How to use DNS over TCP to Prevent MitM Attacks in Android & iOS Apps
Learn to Prevent blocking the transfer of DNS over TCP in Mobile apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.
Why Permit DNS over TCP?
Usually, DNS resolution is performed over UDP. This protocol enables a fast, stateless query-response model and is used by DNS to achieve rapid resolution and lookups between hostnames and IP addresses.
Nevertheless, in some cases it is preferable to resolve DNS queries over TCP, for the following reasons:
- Operationally, the UDP payload is limited in size (up to 512b), while TCP has no such restriction. This means that on a single DNS TCP query you can return more hosts to IP resolutions than over UDP. This capability is a clear advantage for sites that have global resolution based on location.
- From a security standpoint, DNSSEC can only reliably be applied over TCP.
How does Appdome implement DNS Transfer over TCP?
Applying DNS transfer over TCP can be complicated. Moreover, if your infrastructure fails to support TCP, or blocks DNS over TCP at the network layer, this may lead to resolution failure, application-level timeouts, or both.
Appdome’s Permit DNS over TCP feature enables this operation for Android and iOS apps without coding.
Preventing blocking the transfer of DNS over TCP on Mobile apps by Using Appdome
On Appdome, follow these 3 simple steps to create self-defending Mobile Apps that Prevent blocking the transfer of DNS over TCP without an SDK or gateway:
Upload the Mobile App to Appdome.
Upload an app to Appdome’s Mobile App Security Build System
Upload Method: Appdome Console or DEV-API
Mobile App Formats: .ipa For iOS device or .apk or .aab
Build the feature: Permit DNS over TCP.
Congratulations! The Permit DNS over TCP protection is now added to the mobile app
Building Permit DNS over TCP by using Appdome’s DEV-API:
Create and name the Fusion Set (security template) that will contain the Permit DNS over TCP feature as shown below:
Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Permit DNS over TCP feature via Appdome Console, to add the Permit DNS over TCP feature to this Fusion Set.
Open the Fusion Set Detail Summary by clicking the “...” symbol on the far-right corner of the Fusion Set, as shown in Figure 1 above, and get the Fusion Set ID from the Fusion Set Detail Summary (as shown below):
Figure 2: Fusion Set Detail Summary
Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).
Follow the instructions below to use the Fusion Set ID inside any standard mobile DevOps or CI/CD toolkit like Bitrise, App Center, Jenkins, Travis, Team City, Cirlce CI or other system:
Build an API for the app – for instructions, see the tasks under Appdome API Reference Guide
Look for sample APIs in Appdome’s GitHub Repository
Figure 1: Fusion Set that will contain the Permit DNS over TCP feature
Note: Naming the Fusion Set to correspond to the protection(s) selected is for illustration purposes only (not required).
Building the Permit DNS over TCP feature via Appdome Console
To build the Permit DNS over TCP protection by using Appdome Console, follow the instructions below.
Where: Inside the Appdome Console, go to Build > Security Tab > Secure Communication section
How: Toggle (turn ON) Permit DNS over TCP, as shown below.
If needed, Customize the Threat Notification to be displayed to the mobile end-user in a standard OS dialog notification when Appdome Prevents blocking the transfer of DNS over TCP.
Figure 3: Prevent blocking the transfer of DNS over TCP option
Note: The App Compromise Notification contains an easy to follow default remediation path for the mobile app end user. You can customize this message as required to achieve brand specific support, workflow or other messaging.
When you select the Permit DNS over TCP you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Permit DNS over TCP
Figure 4: Fusion Set that displays the newly added Permit DNS over TCP protection
Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
Certify the Permit DNS over TCP feature in Mobile Apps.
After building Permit DNS over TCP, Appdome generates a Certified Secure™ certificate to guarantee that the Permit DNS over TCP protection has been added and is protecting the app. To verify that the Permit DNS over TCP protection has been added to the mobile app, locate the protection in the Certified Secure™ certificate as shown below:
Figure 5: Certified Secure™ certificate
Each Certified Secure™ certificate provides DevOps and DevSecOps organizations the entire workflow summary, audit trail of each build, and proof of protection that Permit DNS over TCP has been added to each Mobile app. Certified Secure provides instant and in-line DevSecOps compliance certification that Permit DNS over TCP and other mobile app security features are in each build of the mobile app
Prerequisites to Using Permit DNS over TCP:
To use Appdome’s mobile app security build system to Prevent blocking the transfer of DNS over TCP , you’ll need:
- Appdome account (create a free Appdome account here)
- A license for Permit DNS over TCP
- Mobile App (.ipa For iOS device or .apk or .aab For Mobile)
- Signing Credentials (see Signing Secure Android apps and Signing Secure iOS apps)
Using Appdome, there are no development or coding prerequisites to build secured Mobile Apps by using Permit DNS over TCP. There is no SDK and no library to code or implement in the app and no gateway to deploy in your network. All protections are built into each app and the resulting app is self-defending and self-protecting.
Releasing and Publishing Mobile Apps with Permit DNS over TCP
After successfully securing your app by using Appdome, there are several available options to complete your project, depending on your app lifecycle or workflow. These include:
- Customizing, Configuring & Branding Secure Mobile Apps
- Deploying/Publishing Secure mobile apps to Public or Private app stores
- Releasing Secured Android & iOS Apps built on Appdome.
All apps protected by Appdome are fully compatible with any public app store, including Apple App Store, Google Play, Huawei App Gallery and more.
Features Similar to Permit DNS over TCP
If you have any questions, please send them our way at support.appdome.com or via the chat window on the Appdome platform.
Thanks for visiting Appdome! Our mission is to secure every app on the planet by making mobile app security easy. We hope we’re living up to the mission with your project.