Module: Msf::Post::Common

Instance Method Summary collapse

Instance Method Details

#clear_screenObject



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# File 'lib/msf/core/post/common.rb', line 21

def clear_screen
  Gem.win_platform? ? (system "cls") : (system "clear")
end

#cmd_exec(cmd, args = nil, time_out = 15, opts = {}) ⇒ Object

Executes cmd on the remote system

On Windows meterpreter, this will go through CreateProcess as the “commandLine” parameter. This means it will follow the same rules as Windows' path disambiguation. For example, if you were to call this method thusly:

cmd_exec("c:\\program files\\sub dir\\program name")

Windows would look for these executables, in this order, passing the rest of the line as arguments:

c:\program.exe
c:\program files\sub.exe
c:\program files\sub dir\program.exe
c:\program files\sub dir\program name.exe

On POSIX meterpreter, if args is set or if cmd contains shell metacharacters, the server will run the whole thing in /bin/sh. Otherwise, (cmd is a single path and there are no arguments), it will execve the given executable.

On Java, it is passed through Runtime.getRuntime().exec(String) and PHP uses proc_open() both of which have similar semantics to POSIX.

On shell sessions, this passes cmd directly the session's shell_command_token method.

Returns a (possibly multi-line) String.



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# File 'lib/msf/core/post/common.rb', line 86

def cmd_exec(cmd, args=nil, time_out=15, opts = {})
  case session.type
  when 'meterpreter'
    #
    # The meterpreter API requires arguments to come separately from the
    # executable path. This has no effect on Windows where the two are just
    # blithely concatenated and passed to CreateProcess or its brethren. On
    # POSIX, this allows the server to execve just the executable when a
    # shell is not needed. Determining when a shell is not needed is not
    # always easy, so it assumes anything with arguments needs to go through
    # /bin/sh.
    #
    # This problem was originally solved by using Shellwords.shellwords but
    # unfortunately, it is unsuitable. When a backslash occurs inside double
    # quotes (as is often the case with Windows commands) it inexplicably
    # removes them. So. Shellwords is out.
    #
    # By setting +args+ to an empty string, we can get POSIX to send it
    # through /bin/sh, solving all the pesky parsing troubles, without
    # affecting Windows.
    #
    if args.nil? and cmd =~ /[^a-zA-Z0-9\/._-]/
      args = ""
    end

    session.response_timeout = time_out
    opts = {
      'Hidden' => true,
      'Channelized' => true,
      'Subshell' => true
    }.merge(opts)

    if opts['Channelized']
      o = session.sys.process.capture_output(cmd, args, opts, time_out)
    else
      session.sys.process.execute(cmd, args, opts)
    end
  when 'powershell'
    if args.nil? || args.empty?
      o = session.shell_command("#{cmd}", time_out)
    else
      o = session.shell_command("#{cmd} #{args}", time_out)
    end
    o.chomp! if o
  when 'shell'
    if args.nil? || args.empty?
      o = session.shell_command_token("#{cmd}", time_out)
    else
      o = session.shell_command_token("#{cmd} #{args}", time_out)
    end
    o.chomp! if o
  end
  return "" if o.nil?
  return o
end

#cmd_exec_get_pid(cmd, args = nil, time_out = 15) ⇒ Object



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# File 'lib/msf/core/post/common.rb', line 142

def cmd_exec_get_pid(cmd, args=nil, time_out=15)
  case session.type
    when 'meterpreter'
      if args.nil? and cmd =~ /[^a-zA-Z0-9\/._-]/
        args = ""
      end
      session.response_timeout = time_out
      process = session.sys.process.execute(cmd, args, {'Hidden' => true, 'Channelized' => true, 'Subshell' => true })
      process.channel.close
      pid = process.pid
      process.close
      pid
    else
      print_error "cmd_exec_get_pid is incompatible with non-meterpreter sessions"
  end
end

#cmd_exec_with_result(cmd, args = nil, timeout = 15, opts = {}) ⇒ Array(String, Boolean)

Executes cmd on the remote system and return an array containing the output and if it was successful or not.

This is simply a wrapper around #cmd_exec that also checks the exit code to determine if the execution was successful or not.

Parameters:

  • cmd (String)

    The command to execute

  • arg (String)

    The optional arguments of the command (can de included in cmd instead)

  • timeout (Integer) (defaults to: 15)

    The time in sec. to wait before giving up

  • opts (Hash) (defaults to: {})

    An Hash of options (see #cmd_exec)

Returns:

  • (Array(String, Boolean))

    Array containing the output string followed by a boolean indicating if the command succeeded or not. When this boolean is `true`, the first field contains the normal command output. When it is `false`, the first field contains the error message returned by the command or a timeout error message if the timeout expired.



