Maybe I'm old but what are some popular use cases for webfinger? (I'm just learning about it now)
Webfinger is when you want to multiplex multiple identities on a single domain
E.g. https://example.com/.well-known/webfinger?resource=nick@exam...
Will serve the challenge proving your handle is @nick@example.com
A few things are effectively grandfathered in due to their vintage: /favicon.ico, /sitemap.xml and /robots.txt are the three that occur to me—so if you’re running something vaguely like S3, you’ll want to make sure users can’t create files at the top level of your domain matching at least those names.
But nothing new should use anything other than /.well-known/ for domain-scoped stuff, or else you run into exactly this problem.
I also recall /crossdomain.xml as an important one; allowing users to create an arbitrary file matching that name could allow certain kinds of cross-site attacks against your site.
You'd hope that people doing job X would seek at least some insight into whether there are best practices for doing X, even if it's not a regulated job where you're required by law to have proper training. Not so much unfortunately.
Example: Many years ago now, early CA/B Forum rules allowed CAs to issue certificates for DNS names under TLDs which don't exist on the Internet. So e.g. back then you could buy a cert for some.random.nonsense and that was somehow OK, and people actually paid for that. It's worthless obviously, nobody owns these names, but until it was outlawed they found customers. But, even though the list of TLDs is obviously public information, some CAs actually didn't know which ones existed. As a result some companies were able to tell a real public CA, "Oh we use .int for our internal services, so just give us a certificate for like www.corp-name.int" and that worked. The CAs somehow didn't realise .int exists, it's for International Organisations, like ISO or the UN, and so they issued these garbage certificates.
[Today the rules require that publicly trusted CAs issue only for names which do exist on the public Internet, or which if they did exist would be yours, and only after seeing suitable Proof of Control over the name(s) on the certificate.]
Reader could have an optional Flash plugin, and better yet, you could configure the PDF interactive plugin to dynamically download the swf file to run.
I built an entire Flex based rich UI that was dynamically loaded by the 1kb PDF you’d receive in email, the Flex app retrieved and posted data via HTTP APIs.
Because reasons.
That product was live for years. I think we shut it down as recently as 2 years ago.
To be 100% clear, wasn’t my idea.
But it was my mistake to joke about the absurd possibility to build such a thing in front of some biz folks.
in an interesting coincidence, I found this today!