CSCBE18 blockchain data exfiltration challenge related info
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This repository contains all information related to a challenge in the CSCBE 18 qualifiers. The challenge was based on data exfiltration using blockchain and consisted of three subchallenges

  • Blockshark
  • BlocksharkNado
  • BlocksharkNado vs Blocksharcopus

For the challenge a network capture file was provided data_exfil.pcap.

A writeup of the challenge was published on the NVISO blog.

The following files are provided:

datai_exfil.pcap: network capture used for the challenges

bt_encrypt.go: encrypts the message contained in secret.txt. Expects to have the 3123xy.json files in a data subfolder. Two files are provided, downloaded the other address blocks from

webserver.go: the webserver that participants could use to check the working of the protocol. Also expects to have the 3123xy.json files in a data subfolder (see above). The address_response_footer file contains the footer for address responses. and perl scripts used during the analysis that is described in the writeup.

Important !!!

The webserver is not intended to be run directly accessible from a hostile environment (read The Internet). Although care was taken to only accept very specific URL's and perform basic santity checking, this was my first decent-sized Go program I've written. During the CSCBE18 challenge it was set up behind an NGINX reverse proxy, which implemented basic filtering and rate limiting.

Kris Boulez - kris [dot] boulez [at] gmail [dot] com