I've searched a lot online but with no use. I want to know what could the attacker do if he obtains the client_id and client_secret of an Google's Oauth2 app. Like what the information he would be able to see? Can he edit the app configurations? Can he see other people information?
I haven't worked with Oauth2.0 before so please make your answer simple
Thanks!
I want to know what could the attacker do if he obtains the client_id
and client_secret of an Google's Oauth2 app.
The OAuth 2 Client Secret must be protected. However, if it is leaked the attacker needs one more item. A valid redirect_uri. If the attacker has both along with the (public) Client ID, they might be able to generate OAuth tokens for your account.
The redirect_uri is often valid for http://localhost because developers forget to remove this URI after development completes. This means that someone could run a local server and generate OAuth tokens. This is a big security hole.
What can they do with the OAuth tokens? depends ...
Like what the information he would be able to see? Can he edit the app
configurations? Can he see other people information?
You did not specify whose OAuth system, what it is authorizing, etc. Therefore the answer is "it depends".
For Google Cloud, the hacker will need the credentials for someone authorized in Google Cloud. Some systems have very poor security, so as they say, anything can happen and often does with poorly designed security.
In a properly designed system, there are several layers that the hacker needs to get thru. Having the Client Secret helps a lot, but is not a total security failure. The hacker can only authenticate with the system. The next layer, which is authorization, needs to be breached. In a correctly designed system, the hacker will need to authenticate with a user with authorized permissions. If the hacker has that, then you are in big trouble. He might have the keys to do anything he wants. Again, it depends.
Related
I'm working on a project using the YouTube Data API. The Python script I'm running uses a client secrets JSON file, which I presume is for verifying the account owner. If I am having issues with it and need assistance, are there any security concerns with sharing this publicly? Is it even alright if it's held privately in a private github repository?
If you check the Google Developer TOS which you agreed to when you created your account on Google developer console
It is against the TOS for you to share this file with anyone. This is secret and only intended for the developer or team of developers who created it. This pertains to the entire client secret json file you download from Google developer console or google cloud console.
Again DO not share your google secret file. No matter what the accepted answer stays about how problematic it may or may not, nor does it matter what type of client it is. Sharing the client secret file would be volatilizing the TOS you agreed to.
My corrections for another answer on this thread here
The answer in question has some statements that i strongly disagree with and feel may cause confusion to developers. Let me start by saying I am not an employee of Google, my comments are my own and from my experience with working googles oauth / identity server server for eight+ years and contact with google identity team. I am concerned that some of the information in the answer above may confuse some developers. Rather than just saying dont share them the other question tries incorrectly IMO to explain why it wouldn't be so bad to share them. I will explain why you should never share them beyond the fact that its against googles TOS.
The security implications depend on the type of client secret. You can tell the difference by whether the key in the JSON file is installed or web.
The type of client has no effect upon I how great the security risk would be. If we ignore the definition of what a constitutes a security risk completely and just say that any chance anyone could get access to a users account or authenticate a user on behalf of the project, would constitute to big of a security risk then there is no difference.
Using the following command I could authenticate myself all i need is the credentials file for your project
https://accounts.google.com/o/oauth2/auth?client_id={clientid}.apps.googleusercontent.com&redirect_uri=urn:ietf:wg:oauth:2.0:oob&scope=https://www.googleapis.com/auth/analytics.readonly&response_type=code
This would only work 100% of the time for an installed application. Why is this bad if i am just authenticating my own user. I could then use my evil powers to send so many requests against the API that the target google developer project would be locked down by Google for spamming.
If i have stolen another users login and password i can login to them from your Google developer project and i have access to their data and Google thinks its you hacking them.
This is a little harder with a web application due to the Redirect URI, However a lot of developers include add localhost as a redirect uri when in development and forget to take it out (Please never leave localhost as a redirect uri when you are in proudcution) . So in the event you have left redirect URI as a valid redirect URI in a web browser client then I can do the exact same thing.
Remember I am now able to authenticate users based upon your project to access mostly my own data. However if you have also set up access to client data for example via google drive I may be able to access that as well. (Note: Im not Sure on this one i havent actually tried.)
If i have manged though man in the middle attack or some other means to get a users refresh token, and I have the client secret file I can now access users data because I can create new access tokens with my refresh token for as long as i want. This is probably a bit harder to achieve.
Web application secrets
If the client secret is of the web type, then yes: you should absolutely not post it, and invalidate it if it gets exposed. This would allow a malicious entity to impersonate your backend and perform actions on your users' accounts on your behalf.
As stated above this will only be the case if the developer in question has left the redirect uri open for localhost or the person who now has your client secret file also has access to your web server. One very important fact is that if you have left localhost open i can then put up my own website using your credentials and set it up so it look exactly like your website. Users then think they are logging into Your super awesome app when in fact they are logging into Hacker Super awesome app giving them access to the users data. Again google thinks its you hacking them.
