Skip to content

The Send Phase

Scope of the phase

This phase is obligatory for a nonmodifying extension to operate (the YAML file should contain the send section).

Note that this phase is absent in a modifying extension because the Send phase would render other phases unusable (except for the Detect phase and implicit Collect phase) if combined with them.

Read about the extension types in detail here.

This phase sends the predefined test requests to test a target application for vulnerabilities. The host that the test requests should be sent to is determined by the Host header value in incoming baseline requests.

The send section has the following structure:

  - method: <HTTP method>
    url: <URI>
    - header 1: value
    - header N: value
    body: <the request body>
  - method: <HTTP method>

The send section in the extension YAML file contains one or more parameter set. Each parameter is specified as a <key: value> pair. A given parameter set describes a single HTTP request to be sent as a test request. The following parameters are part of the set:

  • method: the HTTP method to be used by the request.

    This is a required parameter: it should be present in any parameter set.

    List of the allowed parameter's values
    • GET
    • POST
    • PUT
    • HEAD
    • PATCH
    • COPY
    • DELETE
    • LOCK
    • UNLOCK
    • MOVE
    • TRACE

    method: 'POST'

  • url: a URL string. The request will be targeted to this URI.

    This is a required parameter: it should be present in any parameter set.


    url: '/en/login.php'

  • headers: an array that contains one or more HTTP headers in the header name: header value format.

    If the constructed HTTP request does not use any header, then this parameter can be omitted.

    FAST automatically adds the headers required for the resulting HTTP request to be correct (even if they are missing in the headers array); for example, Host and Content-Length.

    - 'Accept-Language': 'en-US,en;q=0.9'
    - 'Content-Type': 'application/xml'

    Working with the Host header

    You can add a Host header to a test request that differs from the one extracted from a baseline request, if necessary.

    For example, it is possible to add the Host: header to a test request in the Send section.

    If the corresponding extension is running and the FAST node receives a baseline request with the Host: header, then the test request with the header Host: will be sent to the host. The resulting request is similar to this one:

    curl -k -g -X POST -L -H "Host:" -H "Content-Type: application/json" "" --data "{"field":"value"}"
  • body: a string that contains the request's body. You can specify any required request body, as long as you escape special characters, if any, in the resulting string.

    This is a required parameter: it should be present in any parameter set.


    body: 'field1=value1&field2=value2

If the send section is populated with N parameter sets describing the N HTTP requests, then for a single incoming baseline request, the FAST node will send N test requests to the target application that resides on a host specified in the Host header of the baseline request.