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Java Serialized + Zlib + gzip

chrom | Last updated: Jun 06, 2016 09:07AM UTC

I have this issue and I can't seem to solve it without writing an extension. The java thick client communicates with the server by doing the following on the data part of the HTTP POST request: Client: - Java Serialized Object - gzip compression - zlib compression this reaches the server. So in order to be able to inspect and modify/fuzz the traffic I need to: - Open burp1 instance to insert the "Content-Encoding: deflate" header that is missing. Forward the request to burp2 - Set "unpack deflate / gzip in requests" at burp2. Use any JDSer plugin at this instance. Forward the request to burp3 - Here as I imagine it, I should perform the zlib compression, the gzip compression and send to server. This is the part that I have problems with as nothing that I try works and the server always responds with "java.util.zip.ZipException: incorrect header check java.util.zip.InflaterInputStream.read(InflaterInputStream ..." Should I expect an auto/header recognition of the compression method to burp in the near future? Is there any other way or suggestion that I should approach this? Thanks much.

Burp User | Last updated: Jun 06, 2016 09:17AM UTC

Correction: there is no separate gzip layer. The compression is done with zlib. Therefore the actual problem is that I can't configure burp to automatically re-compress the modified request with zlib.

PortSwigger Agent | Last updated: Jun 06, 2016 01:23PM UTC