I managed to implement the auth function described by google using a clientid.
So when visiting the html page, one gets asked to authenticate with a google account.
Question: As it is now, everyone can use the site, as long as he/she has a Google account to authenticate with. How do i restrict the usage to a certain group of users? Do i need to manage a list of unique user ids provided by the User object? Or is there already something prebuild, that i can make use of?
I think the safest would be to keep a list of Ids. What are the basis that you expect google or anyone else to know what kind of users you want to allow?
Even if its only geographic there are times when people might be using proxies or using yor site from a remote location.
The site you linked to also says so much :
Specifying Authorized Clients in the API Backend
You must specify which clients are allowed to access the API backend
by means of a whitelist of client IDs. A client ID is generated by the
Google API console from a client secret, such as the SHA1 fingerprint
of a key used to secure an Android app, or from the Bundle ID/Apple
Store ID pair for an iOS app, as described in Creating OAuth 2.0
Client IDs. At runtime, a client app is granted the authorization
token it needs to send requests to the API backend if its client
secret matches one contained in a client ID within the API backend's
client ID whitelist.
Also its only common authentication (who is it), authorization (what they can do on your site) comes from you.
Related
I have a website and my own server and database, I also have an native Android app. I need to allow users to be able to sign-in with their account from the website inside the app in order to sync information and other things they need to use. I've been stuck for a couple of days trying to figure out how to do that. I've found a lot of content regarding OAuth and AppAuth but they are focused on using an OAuth API to the job. Back on my server, I use Hybridauth for social login, but users can also register directly on the site. How would be the proper way to allow my users to sign-in to their website account through the Android app?
You're overthinking it. OAuth isn't meant for users to log in, it's meant to enable external services to access data on behalf of a user.
To make a user log in? Create a POST endpoint on your webservice named login. It should take two parameters- username and password. The body of the login service should salt and hash the password, then check if the hash equals the hash stored in the db for the same user. If so, you're logged in and you return a success packet with a unique token to authenticate you for later requests. If not, you return a failure. The Android app would ask the user for their data, then send a request to the endpoint. On success it saves the token and sends it in all future requests to authenticate yourself, either as a parameter or as a header.
This is of course the simplest possible version. More advanced features would include expiring of login tokens, refresh tokens, possible lockout if you have too many bad requests, etc. But the above is the basic idea. Although really I'd look for an open source solution you can take, as there's quite a lot of complexity when you get into all the stuff mentioned above, and its a place where a mistake that leads to a vulnerability is probably the most dangerous.
I've a very compelling question to begin first. But this is not about code level, it's just for me to gauge my understanding. Correct me if i'm wrong, now days MobileApps as per design utilizes the session token method for a request.
Currently, for first time user will pass in their deviceID, pin, and timestamp for an encrypted value from the back-end. Subsequently , the front-end system will send this parameter for request and get a response success. The token has expiration date of 30 minutes.
With a recent event, hackers are able to manipulate the request from a script by spoofing. So the hackers are imitating the same behavior as from mobileapps. How do we cater for this kind of scenario? Is there a way to block these kind of request ?
Token Method
Correct me if i'm wrong, now days MobileApps as per design utilizes the session token method for a request.
I think you are referring to OAUTH2 or OpenID tokens.
OAUTH2
OAuth 2.0 focuses on client developer simplicity while providing specific authorization flows for web applications, desktop applications, mobile phones, and living room devices.
OpenID
OpenID Connect 1.0 is a simple identity layer on top of the OAuth 2.0 protocol. It allows Clients to verify the identity of the End-User based on the authentication performed by an Authorization Server, as well as to obtain basic profile information about the End-User in an interoperable and REST-like manner.
OpenID Connect allows clients of all types, including Web-based, mobile, and JavaScript clients, to request and receive information about authenticated sessions and end-users. The specification suite is extensible, allowing participants to use optional features such as encryption of identity data, discovery of OpenID Providers, and session management, when it makes sense for them.
