Source code for plaso.engine.knowledge_base

# -*- coding: utf-8 -*-
"""The artifact knowledge base object.

The knowledge base is filled by user provided input and the pre-processing
phase. It is intended to provide successive phases, like the parsing and
analysis phases, with essential information like the time zone and codepage
of the source data.
"""

import codecs
import pytz

from plaso.containers import artifacts
from plaso.engine import logger
from plaso.helpers.windows import time_zones


[docs]class KnowledgeBase(object): """The knowledge base.""" _DEFAULT_ACTIVE_SESSION = '00000000000000000000000000000000' def __init__(self): """Initializes a knowledge base.""" super(KnowledgeBase, self).__init__() self._active_session = self._DEFAULT_ACTIVE_SESSION self._available_time_zones = {} self._codepage = 'cp1252' self._environment_variables = {} self._hostnames = {} self._language = 'en-US' self._mount_path = None self._time_zone = pytz.UTC self._user_accounts = {} self._values = {} self._windows_eventlog_providers = {} @property def available_time_zones(self): """list[TimeZone]: available time zones of the current session.""" return self._available_time_zones.get(self._active_session, {}).values() @property def codepage(self): """str: codepage of the current session.""" return self.GetValue('codepage', default_value=self._codepage) @property def language(self): """str: language of the current session.""" return self.GetValue('language', default_value=self._language) @property def timezone(self): """datetime.tzinfo: time zone of the current session.""" return self._time_zone @property def user_accounts(self): """list[UserAccountArtifact]: user accounts of the current session.""" return self._user_accounts.get(self._active_session, {}).values()
[docs] def AddAvailableTimeZone(self, time_zone): """Adds an available time zone. Args: time_zone (TimeZoneArtifact): time zone artifact. Raises: KeyError: if the time zone already exists. """ if self._active_session not in self._available_time_zones: self._available_time_zones[self._active_session] = {} available_time_zones = self._available_time_zones[self._active_session] if time_zone.name in available_time_zones: raise KeyError('Time zone: {0:s} already exists.'.format(time_zone.name)) available_time_zones[time_zone.name] = time_zone
[docs] def AddEnvironmentVariable(self, environment_variable): """Adds an environment variable. Args: environment_variable (EnvironmentVariableArtifact): environment variable artifact. Raises: KeyError: if the environment variable already exists. """ name = environment_variable.name.upper() if name in self._environment_variables: raise KeyError('Environment variable: {0:s} already exists.'.format( environment_variable.name)) self._environment_variables[name] = environment_variable
[docs] def AddUserAccount(self, user_account): """Adds an user account. Args: user_account (UserAccountArtifact): user account artifact. Raises: KeyError: if the user account already exists. """ if self._active_session not in self._user_accounts: self._user_accounts[self._active_session] = {} user_accounts = self._user_accounts[self._active_session] if user_account.identifier in user_accounts: raise KeyError('User account: {0:s} already exists.'.format( user_account.identifier)) user_accounts[user_account.identifier] = user_account
[docs] def AddWindowsEventLogProvider(self, windows_eventlog_provider): """Adds a Windows Event Log provider. Args: windows_eventlog_provider (WindowsEventLogProviderArtifact): Windows Event Log provider. Raises: KeyError: if the Windows Event Log provider already exists. """ log_source = windows_eventlog_provider.log_source if log_source in self._windows_eventlog_providers: raise KeyError('Windows Event Log provider: {0:s} already exists.'.format( log_source)) # TODO: store on a per-volume basis? self._windows_eventlog_providers[log_source] = windows_eventlog_provider
[docs] def GetEnvironmentVariable(self, name): """Retrieves an environment variable. Args: name (str): name of the environment variable. Returns: EnvironmentVariableArtifact: environment variable artifact or None if there was no value set for the given name. """ name = name.upper() return self._environment_variables.get(name, None)
[docs] def GetEnvironmentVariables(self): """Retrieves the environment variables. Returns: list[EnvironmentVariableArtifact]: environment variable artifacts. """ return self._environment_variables.values()
[docs] def GetHostname(self): """Retrieves the hostname related to the event. If the hostname is not stored in the event it is determined based on the preprocessing information that is stored inside the storage file. Returns: str: hostname. """ hostname_artifact = self._hostnames.get(self._active_session, None) if not hostname_artifact: return '' return hostname_artifact.name or ''
[docs] def GetSystemConfigurationArtifact(self): """Retrieves the knowledge base as a system configuration artifact. Returns: SystemConfigurationArtifact: system configuration artifact. """ system_configuration = artifacts.SystemConfigurationArtifact() system_configuration.code_page = self.GetValue( 'codepage', default_value=self._codepage) system_configuration.hostname = self._hostnames.get( self._active_session, None) system_configuration.keyboard_layout = self.GetValue('keyboard_layout') system_configuration.language = self._language system_configuration.operating_system = self.GetValue('operating_system') system_configuration.operating_system_product = self.GetValue( 'operating_system_product') system_configuration.operating_system_version = self.GetValue( 'operating_system_version') time_zone = self._time_zone.zone if isinstance(time_zone, bytes): time_zone = time_zone.decode('ascii') system_configuration.time_zone = time_zone available_time_zones = self._available_time_zones.get( self._active_session, {}) # In Python 3 dict.values() returns a type dict_values, which will cause # the JSON serializer to raise a TypeError. system_configuration.available_time_zones = list( available_time_zones.values()) user_accounts = self._user_accounts.get(self._active_session, {}) # In Python 3 dict.values() returns a type dict_values, which will cause # the JSON serializer to raise a TypeError. system_configuration.user_accounts = list(user_accounts.values()) return system_configuration
