38 minutes ago
    “Go to the cloud!”, they said.

    The cloud:

    Let’s see how their platform design holds up in the coming years, and if it can hold up to LLMs doing more of this same type of discovery and whether MSFT can fix it.

  • thewisenerd 4 hours ago
    path traversal and IDOR..

    likely been active since the inception of these capabilities

    wonder if the recommendation to "add randomness to resource names" is because of this (unrelated security by obscurity lol)

    • chinathrow 3 hours ago
      Gotta put these backdoors somewhere.
  • outworlder 57 minutes ago
    Ok so.

    Microsoft had an egregious cross-tenant vulnerability (really, how many cross-tenant vulnerabilities did other clouds have?).

    Vulnerability was reported.

    They fixed it - incorrectly. Reported again.

    They fixed it this time... and broke the previous fix. So it's vulnerable again.

    What a clown show.

  • xmcp123 3 hours ago
    God. I would hate to be the engineer forced to have enough Azure experience to be able to find these bugs and understand Azure’s infrastructure on this level.

    Should have been addressed in the Geneva conventions.

  • gary23w 35 minutes ago
    [flagged]
  • eugenekay 3 hours ago
    Reporting cross-Tenant issues as an outsider with a vulnerability chain gets you $$$.

    Reporting “theoretical” issues with validation as an Employee gets you a lot of questions as to why you were looking.

    Oh well.

    • outworlder 1 hour ago
      So MSFT discourages employees from reporting vulnerabilities?

      That explains a lot.

    • traceroute66 2 hours ago
      > Reporting “theoretical” issues with validation as an Employee

      Microsoft still has employees ? ;)

      (Sorry. Low bar. But in all honesty I thought they outsourced the majority of ops. I was surprised to hear in recent news that they actually had that many employees left)

  • klorbrinnbor 2 hours ago
    [flagged]