Thursday, May 25, 2023

ChopChop - ChopChop Is A CLI To Help Developers Scanning Endpoints And Identifying Exposition Of Sensitive Services/Files/Folders


ChopChop is a command-line tool for dynamic application security testing on web applications, initially written by the Michelin CERT.

Its goal is to scan several endpoints and identify exposition of services/files/folders through the webroot. Checks/Signatures are declared in a config file (by default: chopchop.yml), fully configurable, and especially by developers.



"Chop chop" is a phrase rooted in Cantonese. "Chop chop" means "hurry" and suggests that something should be done now and without delay.


Building

We tried to make the build process painless and hopefully, it should be as easy as:

$ go mod download
$ go build .

There should be a resulting gochopchop binary in the folder.


Using Docker

Thanks to Github Container Registry, we are able to provide you some freshly-build Docker images!

docker run ghcr.io/michelin/gochopchop scan https://foobar.com -v debug

But if you prefer, you can also build it locally, see below:


Build locally
docker build -t gochopchop .

Usage

We are continuously trying to make goChopChop as easy as possible. Scanning a host with this utility is as simple as :

$ ./gochopchop scan https://foobar.com

Using Docker
docker run gochopchop scan https://foobar.com

Custom configuration file
docker run -v ./:/app chopchop scan -c /app/chopchop.yml https://foobar.com

What's next

The Golang rewrite took place a couple of months ago but there's so much to do, still. Here are some features we are planning to integrate : [x] Threading for better performance [x] Ability to specify the number of concurrent threads [x] Colors and better formatting [x] Ability to filter checks/signatures to search for [x] Mock and unit tests [x] Github CI And much more!


Testing

To quickly end-to-end test chopchop, we provided a web-server in tests/server.go. To try it, please run go run tests/server.go then run chopchop with the following command ./gochopchop scan http://localhost:8000 --verbosity Debug. ChopChop should print "no vulnerabilities found".

There are also unit test that you can launch with go test -v ./.... These tests are integrated in the github CI workflow.


Available flags

You can find the available flags available for the scan command :

Flag Full flag Description
-h --help Help wizard
-v --verbosity Verbose level of logging
-c --signature Path of custom signature file
-k --insecure Disable SSL Verification
-u --url-file Path to a specified file containing urls to test
-b --max-severity Block the CI pipeline if severity is over or equal specified flag
-e --export Export type of the output (csv and/or json)
--export-filename Specify the filename for the export file(s)
-t --timeout Timeout for the HTTP requests
--severity-filter Filter Plugins by severity
--plugin-filter Filter Plugins by name of plugin
--threads Number of concurrent threads

Advanced usage

Here is a list of advanced usage that you might be interested in. Note: Redirectors like > for post processing can be used.

  • Ability to scan and disable SSL verification
$ ./gochopchop scan https://foobar.com --insecure
  • Ability to scan with a custom configuration file (including custom plugins)
$ ./gochopchop scan https://foobar.com --insecure --signature test_config.yml
  • Ability to list all the plugins or by severity : plugins or plugins --severity High
$ ./gochopchop plugins --severity High
  • Ability to specify number of concurrent threads : --threads 4 for 4 workers
$ ./gochopchop plugins --threads 4
  • Ability to block the CI pipeline by severity level (equal or over specified severity) : --max-severity Medium
$ ./gochopchop scan https://foobar.com --max-severity Medium
  • Ability to specify specific signatures to be checked
./gochopchop scan https://foobar.com --timeout 1 --verbosity --export=csv,json --export-filename boo --plugin-filters=Git,Zimbra,Jenkins
  • Ability to list all the plugins
$ ./gochopchop plugins
  • List High severity plugins
$ ./gochopchop plugins --severity High
  • Set a list or URLs located in a file
$ ./gochopchop scan --url-file url_file.txt
  • Export GoChopChop results in CSV and JSON format
$ ./gochopchop scan https://foobar.com  --export=csv,json --export-filename results

Creating a new check

Writing a new check is as simple as :

  - endpoint: "/.git/config"
    checks:
      - name: Git exposed
        match:
          - "[branch"
        remediation: Do not deploy .git folder on production servers
        description: Verifies that the GIT repository is accessible from the site
        severity: "High"

An endpoint (eg. /.git/config) is mapped to multiple checks which avoids sending X requests for X checks. Multiple checks can be done through a single HTTP request. Each check needs those fields:

Attribute Type Description Optional ? Example
name string Name of the check No Git exposed
description string A small description for the check No Ensure .git repository is not accessible from the webroot
remediation string Give a remediation for this specific "issue" No Do not deploy .git folder on production servers
severity Enum("High", "Medium", "Low", "Informational") Rate the criticity if it triggers in your environment No High
status_code integer The HTTP status code that should be returned Yes 200
headers List of string List of headers there should be in the HTTP response Yes N/A
no_headers List of string List of headers there should NOT be in the HTTP response Yes N/A
match List of string List the strings there should be in the HTTP response Yes "[branch"
no_match List of string List the strings there should NOT be in the HTTP response Yes N/A
query_string GET parameters that have to be passed to the endpoint String Yes query_string: "id=FOO-chopchoptest"

External Libraries
Library Name Link License
Viper https://github.com/spf13/viper MIT License
Go-pretty https://github.com/jedib0t/go-pretty MIT License
Cobra https://github.com/spf13/cobra Apache License 2.0
strfmt https://github.com/go-openapi/strfmt Apache License 2.0
Go-homedir https://github.com/mitchellh/go-homedir MIT License
pkg-errors https://github.com/pkg/errors BSD 2 (Simplified License)
Go-runewidth https://github.com/mattn/go-runewidth MIT License

Please, refer to the third-party.txt file for further information.


Talks
License

ChopChop has been released under Apache License 2.0. Please, refer to the LICENSE file for further information.


Authors
  • Paul A.
  • David R. (For the Python version)
  • Stanislas M. (For the Golang version)


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