Primer paso de la investigacion. Se aportan el .apk, las carpetas con el apk extraido y el apk descompilado. El archivo API_DOCUMENTATION.md es un archivo donde se anotaran los descubrimientos del funcionamiento de la API, y los .py son scripts para probar la funcionalidad de la API con los métodos que vayamos encontrando. Finalmente, los archivos .js son scripts de Frida para extraer informacion de la APP durante la ejecucion.

apk_decompiled/sources/com/google/firebase/messaging/Metadata.java

@@ -0,0 +1,142 @@
+package com.google.firebase.messaging;
+
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.ResolveInfo;
+import android.util.Log;
+import com.google.android.gms.common.util.PlatformVersion;
+import com.google.firebase.FirebaseApp;
+import java.util.List;
+
+/* JADX INFO: Access modifiers changed from: package-private */
+/* loaded from: classes3.dex */
+public class Metadata {
+    private static final String ACTION_C2DM_REGISTER = "com.google.android.c2dm.intent.REGISTER";
+    private static final String ACTION_IID_TOKEN_REQUEST = "com.google.iid.TOKEN_REQUEST";
+    static final int GMSCORE_NOT_FOUND = 0;
+    private static final String GMSCORE_SEND_PERMISSION = "com.google.android.c2dm.permission.SEND";
+    static final String GMS_PACKAGE = "com.google.android.gms";
+    static final int IID_VIA_RECEIVER = 2;
+    static final int IID_VIA_SERVICE = 1;
+    private String appVersionCode;
+    private String appVersionName;
+    private final Context context;
+    private int gmsVersionCode;
+    private int iidImplementation = 0;
+
+    public Metadata(Context context) {
+        this.context = context;
+    }
+
+    public static String getDefaultSenderId(FirebaseApp firebaseApp) {
+        String gcmSenderId = firebaseApp.getOptions().getGcmSenderId();
+        if (gcmSenderId != null) {
+            return gcmSenderId;
+        }
+        String applicationId = firebaseApp.getOptions().getApplicationId();
+        if (!applicationId.startsWith("1:")) {
+            return applicationId;
+        }
+        String[] split = applicationId.split(":");
+        if (split.length < 2) {
+            return null;
+        }
+        String str = split[1];
+        if (str.isEmpty()) {
+            return null;
+        }
+        return str;
+    }
+
+    private PackageInfo getPackageInfo(String str) {
+        try {
+            return this.context.getPackageManager().getPackageInfo(str, 0);
+        } catch (PackageManager.NameNotFoundException e4) {
+            Log.w(Constants.TAG, "Failed to find package " + e4);
+            return null;
+        }
+    }
+
+    private synchronized void populateAppVersionInfo() {
+        PackageInfo packageInfo = getPackageInfo(this.context.getPackageName());
+        if (packageInfo != null) {
+            this.appVersionCode = Integer.toString(packageInfo.versionCode);
+            this.appVersionName = packageInfo.versionName;
+        }
+    }
+
+    public synchronized String getAppVersionCode() {
+        try {
+            if (this.appVersionCode == null) {
+                populateAppVersionInfo();
+            }
+        } catch (Throwable th) {
+            throw th;
+        }
+        return this.appVersionCode;
+    }
+
+    public synchronized String getAppVersionName() {
+        try {
+            if (this.appVersionName == null) {
+                populateAppVersionInfo();
+            }
+        } catch (Throwable th) {
+            throw th;
+        }
+        return this.appVersionName;
+    }
+
+    public synchronized int getGmsVersionCode() {
+        PackageInfo packageInfo;
+        try {
+            if (this.gmsVersionCode == 0 && (packageInfo = getPackageInfo("com.google.android.gms")) != null) {
+                this.gmsVersionCode = packageInfo.versionCode;
+            }
+        } catch (Throwable th) {
+            throw th;
+        }
+        return this.gmsVersionCode;
+    }
+
+    public synchronized int getIidImplementation() {
+        int i = this.iidImplementation;
+        if (i != 0) {
+            return i;
+        }
+        PackageManager packageManager = this.context.getPackageManager();
+        if (packageManager.checkPermission(GMSCORE_SEND_PERMISSION, "com.google.android.gms") == -1) {
+            Log.e(Constants.TAG, "Google Play services missing or without correct permission.");
+            return 0;
+        }
+        if (!PlatformVersion.isAtLeastO()) {
+            Intent intent = new Intent(ACTION_C2DM_REGISTER);
+            intent.setPackage("com.google.android.gms");
+            List<ResolveInfo> queryIntentServices = packageManager.queryIntentServices(intent, 0);
+            if (queryIntentServices != null && queryIntentServices.size() > 0) {
+                this.iidImplementation = 1;
+                return 1;
+            }
+        }
+        Intent intent2 = new Intent(ACTION_IID_TOKEN_REQUEST);
+        intent2.setPackage("com.google.android.gms");
+        List<ResolveInfo> queryBroadcastReceivers = packageManager.queryBroadcastReceivers(intent2, 0);
+        if (queryBroadcastReceivers != null && queryBroadcastReceivers.size() > 0) {
+            this.iidImplementation = 2;
+            return 2;
+        }
+        Log.w(Constants.TAG, "Failed to resolve IID implementation package, falling back");
+        if (PlatformVersion.isAtLeastO()) {
+            this.iidImplementation = 2;
+        } else {
+            this.iidImplementation = 1;
+        }
+        return this.iidImplementation;
+    }
+
+    public boolean isGmscorePresent() {
+        return getIidImplementation() != 0;
+    }
+}