This decodes fastinfoset encoded requests from client -> burp so they can be read/scanned/intruded etc, then encodes the requests again from burp -> server.
Similarly but in reverse for responses.
If the requests are gzip compressed, they will be decompressed first and re-compressed afterwards.
The original encoded requests are visible in the proxy under the Original request tab, but a new Edited request tab shows the decoded content. This can then be sent to intruder/scanned etc which should then encode them on the fly but only show decoded requests/responses.
Similarly the Original response tab is the decoded response, and the Edited response tab the encoded response. These tab names are perhaps backwards but cannot be changed.
This project requires apache maven to build.
$ cd fista
$ mvn package
Open Burp Suite, switch to "Extender" tab, add the jar in the target folders as an extension.
Alternatively you can use the precompiled jar in this repository.
Pull requests are welcome.