Mobile App Identification to the API
Currently, for first time user will pass in their deviceID, pin, and timestamp for an encrypted value from the back-end. Subsequently , the front-end system will send this parameter for request and get a response success. The token has expiration date of 30 minutes.
Normally developers identify the mobile to the API server with a secret that is normally called api-key or some kind of named token *-token. No matter what the convention name used this is identifier is always a secret that sometimes is a simple unique string to identify the mobile app and sometimes is more sophisticated, like in your case.
With a recent event, hackers are able to manipulate the request from a script by spoofing.
The problem is that anything running in the client side can be reverse engineered
easily by an attacker on a device he controls. He will use introspection frameworks like Frida or xPosed to intercept at runtime the running code of the mobile app or will use a proxy tool like MiTM for watching the communications between the mobile app and the API server. Normally their first step in reverse engineer a mobile app will be to use the Mobile Security Framework to reverse engineer the binary of you mobile app to extract all static secrets and to identify attack vectors.
Frida
Inject your own scripts into black box processes. Hook any function, spy on crypto APIs or trace private application code, no source code needed. Edit, hit save, and instantly see the results. All without compilation steps or program restarts.
xPosed
Xposed is a framework for modules that can change the behavior of the system and apps without touching any APKs. That's great because it means that modules can work for different versions and even ROMs without any changes (as long as the original code was not changed too much). It's also easy to undo.
Mobile Security Framework
Mobile Security Framework is an automated, all-in-one mobile application (Android/iOS/Windows) pen-testing framework capable of performing static analysis, dynamic analysis, malware analysis and web API testing.
MiTM Proxy
An interactive TLS-capable intercepting HTTP proxy for penetration testers and software developers.
So after using all this tools is possible for an attacker to replay all steps your mobile app does to get the token from the API server and use it afterwards to automate the attacks against the API server.
Possible Solution
So the hackers are imitating the same behavior as from mobileapps. How do we cater for this kind of scenario? Is there a way to block these kind of request?
So anything that runs on the client side and needs some secret to access an API can be abused in different ways and you can learn more on this series of articles about mobile api security techniques. This articles will teach you how API Keys, User Access Tokens, HMAC, TLS Pinning can be used to protect the API and how they can be bypassed.
A better solution can be employed by using a Mobile App Attestation solution to enable the API server to know is receiving only requests from a genuine mobile app.
A Mobile App Attestation service will guarantee at run-time that your mobile app was not tampered or is not running in a rooted/jail broken device by running a SDK in the background(without impacting user experience), that will communicate with a service running in the cloud to attest the integrity of the mobile app and the device is running on.
On 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 are aware. In the case of failure on the mobile app attestation the JWT token is signed with a secret that the API server does not know.
Now the App must send with every API call the JWT token in the headers of the request. This will allow the API server to only serve requests when it can verify the signature and expiration time in the JWT token and refuse them when it fails the verification.
Once the secret used by the Mobile App Attestation service is not known by the mobile app, is not possible to reverse engineer it at run-time even when the App is tampered, running in a rooted device or communicating over a connection that is being the target of a Man in the Middle Attack.
The Mobile App Attestation service already exists as a SAAS solution at Approov(I work here) that provides SDKs for several platforms, including iOS, Android, React Native and others. The integration will also need a small check in the API server code to verify the JWT token issued by the cloud service. This check is necessary for the API server to be able to decide what requests to serve and what ones to deny. Your current token could be used as a payload claim in the Approov Token to allow the API server to continue using it with the guarantee that was not tampered with.
I'm in the process of designing a mobile application that will need to connect to a server-side process for its business logic and data transactions. I'm writing my server-side code in Java using Spring Boot and I intend to create a Rest API in order for the mobile app to connect to the server.
