back to article Download this update from Oh, sorry, that was malware on a hijacked sub-domain. Oops

If you saw a link to, would you have trusted it? Downloaded and installed an Edge update from it? How about to change your password? Well, you shouldn't have, because the pair were among sub-domains hijacked by vulnerability researchers to prove Microsoft is lax with its own …

  1. Roland6 Silver badge

    Microsoft's response is concerning. ... and has refused to pay out bug bounties for the issue.

    Being pedantic, it does seem that bugs in MS's own website aren't covered by the bounty program...

    Interestingly, I've noted with some clients their backup email servers - visible in their DNS records, also refer to servers - with similar generic names - on Google/AWS/Azure, which currently don't resolve to an actual host. So this isn't going to be a one off problem...

    1. diodesign (Written by Reg staff) Silver badge


      Yeah, dude, the rub is that the researchers thought the bounty included sub-domain security, Microsoft disagrees.


      1. IGotOut Silver badge

        Re: Pedant would it be if you set up a little "login authentication" asking them to put in their name and say email address with a phone number for y'know password recovery and that sort of shit.

        Would MS be liable under GDPR as the subdomain belongs to them?

        1. Charlie Clark Silver badge

          Re: Pedant

          I don't think GDPR even needs to enter into this. This could almost certainly be considered as being accessory to fraud which could even mean joint action claims in the US.

      2. Dan 55 Silver badge

        Re: Pedant

        Funny how MS are all for blurring the lines between desktop and Internet except when it suits them not to.

    2. LDS Silver badge

      Re: Microsoft's response is concerning. ... and has refused to pay out bug bounties for the issue.

      MS is utterly wrong. This is a case of "use after free" vulnerability.

      1. Claptrap314 Silver badge

        Re: Microsoft's response is concerning. ... and has refused to pay out bug bounties for the issue.

        I disagree. The error was namespace pollution. The use after free is simply one problem that can arise if you allow namespace pollution. Please see my other post.

  2. Stuart Moore

    Others have found this

    Went to a presentation by the authors of the appcheck tool, they showed the same demo - they've been able to take over - it seems MS just don't care.

    1. Mark 85 Silver badge

      Re: Others have found this

      They're just too big to care. The person who decommissions the server probably has no clue who tell to decommission the sub-domain. And no one ever follows up to see if it has been done. Even if they knew who contact regarding decommissioning, they've probably left the company and their email addy is a dead end.

      1. GnuTzu

        Re: Others have found this

        "...too big to care."

        Seems that's the precursor to too-big-fail. It'll be a sad day if the government ends up having to bail out cloud providers.

        Anti-trust laws just aren't what they used to be... as if they were ever enough in the first place.

  3. NibsNiven

    Oh dear, they STILL haven't figured out how dangerous this is!

    "They can detect those vulnerabilities by comparing DNS records and HTTP responses, just as we did."

    Actually, not so simple. An HTTP response might well come from a hijacked subdomain. They have to ensure that the HTML itself is Microsoft created. Judging by their sloppiness so far, I'm guessing they would have a hard time determining theirs from not theirs.

    1. Psion1k

      Re: Oh dear, they STILL haven't figured out how dangerous this is!

      I suspect that what is meant is that if you poke a dead/vulnerable alias, it will either not respond, or respond with a standard message effectively saying "no such website here", so is probably ripe for hijacking.

      Any other response from the URL poked means it is still in use by "something", so they skip to the next possibility.

      For MS, any such responding DNS entries are targets for removal.

      The article is not about finding already compromised sub-domains, but about preventing future compromises from stale DNS records, though some sort of hunt and destroy for such is probably needed.

  4. SImon Hobson Silver badge

    And lets not forget ...

    That whoever does hijack a domain like this can also get an SSL cert for it - all that's required for that is to be able to place a file in the site for the cert validator to check to "prove ownership" of the domain. So :

    subdomain of microsoft,com - tick

    has SSL cert (padlock icon in address bar) - tick

    What could possibly go wrong !

    TBH, having managed DNS before (but definitely not on such a grand scale), it's a PITA. When a business (customer in our case) wants something there an obvious trigger - register domain for customer, setup DNS. When that need goes away, no-one can be ar*ed telling you about it - so you need to run frequent checks so you can infer when a domain (or subdomain in this case) is no longer needed, and either nuke it, or invoke procedures to check and then nuke it.

  5. This post has been deleted by a moderator

  6. Anonymous Coward
    Anonymous Coward


    Works fine for anything that's adding to the monthly bill.

    Fails for anything that could reduce said bill.

    Surpised? Not.

  7. aaaa

    generic names - on Google/AWS/Azure

    We saw this 20-30 years ago with the initial explosion of the web - everyone was using hosting companies, and all it takes is for the greedy host to rent out the same IP address to some SPAMMER and suddenly everyone blocks you because you were on the same IP address. This is just the same, but the modern cloud equivalent using shared hosting services / DNS. It's an inherent fault, and it will (thankfully) push people away from using them.

