Hacker News Reader

Comment by artanis0 | Hacker News Reader

As someone just starting to learn about secure restful web services: what is wrong with this security implementation of theirs?

View on HN

It's wrong because:

1. Passing creds via GET will show up in server logs. 2. The way REST works, you don't want to put anything in a GET which will change anything on the server (which includes generating an auth token). POST is the standard here.

edit It's better that they support POST for the auth creds in a header, but they should still be using HTTP standard authentication methods and return a 401 if unauthorized.

Also, look for already complete solutions for what you want. The whole point of REST is that you don't need to create all these query string parameters or put stuff in headers - the HTTP specs already include most of this functionality. For example HTTP already includes several authentication mechanisms[1], as does TLS[2], which are more secure (and standard!) than a form-based login.

[1] http://en.wikipedia.org/wiki/Digest_access_authentication [2] http://en.wikipedia.org/wiki/Secure_Remote_Password_protocol

If you're learning about REST, do it right and make this book your bible - it's brilliant: http://www.amazon.com/Restful-Web-Services-Leonard-Richardso...

Correct link: http://www.amazon.com/Restful-Web-Services-Leonard-Richardso...

Whoops, sorry!

Why should that particular book be the bible? I haven't read it, but I've flicked through it and seeing things like the suggestion that clients should "construct" URLs made me doubt its worth.

Shouldn't Fielding's original thesis be the bible?

Ok, maybe bible was used to loosely. In my experience, I found it a well written, well balanced, useful primer for real-world development of RESTful web services that also has enough depth to make it a reference I've returned to since. That's better.

Username and password are still sent in plain-text. You could use HTTPS to make the communication secure.

No they aren't sent plain-text:

>https://subdomain.sharefile.com/rest/getAuthID.aspx

Notice the https. The facepalm is just that there's no additional security in using POST vs GET.

POSTed values won't show up in typical server logs, whereas with GET their plaintext password would normally be logged on every request.

And POST over HTTPS keeps the POSTed values hidden from those who might listen, whereas with GET over HTTP it would just be out there in the URL.

This is exactly right.

Deleted comment

The server log is not encrypted when using TLS, which is one reason you want to keep sensitive information out of your URLs.

You have no way of knowing what they log and don't log. If their server logs are compromised, you should be assuming their username/password database was as well.

And HTTPS requests are encrypted. The whole request, including the "GET /someurl&password=s33krit HTTP/1.1" part. As I said, using POST doesn't add any additional security to this.

I don't understand the point you're trying to make here, or the stridency with which you're making it. You in fact do know that the most popular web servers do log the URL, and do not log POST parameters or individual headers.

That's why professional security audits will ding you for putting anything sensitive in a URL.

Actually, we ding you for putting sensitive information in URLs that are used in a browser. The reason is that it will then be sent to other sites in the referrer header. When it is used for an API it doesn't matter. A security audit will check that logs are not logging sensitive information or that they are properly secured and encrypted if they do contain such information. The combination of telling users to put their password into the url and logging the url would be a problem, but not either thing on its own.

No, SomeOtherGuy. This is an HTTPS site. The referer header does not behave the way you're implying it does on HTTPS sites.

And having read and written this particular audit line item about 29074894389734897 times in the last 15 years, let me assure you that logging is clearly an issue.

The bit about how "if someone can see your logs you're already boned" is also message-board-logic more than reality. Logs are shipped all over the place. On a network pentest, one of the things you do when you pop a box is hunt for logs; even after you get root on the machine, you don't automatically have all the passwords that get stuck in the log files. Same goes for all the random LogLogic-style consoles those logs get fed to.

If you have more questions about this stuff, my contact info is in my profile --- just click my username above this comment. I just wanted to chime in to say that 'carbocation was exactly right, but my comments are now repeating themselves, and so I'm done on this thread.

I agree with your concerns. But my comment was talking about "typical server logs" and HTTPS-POST vs HTTP-GET, while yours is addressing different issues.

I addressed why what gets in logs doesn't matter: if their server is compromised you have to assume you are boned anyways. And I don't understand why is your comment would be talking about "HTTP-GET"? The API in question is dealing with HTTPS for both GET and POST requests.

I don't understand why your comments pointing out details of the http spec and common-sense security considerations are being downvoted. I guess they are coming across as overly 'stident'? Anyway, I've found them helpful. Thanks.

If you're using SSL then form data in a POST request will be encrypted. HTTP headers are always encrypted using SSL. What wasn't clear to me from the documentation is whether the 'username' and 'password' are form data, or are actually custom HTTP headers. The latter choice would certainly be a facepalm.

> The latter choice would certainly be a facepalm.

Why?

>If you're using SSL then form data in a POST request will be encrypted

So will everything else, including the URI being requested, and thus the query string in it. Which is why it makes no difference using GET or POST.

