When we talk about securing iOS application we often forget to secure most critically sensitive information such as secret, key, token, encryptionKey. This information is stored in iOS binary. So none of your server side security protocol will help you.
There are lots of suggestion that we should not store such information in the app but store in the server and get it via SSL secured web service call. But this is not possible for all application. E.g. if my application does not need web service at all.
In iOS app we have following option to store information.
UserDefault: Not appropriate for this case
String Constant: Not appropriate for this case. Can be reverse
engineer to retrieve or just use strings command
Secure Database: Store in Secure and encrypted Database. But again have responsibility to secure database username and password.
KeyChain: Best to store critical info. But we cannot save information before installing the app. To store in the keychain, we first need to open the app, read from some source and store in the keychain. Not appropriate for our case either.
Custom Hash String Constant: Not to directly use secret, token, key from service provider (mixpanel, paypal), instead use hash version of that information from custom key. This is also not perfect solution. But add complexity during hacking.
Kindly send some awsome solution to this problem.
If you don't want to use your own backend then use Apple. You can configure On Demand Resources and keep data file with your key, token, any secret on Apple server. After first download you can write this data to Keychain which is secure enough. I'm guessing networking between iOS and Apple server is also secure enough.
On-Demand Resources Essentials
Accessing and Downloading On-Demand Resources
1) Internet Connection Required
1.1) Push Notifications
Great way to have a secure data exchange could be to use (silent) push services from Apple, those use the apns and send data through https - more Details 3.1
1.2)
A more or less similar approach is also used when distributing new user certificates to already deployed applications, if a reinstall of the application is no opportunity AND the application requires a working internet connection anyway.
Downside: working network connection required and basically the information is coming to the application, when it is already being executed => seems not to be appropriate for your case. (see step 4)
2) Static data (as there will be no exchange without network connection / communication partner)
Encryption of data with private key being provided in the bundle itself. Whether it is now a string or a hash, which can be reverse engineered with functions you got emebedded in your application.
Since iOS9 it is pretty hard to decompile iOS applications and basically you will mainly have a look into the provided header-files. So if you had such a function, string, hash value or whatever, make sure you got it in your .m-file!
But again: if the information is not device or user specific, just a secret across your own micro environment, valid across all devices, you would have to provide the encrypted data AND the decryption method in the same bundle, if there is no update process / information exchange or something else, you can think of.
Good for encryption:
iOS System.Security https://developer.apple.com/reference/security
or simply openssl
The difference between your described keychain approach is:
You got a value, which WILL be encrypted and stored securely.
(2) describes the approach to have an encrypted and stored (in bundle) semi secure value, which WILL be decrypted
3) Information exchange
You describe critical data, which was hashed by another instance. Great! - Make sure, relly make sure, the instance you are talking to is really the instance you expect to be (Network Hooking prevention with ssl certificate pinning etc, but even here you might have intruder (men-in-the-middle)). And you will (probably) have a certificate being provided in your application bundle, to ensure the authenticity of the communication server - here you go again, data that is supposed to ensure a secure process between certain instances of your micro environment. Nevertheless, this data is being provided in your application's bundle.
3.1 Secure Information Exchange extended - Silent Push
Make use of Apple's servers to exchange your secrets for this purpose. If you just need to exchange small data chunks. I would recommend to use silent push notifications to the user, those do even work without explicit permission from the user. Huge advantage: In case your secrets or keys change, you can inform users as soon as possible about the change. They will likely only need the change, when they receive new data, which should reliably work in most cases. Exception: Data exchange in local networks or via bluetooth, in this case I would recommend to provide a notification to the user to have the requirement to update a local decryption key. Or exchange the key in this format as well. Once again: I am leaking some detailed information about your environment architecture.
Downside: You don't know, whether a user just used your app for the first time, until the user "tells" you so.
https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/APNSOverview.html#//apple_ref/doc/uid/TP40008194-CH8-SW1
3.1 Secure Information Exchange extended - In App Purchase
Use a frree In-App Purchase for the user to get the data to your phone. Good point here: you can provide larger data chunks easily, as this should be an active request by the user, the user does expect certain processing time and should also be aware of the fact to require a working internet connection.
Downside: User would have to select this on purpose. Up until then the app would not work accordinly.
https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/StoreKitGuide/Introduction.html#//apple_ref/doc/uid/TP40008267
So, it just slightly differs from the approach (2) in its basic idea.
