I've looked at the existing questions/responses in StackOverFlow and there were no working answers so I'm posting this question. Our website is an C# MVC site that uses Javascript for validation etc.
The scenario is this:
We want to display a message in our external website to users (employees) who are actually accessing it from within our office network. The message would remain hidden for users who are outside our network (general public).
Please note that an internal office user is going out to the internet and hitting our external website so they would have a public IP address (not their local network IP) and I can't rely on that public IP address remaining consistent so I can't use the IP as the determining factor.
I would think that this would require a client-side solution but I've looked into JS possible solutions and none have worked.
Can anyone think of a way to determine if the user visiting out external website is an employee or part of the general public?
I don't have enough reputation to comment, however putting anything inside a JS file would still be visible if someone was to inspect it in their browser since it's essentially downloaded when the client browses the site. Just ensure nothing sensitive is added to the message such as a link to an employee only portal, as you'll expose the URL for potential attacks.
You could set up a 'beacon' on a machine in your local network. It would connect to your web server every 5 seconds, and inform your web server of the dynamic IP address that your office network is currently being assigned by your ISP to access the external internet.
Now, your web server knows which IP address to display the special message to.
Note that you will need to check that your office internet service provider is not using Carrier-Grade NAT. This will cause an issue, because a member of the public might be assigned an originating IP address that is the same as one used by people on your office network.
Another approach would be to set up a proxy server inside your local network, which would inject a special header into outgoing requests to your public web server if it sees that the request originates internally. You would configure your office router to force all web traffic through this proxy. The proxy would need to have a valid HTTPS certificate for the web server's domain name, so that is able to alter HTTPS traffic.
Thanks everyone for your suggestions. I ended up going a slightly different route which I has seen suggested in another post on another website I believe...I just didn't know if it would work but it does seem to work.
I put a reference to a .JS file that sits on one of our internal network servers . That JS changes the display value for the message I want do display which is initially hidden. So for the general public the message remains hidden, but for anyone on our network it will unhide the message.
I am building an application that has auth system and a lot of post requests,
I want to know how to make my backend endpoints accept only requests that are coming from my application, not from anything else like Postman.
For example, if a user submitted a registration form, a post request is sent to my backend with user info, how can I make sure this post request is coming from my application?
What I was thinking of, is saving a secret on the client’s side that is to be sent with each request to the backend, so that I can make sure the request is coming from my app.
I think SSL pinning is meant for this.
I know that anyone can access my app source code if they extract the APK file.
I want to make sure that no one can alter or steal my source code.
I read that I can make my code unreadable by Obfuscating it ( I still need to figure out how I am going to do that on my EAS build ), is this enough?
And I have to use JailMonkey to detect if the device is rooted.
I am using Expo secure store to save my sensitive info on the client side.
Is this approach good enough, is there anything I am missing?
I have zero information about security, this is just what I learned through searching.
Let me know if you have better suggestions.
Thank you in advance.
The Difference Between WHO and WHAT is Accessing the API Server
I want to know how to make my backend endpoints accept only requests that are coming from my application, not from anything else like Postman.
First, you need to understand the difference between WHO and WHAT is accessing the API Server to be in a better position to look for a solution to your problem.
I wrote a series of articles around API and Mobile security, and in the article Why Does Your Mobile App Need An Api Key? you can read in detail the difference between who and what is accessing your API server, but I will extract here the main takes from it:
The what is the thing making the request to the API server. Is it really a genuine instance of your mobile app, or is it a bot, an automated script or an attacker manually poking around your API server with a tool like Postman?
The who is the user of the mobile app that we can authenticate, authorize and identify in several ways, like using OpenID Connect or OAUTH2 flows.
So think about the who as the user your API server will be able to Authenticate and Authorize access to the data, and think about the what as the software making that request in behalf of the user.
When you grasp this idea and it's ingrained in your mindset, then you will look into mobile API security with another perspective and be able to see attack surfaces that you never though they existed before.
Certificate Pinning and MitM Atacks
What I was thinking of, is saving a secret on the client’s side that is to be sent with each request to the backend, so that I can make sure the request is coming from my app. I think SSL pinning is meant for this.
Certificate pinning on the mobile app side serves to guarantee that the app is talking only with your API server and not anything else, like when a MitM attack occurs and the app has its requests intercepted, and potentially modified and/or replayed, or simply saved to later extract the secrets from it.
Pinning doesn't guarantee to your API server that the request is coming indeed from what it expects, a genuine and unmodified version of your mobile app, "unless" you implement mutual pinning, that isn't encouraged to do so, because you will need to ship the private key for the API server certificate in the mobile app. Even if you do so, all an attacker needs to do is to extract the private key and will be able to communicate with your API server like if it was your genuine mobile app.