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# File 'lib/msf/core/post/common.rb', line 266

def cmd_exec_with_result(cmd, args = nil, timeout = 15, opts = {})
  # This token will be returned if the command succeeds.
  # Redirection operators (`&&` and `||`) are the most reliable methods to
  # detect success and failure. See these references for details:
  # - https://ss64.com/nt/errorlevel.html
  # - https://stackoverflow.com/questions/34936240/batch-goto-loses-errorlevel/34937706#34937706
  # - https://stackoverflow.com/questions/10935693/foolproof-way-to-check-for-nonzero-error-return-code-in-windows-batch-file/10936093#10936093
  verification_token = Rex::Text.rand_text_alphanumeric(8)

  _cmd = cmd.dup
  _cmd << " #{args}" if args
  if session.platform == 'windows'
    if session.type == 'powershell'
      # The & operator is reserved by Powershell and needs to be wrapped in double quotes
      result = cmd_exec('cmd', "/c #{_cmd} \"&&\" echo #{verification_token}", timeout, opts)
    else
      result = cmd_exec('cmd', "/c #{_cmd} && echo #{verification_token}", timeout, opts)
    end
  else
    result = cmd_exec('command', "#{_cmd} && echo #{verification_token}", timeout, opts)
  end

  if result.include?(verification_token)
    # Removing the verification token to cleanup the output string
    [result.lines[0...-1].join.strip, true]
  else
    [result.strip, false]
  end
rescue Rex::TimeoutError => e
  [e.message, false]
end

#command_exists?(cmd) ⇒ Boolean

Checks if the specified command can be executed by the session. It should be noted that not all commands correspond to a binary file on disk. For example, a bash shell session will provide the `eval` command when there is no `eval` binary on disk. Likewise, a Powershell session will provide the `Get-Item` command when there is no `Get-Item` executable on disk.

Parameters:

  • cmd (String)

    the command to check

Returns:

  • (Boolean)

    true when the command exists



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# File 'lib/msf/core/post/common.rb', line 235

def command_exists?(cmd)
  verification_token = Rex::Text.rand_text_alpha_upper(8)
  if session.type == 'powershell'
    cmd_exec("try {if(Get-Command #{cmd}) {echo #{verification_token}}} catch {}").include?(verification_token)
  elsif session.platform == 'windows'
    # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/where_1
    # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/if
    cmd_exec("cmd /c where /q #{cmd} & if not errorlevel 1 echo #{verification_token}").to_s.include?(verification_token)
  else
    cmd_exec("command -v #{cmd} || which #{cmd} && echo #{verification_token}").include?(verification_token)
  end
rescue
  raise "Unable to check if command `#{cmd}' exists"
end

#get_env(env) ⇒ Object

Returns the value of the environment variable env



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# File 'lib/msf/core/post/common.rb', line 178

def get_env(env)
  case session.type
  when 'meterpreter'
    return session.sys.config.getenv(env)
  when 'powershell'
    return cmd_exec("echo $env:#{env}").strip
  when 'shell'
    if session.platform == 'windows'
      if env[0,1] == '%'
        unless env[-1,1] == '%'
          env << '%'
        end
      else
        env = "%#{env}%"
      end

      return cmd_exec("echo #{env}")
    else
      unless env[0,1] == '$'
        env = "$#{env}"
      end

      return cmd_exec("echo \"#{env}\"")
    end
  end

  nil
end

#get_envs(*envs) ⇒ Object

Returns a hash of environment variables envs



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# File 'lib/msf/core/post/common.rb', line 210

def get_envs(*envs)
  case session.type
  when 'meterpreter'
    return session.sys.config.getenvs(*envs)
  when 'shell', 'powershell'
    result = {}
    envs.each do |env|
      res = get_env(env)
      result[env] = res unless res.blank?
    end

    return result
  end

  nil
end

#initialize(info = {}) ⇒ Object



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# File 'lib/msf/core/post/common.rb', line 5

def initialize(info = {})
  super(
    update_info(
      info,
      'Compat' => {
        'Meterpreter' => {
          'Commands' => %w[
            stdapi_sys_config_getenv
            stdapi_sys_process_execute
          ]
        }
      }
    )
  )
end

#peerObject



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# File 'lib/msf/core/post/common.rb', line 51

def peer
  "#{rhost}:#{rport}"
end

#report_virtualization(virt) ⇒ Object

Reports to the database that the host is using virtualization and reports the type of virtualization it is (e.g VirtualBox, VMware, Xen, Docker)



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# File 'lib/msf/core/post/common.rb', line 163

def report_virtualization(virt)
  return unless session
  return unless virt
  virt_normal = virt.to_s.strip
  return if virt_normal.empty?
  virt_data = {
    :host => session.target_host,
    :virtual_host => virt_normal
  }
  report_host(virt_data)
end

#rhostObject



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# File 'lib/msf/core/post/common.rb', line 25

def rhost
  return super unless defined?(session) and session

  case session.type
  when 'meterpreter'
    session.sock.peerhost
  when 'shell', 'powershell'
    session.session_host
  end
rescue
  return nil
end

#rportObject



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# File 'lib/msf/core/post/common.rb', line 38

def rport
  return super unless defined?(session) and session

  case session.type
  when 'meterpreter'
    session.sock.peerport
  when 'shell', 'powershell'
    session.session_port
  end
rescue
  return nil
end