In short: Can you provide additional information, what kind of data you need to encrypt/want to store securely and whether you will have a network exchange or not?
Would need some more information here :-)
I would like to emphasize once again that an application on iOS is not that easy to decrypt anymore, even decompiling would not get everything, you expect it to get. For instance decryption tools like dumpdecrypt were only working properly up until iOS 8.4
It seems to me that the best way to do this is using the built in CloudKit. You can save your secrets in the CloudKit Dashboard and then fetch them on startup. Since CloudKit is only a transport layer you'll have to store the app secrets in the KeyChain.
I know you mentioned the KeyChain not being ideal for your use case (not sure why), but this is a good way of not including the secrets in your app. You can't get around fetching your app secrets from another source.
CloudKit access is secured using the system iCloud account and if there is no iCloud account you still access the iCloud servers securely. Another added benefit of this is that you can change your app secrets at any time, so if you want to be even more secure you can implement a rotation schedule.
Learn more about CloudKit
Cocoapods-keys might be a best option.
From cocoapods-keys doc's
Key names are stored in ~/.cocoapods/keys/ and key values in the OS X
keychain. When you run pod install or pod update, an Objective-C class
is created with scrambled versions of the keys, making it difficult to
just dump the contents of the decrypted binary and extract the keys.
At runtime, the keys are unscrambled for use in your app.
The generated Objective-C classes are stored in the Pods/CocoaPodsKeys
directory, so if you're checking in your Pods folder, just add
Pods/CocoaPodsKeys to your .gitignore file. CocoaPods-Keys supports
integration in Swift or Objective-C projects.
Check out this link for installation, usage and more info : https://github.com/orta/cocoapods-keys
I agree with #Lobsterman and believe that the best way will be to use a combination of these.
Don't include the secret information in the app initially.
Deliver the secret key either as in-App purchase content ,on-demand resource or send it through push notification. This will add the benefit of changing the key periodically if you want and the change will take effect without any additional effort.
Add the entry to keychain access once the content is delivered.
If the data is extremely sensitive then it should never be stored offline on device because all devices are crackable. If you still want to store on device then keychain is one option for storing data securely, However it's encryption is based on the pin code of the device. User's are not forced to set a pin, so in some situations the data may not even be encrypted. In addition the users pin code may be easily hacked.
A better solution is to use something like SQLCipher which is a fully encrypted SQLite database. The encryption key can be enforced by the application and separate from the user's pin code.
Related
My GoogleService-Info.plist file for iOS was stolen, is it possible to disable access to my Firebase Firestore to all current iOS devices, and reset this file ?
I tried to delete my iOS app in Firebase, but I can still make request from my iPhone...
And I need to disable access only for iOS devices not Android.
As Doug Stevenson pointed out the contents of the GoogleService-Info.plist are public and accessible to every iOS user of your application. Therefore it is inaccurate to say they could be stolen as they're already publicly available.
As explained in the Firebase documentation the file fields contain identifiers used by your application and Firebase servers to route the requests being made to Firestore, Real Time Database and the rest of products the app might be using. Reading the documentation or the post shared by Doug you would see the information exposed is not a security threat.
Moreover, I would like to point out that everybody could try to access your Firestore collections and try to add/drop data. This is indeed expected as Firestore is publicly accessible by mobile and web clients. However, this doesn't mean Firestore is exposed to users to do whatever they please, instead, the actual access is totally under your control by the means of security rules, which enforce what actions a given user could do. In that sense, the developers who left will only have the access level that your security rules grant them, which shouldn't be a threat when having good rules in place.
Lastly, you may revoke the credentials completely removing the application. I'd say it's not a great idea as you would cause a service disruption to app users. Also, this won't improve security or diminish risks.
You can remove the app directly from the Firebase console
Before proceeding make sure to check and understand the consequences.
Click on Settings > General;
Scroll down to Your Apps;
Identify the app and click on Remove this app.
I have a requirement to remove all API keys and app secrets from the source code of the app we are building. Ideally the keys and app secrets should be sent to the app out of band as a configuration file, through an MDM solution.
Is this possible, and if so how? If not, what is the recommended approach to store this kind of information, such that it cannot be viewed in the source or extracted from the binary?
