ChopChop – Web Security Testing Tool

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.

Table Of Contents

• Building
• Usage
  • Available flags
  • Advanced usage
• Creating a new check/signature
• External Libraries
• Talks
• Licence
• Authors

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

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"