I'm currently trying to make a website that allows users to host files, so I intend on buying a business Dropbox account for this purpose, generate an Access Token so the app don't go through OAuth authentication and internally serve and upload files to this single account.
Could it be done using a single Dropbox account? What are limits on calling from a single account. All access token logic would be hardcoded.
The Dropbox API does have a rate limiting system, but we don't have any specific numbers documented. It is only designed to prevent abuse though, and is accordingly very generous. Further, the limits operate on a per-user basis. That being the case, you generally don't need to worry about hitting it in normal use. The Dropbox API rate limiting system operates the same regardless of account type.
Also note that not all 429s or 503s indicate rate limiting, but in any case that you get a 429 or 503 the best practice is to retry the request, respecting the Retry-After header if given in the response, or using an exponential back-off, if not.
The API was designed with the intention that each user would link their own Dropbox account, in order to interact with their own files. However, it is technically possible to connect to just one account. The SDKs don't offer explicit support for it and we don't recommend doing so, for various technical and security reasons. Most of these concerns are allayed for server-side apps though.
So, if you did want to go this route, instead of kicking off the authorization flow, you would manually use an existing access token for your account and app, as you mentioned. (Just be careful not to revoke it, e.g. via https://www.dropbox.com/account/security .)
Related
I'm building an application where I need to make a request in the client-side frontend app to an external API, and I'm at a bit of a loss for how to make this maximally secure so that only valid requests can be forwarded to this external API and not whatever anyone wants.
As a first step in security, I've made it so that the client-side app can't speak to the external API directly, but must instead hit our own server-side API, which then proxies the request to the external API, so that the credentials for hitting the external API are at least stored solely server side and not client side.
This, however, has led to the same fundamental issue - how do I secure whatever credential/authentication system I use to authenticate requests I make from the client-side app to our own server-side app?
The issue is this is an online restaurant ordering service, and so we don't expect users to authenticate themselves with say, usernames and passwords before being able to place orders necessarily, and so order placement, which triggers the external API call, isn't gated behind any username/password scheme, and must be available to all consumers of the frontend app.
What's the best practice for security here? I've enabled CORS whitelisting as a minimum practice, such that only requests from our own domain are theoretically allowed by our server side API endpoint, but CORS is trivially bypassed if someone chooses to just spoof the origin URL.
What other options are available? I'm sure I must just be missing something trivial, since this must be an extraordinarily common issue with an established best practice, but I'm just somehow failing to find it.
Thank you!
As a Developer Advocate for API and Mobile security, seeing a developer that really cares about their app security always makes me smile, especially when they already show some effort was made to secure it, therefore accept my congratulations for your efforts.
My Answer Context
I'm building an application where I need to make a request in the client-side frontend app to an external API, and I'm at a bit of a loss for how to make this maximally secure so that only valid requests can be forwarded to this external API and not whatever anyone wants.
So, you have not detailed if it's a web app or a mobile app, and once my expertise relies on mobile and API security I will be answering with the assumption that is a mobile app.
The Challenge
The issue is this is an online restaurant ordering service, and so we don't expect users to authenticate themselves with say, usernames and passwords before being able to place orders necessarily, and so order placement, which triggers the external API call, isn't gated behind any username/password scheme, and must be available to all consumers of the frontend app.
You have here a complicated challenge to solve, because you have an app that is open to the public, no user authentication/identification of any sort, but that requires rules of access to the underline resources as if it was behind user authentication and authorization, but even if it was, it would still be vulnerable to being abused.
To understand why I need to clear a misconception that usually I find among developers of any seniority, that is about the difference between who and what is accessing an API server.
The Difference Between WHO and WHAT is Accessing the API Server
I wrote a series of articles around API and Mobile security, and in the article Why Does Your Mobile App Need An Api Key? you can read in detail the difference between who and what is accessing your API server, but I will extract here the main takes from it:
The what is the thing making the request to the API server. Is it really a genuine instance of your mobile app, or is it a bot, an automated script or an attacker manually poking around your API server with a tool like Postman?
The who is the user of the mobile app that we can authenticate, authorize and identify in several ways, like using OpenID Connect or OAUTH2 flows.
Think about the who as the user your API server will be able to Authenticate and Authorize access to the data, and think about the what as the software making that request in behalf of the user.
So, in your case you cannot identify who is in the request, thus you need a solution that is able to give a very high degree of confidence to the API backend that the request is indeed from what it expects, a genuine and unmodified instance of your app.
Possible Solutions
I'm building an application where I need to make a request in the client-side frontend app to an external API, and I'm at a bit of a loss for how to make this maximally secure so that only valid requests can be forwarded to this external API and not whatever anyone wants.
This requires very advanced solutions to properly secure, thus isn't at all trivial to achieve as you may think:
I'm sure I must just be missing something trivial, since this must be an extraordinarily common issue with an established best practice, but I'm just somehow failing to find it.
And yes, it's a common issue that often is neglected or not addressed properly, and the first step to solve it is to have a clear picture about the difference between who vs what is in a request, otherwise the devised solutions will fail to address the issue properly.
