Build a REST WebService with GAE using OAuth - google-app-engine

I'm about to build a community platform from scratch. We are going to create the WebServices first and the community might have some third party components, so having solid WebServices is a good idea anyway.
Since the service is stateless we need authentication for every single call. Is it a good idea to implement the OAuth protocol for our service provider to perform this task although we are the only consumer right now?
By the way: We will deliver a mobile application before a website is launched.

The whole point of OAuth is to allow other websites (consumers) to get access to your data (you are the provider). Since you are the only consumer of your data, there is no need to implement OAuth at this stage of development.
Be lean, build something fast and put it in front of users/testers. Only at this point you will discover real bugs and get a feedback on the service so that you can improve it and steer the development in the right direction.
Note: OAuth as provided by App Engine (second paragraph) only supports users with Google Accounts (even if OpenID is used).

From my experience I created the REST WS in a authentication agnostic way: jersey methods accept everything, then there are several filters in order to validate the requests.
I used OpenId authentication for the web part, OAuth and BASIC AUTHENTICATION (with SSL) for API.
Probably it is not needed to create everything from the beginning, but remember to de-couple as much as possible your REST endpoint from the authentication: you will have a great benefit when you want to release APIs.
Last "philosophical" thing: OAuth is not totally stateless, in fact you have a temporary token that authenticates a user and it is similar to a session in the browser!

Related

How to protect my own api from hacking and make it private, so no body can access it exept from the android app?

