Note: To change trusted certificate settings on IE, you must have an account with local administrator privileges.
If you have previously installed a different CA certificate generated by Burp, you should first remove it by following the tutorial to remove Burp's CA certificate from Internet Explorer.
If you have not already done so, configure your browser to use Burp as its proxy, and configure Burp's Proxy listener to generate CA-signed per-host certificates (this is the default setting).
Launch Internet Explorer. On recent versions of Windows, you must run IE as administrator. Click the "Start" button, type "internet explorer" into the search box, right-click the Internet Explorer link, and select "Run as Administrator" from the context menu.
With Burp running, visit http://burp in IE and click the "CA Certificate" link to download and save your Burp CA certificate. Take note of where you save the Burp CA certificate.
You will be prompted with a message, click “Save”. The file “cacert.der” should now download.
You will be prompted with another message, click “Open” and a “Certificate” box will pop up.
Click “Install Certificate”.
In the “Certificate Import Wizard” dialog box click “Next”.
In the Certificate Import Wizard, select "Place all certificates in the following store" and click “Browse”.
In the “Select Certificate Store” window select "Trusted Root Certification Authorities" and click “OK”.
Complete the wizard by clicking “Next” followed by “Finish”.
Click "Yes" on the security warning.
Close all dialogs and restart IE (no need to run as administrator).
If everything has worked, you should now be able to visit any HTTPS URL via Burp without any security warnings.