Caronte : A Tool To Analyze The Network Flow During Attack/Defence Capture The Flag Competitions

Caronte is a tool to analyze the network flow during capture the flag events of type attack/defence. It reassembles TCP packets captured in pcap files to rebuild TCP connections, and analyzes each connection to find user-defined patterns. The patterns can be defined as regex or using protocol specific rules. The connection flows are saved into a database and can be visualized with the web application. REST API are also provided.

Features

• immediate installation with docker-compose
• no configuration file, settings can be changed via GUI or API
• pcaps to be analyzed can be loaded via curl, either locally or remotely, or via the GUI
  • it is also possible to download the pcaps from the GUI and see all the analysis statistics for each pcap
• rules can be created to identify connections that contain certain strings
  • pattern matching is done through regular expressions (regex)
  • regex in UTF-8 and Unicode format are also supported
• connections can be labeled by type of service, identified by the port number
  • each service can be assigned a different color
• ability to filter connections by addresses, ports, dimensions, time, duration, matched rules
• a timeline shows statistics with different metrics sampled per minute
  • some of these metrics are connections_per_service, client_bytes_per_service, server_bytes_per_service, duration_per service, matched_rules
    • with matched_rules metric it can be possible to see the relationship between flag_in and flag_out
  • the timeline contains a sliding window which can be used to search for connections in a certain time interval
• advanced search by term, negated term, exact phrase, regex, negated regex
  • the performed searches are saved to be instantly repeated the following times
• the detected HTTP connections are automatically reconstructed
  • HTTP requests can be replicated through curl, fetch and python requests
  • compressed HTTP responses (gzip/deflate) are automatically decompressed
• ability to export and view the content of connections in various formats, including hex and base64
• JSON content is displayed in a JSON tree viewer, HTML code can be rendered in a separate window
• occurrences of matched rules are highlighted in the connection content view
• supports both IPv4 and IPv6 addresses
  • if more addresses are assigned to the vulnerable machine to be defended, a CIDR address can be used

Installation

There are two ways to install Caronte:

• with Docker and docker-compose, the fastest and easiest way
• manually installing dependencies and compiling the project

Run with Docker

The only things to do are:

• clone the repo, with git clone https://github.com/eciavatta/caronte.git
• inside the caronte folder, run docker-compose up -d
• wait for the image to be compiled and open browser at http://localhost:3333

Manually installation

The first thing to do is to install the dependencies:

• go >= 1.14 https://golang.org/doc/install
• node >= v12 https://nodejs.org/it/download/
• yarnpkg https://classic.yarnpkg.com/en/docs/install/
• hyperscan >= v5 https://www.hyperscan.io/downloads/

Next you need to compile the project, which is composed of two parts:

• the backend, which can be compiled with go mod download && go build
• the frontend, which can be compiled with cd frontend && yarn install && yarn build

Before running Caronte starts an instance of MongoDB https://docs.mongodb.com/manual/administration/install-community/ that has no authentication. Be careful not to expose the MongoDB port on the public interface.

Run the binary with ./caronte. The available configuration options are:

-bind-address address where server is bind (default “0.0.0.0”)
-bind-port port where server is bind (default 3333)
-db-name name of database to use (default “caronte”)
-mongo-host address of MongoDB (default “localhost”)
-mongo-port port of MongoDB (default 27017)

Configuration

The configuration takes place at runtime on the first start via the graphical interface or via API. It is necessary to setup:

• the server_address: the ip address of the vulnerable machine. Must be the destination address of all the connections in the pcaps. If each vulnerable service has an own ip, this param accept also a CIDR address. The address can be either IPv4 both IPv6
• the flag_regex: the regular expression that matches a flag. Usually provided on the competition rules page
• auth_required: if true a basic authentication is enabled to protect the analyzer
• an optional accounts array, which contains the credentials of authorized users

Documentation

The backend, written in Go language, it is designed as a service. It exposes REST API that are used by the frontend written using React. The list of available APIs with their explanation is available here: https://app.swaggerhub.com/apis-docs/eciavatta/caronte/WIP

Screenshots

Below there are some screenshots showing the main features of the tool.

Main window, with connections list and stream content

Main window, with the timeline expanded

Rules and services view

Searches and pcaps view