Installed application secrets
If the client secret is an installed-type secret, then it's less problematic to share privately, as it doesn't grant the sorts of abilities a web application secret does, such as the ability to authenticate as users who grant your application permission to access their data. As the documentation notes, "in this context, the client secret is obviously not treated as a secret."
This is completely false Installed applications give the exact same permissions as web applications there is no difference with-regard to Oauth2 access an access token is an access token no matter if it was created for an installed application or a web application.
As stated above security risk with giving out access to your installed application this is actually worse. As there are no redirect uris with installed applications. Anyone that has access to your client secret file could authenticate users who assume they are you because they are being shown your consent screen. Not only is your Google developer project being hjacked but your reputation to your users who think that they are authenticating to Super awesome app and in fact they are not granting the person who has stolen your credentials access to their data.
I would like to add one last thing. If you give another person your project credentials. The client secret json file. You are giving them access to make calls on your behalf. If you have bulling set up lets say against google maps api. You will be charged for the calls they make.
I hope this helps to clear up some of the confusion related to the accepted anwser.
Yes, this is a problem. It's called a "client secret" for a reason. If it does become exposed, you should take steps to invalidate it and get a new one so that someone doesn't try to impersonate you.
Short answer: the security implications depend on the type of secret, but you should not share it publicly for other reasons, including the Terms of Service, which state that:
You will keep your credentials confidential and make reasonable efforts to prevent and discourage other API Clients from using your credentials. Developer credentials may not be embedded in open source projects.
The security implications depend on the type of client secret. You can tell the difference by whether the key in the JSON file is installed or web.
Web application secrets
If the client secret is of the web type, then yes: you should absolutely not post it, and invalidate it if it gets exposed. This would allow a malicious entity to impersonate your backend and perform actions on your users' accounts on your behalf.
Installed application secrets
If the client secret is an installed-type secret, then it's less problematic to share privately, as it doesn't grant the sorts of abilities a web application secret does, such as the ability to authenticate as users who grant your application permission to access their data. As the documentation notes, "in this context, the client secret is obviously not treated as a secret."
You still should not post it publicly on GitHub, a Stack Overflow question, or other public places, as posting it publicly increases the probability of someone copying your code in its entirety or otherwise using your client secret in their own project, which might cause problems and likely would run afoul of the Terms of Service. People trying to reproduce your issue could pretty easily generate credentials to drop into your code—credentials are a reasonable thing to leave out of a question.
I'm just starting to learn about Identity Server, OAuth 2, and OpenId Connect. While doing so I've spent some time looking over the different OAuth flows and their applications. I understand the risks of using the Resource Owner Password Credential flow when the client is 3rd party or not trusted. However, I haven't really been able to find much on its use when the client(mobile app) and api are trusted 1st party. What are the potential risks of using this flow in this scenario? If you could point to specific security vulnerabilities that would be very helpful.
Thanks!
If you are talking about exactly the following...
Your own Mobile App (using trusted libraries)
Collects User Credentials (as if they were logging on your website, assuming you have one)
Sends them over TLS to your Auth server
Returns the normal token response if correct
Then I would argue there is no security penalty, at least, it is no worse than using username/password auth in the first place.
However, there is a wider problem with mobile authentication of this nature.
There is no way to tell that it's your app sending the requests, this applies to all OAuth2 flows (even if you use a more secure flow, the User can simply pull apart the mobile app and extract the credentials).
There are some features from both Google and Apple that attempt to fix this problem, but I'm not sure how mature or secure they are at the moment, it might be worth looking into.
So you are relying on the User to not get tricked into installing a fake app, however, this lands under social engineering and it does apply to all OAuth 2 flows.
I'm writing a web service which uses OAuth2 for authorization. I'm using C# and WCF, though this isn't really pertinent to my question. Having never used OAuth before, I've been doing my research. I'm on the "verify they're actually authorized to use this service" end of things. I think I have a pretty good idea of how OAuth2 works now, but one aspect of it still confounds me.
OAuth2 is token-based. The token is just text and contains some information, including a "secret" that only your application (the web service, in my case) and the Authorization Server knows. The secret can be just a text phrase or a huge string of semi-random characters (sort of like a GUID). This "proves" the user contacted the Authorization Server and got the secret from it. What confuses me is this only seems to prove that the user contacted the Authorization server sometime in the past. In fact, it doesn't even prove that. It just proves that the user knows the secret. The rest of the token (such as role, duration, other stuff) can all be faked. Once the user gets one token for the service he wants access to, they could whip up new tokens with falsified information as much as they like. In fact, there could be numerous servers set up with thousands of "secrets" for nefarious individuals to use at will. Of course, this wouldn't happen often, but it seems very possible.
Am I correct, or is there something I'm missing? Is this a known weakness of OAuth2?