I have written my own api and I want to upload it to the server but I want to secure it so noone can access it except from my app, I have tried slim-basic-auth library but it didn't work, I don not know why...
any help with that please ?
$app->add(new Tuupola\Middleware\HttpBasicAuthentication([
"secure"=>false,
"users" => [
"userher##" => "passhere##" ]
]));
I think you will never be able to hide the api url being called by the app (an attacker with rooted android device can intercept traffic easily ), If your api response user specific data, you can add auth header in request and same verify this header at server. You can also use Cross-Origin Resource Sharing-CORS and SSL for extra layer of security.
YOUR QUESTIONS
In a glance you want to have a private API, lock your Android App to it, and solve your code issue in the API server. Let's address each one in the order I mentioned them.
PRIVATE APIs
How to protect my own api from hacking and make it private
Well I have a cruel truth to reveal to you, no such thing as a private API exists, unless you don't expose it to the Internet, aka only have it accessible inside a private network, via programs that themselves are not expose also to the internet. By other words your API can only be private if its is air gaped from the internet.
So no matter if an API doesn't have public accessible documentation or if is is protected by any kind of secret or authentication mechanisms, once is accessible from the Internet is not private any-more, and you even have tooling to help with discover them.
You can read more about it in this article section, and I extract to here some bits:
Now just because the documentation for your API is not public or doesn’t even exist, it is still discoverable by anyone having access to the applications that query your API.
Interested parties just need to set up a proxy between your application and the API to watch for all requests being made and their responses in order to build a profile of your API and understand how it works.
A proxy tool:
MiTM Proxy
An interactive TLS-capable intercepting HTTP proxy for penetration testers and software developers.
So the lesson here is that from the moment you release a mobile app that uses your API, you can consider it to belong now to the public domain, because anyone can reverse engineer it and discover how your "private" API works, and use that to build automated attacks against it.
HOW TO LOCK AN API TO AN ANDROID APP
I have written my own api and I want to upload it to the server but I want to secure it so noone can access it except from my app
Well you bought yourself a very hard task to accomplish, that some may say that its impossible to do, but once you dig deep enough in the subject, you will be able to understand that you still have some paths to explore.
First you will need to understand the difference between WHO and WHAT is accessing your API server, followed by learning some of the most common techniques used to secure an API server, and finally you will learn that the Mobile App Attestation may be what your are looking for.
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 WAHT is accessing your API server, but I will extract here the main take aways 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.
So think about the WHO as the user that your API server will be able to Authenticate and Authorize to access the data, and think about the WHAT as the software making that request in behalf of the user.
API Security Defenses
The Basic Defenses
Now that you understand the difference between WHO vs WHAT is accessing your API server you may want to go an read my article about the basic techniques to secure an API:
In this article we will explore the most common techniques used to protect an API, including how important it is to use HTTPS to protect the communication channel between mobile app and API, how API keys are used to identify the mobile app on each API request, how user agents, captchas and IP addresses are used for bot mitigation, and finally how user authentication is important for the mobile security and api security. We will discuss each of these techniques and discuss how they impact the business risk profile, i.e. how easy they are get around.
More Advanced Defenses
You can start by read this series of articles on Mobile API Security Techniques to understand how API keys, HMAC, OAUTH and certificate pinning can be used to enhance the security and at same time how they can be abused/defeated.
Afterwards and depending on your budget and resources you may employ an array of different approaches and techniques to defend your API server, and I will start to enumerate some of the most usual ones.
You can start with reCaptcha V3, followed by Web Application Firewall(WAF) and finally if you can afford it a User Behavior Analytics(UBA) solution.
Google reCAPTCHA V3:
reCAPTCHA is a free service that protects your website from spam and abuse. reCAPTCHA uses an advanced risk analysis engine and adaptive challenges to keep automated software from engaging in abusive activities on your site. It does this while letting your valid users pass through with ease.
...helps you detect abusive traffic on your website without any user friction. It returns a score based on the interactions with your website and provides you more flexibility to take appropriate actions.
WAF - Web Application Firewall:
A web application firewall (or WAF) filters, monitors, and blocks HTTP traffic to and from a web application. A WAF is differentiated from a regular firewall in that a WAF is able to filter the content of specific web applications while regular firewalls serve as a safety gate between servers. By inspecting HTTP traffic, it can prevent attacks stemming from web application security flaws, such as SQL injection, cross-site scripting (XSS), file inclusion, and security misconfigurations.
UBA - User Behavior Analytics:
User behavior analytics (UBA) as defined by Gartner is a cybersecurity process about detection of insider threats, targeted attacks, and financial fraud. UBA solutions look at patterns of human behavior, and then apply algorithms and statistical analysis to detect meaningful anomalies from those patterns—anomalies that indicate potential threats. Instead of tracking devices or security events, UBA tracks a system's users. Big data platforms like Apache Hadoop are increasing UBA functionality by allowing them to analyze petabytes worth of data to detect insider threats and advanced persistent threats.
All this solutions work based on a negative identification model, by other words they try their best to differentiate the bad from the good by identifying what is bad, not what is good, thus they are prone to false positives, despite of the advanced technology used by some of them, like machine learning and artificial intelligence.
So you may find yourself more often than not in having to relax how you block the access to the API server in order to not affect the good users. This also means that this solutions require constant monitoring to validate that the false positives are not blocking your legit users and that at same time they are properly keeping at bay the unauthorized ones.
Regarding APIs serving mobile apps a positive identification model can be used by implementing a Mobile App Attestation solution that attests the integrity of your mobile app and device its running on before any request is made to the API server.
Mobile App attestation
Finally if you have the resources you can go even further to defend your API server and Mobile App, by building your own Mobile APP Attestation, and you can read in this article section about the overall concept of it, from where I extracted this:
The role of a Mobile App Attestation service is to authenticate what is sending the requests, thus only responding to requests coming from genuine mobile app instances and rejecting all other requests from unauthorized sources.
In order to know what is sending the requests to the API server, a Mobile App Attestation service, at run-time, will identify with high confidence that your mobile app is present, has not been tampered/repackaged, is not running in a rooted device, has not been hooked into by an instrumentation framework(Frida, xPosed, Cydia, etc.), and is not the object of a Man in the Middle Attack (MitM). This is achieved by running an SDK in the background that will communicate with a service running in the cloud to attest the integrity of the mobile app and device it is running on.
On a successful attestation of the mobile app integrity, a short time lived JWT token is issued and signed with a secret that only the API server and the Mobile App Attestation service in the cloud know. In the case that attestation fails the JWT token is signed with an incorrect secret. Since the secret used by the Mobile App Attestation service is not known by the mobile app, it is not possible to reverse engineer it at run-time even when the app has been tampered with, is running in a rooted device or communicating over a connection that is the target of a MitM attack.
The mobile app must send the JWT token in the header of every API request. This allows the API server to only serve requests when it can verify that the JWT token was signed with the shared secret and that it has not expired. All other requests will be refused. In other words a valid JWT token tells the API server that what is making the request is the genuine mobile app uploaded to the Google or Apple store, while an invalid or missing JWT token means that what is making the request is not authorized to do so, because it may be a bot, a repackaged app or an attacker making a MitM attack.
A great benefit of using a Mobile App Attestation service is its proactive and positive authentication model, which does not create false positives, and thus does not block legitimate users while it keeps the bad guys at bay.
So a Mobile App Attestation will allow your API server to identify, with a very high degree of confidence, that the request is coming from WHAT you expect, the original and unmodified APK you have uploaded to the Google Play store.
THE API SERVER CODE ISSUE
I have tried slim-basic-auth library but it didn't work, I don not know why
I am not familiar at all with the Tuupola project, but from a look into the README.md for the Slim API Skeleton, specially the section for how to get a token and then how to use it. The related code that generates the token can be found at routes/token.php, and to use the token to protect an API route you can find an example at routes/todos.php. This is all configured in the config file config/middleware.php. But I have to say that I am not impressed, security wise, with their posture, and this is because they encourage the exposure of server sensitive data via API endpoints, as we can see at routes/token.php, thus I strongly advise you to immediately delete all this endpoints if they are present in your project.
SUMMARY
In my opinion the best solution is defense in depth, by applying as many layers as you can, so that you increase the time, effort and skill-set necessary to by pass all your security layers, thus keeping at bay the script kids and occasionally hackers from abusing your API server and Mobile App.
So you should employ has much techniques as possible in both sides of the equation, mobile app and API, like the ones you have learned when reading the articles I have linked: HTTPS, API keys, User Agents, Captchas, Rate Limiting, OAuth, HMAC, Certificate Pinning, Code Obfuscation, JNI/NDK to hide secretes, WAF, UBA, etc.
In the end, the solution to use in order to protect your API server and Mobile App must be chosen in accordance with the value of what you are trying to protect and the legal requirements for that type of data, like the GDPR regulations in Europe.
GOING THE EXTRA MILE
I would strongly recommend you, to also take a look into the 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.
The thing you need is to add a Variable from your client app passing to your server application. Like APP_KEY or CLIENT_ID, which allows your app connecting to the server. You can add encryption so that your server application can only decrypt it and identify the request coming from your client app.
If your app is a web application and hosted in another server, you can implement IP whitelisting in your server.
But if your app is Mobile, you need to pass like a secret_key from mobile to your server.

