Class: Rex::Post::Meterpreter::Extensions::Bofloader::CnaParser

Inherits:
Object
  • Object
show all
Defined in:
lib/rex/post/meterpreter/extensions/bofloader/cna_parser.rb

Overview

Statically imports conventional BOF launchers from Aggressor scripts.

Defined Under Namespace

Classes: Error, Unsupported

Constant Summary collapse

FORMAT_TYPES = 
{
  'b' => 'bytes',
  'i' => 'int32',
  's' => 'int16',
  'z' => 'string',
  'Z' => 'wstring'
}.freeze
INTEGER_RANGES = 
{
  'i' => (-2**31)..(2**31 - 1),
  's' => (-2**15)..(2**15 - 1)
}.freeze
REQUIRED_INTRINSICS = 
%w[
  barch beacon_command_register beacon_inline_execute bof_pack iff openf readb script_resource
].freeze
NULL = 
Object.new.freeze
PARAMETER_PATTERN = 
/\A\$(\d+)\z/
USAGE_MARKER_PATTERN = 
/\A(?:(?<optional>optional|opt)|required)(?=\s|:|\z)\s*:?\s*/i
VARIABLE_PATTERN = 
/\A\$[a-zA-Z_]\w*\z/

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path:) ⇒ CnaParser

Creates a CNA parser.

Parameters:

  • path (String) —

    Aggressor script path.



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# File 'lib/rex/post/meterpreter/extensions/bofloader/cna_parser.rb', line 43

def initialize(path:)
  @path = path
  @base_path = ::File.dirname(path)
end

Class Method Details

.parse(path:) ⇒ Hash

Parses an Aggressor script.

Parameters:

  • path (String) —

    Aggressor script path.

Returns:

  • (Hash) —

    Normalized BOF catalog.



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# File 'lib/rex/post/meterpreter/extensions/bofloader/cna_parser.rb', line 36

def self.parse(path:)
  new(path: path).parse
end

Instance Method Details

#parse ⇒ Hash

Returns a normalized catalog of statically supported CNA aliases.

Returns:

  • (Hash) —

    Catalog and per-alias import warnings.



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# File 'lib/rex/post/meterpreter/extensions/bofloader/cna_parser.rb', line 51

def parse
  source = read_source
  @code = remove_comments(source)
  @subroutines = named_blocks('sub')
  @overridden_intrinsics = (declared_block_names('sub') + declared_block_names('inline')).uniq & REQUIRED_INTRINSICS

  aliases = named_blocks('alias')
  registrations = command_registrations
  bofs = {}
  warnings = []
  duplicate_aliases = aliases.map(&:first).tally.select { |_name, count| count > 1 }.keys
  duplicate_aliases.each { |alias_name| warnings << "CNA alias '#{alias_name}' is declared more than once" }

  aliases.each do |alias_name, body|
    next if duplicate_aliases.include?(alias_name)
    next if function_calls(body, 'beacon_inline_execute').empty?

    begin
      definition = import_alias(alias_name, body, registrations[alias_name])
      bofs[alias_name] = definition
    rescue Unsupported => e
      warnings << "CNA alias '#{alias_name}' was skipped: #{e.message}"
    end
  end

  if bofs.empty?
    reason = warnings.first || 'the script does not contain a beacon_inline_execute alias'
    raise Error, "No compatible BOFs found in CNA script #{@path}: #{reason}"
  end

  { 'path' => @path, 'bofs' => bofs, 'warnings' => warnings }
end