For Mobile Apps
Here I recommend you to go through this answer I gave to the question How to secure an API REST for mobile app?, especially the sections Hardening and Shielding the Mobile App, Securing the API Server and A Possible Better Solution.
This answer will show you several solutions, like WAFs and UBAs, but ends with a recommendation to use a Mobile App Attestation concept.
In a nutshell the Mobile App Attestation will allow the API backend to have a very high degree of confidence that the request is indeed from what it expects, a genuine and modified instance of the mobile app.
For Web Apps
You can learn some useful techniques to help your API backend to try to respond only to requests coming from what you expect, your genuine web app, and to do so I invite you to read my answer to the question Secure api data from calls out of the app, especially the section dedicated to Defending the API Server.
Do You Want To Go The Extra Mile?
In any response to a security question I always like to reference the excellent work from the OWASP foundation.
For APIS
OWASP API Security Top 10
The OWASP API Security Project seeks to provide value to software developers and security assessors by underscoring the potential risks in insecure APIs, and illustrating how these risks may be mitigated. In order to facilitate this goal, the OWASP API Security Project will create and maintain a Top 10 API Security Risks document, as well as a documentation portal for best practices when creating or assessing APIs.
For Mobile Apps
OWASP Mobile Security Project - Top 10 risks
The OWASP Mobile Security Project is a centralized resource intended to give developers and security teams the resources they need to build and maintain secure mobile applications. Through the project, our goal is to classify mobile security risks and provide developmental controls to reduce their impact or likelihood of exploitation.
OWASP - Mobile Security Testing Guide:
The Mobile Security Testing Guide (MSTG) is a comprehensive manual for mobile app security development, testing and reverse engineering.
For Web Apps
The Web Security Testing Guide:
The OWASP Web Security Testing Guide includes a "best practice" penetration testing framework which users can implement in their own organizations and a "low level" penetration testing guide that describes techniques for testing most common web application and web service security issues.
Ultimately your client needs to perform some operation on 3rd party API.
So we know that some operations should be allowed, and based on your description we also know that not every operation should be allowed.
So your security should be based on this premise. Don't create a dumb proxy that forwards every single request, but your intermediate API should only specifically allow the operations that you want it to allow, based on the rules you set.
If you don't have a username & password, you probably still have some other kind of rule that identifies a person (email/phone number?), which means you can create an authentication system.
Or maybe your 3rd party service should only be called after a user completed an order with a credit card, that logic needs to exist on your API.
Here is my scenario. Imagine there is a Yoga studio that uses a professional booking and reservation system that exposes an API. Through this API an application can make a reservation for a client. The API takes the client's userid and password to make the reservation. The booking API doesn't use OAuth or any social media sign-ins.
My desire is to create an Assistant Action that would retrieve the list of classes and allow the client to make a booking.
My puzzle is what design/architecture to look towards to supply the userid/password pair required by the booking API.
How have others solved this puzzle?
Should I store the userid/password as "user state" associated with the action?
First, you should have a conversation with the API provider about why they don't provide an OAuth-based solution. This is a security vulnerability waiting to happen, if it hasn't already.
Second, you need to think very carefully about your own risk profile in this case:
Google does not allow you to collect credential information (ie - passwords) through your Action.
Because of this, you must use Account Linking to authenticate them.
This means that you will need something (ie - a database or data store) to manage their account on your side.
This database would be a good place to keep the username/password you need to use for them for the API...
...but it now means that you need to take extreme care about protecting this database.
You don't really say how this API allows for accounts to be created and managed. If these accounts are just used for you (ie - the user doesn't necessarily see them), then you can mitigate some of that risk by treating the username/password as an opaque token that you manage and generate and that the user never sees.
If this is something that the user is aware of, then you'll need to approach the account linking in one of two ways:
Have them log into your service via an app or webapp using this credential info that you will need to save (ack!) and then link to the Assistant using OAuth.
Have them log into your service via an app or webapp using Google Sign-In, which will carry over to your Action. Then have them provide the credential info for the API, which you will need to save (ack!).
I use the Dropbox Datastore in an app that uses both the iOS and JavaScript SDKs. Aside from the 10MB datastore limit, it works pretty well.
But nearly every support request I get makes me wish I could have access to the user's data for debugging. Being able to see exactly what the user sees helps me to find and fix bugs very quickly.
Is there any way for me to access a user's data without logging into their account? Can I maybe store their access token and gain access to just their Dropbox Datastore data?
This is one of the attractive things about Parse: you can see all user data. While there is a lot of wisdom in sharding user data across Dropbox user accounts, it makes app debugging crazy-hard.
Any ideas? What do you do to get around this?
Dropbox datastores, like files, are considered the user's private data, and as such there isn't a way for an arbitrary party to gain access to said data without some sort of authorization (e.g., access to the account, having the data explicitly shared with them, etc.) Likewise, even the developer of an API app that a user happens to be using doesn't automatically get access to the data.