Implementation concerns regarding IndetityServer4

I have some questions regarding Identityserver4 in the following context:
I have a number of domains (domainA, domainB, domainC ect.) and I’d like all of them to use Identityserver4 for authentication, but I’d like only one implementation of Identityserver4 (with asp.net identity and EF) and have the all domains use this implementation as clients. All domains is in a hosted environment with MS SQL as database, if that has any relevance.
Question 1:
Can IdentityServer4 run in a subfolder/area of domainA, and if so what are the necessary steps for getting this to work, e.g. the endpoints shown in the .well-known endpoint?
Question2:
What are the pitfalls, if any, in hosting Identityserver4 in a subfolder/area under domainA, and also having domainA use Identityserver for authenticating users for the rest of the site, and how to avoid the pitfalls if there are any?
The authorization part that permits one user to do this and not that, and the opposite for another user is not the concern of Identityserver4, but the respective domains/sites own responsibility as I understand what I can find online. In order to make use of roles and roleclaims in asp.net identity core 2 in each domain/site there has to be a user in that domain/site, that has a reference to a user in Identityserver4 in order for the domain to use Identityserver4 for authentication.
Question 3:
How do I avoid that the user must register both on the domain and in Identityserver4, one registration would be preferable and have the other made behind the scenes along with the reference?
I hope someone can provide the answers to one or all of my questions. Links to relevant blogs etc. are welcome, but I have scoured the web to find useful answers without any luck – hopefully some of you have better search engine skills than me.
Q1
Yes you can. IdentityServer is OWIN hosted environment, thus it will be working as a middleware for your domainA, if you set it up so. Having a public endpoint entirely depends on your domainA.
Q2
The possible problem you will possibly encounter would be performance issues. your domainA is going to receive requests from domainB and domainC including, of course, domainA itself. And IdentityServer's checks-up such as authentications, validations, issuing tokens could be obviously time consuming jobs compared to the plain HTTP requests.
While the middleware is doing its job, the performance will hit slightly lower rate then domanB and domainC. But this is a necessary, unavoidable backfire because you added one another layer in your HTTP windows to deal with the authentication / authorization / validation issues on your service endpoints.
You may want to scale out your IdentityServer if the traffic gets much more huger then you expected and you feel your authorization server is dragging the whole services down. I recommend you to perform some stress tests beforehand and compare the performance differences between the services using the identity service and the services using none of that.
Q3
This could be highly opinionated answer. But as you mentioned ASP.NET Identity and EF I think you already know the answer. It seems that you're going to manage the token and identity information in your own hosted DBMS. Then consider it done with the possible duplicated registrations. Your DBMS and your implementation for storing and fetching such data will do it for you as long as you've done it right.
If you're not going to use DBMS for the identity and token data, and use a cache or a file system instead, then you will have to pour some efforts into the implementation in order to guarantee concurrency on the transactions for such data.

