[Question] - Possible false-positive on emulator detection

[gabcarneiro]

Hello guys, first i wanna thank you for all the effort you have been putting on this project, im working on an app that requires resilience against reverse engineering and this project saved my life.

The issue is: im applying an emulator detection on an Android project based on these build.props here.

I noticed that running the app on a Pixel 3 (API 28) from Firebase Test Lab triggers the emulator detection due to value of the prop Build.User beeing android-build.

I get the same behaviour running the app on some devices from AWS Device Farm, tested with the following devices:

• Pixel 3 (API 28)
• Pixel 3 (API 29)
• Pixel 4 (API 29)
• Pixel 5 (API 31)

All of them have the value of the property Build.USER as android-build.

Unfortunately i couldnt get my hands on any "real physical device" from this list and test it.

Can we realy relly on this build.prop?
Is there any chance that devices from Firebase Test Lab or AWS Device Farm would behave differenlty than a common physical device?

Thanks in advance

[cpholguera]

Thanks for your nice words @gabcarneiro , we're very happy to hear that ☺️ I've relocated your question to the Q&A section of our Discussions. Whenever you get your answer you can mark it as "the answer". That'll be very useful for other people having the same problem.

[julepka]

Hi @gabcarneiro

I can share my experience of building emulator detection. I have access to several Android devices for testing. During development I've experienced false positives as well, including the case when I used build.props from the MSTG. My recent project with emulator detection is using the library to detect emulator and I'm satisfied with its approach. I've received no complaints about false positives when using it.

Here is what it checks for: https://github.com/react-native-device-info/react-native-device-info/blob/e186394d1b1afc6af74703e52c99192dccc9b9d9/android/src/main/java/com/learnium/RNDeviceInfo/RNDeviceModule.java#L226

  public boolean isEmulatorSync() {
    return Build.FINGERPRINT.startsWith("generic")
            || Build.FINGERPRINT.startsWith("unknown")
            || Build.MODEL.contains("google_sdk")
            || Build.MODEL.toLowerCase(Locale.ROOT).contains("droid4x")
            || Build.MODEL.contains("Emulator")
            || Build.MODEL.contains("Android SDK built for x86")
            || Build.MANUFACTURER.contains("Genymotion")
            || Build.HARDWARE.contains("goldfish")
            || Build.HARDWARE.contains("ranchu")
            || Build.HARDWARE.contains("vbox86")
            || Build.PRODUCT.contains("sdk")
            || Build.PRODUCT.contains("google_sdk")
            || Build.PRODUCT.contains("sdk_google")
            || Build.PRODUCT.contains("sdk_x86")
            || Build.PRODUCT.contains("vbox86p")
            || Build.PRODUCT.contains("emulator")
            || Build.PRODUCT.contains("simulator")
            || Build.BOARD.toLowerCase(Locale.ROOT).contains("nox")
            || Build.BOOTLOADER.toLowerCase(Locale.ROOT).contains("nox")
            || Build.HARDWARE.toLowerCase(Locale.ROOT).contains("nox")
            || Build.PRODUCT.toLowerCase(Locale.ROOT).contains("nox")
            || Build.SERIAL.toLowerCase(Locale.ROOT).contains("nox")
            || (Build.BRAND.startsWith("generic") && Build.DEVICE.startsWith("generic"));
  }

[gabcarneiro]

Hi @julepka thank you for sharing!

I am currently using a similar approach, after some tests i ended up removing the condition testing the Build.USER prop.

return Build.FINGERPRINT.startsWith("generic")
                || Build.MODEL.contains("google_sdk")
                || Build.MODEL.contains("droid4x")
                || Build.MODEL.contains("Emulator")
                || Build.MODEL.contains("Android SDK built for x86")
                || Build.MANUFACTURER.contains("Genymotion")
                || Build.HARDWARE.equals("goldfish")
                || Build.HARDWARE.equals("vbox86")
                || Build.HARDWARE.contains("ranchu")
                || Build.HARDWARE.contains("nox")
                || Build.PRODUCT.equals("sdk")
                || Build.PRODUCT.equals("google_sdk")
                || Build.PRODUCT.equals("sdk_x86")
                || Build.PRODUCT.equals("vbox86p")
                || Build.BOARD.contains("nox")
                || Build.BOOTLOADER.contains("nox")
                || Build.PRODUCT.contains("nox")
                || Build.TAGS.contains("test-keys")
                || Build.PRODUCT == "google_sdk"
                || Build.ID.contains("FRF91")
                || (Build.BRAND.startsWith("generic") && Build.DEVICE.startsWith("generic"))

I was just thinking... isn't it dangerous to keep the Build.USER prop here with the meaning "Emulator"? This might lead other people into the same problem.