I'm just doing some research at the moment for the best way to secure the connection between mobile app and server. What I'd like to do is allow the user on the mobile app to log in once they open the app and for them to use the app for as long as they like and for their access to time out after a period of inactivity.
Can anyone recommend any very simple reading on this? I've looked at OAuth2 but that appears to be for logging into web services using another account (like Google, GitHub, etc).
Would it be acceptable to login over https (SSL) by passing username and password to a rest endpoint and returning some sort of token (a GUID?). Then have the client (mobile app) pass that GUID with each subsequent call so the server can verify the call? Is it better to just do everything over SSL in this scenario?
I have done a fair bit of research but I don't seem to be able to find anything that quite matches what I'm trying to do.
Hope someone can help
Thanks
OAUTH2 IS NOT ONLY FOR WEB
Can anyone recommend any very simple reading on this?
I've looked at OAuth2 but that appears to be for logging into web services using another account (like Google, GitHub, etc).
No OAUTH2 is not only for web apps is also for mobile apps and you read this article for a more in depth explanation, but I will leave you with the article introduction:
Like single-page apps, mobile apps also cannot maintain the confidentiality of a client secret. Because of this, mobile apps must also use an OAuth flow that does not require a client secret. The current best practice is to use the Authorization Flow along with launching an external browser, in order to ensure the native app cannot modify the browser window or inspect the contents. If the service supports PKCE, then that adds a layer of security to the mobile and native app flow.
The linked article is very brief, you will need to follow the next chapters to get the full picture.
DO NOT ROLL YOUR OWN AUTHENTICATION / AUTHORIZATION SOLUTION
Would it be acceptable to login over https (SSL) by passing username and password to a rest endpoint and returning some sort of token (a GUID?). Then have the client (mobile app) pass that GUID with each subsequent call so the server can verify the call?
While you can do it I strongly advise you to use an already established OAUTH2 or OPENID connect solution, because they are developed and maintained by experts in the field and battle tested by millions of web and mobile apps using them. This enables to identify ans fix security issues much more quickly that anyone could do in their own in-house solution.
OAuth2
OAuth 2.0 is the industry-standard protocol for authorization. OAuth 2.0 supersedes the work done on the original OAuth protocol created in 2006. OAuth 2.0 focuses on client developer simplicity while providing specific authorization flows for web applications, desktop applications, mobile phones, and living room devices. This specification and its extensions are being developed within the IETF OAuth Working Group.
OpenID Connect
OpenID Connect 1.0 is a simple identity layer on top of the OAuth 2.0 protocol. It allows Clients to verify the identity of the End-User based on the authentication performed by an Authorization Server, as well as to obtain basic profile information about the End-User in an interoperable and REST-like manner.
OpenID Connect performs many of the same tasks as OpenID 2.0, but does so in a way that is API-friendly, and usable by native and mobile applications. OpenID Connect defines optional mechanisms for robust signing and encryption. Whereas integration of OAuth 1.0a and OpenID 2.0 required an extension, in OpenID Connect, OAuth 2.0 capabilities are integrated with the protocol itself.
So for your authentication/authorization needs I would recommend you to go with an OpenID connect solution, that leverages OAuth2 under the hood.
SSL IS ALWAYS NECESSARY?
Is it better to just do everything over SSL in this scenario?
SSL must be always used for everything, http MUST not be used at all in any situation, because once you allow an http request you are vulnerable to a man in the middle attack and I strongly recommend you to read this article from a well know security researcher, Troy Hunt, to see how even a static website must use https and he goes to a great extent to explain why and names very important attack vectors that can harm an application not using https, like WiFi hot-spots hijacking, DNS Hijeacking, Router Exploits, China great cannon, and others.
IMPROVE SSL WITH CERTIFICATE PINNING
Communicating using https is the way to go for any kind of application but developers must be aware that an attacker in control of device where the application is installed can spy https traffic by doing a man in the middle attack with a custom certificate installed in the device the mobiel app is installed, enabling this way for him to understand how the mobile app communicates with the API server in order to mount automated attacks to abuse from same API.
