SHELLING is a plugin that is not available in the BApps Store, so you will need to go the GitHub to get it https://github.com/ewilded/shelling. Download the .jar file and install it using the Extender option in Burp Suite:
- To do this, click on the Extender tab, and click on the Manual install button. Burp Suite will launch a window to select the .jar file. Because SHELLING is not included as an official extension, Burp Suite will launch the following warning message to confirm that you want to install it:

- After it is installed, you will not see anything different on your Burp Suite instance. This is because SHELLING does not modify ...