So will everything else, including the URI being requested

I disagree from the data I'm seeing in the access logs from my SSL-hosted site running nginx. In the logs I can see lines such as:

GET /path/script?variable=blahblah&another_variable=123

EDIT since I appear to have lost the ability to reply to comments: I disagree with SomeOtherGuy2 that The fact that it may get logged is a red-herring.

Ignoring how secure a server with a rogue user accessing it is, it's possible that there will be more than one server involved in this scenario, and central logging servers are common. Will the traffic sent to the logging server be encrypted? And what if the logging server is compromised? You're essentially storing passwords in plain text.

It's all encrypted over the network. Obviously, your servers have to be able decrypt URL strings (and everything else), or they wouldn't be able to respond correctly. I think the assumption is just that servers may by default log decrypted URLs for GET requests, but not POST requests. But, as people have noted, that's not exactly reassuring, since you have no idea how their logging is set up.

You are very confused. SSL is used to encrypt transmission between the browser and web server. Of course the web server decrypts the data it receives, otherwise it wouldn't be able to use it. I am saying you can not sniff someone's HTTPS traffic and see the urls they are requesting, so sensitive information being in the url is not a problem. The fact that it may get logged is a red-herring, as if someone has compromised the server to gain access to the logs, they can access whatever they want, your username and password included.

But you can be 99.994% sure they're writing your plan text user name and password into their logs if you're using get, and if somebody breaks in and gets them, then they have your password, even if those passwords are properly hashed in the user database.

No, I wouldn't be 99.994% sure of that at all. In fact, I would assume that if they are suggesting that people use GET, that they are in fact not logging the query params, as any security audit would catch that.

And again, if they are compromised, then they are compromised. It doesn't matter if they have logging disabled, someone who would have access to the logs also has access to either the httpd account or the root account. Either way, they can already read your plaintext usernames and passwords directly when they are being submitted. Of course, they don't need your username and password anyways, as they already have full access to the system.

Picking a comment at random to thank you for at least trying to explain to people why their assumption of what's being logged relates in no way to security.

At least one person appreciates someone taking the time to correct this rather serious misunderstanding.

Does HTTPs encrypt headers or just the body? Are both things they're offering secure?

TLS is one layer below HTTP. So yes, both headers and body are encrypted.

"Everything in the HTTPS message is encrypted, including the headers, and the request/response load. With the exception of the possible CCA cryptographic attack described in limitations section below, the attacker can only know the fact that a connection is taking place between the two parties, already known to him, the domain name and IP addresses."

It's not compliant with the HTTP standard.

In what way is it not compliant?

It's not 'compliancy' as much as they're reinventing the wheel.

REST was born out of a philosophy that the HTTP protocol already solved much of what you wanted to do. HTTP not only solved this, but solved this a long time ago and with 'great success' (aka The Interwebs ;-)

- Authentication mechanism

- Operations (CRUD) -> GET, PUT, POST, DELETE, ...

- Caching -> Use HTTP caching mechanisms...

- Resources -> URL's

- Formats -> mime-types + use a HTTP Accept: header

- ...

They reinvent the wheel on many of the bullet points above: custom operations, custom format handling, custom authentication mechanisms, ... That's why this really is one of the worst implementation of an 'RESTful' API

I'm not saying it is a nice API, or that it is in any way a REST API. Just that unless I am missing something, it is HTTP compliant.

It isn't compliant, it doesn't use the verbs properly.

Would you care to point out where in the HTTP RFCs it requires the use of certain methods for certain operations? The reality is, you can do whatever you like as far as HTTP is concerned. In fact, only GET and HEAD are required to be implemented, all the other methods are optional.

HTTP does not have "verbs". That is REST. Just because they aren't using a REST API, doesn't mean they are not HTTP compliant.

I'm not sure that it actually violates the letter of the law of the spec, but I think it definitely violates the spirit, based on this section: http://tools.ietf.org/html/rfc2616#page-51.

I thought that GET (along with a few other methods) were supposed to be "safe" and not result in any action on the server except possibly logging and stuff like that? Is this required to be HTTP compliant or is this more of a recommendation?

RFC 2616

http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html

Custom headers should be prepended with "X-".

Also, the top line should read POST rest/getAuthID.aspx HTTP/1.1

Correction: Use of "X-" has been depreciated in a draft resolution.

Edit: As mentioned below, it isn't compliant in its use of the verbs (GET/POST etc).

Custom headers do not REQUIRE a prefix. So the lack of prefix does not make it non-compliant. In fact, the HTTP RFC doesn't even say they SHOULD have a prefix. And RFC822 which defines headers only says that protocol mandated headers MUST NOT be prefixed with "X-". Also, there's a draft proposal to deprecate the "X-" header prefix as it does more harm than good: http://tools.ietf.org/html/draft-ietf-appsawg-xdash-02

Second, absolute URIs are perfectly valid, all HTTP/1.1 servers MUST accept them: http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.1

Reply on news.ycombinator.com