I don't have an article to implement pinning on a react-native mobile app but you can take a look to the one I wrote for Android to understand better all the process. Read my article Securing HTTPS with Certificate Pinning on Android on how you can implement certificate pinning and by the end you will understand how it can prevent a MitM attack.
In this article you have learned that certificate pinning is the act of associating a domain name with their expected X.509 certificate, and that this is necessary to protect trust based assumptions in the certificate chain. Mistakenly issued or compromised certificates are a threat, and it is also necessary to protect the mobile app against their use in hostile environments like public wifis, or against DNS Hijacking attacks.
You also learned that certificate pinning should be used anytime you deal with Personal Identifiable Information or any other sensitive data, otherwise the communication channel between the mobile app and the API server can be inspected, modified or redirected by an attacker.
Finally you learned how to prevent MitM attacks with the implementation of certificate pinning in an Android app that makes use of a network security config file for modern Android devices, and later by using TrustKit package which supports certificate pinning for both modern and old devices.
Bypassing Certificate Pinning
I think SSL pinning is meant for this.
The good news is that you already learned how good pinning is to prevent MitM attacks, now the bad news is that it can be bypassed, and yes I also wrote an article on how to it on Android (sorry to not be specific on react-native). If you want to learn the mechanics of it then read my article How to Bypass Certificate Pinning with Frida on an Android App:
Today I will show how to use the Frida instrumentation framework to hook into the mobile app at runtime and instrument the code in order to perform a successful MitM attack even when the mobile app has implemented certificate pinning.
Bypassing certificate pinning is not too hard, just a little laborious, and allows an attacker to understand in detail how a mobile app communicates with its API, and then use that same knowledge to automate attacks or build other services around it.
Code Obfuscation and Modifying Code
I know that anyone can access my app source code if they extract the APK file. I want to make sure that no one can alter or steal my source code.
Sorry, but once you release it to the public is up for grabs for everyone, even if heavily obfuscated its still possible to modify it statically or during runtime.
I read that I can make my code unreadable by Obfuscating it ( I still need to figure out how I am going to do that on my EAS build ), is this enough?
No, you can use the best obfuscation tool, but then an attacker well versed in deobuscation techniques will be able to understand your code and modify it statically or at runtime. Several open-source tools exist to ake this easy, and if you read the article to bypass certificate pinning then you already saw an example of doing it at runtime with 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.
RASP - Runtime Application Self-Protection
And I have to use JailMonkey to detect if the device is rooted.
Using Frida the check can be modified to always return that the device is not rooted. Also JailMonkey may not detect all ways used to hide that a device is rooted, and this a moving target, because hackers and developers are in a constant cat and mouse game.
Sensitive Info Security
I am using Expo secure store to save my sensitive info on the client side.
Even when a secret is securely stored it will need to be used at some point, and the attacker will hook Frida to this point and extract the secret or do it in a MitM attack.
Possible Solutions
Is this approach good enough, is there anything I am missing?
From all I wrote it looks no matter what you are doomed to failure in properly secure your sensitive info and to guarantee that your API server knows that what is making the request is the genuine mobile app it expects, but security its all about of applying as many layers of defences as possible, like done in medieval castles, prisons, etc., because this will increase the level of effort, time and expertise required to succeed in an attack.
You now need to find a solution that allows you to detect MitM attacks, tampered and modified apk binaries, Frida present at runtime and that can deliver a runtime secret to mobile apps that pass a mobile app attestation that guarantees with a very high degree of confidence that such threats are not present. Unfortunately I don't know any open-source project that can deliver all this features, but a commercial solution exists (I work there), and if you want to learn more about you can read the article:
Hands-on Mobile App and API Security - Runtime Secrets Protection
In a previous article we saw how to protect API keys by using Mobile App Attestation and delegating the API requests to a Proxy. This blog post will cover the situation where you can’t delegate the API requests to the Proxy, but where you want to remove the API keys (secrets) from being hard-coded in your mobile app to mitigate against the use of static binary analysis and/or runtime instrumentation techniques to extract those secrets.
We will show how to have your secrets dynamically delivered to genuine and unmodified versions of your mobile app, that are not under attack, by using Mobile App Attestation to secure the just-in-time runtime secret delivery. We will demonstrate how to achieve this with the same Astropiks mobile app from the previous article. The app uses NASA's picture of the day API to retrieve images and descriptions, which requires a registered API key that will be initially hard-coded into the app.
Do You Want To Go The Extra Mile?
In any response to a security question I always like to reference the excellent work from the OWASP foundation.
