WapiFuzz - fully autonomous web APIs fuzzer

Fuzzing is popular testing technique for various error types detection. There are many fuzzing engines and fuzzers, which can help you with fuzzing itself. But there is currently no tool which can fully automate fuzzing just by providing API specification.

And that is why WapiFuzz was created. We believe that web API documentation is all that fuzzer needs to do his job. WapiFuzz can be easily deployed to almost any continuous integration (CI) service. It is based on popular Boofuzz fuzzer and provides test reports to JUnit XML format.

What does the WapiFuzz test?

WapiFuzz can find vulnerabilities in following parts of HTTP request:

• HTTP header
• Path and query attributes
• JSON body primitive types

All requests are automatically generated from provided OpenAPI documentation.

What types of vulnerabilities does WapiFuzz testing?

• Numeric strings (overflows, reserved words, etc.)
• Command injection
• SQL injection
• Path traversal
• Special characters
• Unicode sequences
• XML / XPath attacks

Requirements for your web API

You can automatically test your web API if it meets following criteria:

• Documented in OpenAPI 2 or OpenAPI 3
• Consumes and produces only application/json or text/plain content

If you have your API documented in other documentation formats, you can try use some convertors. There are plenty convertors online. Some of theme are listed here: https://openapi.tools/.

Consuming JSON data is not mandatory requirement. If your API does not consumes JSON, WapiFuzz will still tests HTTP header and URI attributes processing of your server. The fuzzing of HTTP body part will be limited due to unsupported content format.

Dependencies

• Python 3
• .NET Core runtime 2.1 and higher
• JRE or Docker
• PowerShell or Bash

Usage

The only thing you need to do is create WapiFuzz config file. You can find template in root of repository in config_example.json file. You can just modify this file and then pass it's path to runner script.

In config file you are able to specify following options:

• fixed_url_attributes -> if you want to set some URL attributes to static values
• headers -> headers which are sent by each request (useful for AUTH token insertion)
• receive_timeout -> maximum amount of time waiting for response (in seconds)
• reporting_interval -> progress reporting interval (in seconds)
• http_fuzzing -> boolean value for enabling / disabling fuzzing of bare HTTP protocol
• skipping_endpoints_keywords [list of keywords] -> endpoints containing any keyword in it from this list will be skipped (can be used for skipping auth/logout endpoints)
• startup_command (use only if you want to use process monitor) -> startup command for your tested process / service, see more details in procmon/README.md
• are_non_required_attributes_in_requests -> boolean value, set to true, if you want attributes, that are specified as non-required to be part of URL part of request
• payloads_to_json_primitives_mapping -> mapping of payloads folders to JSON primitives
  • boolean -> array of folder names with payloads which will be used for JSON boolean fuzzing
  • number -> array of folder names with payloads which will be used for JSON number fuzzing
  • string -> array of folder names with payloads which will be used for JSON string fuzzing
• target -> information about tested application
  • hostname -> victim hostname or IP address
  • port -> victim port
  • ssl -> boolean value, set to true if you want use SSL tcp connections, otherwise false

Great, WapiFuzz is now ready for fuzzing! Run it by following commands.

Windows

Execute run.ps1 -c config_file_path -openapi openapi_doc_file_path [-payloads custom_payloads_file_path] script in PowerShell.

Unix

Execute run.sh config_file_path openapi_doc_file_path [custom_payloads_file_path] command from Bash.

Docker

You just need to run the container with following arguments:

docker run -p {host_port}:{container_port} -v $(pwd):/usr/local/fuzzer/mnt/ starek4/wapifuzz:latest config.json sqta.yaml [custom_payloads.txt]

where files config.json, sqta.yaml and custom_payloads.txt needs to be stored in the working directory. With parameter -p you also need to bind port number, which is used for communication with your web API, to the container. So for example, if your API listen on the port 80, you can simply do -p 80:80.

Custom payloads file

As you can see in run script parameters, you may even specify your own payloads! Just create text file with your strings (one on each line) and pass path to this file via run script parameters! They will be automatically added into every fuzzed part of request.

Where I can find test reports?

After WapiFuzz finish, three main report files are generated. If you are using docker image just the way that is described above, you simply find these three files in your working directory. If you are running WapiFuzz by run scripts, you can find these files in the following paths:

• JUnit File: ./reporter/results.junit.xml
• HTML report: ./reporter/reports.html
• Full text log: ./fuzzing.log

JUnit report

The first is the JUnit file (./reporter/results.junit.xml), which contains full test report and contains logs for failed tests. Almost every CI system provides a way how to present JUnit test reports in some human friendly way.

HTML report

WapiFuzz also generates nicely formatted HTML test report, stored at ./reporter/reports.html.

Full text log

Detailed text log with all information what you need to understand what happened when fuzzing.