"""Text parser plugin for Sophos anti-virus logs (SAV.txt) files."""
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 SophosAVLogEventData(events.EventData):
"""Sophos anti-virus log event data.
Attributes:
added_time (dfdatetime.DateTimeValues): date and time the log entry
was added.
text (str): Sophos anti-virus log message.
"""
DATA_TYPE = "sophos:av:log"
[docs]
def __init__(self):
"""Initializes event data."""
super().__init__(data_type=self.DATA_TYPE)
self.added_time = None
self.text = None
[docs]
class SophosAVLogTextPlugin(interface.TextPlugin):
"""Text parser plugin for Sophos anti-virus logs (SAV.txt) files."""
NAME = "sophos_av"
DATA_FORMAT = "Sophos anti-virus log file (SAV.txt) file"
ENCODING = "utf-16-le"
_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: YYYYMMDD hhmmss
# For example: 20100720 183814
_DATE_TIME = pyparsing.Group(
_FOUR_DIGITS
+ _TWO_DIGITS
+ _TWO_DIGITS
+ _TWO_DIGITS
+ _TWO_DIGITS
+ _TWO_DIGITS
)
_END_OF_LINE = pyparsing.Suppress(pyparsing.LineEnd())
_LOG_LINE = (
_DATE_TIME.set_results_name("date_time")
+ pyparsing.restOfLine().set_results_name("text")
+ _END_OF_LINE
)
_LINE_STRUCTURES = [("log_line", _LOG_LINE)]
VERIFICATION_GRAMMAR = _LOG_LINE
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.
"""
time_elements_structure = self._GetValueFromStructure(structure, "date_time")
event_data = SophosAVLogEventData()
event_data.added_time = self._ParseTimeElements(time_elements_structure)
event_data.text = self._GetStringValueFromStructure(structure, "text")
parser_mediator.ProduceEventData(event_data)
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
)
# TODO: check if date and time values are local time or in UTC.
date_time.is_local_time = True
return date_time
except (IndexError, TypeError, ValueError) as exception:
raise errors.ParseError(
f"Unable to parse time elements with error: {exception!s}"
)
[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:
structure = self._VerifyString(text_reader.lines)
except errors.ParseError:
return False
time_elements_structure = self._GetValueFromStructure(structure, "date_time")
try:
self._ParseTimeElements(time_elements_structure)
except ValueError:
return False
return True
text_parser.TextLogParser.RegisterPlugin(SophosAVLogTextPlugin)