For APIS
OWASP API Security Top 10
The OWASP API Security Project seeks to provide value to software developers and security assessors by underscoring the potential risks in insecure APIs, and illustrating how these risks may be mitigated. In order to facilitate this goal, the OWASP API Security Project will create and maintain a Top 10 API Security Risks document, as well as a documentation portal for best practices when creating or assessing APIs.
For Mobile Apps
OWASP Mobile Security Project - Top 10 risks
The OWASP Mobile Security Project is a centralized resource intended to give developers and security teams the resources they need to build and maintain secure mobile applications. Through the project, our goal is to classify mobile security risks and provide developmental controls to reduce their impact or likelihood of exploitation.
OWASP - Mobile Security Testing Guide:
The Mobile Security Testing Guide (MSTG) is a comprehensive manual for mobile app security development, testing and reverse engineering.
short answer you can't.
I want to know how to make my backend endpoints accept only requests
that are coming from my application, not from anything else like
Postman
the only thing you can do here is cors Cross-Site Request Forgery Prevention. Y to stop other servers from calling your api.
and you can't make only your application communicate with the server
you can hard code(parameters in the request) in the application to send to the server.but hackers can listen to request made from devices
I know that anyone can access my app source code if they extract the
APK file. I want to make sure that no one can alter or steal my source
code.
short answer you also can't
you can use ProGuard(native code) to obfuscate on native android and ios have compiled binary on release but those are not to js
so basically anyone can read your bundle js in plain text editor.
maybe in the future facebook can make something for hermes.
Would love to get peoples thoughts on this.
I have a front-end application that lives on the apple store. It interacts with custom JavaScript APIs that we've built and that are deployed on an EKS cluster. The cluster and the EC2 instances of the cluster live in private subnets in AWS, but are exposed to the world through an application load balancer that lives in a public subnet.
Since the front end application lives on apples servers, I can't think of an easy way to securely access the APIs in AWS without exposing them to the world. This is what I have in mind:
Use API keys. Not ideal as the keys could still potentially be scraped from a header
Restrict access to the APIs to the apple server network via ACLs and security groups. Again, not something that seems achievable since there is no network CIDR that apple provide (that I know of)
Set up some sort of SSH tunnel
I've hit a wall on this and would really appreciate anyones thoughts if they've had a similar issue.
Thanks!
In Google CDP you can have another type of ACL which monitors the client URL. If requests wont come from your.frontend.app, they are denied. Check if you can find that in AWS as well
I recommend to further think about if possible in you project:
1.) CSRF strategy. Apply tokens to clients which must be provided on request to API.
2.) AccessLimiter. Maintain Fingerprint or Session for your clients and count/limit requests as you need. E.g. if the request didnt run through an index file before, no request is possible as clients didnt collect a token.
So with all the new stuff like notifications and offline caching available now with the service worker api I've been looking to add it to my web app.
The only thing is I can't seem to figure out is how to deal with the the https/ssl issue.
My site allows people to host websites in an online no code environment. New sites are accessed by subdomains off the main domain. This by itself I can only see requiring a wildcard subdomain ssl cert.
The complication I'm facing is that premium sites can add their own top level domain. Which will break the service worker as far as I can tell.
All these sites only require the user to sign up once so users are shared between sites and you can also get your notifications and messages cross site.
I would like to take advantage of the notifications part of the api for mobile but I'm going to need to get around this issue first.
Any help or enlightenment on this would be much appreciated :).
As Alex Russel pointed in his article:
Service Worker scripts must be hosted at the same origin
and Service Worker can't work outside its scope. Subdomains are not the same origin, so you'll need specific worker for specific client's page.
However, I can't see a problem here - when someone will enter yourpremiumclient.com, DNS server (ex. cloudflare, which offers free HTTPS and can force HTTPS) will point to your server, where worker could install and control this domain scope. Of course, the same worker won't be able to control your default scope ex. yourclient.yourdomain.com.
I'm working on a project which uses HTML5 WebSockets to connect with an iOS App. I need to display a list of near by (within the same local WiFi network) iPhones/iPads inside the webpage.
Is it possible to use any discovery mechanism like Bonjour to achieve this?
Is there any way to detect the local IP address from the website (using Javascript or from server side script) so that I can scan the local IP range?
If you're only looking to match devices on the same network, you could just check the public IP, since everyone connected to the same router will likely share one. That said, while a native iOS app should be able to detect a local IP address, I don't know of any way to do so using Javascript.
The one exception is if you have a server running inside the local network (or a custom binary running on their machine). It doesn't sound from your description like this is an option for you, but in case it is, a server within the user's LAN will see their local IP rather than their public IP. It could then relay that to a public server if needed.
I'd love to be proven wrong though, because I could think of some really cool things to do if it were possible.