Securing Symfony RESTful API consumed by angular front?

I have set up a Symfony based API which is being used by an Angular front end which is totally dependent of it (User registration included)
I have read multiple threads recommending using WSSE or FOSOAuthServerBundle but I'm not sure about the best method ?
If I understood correctly, WSSE has to send for each API request x-wsse headers which make me think it is not the best suited for performance.
About the FOSAuthServerBundle I have never used it and looks a bit complicated to me compared to WSSE, thus that's why I'm asking there before trying to implement it.
I have 2 simple groups of user (basic and admin), what would be the best way to secure my API, additionally providing an easy way to keep user persistence (I mean accesses through the different pages)?
How should it be in the Angular front side ?
Thanks for your help.
Refs: http://blog.tankist.de/blog/2013/07/16/oauth2-explained-part-1-principles-and-terminology/
http://obtao.com/blog/2013/06/configure-wsse-on-symfony-with-fosrestbundle/
It all depends on what your requirements are.
First of all, OAuth 2 is an authentication mechanism/spec which you can use in combination with sessions/bearer tokens/... This also applies for local accounts (since you want to do user registration).
FOSAuthServerBundle is a bundle to implement the server-side of the OAuth2 specification. This basically means you can expose your OAuth2 side of the API to other applications and allow them to use your accounts to authenticate. Think google login, twitter login, etc but for your own app.
This all has nothing to do with the way you validate / authorize your requests after the initial login has taken place.
Do you want to implement stateless authentication? Then I would recommend using the new JSON Web Token (JWT) specification.
See Symfony Bundle (LexikJWTAuthenticationBundle) and JWT description (JWT.io)
There are many resources on it from the angular side of things and the API part is pretty straightforward.
WSSE does not seem suited to implement in a RESTful API and I have no experience using/implementing it so I cannot comment on it too much.

Protecting API endpoint when developing two separate apps, Angular app & Laravel app

I've picked up Angular and am now developing two separate applications, the frontend, Angular app, and the backend, the Laravel app.
As of now my backend app is just an API endpoint that handles requests, database interaction, logic, validation, etc.
However, what stops someone from requesting /api/users/1 and getting that data?
Right now there is nothing in place that prevents this from occurring.
What's the best way to prevent this from occurring and verify the request is sent through the application and not through something like http://hurl.it from some random user?
You should first evaluate what routes need to be protected, and who should have access. Sometimes it might be fine to leave them open to the public.
Once you've figured that out you have a few options. I personally lean towards the oAuth 2.0 protocol. Some people find it to be over kill. Then there is also WSSE, I personally feel like today there is far better resources explaining the use of oAuth and would probably be easier to follow.
You can google around for oAuth server libraries for laravel. One such is: https://github.com/lucadegasperi/oauth2-server-laravel
You will also probably want to enable CORS if your angular app is on a different domain from your api. IE: api.example.com (holds api). And example.com is where your app lives.
For CORS laravel also has some packages, one such being: https://github.com/barryvdh/laravel-cors

Is OAuth and OpenID the right approach in this case?

I am still trying to wrap my mind around the workings of OAuth/OpenID, as such...
I am developing an "installed app" that will run on computers and iPhone. A given user may install the client app on multiple machines, and all of the user's installed clients will synchronize via a centralized Google App Engine service. The GAE service will also allow multiple users to collaborate on the data produced by the installed app, via a web app.
I don't want to roll my own authentication system, for my own ease and also to spare users from yet another set of credentials. As such I was initially thinking of using Google's clientlogin service, but then I thought OAuth/OpenID would be better because it would allow users to use not just Google credentials but also credentials from the other OpenID providers. Also, avoiding asking the user for a login/password seems more secure.
My question is... I'm not sure if this is the right use case for OAuth/OpenID. I am not accessing data from any other service, I am just looking for an authentication solution. Also, how difficult is this scenario to accomplish using Google App Engine (java)?
Any advice and/or starting points would be much appreciated!
My question is... I'm not sure if this is the right use case for OAuth/OpenID.
The "use case" for oAuth is: App X requires access to App Y. App X "asks" permission for access to App Y through your credentials. App X received an "authorized access token".
In your case, assuming I understood correctly, you could have the App on GAE implement an OpenID consumer and have your mobile app access the GAE app through oAuth.
In other words, your approach seems like a sensible one.

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