Certificate Pinning
Pinning is the process of associating a host with their expected X509 certificate or public key. Once a certificate or public key is known or seen for a host, the certificate or public key is associated or 'pinned' to the host. If more than one certificate or public key is acceptable, then the program holds a pinset (taking from Jon Larimer and Kenny Root Google I/O talk). In this case, the advertised identity must match one of the elements in the pinset.
You can read this article, with code sample to see how easy is to implement certificate pinning, how it can be difficult to maintain in the operational side, and with a video to see how an attacker can bypass pass certificate pinning in the client side by using Xposed framework.
xPosed
Xposed is a framework for modules that can change the behavior of the system and apps without touching any APKs. That's great because it means that modules can work for different versions and even ROMs without any changes (as long as the original code was not changed too much). It's also easy to undo.
EDIT:
Nowadays, you can use the Mobile Certificate Pinning Generator to help you with implementing certificate pinning in your mobile app:
That will give you a ready to use pinning configuration for Android and iOS:
RESEARCHING FOR A SOLUTION
Before I point you out to a possible solution I would like to make clear the distinction between 2 concepts that developers frequently are not aware off or take as being the same thing...
The Difference Between WHO and WHAT is Accessing the API Server
The WHO is the user of the mobile app that you can authenticate,authorize and identify in several ways, like using OpenID Connect or OAUTH2 flows.
Now you need a way to identify WHAT is calling your API server and here things become more tricky than most developers may think. The WHAT is the thing making the request to the API server, is it really your genuine mobile app or is a bot, an automated script or an attacker manually poking around your API server with a tool like Postman?
Well to identify the WHAT developers tend to resort to an API key that usually they hard-code in the code of their mobile app and some go the extra mile and compute it at run-time in the mobile app, thus becomes a dynamic secret in opposition to the former approach that is a static secret embedded in the code.
Some Mobile API Security Techniques
I have done a fair bit of research but I don't seem to be able to find anything that quite matches what I'm trying to do.
You can start by read this series of articles about Mobile API Security techniques to understand how Https, Certificate Pinning, APi Keys, HMAC, OAuth2 and other techniques can be used to protect the communication channel between your mobile app and the API serve, and how they can be bypassed.
To solve the problem of WHAT is accessing your mobile app you need to use one or all the solutions mentioned in the series of articles about Mobile API Security Techniques that I mentioned above and accepted that they can only make unauthorized access to your API server harder to bypass but not impossible.
A better solution can be employed by using a Mobile App Attestation solution that will enable the API server to know is receiving only requests from a genuine mobile app.
A POSSIBLE BETTER SOLUTION
The use of a Mobile App Attestation solution will enable the API server to know WHAT is sending the requests, thus allowing to respond only to requests from a genuine mobile app while rejecting all other requests from unsafe sources.
The role of a Mobile App Attestation service is to guarantee at run-time that your mobile app was not tampered or is not running in a rooted device by running a SDK in the background that will communicate with a service running in the cloud to attest the integrity of the mobile app and device is running on.
On 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 are aware. In the case of failure on the mobile app attestation the JWT token is signed with a secret that the API server does not know.
Now the App must sent with every API call the JWT token in the headers of the request. This will allow the API server to only serve requests when it can verify the signature and expiration time in the JWT token and refuse them when it fails the verification.
Once the secret used by the Mobile App Attestation service is not known by the mobile app, is not possible to reverse engineer it at run-time even when the App is tampered, running in a rooted device or communicating over a connection that is being the target of a Man in the Middle Attack.
This is a positive model where false positives do not occur, thus the API server is able to deny requests with the confidence of not blocking legit users of your mobile app.
The Mobile App Attestation service already exists as a SAAS solution at Approov(I work here) that provides SDKs for several platforms, including iOS, Android, React Native and others. The integration will also need a small check in the API server code to verify the JWT token issued by the cloud service. This check is necessary for the API server to be able to decide what requests to serve and what ones to deny.
