[ta1243]

The problem is links leak.

In theory a 256 hex-character link (so 1024 bits) is near infinitely more secure than a 32 character username and 32 character password, as to guess it

https://site.com/[256chars]

As there's 2^1024 combinations. You'd never brute force it

vs

https://site,com/[32chars] with a password of [32chars]

As there's 2^256 combinations. Again you can't brute force it, but it's more likely than the 2^1024 combinations.

Imagine it's

https://site,com/[32chars][32chars] instead.

But while guessing the former is harder than the latter, URLs leak a lot, far more than passwords.

[internetter]

Dorking is the technique of using public search engine indexes to uncover information that is presumed to be private. It has been used to uncover webcams, credit card numbers, confidential documents, and even spies.

The problem is the website administers who are encoding authentication tokens into URL state, not the naive crawlers that find them.

[thayne]

That isn't an inherent problem with having a secret in the url. The problem is the url was leaked somewhere where it could get indexed.

And sometimes it isn't practical to require a POST request or a cookie.

And the risk of a url leaking can be greatly mitigated if the url is only valid for a short period of time.

[ta1243]

> That isn't an inherent problem with having a secret in the url. The problem is the url was leaked somewhere where it could get indexed.

Technically you're right -- after all sending an authentication as a separate header doesn't make any difference.

    GET /endpoint/?Auth=token

or

    GET /endpoint
    Auth: token

Sends the same data over the wire.

However software treats URLs differently to headers. They sit in browser histories, server logs, get parsed by MITM firewalls, mined by browser extensions, etc

using https://user:[e-mail]/endpoint or https://auth:[e-mail]/endpoint

Would be better than

https://site.com/endpoint/user/pass or https://site.com/endpoint/?auth=token

As the former is less likely to be stored, either on the client or on the server. I don't do front end (or backend authentication -- I just rely on x509 client certs or oidc and the web server passes the validated username)

[paulgb]

For better or worse, basic auth in the URL isn't really an option any more, (e.g. see https://stackoverflow.com/a/57193064). I think the issue was that it reveals the secret to anyone who can see the URL bar, but the alternative we got still has that problem and also has the problem that the secret is no longer separable from the resource identifier.

[thayne]

The browser could hide the secret after it is entered.

[paulgb]

Yeah, and it would still be useful for queries that never appear in the URL bar (like EventSource and WebSocket, where setting an Authorization header is not something that’s exposed by the browser)

[shkkmo]

It can be OK to put authentication tokens in urls, but those tokens need to (at a bare minimum) have short expirations.

[knome]

>It can be OK to put authentication tokens in urls

When would this ever be necessary? URL session tokens have been a bad idea ever since they first appeared.

The only things even near to auth tokens I can reasonably see stuffed into a URL are password reset and email confirmation tokens sent to email for one time short expiration use.

Outside of that, I don't see any reason for it.

[albert_e]

"presigned" URLs[1] are a pretty standard and recommended way of providing users access to upload/download content to Amazon S3 buckets without needing other forms of authentication like IAM credential pair, or STS token, etc

Web Applications do utilize this pattern very frequently

But as noted i previous comment these do have short expiry times (configurable) so that there is no permanent or long-term risk on the lines of the OP article

[1]: https://docs.aws.amazon.com/AmazonS3/latest/userguide/using-...

[vin10]

You are right about short expiry times but another catch here is that if pre-signed URLs are being leaked in an automated fashion, these services also keep the downloaded content from these URLs around. I found various such examples where links no longer work, but PDFs downloaded from pre-signed URLs were still stored by scanning services.

From https://urlscan.io/blog/2022/07/11/urlscan-pro-product-updat...

> In the process of scanning websites, urlscan.io will sometimes encounter file downloads triggered by the website. If we are able to successfully download the file, we will store it, hash it and make it available for downloading by our customers.

[couchand]

Indeed, the only valid operation with the magic URL is exchanging the URL-based token with something else (your PDF, a session token, etc.) and then expiring the URL, so by the time the scanner gets around to it the original URL is invalid.

[albert_e]

Aha. That is an interesting issue indeed.

[knome]

Interesting. I haven't built on s3, and if I did my first instinct would probably have been to gate things through a website.

Thanks for sharing your knowledge in that area.

[dylanowen]

They're useful for images when you can't use cookies and want the client to easily be able to embed them.

[layer8]

I wonder if there would be a way to tag such URLs in a machine-recognizable, but not text-searchable way. (E.g. take every fifth byte in the URL from after the authority part, and have those bytes be a particular form of hash of the remaining bytes.) Meaning that crawlers and tools in TFA would have a standardized way to recognize when a URL is meant to be private, and thus could filter them out from public searches. Of course, being recognizable in that way may add new risks.