EDIT: Update
It is possible to send NSUserDefaults to the app via the MDM solution using Managed App Configuration. However, NSUserDefaults is not secure, easily viewed and modified by a casual user.
My plan is to encrypt the NSUserDefaults to prevent this using the common crypto library included in iOS. Is this the best approach to this problem? Should I also be sending a certificate as part of the MDM config?
Any thoughts, comments, and recommendations appreciated before I go too far down this route.
I know it's been a while, but I recently looked into this (not for an MDM application). I don't have any experience with MDM and that may have another solution. The route I chose to go was using CloudKit. It's a 1st party solution, always available whether the user is logged in to iCloud or not and you communicate securely with Apple's servers and only your App can access these keys.
Also depending how you set it up you can easily rotate out keys.
See more info here
I need to secure some sensitive data in my app. I would like to use NSFileProtection to do that. I'm wondering, will user be able to browse files protected with NSFileProtection if he will jailbroke its device? If yes, is there any other way to protect such data against jailbreaking device?
NSFileProtection does not offer any real protection from code executed on the device with root privileges. Without pincode you can just open any file. With pincode files will not be accessible when device is locked but it's easy to intercept pincode being entered and use it later to programmatically disable protection and open any file at any time. But if the user himself wants to get access then he will not be using pincode in the first place.
As to other ways of protection, I don't think you can properly secure anything from skilled user. There're a couple of ways but there're always ways around them:
Encrypt the data and store encryption keys localy. User could find the keys and decrypt everything
Encrypt the data but store encryption keys on the server side, never cache them anywhere localy. User could sniff web traffic and get the keys. SSL with certificate pinning will protect you from that. But user can always patch your app's binary or use hooks to either disable encryption altogether or dump encryption keys.
Don't store anything localy, always access data from the web. Use SSL with ceertificate pinning to avoid sniffing. But again, binary patches and hooks are still possible.
So I don't think you can fully secure your data but you can make protection sufficiently difficult to reverse engineer and disable so that most of the users will not go through it.
I'd appreciate that someone could make it clear some questions I have regarding Data Protection feature:
Is needed/recommended to enable Data Protection to encrypt and protect the SQLite files managed by Core Data? If so, what should I do to encrypt and protect such files?
I followed a tutorial for using Keychain and it said that complete level of Data Protection had to be enabled for the App ID in the Apple Member Center, so that I did. However, it said nothing about also enabling Data Protection in the Xcode's project, so I didn't. It seems that I can access Keychain in my iOS app without problem, but this looks weird... should I also enable Data Protection in the target's settings?
Thanks so much
It depends what you're storing there and thus what is at risk if someone gains access to it. In most cases you don't need to encrypt the data in the DB specifically as someone will use a device lock to secure the device and any specific data that you want to make secure should be stored in the keychain. This is usually the user identifying data and account authentication tokens.
If someone gets access to a device that is unlocked (pin code / touch ID has been cleared or authenticated) then they can do pretty much whatever they want with the device (keychain and automatically encrypted data) and you can't stop them (at best you can slow them down).
Apple does mention you can limit access to Keychain data if someone tries to add their fingerprint after-the-fact. More info in the Keychain section of https://www.apple.com/business/docs/iOS_Security_Guide.pdf
The only thing you can do really is to explicitly encrypt the data which requires it using a key that is explicitly entered by the user each time you need to encrypt / decrypt. That key could be stored in memory temporarily, but you can never write it to disk. In this way the user has to enter the key to use the data and the key can only come from the user.
I am developing a corporate app that will be publish on an internal store.
The app is just supposed to keep in memory some credentials but I can't store them on the device for security reasons.
I want the app to stay in background as long as possible but I don't know what is the best solution knowing that I won't have to publish the app in the AppStore.
I read about the option in plist Required background modes, but I don't know which option is the most efficient for my situation.
Firstly, you don't need to keep running app in background, second you can store "those [secret] credentials" in keychain store with some encrypted format, SHA1 or MD5 or any other cryptographic hash functions can be use for this, third the benefit of this is you can access to them from your different apps as well (by using the same encryption key to decryption and accessing keychain store item), at last when you no longer need it, you can even delete it. The only thing you need to keep secret is keychain store key (which you used to store credentials) and also your encryption key (to used with cryptographic hash function).
There's are several libraries available to easily manipulate data in keychain store, here's the one, and here's the solution to apply MD5 or SHA1.