# -*- coding: utf-8 -*-
"""Text parser plugin for PowerShell transcript log files."""
import copy
import pyparsing
from dfdatetime import time_elements as dfdatetime_time_elements
from plaso.containers import events
from plaso.lib import errors
from plaso.parsers import text_parser
from plaso.parsers.text_plugins import interface
[docs]
class PowerShellTranscriptLogEventData(events.EventData):
"""PowerShell transcript log event data.
Attributes:
build_version (str): Build number of current version.
clr_version (str): Common Language Runtime version.
commands (str): Commands that were executed.
compatible_versions (str): Compatible PowerShell versions.
configuration_name (str): Configuration name.
edition (str): PowerShell edition
host_application (str): Application that executed the commands.
machine (str): Hostname of machine.
process_identifier (str): Process identifier.
remoting_protocol_version (str): PowerShell remote management protocol
version.
runas_user (str): User context of execution.
serialization_version (str): Serialization method version.
start_time (dfdatetime.DateTimeValues): date and time the start of
the PowerShell transcript.
username (str): User that executed the commands.
version (str): PowerShell version.
ws_man_stack_version (str): WS-Management stack version
"""
DATA_TYPE = 'powershell:transcript_log:entry'
[docs]
def __init__(self):
"""Initializes event data."""
super(PowerShellTranscriptLogEventData, self).__init__(
data_type=self.DATA_TYPE)
self.build_version = None
self.clr_version = None
self.commands = None
self.compatible_versions = None
self.configuration_name = None
self.edition = None
self.host_application = None
self.machine = None
self.process_identifier = None
self.remoting_protocol_version = None
self.runas_user = None
self.serialization_version = None
self.start_time = None
self.username = None
self.version = None
self.ws_man_stack_version = None
[docs]
class PowerShellTranscriptLogTextPlugin(interface.TextPlugin):
"""Text parser plugin for PowerShell transcript log files."""
NAME = 'powershell_transcript'
DATA_FORMAT = 'PowerShell transcript event'
ENCODING = 'utf-8'
_TWO_DIGITS = pyparsing.Word(pyparsing.nums, exact=2).set_parse_action(
lambda tokens: int(tokens[0], 10))
_FOUR_DIGITS = pyparsing.Word(pyparsing.nums, exact=4).set_parse_action(
lambda tokens: int(tokens[0], 10))
# Date and time values are formatted as: YYYYMMDDhhmmss
# For example: 20220824124237
_DATE_TIME = (_FOUR_DIGITS + _TWO_DIGITS + _TWO_DIGITS +
_TWO_DIGITS + _TWO_DIGITS + _TWO_DIGITS)
_SEPARATOR = pyparsing.Literal('**********************')
_END_OF_LINE = pyparsing.Suppress(pyparsing.LineEnd())
_SEPARATOR_LINE = _SEPARATOR + _END_OF_LINE
_TRANSSCRIPT_START_LINE = pyparsing.Regex(r'.*Windows PowerShell.*\n')
# A Metadata key always start with an uppercase character.
_METADATA_KEY = pyparsing.Word(
pyparsing.alphas.upper(), pyparsing.alphas + '- ')
_METADATA_LINE = pyparsing.Combine(
pyparsing.Suppress(_METADATA_KEY) + pyparsing.Suppress(':') +
pyparsing.restOfLine() + _END_OF_LINE)
_LOG_LINE = (
pyparsing.NotAny(_SEPARATOR) +
pyparsing.restOfLine().set_results_name('body') + _END_OF_LINE)
_HEADER_GRAMMAR = (
_SEPARATOR_LINE + _TRANSSCRIPT_START_LINE +
_METADATA_LINE.set_results_name('date_time') +
_METADATA_LINE.set_results_name('username') +
_METADATA_LINE.set_results_name('runas_user') +
_METADATA_LINE.set_results_name('configuration_name') +
_METADATA_LINE.set_results_name('machine') +
_METADATA_LINE.set_results_name('host_application') +
_METADATA_LINE.set_results_name('process_identifier') +
_METADATA_LINE.set_results_name('version') +
_METADATA_LINE.set_results_name('edition') +
_METADATA_LINE.set_results_name('compatible_versions') +
_METADATA_LINE.set_results_name('build_version') +
_METADATA_LINE.set_results_name('clr_version') +
_METADATA_LINE.set_results_name('ws_man_stack_version') +
_METADATA_LINE.set_results_name('remoting_protocol_version') +
_METADATA_LINE.set_results_name('serialization_version') +
_SEPARATOR_LINE)
_LINE_STRUCTURES = [
('log_line', _LOG_LINE),
('separator_line', _SEPARATOR_LINE)]
VERIFICATION_GRAMMAR = _SEPARATOR_LINE + _TRANSSCRIPT_START_LINE
VERIFICATION_LITERALS = ['Windows PowerShell']
# TODO: handle footer with end time.
[docs]
def __init__(self):
"""Initializes a text parser plugin."""
super(PowerShellTranscriptLogTextPlugin, self).__init__()
self._command_history = []
self._event_data = None
self._in_command_history = False
def _ParseHeader(self, parser_mediator, text_reader):
"""Parses a text-log file header.
