How to send an HTTP request using Rex::Proto::Http::Client

The Rex library (Ruby Extension Library) is the most fundamental piece of the Metasploit Framework architecture. Modules normally do not interact with Rex directly, instead they depend on the framework core and its mixins for better code sharing. If you are a Metasploit module developer, the lib/msf/core directory should be more than enough for most of your needs. If you are writing a module that speaks HTTP, then the Msf::Exploit::Remote::HttpClient mixin (which is found in lib/msf/core/exploit/http/client) is most likely the one you want.

However, in some scenarios, you actually can't use the HttpClient mixin. The most common is actually when writing a form-based login module using the LoginScanner API. If you find yourself in that situation, use Rex::Proto::Http::Client.

Initializing Rex::Proto::Http::Client

Making an HTTP request

Even though our main topic of this documentation is about Rex::Proto::Http::Client, it does not know how to make HTTP requests. Instead, Rex::Proto::Http::ClientRequest is actually the mother of all Metasploit's HTTP requests.

So how does Rex::Proto::Http::ClientRequest give birth to an HTTP request? Well, you see son, it all begins when Rex::Proto::Http::Client asks for one with either the #request_cgi or the #request_raw method. The difference is that if #request_cgi is used, the request is meant to be CGI compatible, and in most cases this is what you want. If #request_raw is used, technically it means less options, less CGI compatible.

A raw HTTP request supports the following options:

Option/key name	Description
query	Raw GET query string
data	Raw POST data string
encode	URI encoding
uri	Raw URI string
uri_encode_count	Number of times to encode
uri_full_url	Full URL
uri_dir_fake_relative	A fake relative URL
ssl	True to use https://, otherwise http://
agent	User-Agent. Default is: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
method	HTTP method
method_random_valid	A random HTTP method: GET, POST, or HEAD
method_random_invalid	A random string as an HTTP method
method_random_case	A random string with casings as an HTTP method
pad_method_uri_count	Number of spaces
pad_method_uri_type	Either a space, or a tab, or Apache specific
uri_fake_params_start	Appends '/%3fa=b/../'
uri_fake_end	Appends '/%20HTTP/1.0/../../'
pad_uri_version_count	Number of spaces between the URI and the version
pad_uri_version_type	Either a space, or a tab, or Apache specific
proto	Protocol
version	Version
version_random_valid	A random version between 1.0 or 1.1
version_random_invalid	A random numeric string for the version
version_random_case	A string with random casings for the version
vhost	Host header
port	Port for the host header
authorization	The authorization header
cookie	The cookie header
connection	The connection header
pad_fake_headers	Number of fake alphanumeric headers
headers	A hash of custom headers. Safer than raw_headers
raw_headers	A string of raw headers
ctype	Content type
chunked_size	Body chunk size. Will also set Transfer-Encoding and Content-Length to ""

If the number of options #request_raw supports doesn't blow you mind, don't be disappointed. #request_cgi inherits all the above, and more:

Option/key name	Description
pad_get_params	Enable padding for GET parameters
pad_get_params_count	Number of random GET parameters. You also need pad_get_params for this
vars_get	A hash of GET parameters
encode_params	Enable URI encoding for GET or POST parameters
pad_post_params	Enable padding for POST parameters
pad_post_params_count	Number of random POST parameters. You also need pad_post_params for this

An example of using one of #request_cgi options:

req = cli.request_cgi({
	'uri'      =>'/test.php',
	'vars_get' => {
		'param1' => 'value',
		'param2' => 'value'
	}
})

Sending an HTTP request

Here are examples of how to actually speak to an HTTP server with either #request_cgi or #request_raw:

#request_cgi

cli = Rex::Proto::Http::Client.new(rhost),
cli.connect
req = cli.request_cgi({'uri'=>'/'})
res = cli.send_recv(req)
cli.close

#request_raw

cli = Rex::Proto::Http::Client.new(rhost),
cli.connect
req = cli.request_raw({'uri'=>'/'})
res = cli.send_recv(req)
cli.close

Configuring advanced options

URI Parsing

Full Example