'Tests an URL for OS Commanding vulnerabilities using cat/type to write
the content of a known file (i.e. /etc/passwd) to the HTML.
:param freq: A FuzzableRequest'

def _with_echo(self, freq, orig_response):

    command_list = self._get_echo_commands()
    only_command_strings = [v.get_command() for v in command_list]
    mutants = create_mutants(freq, only_command_strings, orig_resp=orig_response)
    mutants.extend(create_mutants(freq, only_command_strings, append=True, orig_resp=orig_response))
    self._send_mutants_in_threads(self._uri_opener.send_mutant, mutants, self._analyze_echo)