That said, if, as the developer of the app, you want to troubleshoot using your user's data, the most straightforward method would probably be to get an access token for that app/user pair from the user. That would replicate their setup most accurately. (Unfortunately, the Sync/Datastore SDK doesn't make it easy to extract/insert arbitrary access tokens like that though. So, in that case, this would be a bit of work to build some flow to get an access token, e.g., a small web app, and then some work to read data directly from the API.)
Alternatively, you may want to make it possible for the user to share the datastore with your own account.
In any case, it's very important that the user not be misled or confused as to what is happening or what the developer is requesting. That means being clear with user with regards to what the developer is requesting and what will be done with the data. In addition, apps should provide privacy policies in general.
I have a newbie question regarding google cloud storage. I'm looking to create a website where people can upload files (similar to Flickr in concept) and view them. I was looking at google's cloud storage option and it seemed interesting. I got a little hung up on the authentication process. Do all users need a Google account or did I just misread it? I guess my question is can I create a site where everyone doesn't have to sign up for a google account?
Thank you for your patience and help
Nope, there's no need for customers to have their own Google accounts. Google Cloud Storage supports that, in case you want to say "these accounts have access to this data", but you can also let your app grant access on a per-request basis using whatever logic or authentication scheme you like.
This is usually accomplished with signed URLs. Basically, you'd use your credentials to sign a very specific request (download object X, upload an object with name Y) and pass that URL to the user for them to use. Signed URLs are only valid for as long as you like (one of the parameters is how long the URL is good for).
Documentation on signed URLs are here: https://developers.google.com/storage/docs/accesscontrol#Signed-URLs
It's not strictly necessary to require a user to be logged in in order to write to your bucket (e.g., we have a public-read-write canned ACL for buckets), but it's generally a bad idea. Any data stored in your bucket will ultimately be charged to you, so allowing anyone to write without authentication opens you up to a great deal of abuse.
Likewise, you could make all of your objects public-read, but then you get charged for the bandwidth costs and have no control over it (though this is a much more reasonable thing to do than public-write).
A safer option would be to proxy bytes for your users - i.e., only you/your app can write to your bucket, and your users hand their bytes to you.
Generally speaking, though, the only types of authentication we support are Google accounts, signed URLs, and anonymous users.
We intend to develop rest based api. I explored the topic but it seems, you can secure api when your client is an app (So there are many ways, public key - private key etc). What about websites / mobile website, if we are accessing rest based api in website which do not use any login for accessing contents ( login would be optional ) then how could we restrict other people from accessing rest based api ?
Does it make sense using Oauth2.0 ? I don't have clear idea of that.
More clear question could be ,How can we secure get or post request exposed over web for the website which doesn't use any login ?
If it's simple get request or post request , which will return you json data on specific input, now i have mobile website , who will access those data using get request or post request to fetch data. Well, some else can also access it , problem is i am not using Login, user can access data directly. But how can we restrict other people from accessing that data.
What do you think is the difference between securing a website that is not using REST vs one that is using REST API?
OAuth provides authorisation capabilities for your site, in a REST architecture this means a user of the mobile application will have to provide their credentials before being allowed to access the resource. The application can then decide on if that user has access to the requested resource. However you've said your website doesn't need use authorisation.
You can use certificates however good luck managing the certificate for each client. My take on it is for your explanation you don't need to secure your website because you will never be able to manage a trust relationship between the client and the server. There are some options though:
You build your own client application that you ship out to people which can verify itself with the server using a packaged certificate with the client. E.g. iOS has this kind of feature if you build for that device.
You provide a capability to download a certificate that is 'installed' in the browser and used when communicating to your REST API
Use something like a handshaking protocol so when a client wants to make the first request it says; 'hi I'm a client can we chat?' And the server responds with 'yes for the next X minutes we can however make sure you send me this key everytime you tell me something YYYYYY' (you can use something like SecureUDID or equivalent for other devices than iOS).
There are probably others but you get the basic idea. Again in my opinion if your resource doesn't need authorisation then you don't need to secure that REST API. Can I ask what kind of data are you exposing via this REST API or functionality your providing? That might help provide a better answer.
You want authorization: only some agents (mobile clients) and/or users should be allowed to access those APIs.
To solve that problem, you need identification: a way for the server to tell who is who (or what), so the right decision can be made.
There are many different way to provide some form of identification, depending how much you care about security.
The simplest is a user agent string, specific to your mobile clients. But it can be faked easily. Slightly harder to fake are client based 'secrets' - embed some kind of secret or key in your mobile client code. You can make it really complicated and secret, but as ramsinb pointed out, you can't get security this way as it would require you to be able to guarantee that the secret you're shipping with the client (wether it's code, algorithm or any other fancy construct) can't be compromised or reverse engineered. Not happening when you don't control the client.
From there, 3 choices:
Security isn't really required, don't bother
Security isn't really required, but you still want to limit access to your API to either legit users/agents or people ready to invest some time hacking your protection - go with a specific user agent or a client embedded secret - don't invest much into it as it won't block people who really want access to get it anyway
Security IS required - and then I don't think there is a way around authentication, wether it's login/password, user specific (device specific?) keys, OpenID, etc... No matter what, you'll have to add to the user burden to some extent, although you can limit that burden by allowing authentication to persist (cookies, storage....)