[docs] def GetUsernameByIdentifier(self, user_identifier): """Retrieves the username based on an user identifier. Args: user_identifier (str): user identifier, either a UID or SID. Returns: str: username. """ user_accounts = self._user_accounts.get(self._active_session, {}) user_account = user_accounts.get(user_identifier, None) if not user_account: return '' return user_account.username or ''
[docs] def GetUsernameForPath(self, path): """Retrieves a username for a specific path. This is determining if a specific path is within a user's directory and returning the username of the user if so. Args: path (str): path. Returns: str: username or None if the path does not appear to be within a user's directory. """ path = path.lower() user_accounts = self._user_accounts.get(self._active_session, {}) for user_account in user_accounts.values(): if not user_account.user_directory: continue user_directory = user_account.user_directory.lower() if path.startswith(user_directory): return user_account.username return None
[docs] def GetValue(self, identifier, default_value=None): """Retrieves a value by identifier. Args: identifier (str): case insensitive unique identifier for the value. default_value (object): default value. Returns: object: value or default value if not available. Raises: TypeError: if the identifier is not a string type. """ if not isinstance(identifier, str): raise TypeError('Identifier not a string type.') identifier = identifier.lower() return self._values.get(identifier, default_value)
[docs] def GetWindowsEventLogProvider(self, log_source): """Retrieves a Windows EventLog provider by log source. Args: log_source (str): EventLog source, such as "Application Error". Returns: WindowsEventLogProviderArtifact: Windows EventLog provider artifact or None if not available. """ return self._windows_eventlog_providers.get(log_source, None)
[docs] def GetWindowsEventLogProviders(self): """Retrieves the Windows EventLog providers. Returns: list[WindowsEventLogProviderArtifact]: Windows EventLog provider artifacts. """ return self._windows_eventlog_providers.values()
[docs] def HasUserAccounts(self): """Determines if the knowledge base contains user accounts. Returns: bool: True if the knowledge base contains user accounts. """ return self._user_accounts.get(self._active_session, {}) != {}
[docs] def ReadSystemConfigurationArtifact(self, system_configuration): """Reads the knowledge base values from a system configuration artifact. Note that this overwrites existing values in the knowledge base. Args: system_configuration (SystemConfigurationArtifact): system configuration artifact. """ if not system_configuration: return if system_configuration.code_page: try: self.SetCodepage(system_configuration.code_page) except ValueError: logger.warning( 'Unsupported codepage: {0:s}, defaulting to {1:s}'.format( system_configuration.code_page, self._codepage)) self._hostnames[self._active_session] = system_configuration.hostname self.SetValue('keyboard_layout', system_configuration.keyboard_layout) if system_configuration.language: self.SetLanguage(system_configuration.language) self.SetValue('operating_system', system_configuration.operating_system) self.SetValue( 'operating_system_product', system_configuration.operating_system_product) self.SetValue( 'operating_system_version', system_configuration.operating_system_version) # Set the available time zones before the system time zone so that localized # time zone names can be mapped to their corresponding Python time zone. self._available_time_zones[self._active_session] = { time_zone.name: time_zone for time_zone in system_configuration.available_time_zones} if system_configuration.time_zone: try: self.SetTimeZone(system_configuration.time_zone) except ValueError: logger.warning( 'Unsupported time zone: {0:s}, defaulting to {1:s}'.format( system_configuration.time_zone, self._time_zone.zone)) self._user_accounts[self._active_session] = { user_account.identifier: user_account for user_account in system_configuration.user_accounts}
[docs] def SetActiveSession(self, session_identifier): """Sets the active session. Args: session_identifier (str): session identifier where None represents the default active session. """ self._active_session = session_identifier or self._DEFAULT_ACTIVE_SESSION
[docs] def SetCodepage(self, codepage): """Sets the codepage. Args: codepage (str): codepage. Raises: ValueError: if the codepage is not supported. """ try: codecs.getencoder(codepage) self._codepage = codepage except LookupError: raise ValueError('Unsupported codepage: {0:s}'.format(codepage))
[docs] def SetEnvironmentVariable(self, environment_variable): """Sets an environment variable. Args: environment_variable (EnvironmentVariableArtifact): environment variable artifact. """ name = environment_variable.name.upper() self._environment_variables[name] = environment_variable
[docs] def SetHostname(self, hostname): """Sets a hostname. Args: hostname (HostnameArtifact): hostname artifact. """ self._hostnames[self._active_session] = hostname
[docs] def SetLanguage(self, language): """Sets the language. Args: language (str): language. """ self._language = language
[docs] def SetTimeZone(self, time_zone): """Sets the time zone. Args: time_zone (str): time zone. Raises: ValueError: if the time zone is not supported. """ # Get the "normalized" name of a Windows time zone name. if time_zone.startswith('@tzres.dll,'): mui_form_time_zones = { time_zone_artifact.mui_form: time_zone_artifact.name for time_zone_artifact in self.available_time_zones} time_zone = mui_form_time_zones.get(time_zone, time_zone) else: localized_time_zones = { time_zone_artifact.localized_name: time_zone_artifact.name for time_zone_artifact in self.available_time_zones} time_zone = localized_time_zones.get(time_zone, time_zone) # Map a Windows time zone name to a Python time zone name. time_zone = time_zones.WINDOWS_TIME_ZONES.get(time_zone, time_zone) try: self._time_zone = pytz.timezone(time_zone) except pytz.UnknownTimeZoneError: raise ValueError('Unsupported time zone: {0!s}'.format(time_zone))
[docs] def SetValue(self, identifier, value): """Sets a value by identifier. Args: identifier (str): case insensitive unique identifier for the value. value (object): value. Raises: TypeError: if the identifier is not a string type. """ if not isinstance(identifier, str): raise TypeError('Identifier not a string type.') identifier = identifier.lower() self._values[identifier] = value