Whenever the Resource Server (or "service") receives a token, it needs to validate it. Depending on the token type it can check its signature that was created with the private key that Authorization Server has or it can call into the Authorization Server to validate the token. This way a user cannot forge a token: it would be impossible to forge the signature or to make the Authorization Server verify a token that it did not issue.
FWIW: you seem to be conflating the "token" and "client secret" and perhaps even the private key of the Authorization Server; they're all different concepts.
As a security best practice, when an engineer/intern leaves the team, I want to reset the client secret of my Google API console project.
The project has OAuth2 access granted by a bunch of people, and I need to ensure that those (grants as well as refresh tokens) will not stop working. Unfortunately, I've not been able to find documentation that explicitly states this.
Yes. Client Secret reset will immediately (in Google OAuth 2.0, there may be a few minutes delay) invalidate any authorization "code" or refresh token issued to the client.
Client secret reset is a countermeasure against abuse of revealed client secrets for private clients. So it makes sense to require re-grant once the secret is reset.
I did not find any Google document states this explicitly either. But my practice proves that reset will impact users, also you can do a test on it.
And in our work, we programmers do not touch product's secret, we have test clients. Only a very few product ops guys can touch that. So I think you need to try your best to narrow down the visibility of the secret in your team. Rest is not a good way.
This is more of a general question but I hope it is still valid for SO.
So far I have learned, that in general, a mobile app (such as official Pinterest app) use the Password credential flow to let their users login and access the API directly. (let's just assume they use OAuth for this)
So they collect username and password, send it to their server and get a token in return which is used for subsequent requests.
Now a user did not want to register and created an account using e.g. Facebook as the authorization server. So my question is:
How is this flow implemented?
My educated guess:
User chooses "Login with Facebook" in mobile app
Facebook Login Page opens with return_uri = mobile app
Mobile app receives auth token
Mobile app uses client credentials and says the API: Use this token for user X
Is this correct?
First of all, apps should not use the Password Credentials Grant. The specification is rather clear about it:
In the traditional client-server authentication model, the client
requests an access-restricted resource (protected resource) on the
server by authenticating with the server using the resource owner's
credentials. In order to provide third-party applications access to
restricted resources, the resource owner shares its credentials with
the third party. This creates several problems and limitations
The specification then goes on describing those problems.
And about the Resource Owner Password Credentials Grant:
The authorization server should take special care when enabling this grant type and only allow it when other flows are not viable.
The entire purpose of OAuth 2.0, I to not have to use something like the Password Credentials Grant, where the user hands over their password to the application.
About your second question: what happens when a user does not want to register and create an account with your app, but wants to use e.g. Facebook for authentication?
Remember that both the Implicit Grant, as well as the Authorization Code Grant, work by using a browser control to authenticate the user. In that browser session with the Authorization Server, you are free to authenticate your user in any which way you want. Certainly, you can use your own user/password database, but you could also use other mechanisms, such as WS-Federation. In your case, it sounds like the user want to authenticate using Facebook.
Authenticating using Facebook is then not done by your client app, but by your Authorization Server. It typically does that by using the Facebook Authorization Code Grant, followed by a call to read the user's profile to obtain their Facebook user id, name, and so on.
If you do not want to build such an Authorization server yourself, you can use an existing one. Several companies offer login-as-a-service solutions, including the one I work for.
UPDATE: You asked several follow up questions in a comment below. I'll answer them briefly here:
First of all, the fact that some companies that use OAuth to secure their services allow for a Password Credentials Grant, does not imply that you should. In fact, there are probably more examples of companies that don't offer this possibility, than companies that do.
There are real trust issues, and real security risks with sharing your password with a device app. To start with, the app on the device is easier to hack than a server. Furthermore, if you give the app your password, presumably that app also needs to store it somewhere for future use. As a user, I just have to hope that that storage is safe form possible malware running on my machine. For more issues, see the introduction in the OAuth 2.0 specification mentioned above.
Secondly, all good Authorization Servers differentiate between First Party Clients and Third Party Clients. A First Party Client such as yours is controlled by the same company that controls the Authorization Server, and for such an app the Authorization Server does not ask for user permission to share data, since it makes no sense to talk about sharing data with yourself. That is why the web sites of these companies don't ask you whether you allow to share the data they hold on your behalf with them. They already have it, and there is no "sharing" going on.
Of course, you might argue that you have never seen any of these companies talking about this distinction between First Party Clients and Third Party Clients. But the reason they don't should be obvious: when you deal with them, you are always a Third Party App. They don't need to tell you that they treat themselves differently.
The mechanism I would choose in your scenario depends on the nature of the client app, and the nature of the services it accesses. What are your requirements?
Anyway, if the device the application is running on has a secure storage facility, such as Windows Phone 8.1, I would probably consider using the Authorization Code Grant without client credentials. That way, the user never has to log in again. If we're talking about a web site or a SPA, I would consider the Implicit Grant (where the "remember me" feature, if any, is offered by the Authorization Server). Again, the specification gives advantages and disadvantages of each grant type for several scenario's.