[internetter]

We already have a solution to this. It’s called not including authentication information within URLs

Even if search engines knew to include it, would every insecure place a user put a link know it? Bad actors with their own indexes certainly wouldn’t care

[layer8]

How do you implement password-reset links otherwise? I mean, those should be short-lived, but still.

[andersa]

You could send the user a code that they must copy paste onto the page rather than sending them a link.

[vmfunction]

Hopefully using POST not GET. The GET links get logged in the HTTP server most of time. Just another great way to store your 'security credential' in plain text. Logs gets zipped and archive. Good luck with any security measure.

[hnlmorg]

As you said, short lived codes. And the codes don’t contain any PII. So even if the link does get indexed, it’s meaningless and useless.

[1231232131231]

A short-lived link that's locked down to their user agent/IP would work as well.

[tsimionescu]

Actually, there are cases where this is more or less unavoidable.

For example, if you want a web socket server that is accessible from a browser, you need authentication, and can't rely on cookies, the only option is to encode the Auth information in the URL (since browsers don't allow custom headers in the initial HTTP request for negotiating a web socket).

[zer00eyz]

Authentication: Identify yourself

Authorization: Can you use this service.

Access Control/Tokenization: How long can this service be used for.

I swipe my badge on the card reader. The lock unlocks.

Should we leave a handy door stopper or 2x4 there, so you can just leave it propped open? Or should we have tokens that expire in a reasonable time frame.. say a block of ice (in our door metaphor) so it disappears at some point in future? Nonce tokens have been a well understood pattern for a long time...

Its not that these things are unavoidable its that security isnt first principal, or easy to embed due to issues of design.

[bigiain]

> Or should we have tokens that expire in a reasonable time frame.

And that are single-use.

(Your password reset "magic link" should expire quickly, but needs a long enough window to allow for slow mail transport. But once it's used the first time, it should be revoked so it cannot be used again even inside that timeout window.)

[skissane]

> the only option is to encode the Auth information in the URL (since browsers don't allow custom headers in the initial HTTP request for negotiating a web socket).

Put a timestamp in the token and sign it with a private key, so that the token expires after a defined time period.

If the URL is only valid for the next five minutes, the odds that the URL will leak and be exploited in that five minute window is very low

[dmurray]

Also, it would allow bad actors to just opt out of malware scans - the main vector whereby these insecure URLs were leaked.

[fullspectrumdev]

So there was an interesting vector a while back where some email firewalls would reliably click on any link sent to them that was abused by spammers.

Spammers would sign up for services that required a click on a link using blabla@domainusingsuchservice

The services bots to check phishing would reliably click on the link, rendering the account creation valid.

One particularly exploitable vendor for getting such links clicked was one that shares the name with a predatory fish that also has a song about it :)

[rkagerer]

SharkGate?

Why coy about naming them?

[bigiain]

Yeah - that's just red-flagging "interesting" urls to people running greyhat and blackhat crawlers.

[loa_in_]

We already have robots.txt in theory.

[layer8]

I didn’t think robots.txt would be applicable to URLs being copied around, but actually it might be, good point. Though again, collecting that robots.txt information could make it easier to search for such URLs.

[FrustratedMonky]

"public search engine indexes"

Then it should be the search engine at fault.

If you leave your house unlocked is one thing.

If there is a company trying everyone's doors, then posting a sign in the yard "this house is unlocked", has to account for something.

[lmm]

A plain URL is an open door not a closed one. Most websites are public and expected to be public.

[FrustratedMonky]

Isn't that the point of the post?

There are URL's that are out there 'as-if' public, but really should be private.

And some people argue they should be treated as private, even if it is just a plain URL and public.

[lmm]

You can't blame the search engine for indexing plain URLs. Listing a closed-but-unlocked door is a bad analogy.

[FrustratedMonky]

Well. You also can't charge joe blow with a crime for browsing URL's, that happen to be private but accidentally made public.

Just by looking, you are guilty. That is wrong.

[pixl97]

You've been appropriately downvoted for a terrible take.

Imagine if you left your house unlocked it would be broken into seconds later. Even worse, the people that broke into it live in a different country with no extradition law and you'd never figure out who they are anyway.

In this case your insurance company would tell you lock your damned doors and the police may even charge you under public nuisance laws.

[FrustratedMonky]

Yeah, it is a terrible take. It's a bad situation.

Just like charging people for a crime for accessing private material, simply by browsing a public URL.

Maybe Better take:

It is like someone being charged for breaking and entering, simply by looking at a house from the street, when the door was left open. Your guilty by simply looking, and seeing inside. But you were just walking by, you saw inside before realizing it was a crime, now your guilty.

If you are going to charge people for accessing private sites, potentially by accident, by simply being provided a public URL from a search engine. Then shouldn't the search engine have some culpability?

Or. Better. Change the law so the onus is on the site to protect itself.

