# Bypass Biometric Authentication (Android)
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These methods were copied from ## **Method 1 – When the crypto object is not used** The authentication implementation relies on the callback \_**onAuthenticationSucceded** \_ being called. The researchers from F-Secure developed a [**Frida script**](https://github.com/FSecureLABS/android-keystore-audit/blob/master/frida-scripts/fingerprint-bypass.js) that can be used to **bypass** the NULL \_**CryptoObject** \_ in ***onAuthenticationSucceeded(…)***. The script will automatically bypass the fingerprint when the aforementioned method is called. Here is a short example that shows the bypass for the Android Fingerprint. The complete application can be downloaded from my [GitHub](https://github.com/St3v3nsS/InsecureBanking). ```javascript biometricPrompt = new BiometricPrompt(this, executor, new BiometricPrompt.AuthenticationCallback() { @Override public void onAuthenticationSucceeded(@NonNull BiometricPrompt.AuthenticationResult result) { Toast.makeText(MainActivity.this,"Success",Toast.LENGTH_LONG).show(); } }); ``` ``` frida -U -f com.st3v3nss.insecurebankingfingerprint --no-pause -l fingerprint-bypass.js ``` ### **Method 2 – Exception Handling** This [**Frida script**](https://github.com/FSecureLABS/android-keystore-audit/blob/master/frida-scripts/fingerprint-bypass-via-exception-handling.js) developed by F-Secure can be used to bypass the insecure usage of the crypto object. All the script needs to do is manually call the ***onAuthenticationSucceded*** with a **non-authorized** (not unlocked by fingerprint) ***CryptoObject*** stored in the Keystore. The catch is if the application will attempt to use another cipher object, then an **exception will be thrown**. This script will attempt to call \_**onAuthenticationSucceded** \_ and catch the exception ***javax.crypto.IllegalBlockSizeException*** in *Cipher* class. From now on, **any objects the application uses will be encrypted using this new key**. ``` frida -U -f com.st3v3nss.insecurebankingfingerprint --no-pause -l fingerprint-bypass-via-exception-handling.js ``` Now, go to the fingerprint screen and wait for the *authenticate*() to be called. Once you see that on the screen, go ahead and type ***bypass()*** in the Frida console: ``` Spawning `com.st3v3nss.insecurebankingfingerprint`... [Android Emulator 5554::com.st3v3nss.insecurebankingfingerprint ]-> Hooking BiometricPrompt.authenticate()... Hooking BiometricPrompt.authenticate2()... Hooking FingerprintManager.authenticate()... [Android Emulator 5554::com.st3v3nss.insecurebankingfingerprint ]-> bypass() ```
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