The background first:
I have an application where a logged-in user(employee) X can see a list of all other users (employees). If the logged-in user X is a manager (their designation), then they can also edit certain attributes of the users they manage. For example, the location, designation, and the department of the user being edited. It should be noted X can edit only those employees who report to him/her, which means there are users which X is not allowed to edit.
When X clicks on a user to edit it, they navigate to a page like http:myapp.com/dashboard/editUser/<ID_OF_THE_USER_BEING_EDITED>
Obviously, X can get smart and manually edit the URL and put in the id of a user they are NOT allowed to edit, so before loading the edit form I need to check whether X has the authorization to edit user Y.
if X is authorized to do so, then that page displays a form (with the current attributes of the users pre-filled in the appropriate fields) to edit the user. Else, I display an 'Access Denied' kind of message.
Right now I have created a very badly named temporary endpoint (/api/v1/maybe_edit_user/?jwt=<TOKEN>&userId=<USER_BEING_EDITED>).
This grotesque-looking endpoint does 2 things:
It extracts the currently logged-in user from the token, and checks whether it has the required access level to edit the user (passed through the GET parameter userId)
If yes, then it returns the current attributes (name, email, location, designation, and other stuff) in the response, which is then pre-filled in appropriate fields when the form is displayed.
Once X submits the form, a PUT request is sent to another endpoint (/api/v1/users/<USER_ID_OF_Y> PUT) and the user Y is updated.
While this works, I don't find it attractive. I am trying to learn to write better, cleaner, and more organized code that is compliant with the standards.
The best practices for REST suggest that all endpoints should be nouns. My endpoint, on the other hand, is not even a simple verb. It's a god-forsaken phrase at the very minimum.
So, the questions here are:
How should I name my endpoint.
Should I use a single endpoint to check for permission, AND fetching the attributes of the user being edited, like I am doing right now? Or should I break them into 2 separate endpoints?
The fact that there is an access control list is an unrelated concern; ignore it.
Resource identifier identify resources. Resources are generalizations of documents.
You want an identifier that is consistent with the production rules of RFC 3986, and it is often convenient (but not required) to choose spellings that enable leverage of URI Templates (RFC 6570), but otherwise the machines don't care.
That means you can choose a spelling that makes things easier for humans; you get to choose which humans get priority here.
it returns the current attributes (name, email, location, designation, and other stuff) in the response
That's your hint as to what the document is; some sort of digest of Bob's... profile? employee record? dossier? that is apparently optimized for use in this specific kind of form.
So the identifier could be as simple as
/this-specific-kind-of-form/source-data/Bob
and a request might look like
GET /this-specific-kind-of-form/source-data/Bob HTTP/1.1
Authorization: Bearer <token>
The implementation looks largely like your sketch - verify the token, compare the claims to those that are required, and return either the resource or some flavor of Client Error (4xx).
The best practices for REST suggest that all endpoints should be nouns.
Don't read too much into that.
Notice that all of the following resource identifiers work:
https://www.merriam-webster.com/dictionary/get
https://www.merriam-webster.com/dictionary/post
https://www.merriam-webster.com/dictionary/put
https://www.merriam-webster.com/dictionary/patch
https://www.merriam-webster.com/dictionary/delete
You can click on any of those links, and your browser will create the correct HTTP request, and the server will do the expected thing.
Related
In some webpages or views, I have information displayed in table. Column values are rendered as links.
Problems:
When I hover over the link, it's URL is visible at the bottom of browser.
When I click on link, I show information for the resource requested in URL. (www.someurl.com/Employee/67 gives me information of employee with id = 67).
Now, this URL is displayed in browser. If you change URL to www.someurl.com/Employee/88, it shows information of employee with id = 88 though the logged in user is not supposed to see information for employee id 88
This are serious security breaches.
I am thinking of following as possible solutions:
URL masking at application level
Base64 encoding of URL to shorten and obfuscate it, so that users can't just throw values in the URL.
#Html.AntiForgeryToken() and ValidateAntiForgeryTokenValidation mechanism
Is there better and more secure approach other than above to solve this issue?
Check in Controller serving www.someurl.com/Employee/88 if currently authenticated user has access to Employee with ID 88 and throw exception if he does not - no need to mask url.
If the user is not supposed to be able to see the employee with the id of 88 then they should not be able to see the information for the employee with id 88. The URL is more or less irrelevant and is in your case only giving them an obvious clue as to how to gain unauthorised access to data in your system.
You need a proper security plan where data is only served from the database to the UI via the business layer if the logged in user if authorised to see that data.
Here is my idea about your first approach security breach:
Mix your id with some GUID or complex structure while sending it, and when you receive it, took out your id from this and then proceed. [ Your masking idea]
I'm generally a fan of RESTful API design, but I'm unsure of how to apply REST principles for a validation API.
Suppose we have an API for querying and updating a user's profile info (name, email, username, password). We've deemed that a useful piece of functionality to expose would be validation, e.g. query whether a given username is valid and available.