CONCLUSION
Properly securing a mobile app and the API server is a task composed of several layers of defense that you must put together in order to protect it.
How many layers to use will depend on the data your are protecting, the value it have for the business, the damage it can cause when leaked in a data breach and how much you may be penalized by law enforcement, like GDPR in Europe.
What I usually do is crafting a JSON web token (https://jwt.io/), and handle the sessions on my own.
JWT is really nice, since you only need to define a secret key on the server side. As long as your clients are able to pass the string you crafted (inside the headers for example), and as long as nobody gets to retrieve your secret key, you are sure that every data you push when creating the token was generated by you. (Don't hesitate to use the strongest encryption algorithm)
For a secure connection use HTTPS at level TLS 1.2 level. Then pin the server certificate in the app, that will prevent MITM attacks.
It is safe to pass the user name and password. You can return a time-limited token for further authentication is needed/desired.
With HTTPS everything but the address portion of the URL is encrypted. But be careful with the query string, it may end up in the server logs.
Thanks again for these replies. I've been implementing my service to run under https by using server.ssl.key-store parameters and it looks like it's working okay. I have used keytool.exe to create a trust store and I run my SpringBoot app (with Tomcat embedded) using that trust store. I can open a browser to my REST endpoint (using https this time, not http), the browser asks for authentication and when I enter my user details, it matches them against my db user and allows me to see the response from the server.
One question though, what's the point of having a trust store on the server side (Java) if I can just access the REST endpoint using any old browser and just enter my user name and password? Eventually, this REST endpoint won't be accessed via a browser, it'll be accessed using a mobile app programmatically, so I assume I'll be logging on using that with username and password over https. I thought I'd need to have a certificate of some sort on the client side in order to communicate or does it not work like this?
Thanks again
My company is building a RESTful API that will return moderately sensitive information (i.e. financial information, but not account numbers). I have control over the RESTful API code/server and also am building the Android app. I've setup the API to use OAuth 2 with authorization code grant flow (with client ID and secret), and I auto-approve users without them having to approve the client since we own both client and provider. We use CAS for SSO and I am using this for the Authorization server as part of the OAuth 2 process when the user logs in to retrieve the token.
I am contemplating various ways to secure the data on the Android app. I've concluded that storing the client id and secret on the device is definitely not going to happen, but am thinking that storing the auth token might work, since it is only risk to the individual user (and really only if they happen to have a rooted phone).
Here are two options I have thought of. They both require me to have a sort of proxy server that is CAS protected, does the dance with the API server, and returns the auth token. This gets rid of the need for storing the client id and secret in the app code.
Here are what I've come up with:
1) Require the user to enter their password to access data each time they startup the App. This is definitely the most foolproof method. If this were done, I'd probably want to save the userID for convenience, but in that case couldn't use the CAS login (since it's web-based). I might be able to use a headless browser on the backend to log the user into CAS and retrieve the token based on what they enter in the Android form, but this seems hacky. Saving the userID is similar to what the Chase app does (if you happen to use this one) - it saves the userID but not your password between sessions.
2) Store the auth token on the Android device. This is a little less secure, but almost foolproof. When the user starts the app for the first time, open the webpage to the CAS login of the proxy server that returns the token (similar to https://developers.google.com/accounts/docs/MobileApps). After the user logs in and the token is returned to the app, encrypt it and store it private to the application. Also, use ProGuard to obfuscate the code, making the encryption algorithm more difficult to reverse engineer. I could also work in a token refresh, but I think this would be more of a false sense of security.
3) Don't use CAS but come up with another way to get an auth token for the service.
Any advice of how others have implemented similar scenarios (if it's been done)?
Thanks.
Well the reason why standards like OAuth are developed is that not everyone has to rethink the same attack vectors again and again. So most often it is your best choice to stick to something already available instead of baking your own thing.
