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287 points govideo | 1 comments | | HN request time: 0s | source

I have a domain that is not live. As expected, loading the domain returns: Error 1016.

However...I have a subdomain with a not obvious name, like: userfileupload.sampledomain.com

This subdomain IS LIVE but has NOT been publicized/posted anywhere. It's a custom URL for authenticated users to upload media with presigned url to my Cloudflare r2 bucket.

I am using CloudFlare for my DNS.

How did the internet find my subdomain? Some sample user agents are: "Expanse, a Palo Alto Networks company, searches across the global IPv4 space multiple times per day to identify customers' presences on the Internet. If you would like to be excluded from our scans, please send IP addresses/domains to: scaninfo@paloaltonetworks.com", "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_7; en-us) AppleWebKit/534.20.8 (KHTML, like Gecko) Version/5.1 Safari/534.20.8", "Mozilla/5.0 (Linux; Android 9; Redmi Note 5 Pro) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.89 Mobile Safari/537.36",

The bots are GET requests which are failing, as designed, but I'm wondering how the bots even knew the subdomain existed?!

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yatralalala ◴[] No.43289743[source]
Hi, our company does this basically "as-a-service".

The options how to find it are basically limitless. Best source is probably Certificate Transparency project as others suggested. But it does not end there, some other things that we do are things like internet crawl, domain bruteforcing on wildcard dns, dangling vhosts identification, default certs on servers (connect to IP on 443 and get default cert) and many others.

Security by obscurity does not work. You can not rely on "people won't find it". Once it's online, everyone can find it. No matter how you hide it.

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TZubiri ◴[] No.43289843[source]
"Security by obscurity does not work"

This is one of those false voyeur OS internet tennets designed to get people to publish their stuff.

Obscurity is a fine strategy, if you don't post your source that's good. If you post your source, that's a risk.

The fact that you can't rely on that security measure is just a basic security tennet that applies to everything: don't rely on a single security measure, use redundant barriers.

Truth is we don't know how the subdomain got leaked. Subdomains can be passwords and a well crafted subdomain should not leak, if it leaks there is a reason.

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0hijinks ◴[] No.43292414[source]
Depending on one's threat model, any technique can be a secure strategy.

Is my threat model a network of dumb nodes doing automatic port scanning? Tucking a system on an obscure IPv6 address and never sharing the address may work OK. Running some bespoke, unauthenticated SSH-over-Carrier-Pigeon (SoCP) tunnel may be fine. The adversaries in the model are pretty dumb, so intrusion detection is also easy.

But if the threat model includes any well-motivated, intelligent adversary (disgruntled peer, NSA, evil ex-boyfriend), it will probably just annoy them. And as a bonus, for my trouble, it will be harder to maintain going forward.

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1. TZubiri ◴[] No.43295327[source]
It's a bit more complex than that as well. You might have attackers of both types and different datapoints that have different security requirements. And these are not necessarily scalars, you may need integrity for one, privacy for the other.

Even when considering hi sophistication attackers, and perhaps especially with regards to them, you may want to leave some breadcrumbs for them to access your info.

If the deep state wants my company's info, they can safely get it by subpoenaing my provider's info, I don't need to worry about them as an attacker for privacy, as they have the access to the information if needed.

If your approach to security is to add cryptography everywhere and make everything as secure as possible and imagine that you are up against a nation-state adversary (or conversely, that you add security until you satisfy a requirement conmesurate with your adversary), then you are literally reducing one of the most important design requirements of your system to a single scalar that you attempt to maximize while not compromising other tradeoffs.

A straightforward lack of nuance. It's like having a tax strategy consisting of number go down, or pricing strategy of price go up, or cost strategy of cost go down, or risk strategy of no risk for me, etc...