What are the resource(s) in this case? What HTTP status codes and/or headers should be used?
As a start, I have GET /profile/validate which takes query string params and returns 204 or 400 if valid or invalid. But validate is clearly a verb and not a noun.
The type of thing you've described is certainly more RPC-style in its' semantics, but that doesn't mean you can't reach your goals in a RESTful manner.
There's no VALIDATE HTTP verb, so how much value can you get from structuring an entire API around that? Your story centers around providing users with the ability to determine whether a given user name is available - that sounds to me like a simple resource retrieval check - GET: /profile/username/... - if the result is a 404, the name is available.
What this highlights is that that client-side validation is just that - client side. It's a UI concern to ensure that data is validated on the client before being sent to the server. A RESTful service doesn't give a whit whether or not a client has performed validation; it will simply accept or reject a request based on its' own validation logic.
REST isn't an all-encompassing paradigm, it only describes a way of structuring client-server communications.
We have also encountered the same problem. Our reasoning for having the client defer to the server for validation was to prevent having mismatched rules. The server is required to validate everything prior to acting on the resources. It didn't make sense to code these rules twice and have this potential for them to get out of sync. Therefore, we have come up with a strategy that seems to keep with the idea of REST and at the same time allows us to ask the server to perform the validation.
Our first step was to implement a metadata object that can be requested from a metadata service (GET /metadata/user). This metadata object is then used to tell the client how to do basic client side validations (requiredness, type, length, etc). We generate most of these from our database.
The second part consist of adding a new resource called an analysis. So for instance, if we have a service:
GET /users/100
We will create a new resource called:
POST /users/100/analysis
The analysis resource contains not only any validation errors that occurred, but also statistical information that might be relevant if needed. One of the issues we have debated was which verb to use for the analysis resource. We have concluded that it should be a POST as the analysis is being created at the time of the request. However, there have been strong arguments for GET as well.
I hope this is helpful to others trying to solve this same issue. Any feedback on this design is appreciated.
You are confusing REST with resource orientation, there's nothing in REST that says you cannot use verbs in URLs. When it comes to URL design I usually choose whatever is most self-descriptive, wheather is noun or verb.
About your service, what I would do is use the same resource you use to update, but with a test querystring parameter, so when test=1 the operation is not done, but you can use it to return validation errors.
PATCH /profile?test=1
Content-Type: application/x-www-form-urlencoded
dob=foo
... and the response:
HTTP/1.1 400 Bad Request
Content-Type: text/html
<ul class="errors">
<li data-name="dob">foo is not a valid date.</li>
</ul>
A very common scenario is having a user or profile signup form with a username and email that should be unique. An error message would be displayed usually on blur of the textbox to let the user know that the username already exists or the email they entered is already associated with another account. There's a lot of options mentioned in other answers, but I don't like the idea of needing to look for 404s meaning the username doesn't exist, therefore it's valid, waiting for submit to validate the entire object, and returning metadata for validation doesn't help with checking for uniqueness.
Imo, there should be a GET route that returns true or false per field that needs validated.
/users/validation/username/{username}
and
/users/validation/email/{email}
You can add any other routes with this pattern for any other fields that need server side validation. Of course, you would still want to validate the whole object in your POST.
This pattern also allows for validation when updating a user. If the user focused on the email textbox, then clicked out for the blur validation to fire, slightly different validation would be necessary as it's ok if the email already exists as long as it's associated with the current user. You can utilize these GET routes that also return true or false.
/users/{userId:guid}/validation/username/{username}
and
/users/{userId:guid}/validation/email/{email}
Again, the entire object would need validated in your PUT.
It is great to have the validation in the REST API. You need a validation anyway and wy not to use it on the client side. In my case I just have a convention in the API that a special error_id is representing validation errors and in error_details there is an array of error messages for each field that has errors in this PUT or POST call. For example:
{
"error": true,
"error_id": 20301,
"error_message": "Validation failed!",
"error_details": {
"number": [
"Number must not be empty"
],
"ean": [
"Ean must not be empty",
"Ean is not a valid EAN"
]
}
}
If you use the same REST API for web and mobile application you will like the ability to change validation in both only by updating the API. Especialy mobile updates would take more than 24h to get published on the stores.
And this is how it looks like in the Mobile application:
The response of the PUT or POST is used to display the error messages for each field. This is the same call from a web application using React:
This way all REST API response codes like 200 , 404 have their meaning like they should. A PUT call responses with 200 even if the validation fails. If the call passes validation the response would look like this:
{
"error": false,
"item": {
"id": 1,
"created_at": "2016-08-03 13:58:11",
"updated_at": "2016-11-30 08:55:58",
"deleted_at": null,
"name": "Artikel 1",
"number": "1273673813",
"ean": "12345678912222"
}
}
There are possible modifications you could make. Maby use it without an error_id. If there are error_details just loop them and if you find a key that has the same name as a field put his value as error text to the same field.
I'm working on a REST server. I have an order RESOURCE.