The first problem with clients that are not capable of secretly storing data is that the user's data could be accessed by some attacker. As it is technically not possible to prevent this (code obfuscation won't help you against an expert attacker), the access token in OAuth 2 typically expires after short time and doesn't give an attacker full access (bounded by scope). Certainly you shouldn't store any refresh token on such a device.
The second problem is client impersonation. An attacker could steal your client secret and access your API in his own (maybe malicious) app. The user would still have to login there himself. The OAuth draft there requires the server to do everything it can to prevent this, but it is really hard.
The authorization server MUST authenticate the client whenever possible. If the authorization server cannot authenticate the client due to the client's nature, the authorization server MUST require the registration of any redirection URI used for receiving authorization responses, and SHOULD utilize other means to protect resource owners from such potentially malicious clients. For example, the authorization server can engage the resource owner to assist in identifying the client and its origin.
I think Google are the first to try another approach to authenticate a client on such devices, by checking the signature of the application, but they are not yet ready for prime time. If you want more insight into that approach, see my answer here.
For now, your best bet is to stay on the OAuth way, i.e. having the access token, client ID and client secrect (when using the authorization code grant flow) on the device, and configure your server to do additional checks. If you feel more secure obfuscating these, just do it, but always think of it as if these values were publicly available.
I am developing a Java application that needs to access personal account Google Data of a user. The development is currently in netbeans on my localhost. I am implementing 3-legged OAuth. And while sending Grant request, it sends me Unauthorized Request Token and then redirects to Callback URL.
While trying to access Access Token, it gives me Error "Error Getting HTTP Response". Now, as per it given in Google Documentation, it is given that "If the application is not registered, Google uses the oauth_callback URL, if set; if it is not set, Google uses the string "anonymous"." Does it mean that I must register my application on Google Apps Engine before granting authorization & accessing request ? Please Help.
For reference : OAuth for Web Applications, OAuth in the Google Data Protocol Client Libraries
Based on your question, it's probably not the registration piece that's causing you trouble. It sounds like you just haven't implemented OAuth correctly — not that doing so is easy. The OAuth process is roughly as follows:
Get a request token. You must pass in a bunch of stuff that declares what kind of stuff you want access to and where you want Google to send the user when they're done granting you access to that data. This is where you pass in your consumer key, which you get by registering. The consumer key will be the string anonymous if you are developing an installed application (i.e., mobile app, desktop app, etc). This is a work-around; the alternative would be to embed your client secret or RSA private key within the application itself, which is a very, very bad idea. If you use 'anonymous', you should absolutely be setting the xoauth_displayname parameter. (Actually, everyone should set this parameter, but it's especially important if you're using anonymous.)
Once you have a request token, you then redirect the user to the special authorization endpoint, passing along the request token key in the query string. Assuming the user grants access, Google will redirect the user back to the callback URL that you associated with your request token. The request token is now authorized, but it can't be used directly just yet.
Once the request token is authorized, you can exchange it for an access token key/secret pair. The access token key/secret can then be used to sign requests for protected resources, such as the private data in the API you're trying to access.
For web applications, registering is almost always a good idea. It makes it much easier for users to manage their access tokens and revoke them if your application misbehaves or if they don't want you to have access anymore. If you don't register, your application will probably show up as a fairly scary-looking 'anonymous' in that list. It's really only installed applications that you wouldn't want to register for. You probably also want to register for an API key. An API key will dramatically increase your rate limit and it will also allow Google to get in touch with you if your application starts to malfunction.
I'd link to the OAuth docs, but you've already found them. Hope my explanation helps!
If you're developing on your local machine, you'll continue to get the same result as above.
For more interesting tests, then yes, you'll have to register your app and push it to the app engine.
Google will check if the domainname of the return-url is registered. You could also modify your dns/host-file to point the domain-name you're using to localhost.