    I'm already blocking most email from generic SMTP servers Google/AWS/Azure that use a generic DKIM. So it looks like I'll start to block most web sites hosted on generic domain names on Google/AWS/Azure too. If you want your email delivered, set up your own email server and your own domain name and your own private DKIM. It you want people to go to your own web site, don't redirect.

    For the technically curious: we have two SPAM rule classes: for non-generic SMTP we look for keywords/SPAM scores and quarantine emails based on that; for generic SMTP/DKIM we look for keywords and quarantine ALL EMAILS unless they match a particular keywords that leads use/whitelist for existing customer email addresses.

    1. Anonymous Coward Silver badge

      Re: generic names - on Google/AWS/Azure

      This is not about website redirection. It's just using DNS CNAMEs which are susceptible to re-registration. Same would happen if it were an IP address in a pool that could be re-used.

  8. thondwe

    Hands Up

    Who's got clutter in their DNS, reverse DNS, dead (literally) users in AD, AAD, LDAP, ACLs for long gone servrices, etc that was useful once, but no longer.

    Bet there's loads of DevOps "Infrastructure as Code" scripts which create stuff, but almost no scripts to decommission something?

    Bottom Line - People don't like tiding up (have teen daughters!), but someone the size of Microsoft should be better at it!

    1. LDS Silver badge

      Re: Hands Up

      It's a typical case of what I call SLaCK (Sysadmin Laziness and CocKups).

      Asked my sysadmin to cleanup the DNS some time ago - he didn't anything yet. Systems work, why spend time to clear the cruft?

      1. bombastic bob Silver badge

        Re: Hands Up

        How to get junior system admins interested in cleaning up DNS: put some "easter eggs" in there deliberately so they can be "found" and eliminated.. These can include amateur pr0n as well as "potential blackmail material" and other fun things. And don't announce the grand prize, let them FIND the thing within the matrix of unmaintained sub-domains. First to find it gets the prize. And have more than one available, evn simple things like a free beer, half-day off, etc.

      2. Anonymous Coward
        Anonymous Coward

        Re: Hands Up

        It’s a nice theory, but unless you’re also the person who manages the systems those records point to then how do you know if they’re dead or not? Doesn’t respond to ping? OK, but did it before? Is the thing at the other end always online or just when it’s in use? Does some legacy critical bit of code reference that record?

        It gets even more tricky where multiple services use the same resources. Remove a service, but can you remove that resource? Is anything else using it? Are things documented so you know when the last service is switched off so the resource can be removed? Crucially, can you trust the documentation?

        It’s very easy to descend into a view where there’s little risk of leaving old records where they are, but there’s potentially major risks if you remove them and they’re still in use. And if you’re in a blame culture, leave it and it’s the fault of someone else not telling you it’s no longer in use, remove it (and things go wrong) and it’s your fault.

  9. N2


    The bit would instantly raise the alarm

  10. Claptrap314 Silver badge

    Do NOT cross the streams!

    Yes, use after free is certainly part of the problem. But it is not the root issue. The root issue is that, in its infinite wisdom and attention to security, it is allowing customers (attackers) to register domain names in the same namespace as it is using for its own business. Certainly, it needs to allow customers some name space to register their domains. But there is no excuse for using that same namespace for its business. None.

    This is an architecture issue. Architect things properly, and sloppy housekeeping won't burn you down. Architect them poorly....

  11. Claptrap314 Silver badge

    Subdomain security

    I'm no OpsE, but I don't quite understand the problem with subdomain maintenance, assuming that you are set up as a CA. I know my previous post arguing that everyone should be a CA had a mixed voting response, but this is precisely the class of thing that can and should be automated into oblivion. With your own CA, you can issue and revoke subdomain certs at will. If someone, somewhere, is on the hook to assert the continuing need for each subdomain in the business, then if they fail to assert, the automated process to remove the domain begins. (Warning email to them and their supervisor, wait X days...)

    Yes, this is work to set up, but magnitudes less than cleaning up after a hijacking.

    1. Anonymous Coward
      Anonymous Coward

      Re: Subdomain security

      a) Because certificate revocation is broken and doesn't work (see

      b) Why do you need your own CA to do that? You would just need any CA that you can automate the revocation

      c) If you've got the ability to create such an automated process then why don't you automate the process of removing the entries from the DNS? Better to have the subdomain nuked than just the cert for it.

      1. Claptrap314 Silver badge

        Re: Subdomain security

        Uggh. I got things conflated as I was typing.

        Yes, removing DNS entries is the primary act. Cert revocation for the deactivated subdomains is a secondary matter.

  12. Anonymous Coward
    Anonymous Coward

    At least as insidious...

    It seems that "sway" is a service that end-users can set up web-pages and back-ends on.

    And guess what, spammers and scammers and other miscreants send messages saying that you have "new voice messages" and links to to retrieve them - I've received a few since early January.

    The URL really is a legit, owned-by-Microsoft domain.

    And with "office" taking over everything, the ruse is almost believable...

POST COMMENT House rules

Not a member of The Register? Create a new account here.

  • Enter your comment

  • Add an icon

Anonymous cowards cannot choose their icon

Other stories you might like

Biting the hand that feeds IT © 1998–2022