Args:
parser_mediator (ParserMediator): mediates interactions between parsers
and other components, such as storage and dfVFS.
text_reader (EncodedTextReader): text reader.
Raises:
ParseError: when the header cannot be parsed.
"""
try:
structure_generator = self._HEADER_GRAMMAR.scan_string(
text_reader.lines, max_matches=1)
structure, start, end = next(structure_generator)
except StopIteration:
structure = None
except pyparsing.ParseException as exception:
raise errors.ParseError(exception)
if not structure or start != 0:
raise errors.ParseError('No match found.')
event_data = PowerShellTranscriptLogEventData()
event_data.build_version = self._GetStringValueFromStructure(
structure, 'build_version')
event_data.clr_version = self._GetStringValueFromStructure(
structure, 'clr_version')
event_data.compatible_versions = self._GetStringValueFromStructure(
structure, 'compatible_versions')
event_data.configuration_name = self._GetStringValueFromStructure(
structure, 'configuration_name')
event_data.edition = self._GetStringValueFromStructure(
structure, 'edition')
event_data.host_application = self._GetStringValueFromStructure(
structure, 'host_application')
event_data.machine = self._GetStringValueFromStructure(
structure, 'machine')
event_data.process_identifier = self._GetStringValueFromStructure(
structure, 'process_identifier')
event_data.remoting_protocol_version = self._GetStringValueFromStructure(
structure, 'remoting_protocol_version')
event_data.runas_user = self._GetStringValueFromStructure(
structure, 'runas_user')
event_data.serialization_version = self._GetStringValueFromStructure(
structure, 'serialization_version')
event_data.username = self._GetStringValueFromStructure(
structure, 'username')
event_data.version = self._GetStringValueFromStructure(
structure, 'version')
event_data.ws_man_stack_version = self._GetStringValueFromStructure(
structure, 'ws_man_stack_version')
date_time_structure = self._GetStringValueFromStructure(
structure, 'date_time')
try:
time_elements_structure = self._DATE_TIME.parse_string(
date_time_structure)
except pyparsing.ParseException:
raise errors.ParseError('Unable to parse date time.')
event_data.start_time = self._ParseTimeElements(time_elements_structure)
self._event_data = event_data
self._in_command_history = True
text_reader.SkipAhead(end)
def _ParseRecord(self, parser_mediator, key, structure):
"""Parses a pyparsing structure.
Args:
parser_mediator (ParserMediator): mediates interactions between parsers
and other components, such as storage and dfVFS.
key (str): name of the parsed structure.
structure (pyparsing.ParseResults): tokens from a parsed log line.
Raises:
ParseError: if the structure cannot be parsed.
"""
if self._in_command_history:
if key == 'log_line':
body = self._GetStringValueFromStructure(structure, 'body')
if body:
self._command_history.append(body)
elif key == 'separator_line':
event_data = copy.deepcopy(self._event_data)
event_data.commands = '; '.join(self._command_history)
parser_mediator.ProduceEventData(event_data)
self._command_history = []
self._in_command_history = False
else:
if key == 'log_line':
body = self._GetStringValueFromStructure(structure, 'body')
if ':' in body:
date_time_structure = body.rsplit(':', maxsplit=1)[-1].strip()
try:
time_elements_structure = self._DATE_TIME.parse_string(
date_time_structure)
except pyparsing.ParseException:
raise errors.ParseError('Unable to parse date time.')
self._event_data.start_time = self._ParseTimeElements(
time_elements_structure)
elif key == 'separator_line':
self._in_command_history = True
def _ParseTimeElements(self, time_elements_structure):
"""Parses date and time elements of a log line.
Args:
time_elements_structure (pyparsing.ParseResults): date and time elements
of a log line.
Returns:
dfdatetime.TimeElements: date and time value.
Raises:
ParseError: if a valid date and time value cannot be derived from
the time elements.
"""
try:
# Ensure time_elements_tuple is not a pyparsing.ParseResults otherwise
# copy.deepcopy() of the dfDateTime object will fail on Python 3.8 with:
# "TypeError: 'str' object is not callable" due to pyparsing.ParseResults
# overriding __getattr__ with a function that returns an empty string
# when named token does not exists.
year, month, day_of_month, hours, minutes, seconds = (
time_elements_structure)
time_elements_tuple = (year, month, day_of_month, hours, minutes, seconds)
date_time = dfdatetime_time_elements.TimeElements(
time_elements_tuple=time_elements_tuple)
date_time.is_local_time = True
return date_time
except (TypeError, ValueError) as exception:
raise errors.ParseError(
'Unable to parse time elements with error: {0!s}'.format(exception))
def _ResetState(self):
"""Resets stored values."""
self._command_history = []
self._event_data = None
self._in_command_history = False
[docs]
def CheckRequiredFormat(self, parser_mediator, text_reader):
"""Check if the log record has the minimal structure required by the plugin.
Args:
parser_mediator (ParserMediator): mediates interactions between parsers
and other components, such as storage and dfVFS.
text_reader (EncodedTextReader): text reader.
Returns:
bool: True if this is the correct plugin, False otherwise.
"""
try:
self._VerifyString(text_reader.lines)
except errors.ParseError:
return False
self._ResetState()
return True
text_parser.TextLogParser.RegisterPlugin(PowerShellTranscriptLogTextPlugin)