From my understanding the PUT verb should create a new order based on the URL. My question is: How can this work if the resource is new and you don't know the ID of the new order?
I know the debate about POST vs PUT, but I'm quoting the w3 specs for PUT http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
"If the Request-URI does not point to an existing resource, and that URI is capable of being defined as a new resource by the requesting user agent, the origin server can create the resource with that URI"
In RESTful APIs, PUT is typically used to update a resource or create one if it doesn't exist at the specified URL (i.e. the client provides the id). If the server generates the id, RESTful APIs typically use a POST to create new resources. In the latter scenario, the generated id/url is usually returned or specified in a redirect.
Example: POST /orders/
According to W3C Both PUT and POST can be used for update and/or create.
The basic difference between them is how the server handles the Request-URI. PUT URI identifies the entity and the server should't try to map it to another URL, while POST URI can be a handler for that content. Examples:
It's OK to POST a new order to /order, but not a PUT. You can update order 1 with a PUT or POST to /order/1.
To put it simply POST is for creating and PUT is for updating. If you don't have an ID for an object because it isn't created yet, you should be using a POST. If an object DOES exist and you just don't have the ID for it, you're going to have to search for it using a GET of some kind.
The thing to remember is Idempotence. A PUT (and GET for that matter) is idempotent. Basically meaning, you can hit the same URL over and over and it shouldn't make a difference the 2nd or 3rd time (It edits the data once, and calling it again it doesn't make that change again). However a POST is not idempotent. Meaning, you hit the same URL 3 or 4 times in a row and it's going to keep changing data (creating more and more objects). This is why a browser will warn you if you click back to a POST url.
You say, "don't know the ID of the new order" therefore the following is not true "URI is capable of being defined as a new resource by the requesting user agent", therefore PUT is not appropriate in your scenario.
Where is the confusion? I am of course assuming the Id would be part of the URL.
I am looking for some best practices when is comes to creating EditMoels and updating data in an ASP.NET MVC app. Lets say I have a Url like so /Post/Edit?Id=25
I am ensuring the user has permissions to edit the specific post by Id on the Get request and the same for my Post in the controller. I am using the ValidateAntiForgeryToken.
Questions: Should I include the Id property in my EditModel? If so, Should I encrypt it?
The problem is I can use FireBug to edit the Id hiddedinput and edit a different post as long as I have permission to do so. This is not horrible, but seems wrong.
Any help would be great!
There are several ways to prevent this.
The first - don't send sensitive data to the client at all. Keep the post id in session variables, so the user can never edit it. This may or may not be an option depending on your architecture.
The next approach is to convert the direct reference to an indirect one. For example, instead of sending postids = {23452, 57232, 91031} to the client to render a drop-down list, you should send an opaque list {1,2,3}. The server alone knows that 1 means 23452, 2 means 57232 and so on. This way, the user can't modify any parameter you don't want him to.
The last approach is including some kind of hash value that adds as an integrity check. For example, suppose you have 3 hidden fields in a html page - {userId=13223, postId=923, role=author}. You first sort the field names and then concatenate the values to get a string like postId=923&userId=13223&role=author. Then, append a server secret to this string, and hash (SHA-1 or MD5) the entire string. For eg. SHA-1('postId=923&userId=13223&role=author&MySuperSecretKey'). Finally add this hashed value as a hidden parameter. You may also want to add another hidden field called ProtectedParameters=userId,postId,role.
When the next request is made, redo the entire process. If the hash differs, balk the process.
Security wise, I have listed the options in decreasing order. At the same time, its probably in the increasing order of convenience. You have to pick the right mix for your application.
I don't think you should worry with that, if the user does what you said, i suppose that you'll know who edited what, so if he edits the wrong post, doing as you said, you can always remove his edition rights...
If you can't thrist your users, don't let them edit anything...
I want find a platform/language agnostic solution to ensuring the origin of a FORM POST is from an expected source. I.e. Page1.aspx posting to Page2.php within the same web site.
Specifically what I am attempting to do here is to prevent request forgery.
Use a hidden field in your form, which contains a token your app generated. Store the token in the user session. When the form is submitted, your app will check that the value of the hidden field is identical to the value stored in the user session.
If it is identical, then you know the submitted form comes from where it is expected to come.
Old Thread, but might still be useful.
If you do not have session info set (best option) then you can include a hidden field with an encrypted timestamp then compare it (after de-crypt) to the current time on the process end to make sure it is relatively close and thus as recent as you deem necessary.
You could include into the form a hidden field which would be the SHA1Hash("some-secret" + Remote_IP + PerSessionSecret).
The PerSessionSecret is something you autogenerate in the beginning of the session. "some-secret" is a global secret value - which will help a little bit in case the randomly generated PerSessionSecret turns out not to be very random enough.
Then do the same calculation upon the form submission and you know it's most probably submitted from the same client that it was sent to. (Of course, if you have multiple clients behind the single address, like a proxy or a NAT, you can not distinguish between them reliably).