[FrustratedMonky]

"" Imagine a journalist finds a folder on a park bench, opens it, and sees a telephone number inside. She dials the number. A famous rapper answers and spews a racist rant. If no one gave her permission to open the folder and the rapper’s telephone number was unlisted, should the reporter go to jail for publishing what she heard?

If that sounds ridiculous, it’s because it is. And yet, add in a computer and the Internet, and that’s basically what a newly unsealed federal indictment accuses Florida journalist Tim Burke of doing when he found and disseminated outtakes of Tucker Carlson’s Fox News interview with Ye, the artist formerly known as Kanye West, going on the first of many antisemitic diatribes.""

https://arstechnica.com/tech-policy/2024/03/charges-against-...

"According to Burke, the video of Carlson’s interview with Ye was streamed via a publicly available, unencrypted URL that anyone could access by typing the address into your browser."

[4death4]

Passwords are always private. Links are only sometimes private.

[QuinnyPig]

Yup. There’s a reason putting credentials into url parameters is considered dangerous.

[bachmeier]

Well-chosen passwords stored properly are always private. Passwords also tend to have much longer lifetimes than links.

[noahtallen]

You can easily rate-limit an authentication attempt, to make brute-forcing account access practically impossible, even for a relatively insecure passwords.

How would you do that for the URLs? 5 requests to site.com/[256chars] which all 404 block your IP because you don't have a real link? I guess the security is relying on the fact that only a very a small percentage of the total possible links would be used? Though the likelihood of randomly guessing a link is the same as the % of addressable links used.

[ummonk]

I don’t think you realize how exponentially large the possible combinations of 256 characters would be. In fact it doesn’t need to be anywhere near 256 characters. 64 hexadecimal characters would suffice.

[ablob]

Which alphabet did you take as a basis to reach 2^256 combinations?

[1231232131231]

Binary?

[hiddencost]

No. In theory they are both totally insecure.

[Y_Y]

> site-comma-com

Did you do that just to upset me?

[masom]

You won't find a specific link, but at some point if you generate millions of urls the 1024 bits will start to return values pretty quick through bruteforce.

The one link won't be found quickly, but a bunch of links will. You just need to fetch all possibilities and you'll get data.

[duskwuff]

> You won't find a specific link, but at some point if you generate millions of urls the 1024 bits will start to return values pretty quick through bruteforce.

Not even close. 1024 bits is a really, really big address space.

For the sake of argument and round numbers, let's say that there are 4.2 billion (2^32) valid URLs. That means that one out of every 2^992 randomly generated URLs is valid. Even if you guessed billions of URLs every second, the expected time to come up with a valid one (~2^960 seconds) is still many orders of magnitude greater than the age of the universe (~2^59 seconds).

[charleslmunger]

I'm not sure your math checks out. With 1024 bits of entropy and, say, 1 trillion valid links, your chances of any one link being valid are 1/2^984

So test a million links - your probability of finding a real one is (1-1/2^984)^1000000. That's around 1/10^291 chance of hitting a valid URL with a million tries. Even if you avoid ever checking the same URL twice it will still take you an impractical amount of time.

[mbrumlow]

All this is fine and dandy until your link shows up in a log at /logs.

[ummonk]

The same can almost as easily happen with user-submitted passwords.

[1231232131231]

Passwords usually don't show up in server logs if submitted correctly.

[mbrumlow]

Love your qualifier. “If submitted correctly”.

[blueflow]

1024 bits seems a bit too much for the birthday problem to be a thing.

I looked at [1] to do the calculation but (2^1024)! is a number too large for any of my tools. If someone has a math shortcut to test this idea properly...

[1] https://en.wikipedia.org/wiki/Birthday_problem#Calculating_t...

[Dylan16807]

This isn't the birthday problem. That would be the chance of two random links overlapping. The birthday problem scales with n^2, while trying to guess links scales with m * n, number of guesses multiplied by number of links.

(Well, before you apply the logistic taper to it. So you wanted an approximation? There you go. Until you get the chance of a hit to be quite high, it's basically equal to guesses * valid links / 2^1024.)

[ta1243]

The chance is less than guessing a random 128 bit username and random 128 bit password. And then guessing a completely different username and password on the very next go.

You'd get far more return on investment breaking bitcoin wallets.

2^1024 is 10^308

Lets say there are 12 billion links per person, and 8 billion people. That's 100 billion billion, or 10^20 links.

10^20 / 10^308 is zero.

Lets say you can test 10 trillion links a second, and started when the big bang happened, you'll have tested 10^30 links so far.

The number of links you'll have found so far is zero.

[Dylan16807]

Yes, but I'm not sure why you replied to me?

[rjmunro]

2^1024 ≈ 10^300. There's only ≈10^80 atoms in the whole known universe. And we haven't even done the factorial.

[saagarjha]

Stirling’s approximation?

[eknkc]

We call 128 bit random data “universally” unique ids. 1024 bits won’t ever get close to returning any random hits.