An extension for BurpSuite used to access and modify compressed HTTP payloads without changing the content-encoding.

Often, HTTP traffic is compressed by the server before it is sent to the client in order to reduce network load. Typically used algorithms are gzip or deflate. By default, BurpSuite will decompress all intercepted data in the body of HTTP messages in order to display plain text payloads in the different tabs and make stuff searchable. However, the content is not recompressed back before it is sent to the browser. Usually, this isn't a problem.

In cases where the traffic is intended for other types of client instead of a browser, e.g. a fat/rich client using RMI over HTTP, the used content-encoding may sometimes be fixed and changing it will result in an error.

When using this extension, you will be able to access and modify compressed HTTP content in requests and responses within a new tab in BurpSuite. The tab will appear as soon as compressed data is detected in a message body. For this, you need to disable automatic unpacking of data by BurpSuite.

Launch BurpSuite, go to the Extender tab and then open the Extensions tab and click on "Add". In the dialog window, select "java" as Extension Type and select the burp-decompressor.jar, that you can download from the releases. For further details about BurpSuite extensions, refer to their documentation.

In BurpSuite, open the Proxy tab, then the Options tab. Scroll to the bottom of the pane, under the title "Miscellaneous", untick both "Unpack gzip / deflate in requests" and "Unpack gzip / deflate in responses".

Either use the build.xml with ant, this will automatically download the latest free version of BurpSuite to compile against. Or open the project in Eclipe, create a lib directory and put the burpsuite.jar in it, that you can download from portswigger.net.

This is my first BurpSuite extension, highly inspired by federicodotta/BurpJDSer-ng-edited