def _matches_yara_signatures(evidence):
for ruleset in Identifier._iterate_signatures():
try:
rules = yara.compile(ruleset, includes=True, error_on_warning=True)
except yara.SyntaxError:
_log.exception("Syntax error in YARA ruleset <{}>.".format(ruleset))
def _compile_ruleset(self, name, ruleset):
"""
.. py:function:: _compile_ruleset(self, name, ruleset)
Compiles and saves YARA rule(s) to the dictionary to be passed to the asynchronous job(s).
:param self: current class instance
:type self: class
:param name: name of the ruleset file to compile the rule(s) from
:type name: str
:param ruleset: absolute path to the ruleset file to compile the rule(s) from
:type ruleset: str
:return: tuple containing the final status of the compilation and the number of successfully loaded rule(s)
:rtype: bool, int
"""
count = 0
try:
buffer = io.BytesIO()
rules = yara.compile(ruleset, includes=_conf.YARA_INCLUDES, error_on_warning=(not self.case.arguments.ignore_warnings))
rules.save(file=buffer)
self.buffers[ruleset] = buffer
count += sum(1 for _ in rules)
_log.debug("Precompilated YARA ruleset <{}> in memory with a total of <{}> valid rule(s).".format(name, count))
return True, count
except yara.SyntaxError:
_log.exception("Syntax error in YARA ruleset <{}>.".format(ruleset))
except (
Exception,
yara.Error):
_log.exception("Failed to pre-compile ruleset <{}>.".format(ruleset))
return False, count
def _store_matching_evidences(self):
"""
.. py:function:: _store_matching_evidences(self)
Saves the matching evidence(s) to the specified storage directory.
:param self: current class instance
:type self: class
"""
for evidence in self.results[2]:
if not os.path.isdir(self.target["storage"]):
_fs.create_local_directory(self.target["storage"])
try:
storage_path = (
os.path.join(self.target["storage"],
os.path.basename(evidence)) if
not _conf.NEUTRALIZE_MATCHING_EVIDENCES else os.path.join(
self.target["storage"], "{}.{}".format(
os.path.basename(evidence), _meta.__package__)))
shutil.copy2(evidence, storage_path)
if _conf.NEUTRALIZE_MATCHING_EVIDENCES:
os.chmod(
storage_path,
stat.S_IMODE(os.lstat(storage_path).st_mode)
& ~stat.S_IEXEC)
_log.debug("Saved {}matching evidence <{}> as <{}>.".format(
"and neutralized "
if _conf.NEUTRALIZE_MATCHING_EVIDENCES else "",
os.path.basename(evidence), storage_path))
except (OSError, shutil.Error, Exception):
_log.exception(
"Failed to save matching evidence <{}> as <{}>.".format(
os.path.basename(evidence), storage_path))
def _tear_down(self):
"""
.. py:function:: _tear_down(self)
Cleanup method called on class destruction that gets rid of the temporary artifact(s).
:param self: current class instance
:type self: class
"""
for artifact in self.resources["temporary"]:
try:
shutil.rmtree(artifact)
_log.debug("Removed temporary artifact <{}>.".format(artifact))
except FileNotFoundError:
_log.debug("Temporary artifact not found <{}>.".format(artifact))
except (
OSError,
Exception):
_log.exception("Failed to remove temporary artifact <{}>.".format(artifact))
def _append_json(self, data):
"""
.. py:function:: _append_json(self, data)
Encodes the match data using the given format and appends the match data to the output file.
:param self: current class instance
:type self: class
:param data: dictionary containing the match data
:type data: dict
"""
try:
self.output.write("{}\n".format(_renderer.to_json(data)))
except _errors.CharacterEncoding:
_log.error("Cannot decode data from <{}>.".format(
data["target"]["identifier"]))
except InvalidObject:
_log.exception(
"Exception raised while retrieving matching data from <{}>.".
format(data["target"]["identifier"]))
def run(self):
"""
.. py:function:: run(self)
Main entry point for the module.
:param self: current class instance
:type self: class
"""
tmp = self.case.require_temporary_directory()
for evidence in self.feed:
try:
mail = eml_parser.eml_parser.decode_email(
evidence,
include_raw_body=True,
include_attachment_data=True)
_log.info("Extracted <{}> attachment(s) from <{}>.".format(
len(mail["attachment"]), evidence))
except Exception:
_log.exception(
"Failed to extract data from <{}>. Ignoring evidence.".
format(evidence))
continue
output_directory = os.path.join(tmp, os.path.basename(evidence))
if not os.path.isdir(output_directory):
_fs.create_local_directory(output_directory)
for attachment in mail["attachment"]:
if not attachment["filename"]:
attachment["filename"] = idx
if not _fs.matches_patterns(attachment["filename"],
self.case.arguments._include):
_log.warning(
"Ignoring attachment <{}> not matching inner inclusion pattern(s)."
.format(attachment["filename"]))
continue
if _fs.matches_patterns(attachment["filename"],
self.case.arguments._exclude):
_log.warning(
"Ignoring attachment <{}> matching inner exclusion pattern(s)."
.format(attachment["filename"]))
continue
output_path = os.path.join(output_directory,
attachment["filename"])
with open(output_path, "wb") as out:
out.write(base64.b64decode(attachment["raw"]))
_log.debug(
"Attachment <{}> extracted from <{}> stored locally as <{}>."
.format(attachment["filename"], evidence, output_path))
self.case.track_file(output_path)
def _consume_evidence(self):
"""
.. py:function:: _consume_evidence(self)
Main loop that processes the evidence(s) and formats the match(es).
:param self: current class instance
:type self: class
"""
for _, buffer in self.buffers.items():
try:
for match in buffer.match(self.evidence,
timeout=_conf.YARA_MATCH_TIMEOUT,
fast=self.fast):
hashes = {}
for algorithm in self.algorithms:
hashes[algorithm] = self._compute_hash(
self.evidence, algorithm=algorithm)
for action in [self.queue.put, self._invoke_callbacks]:
action({
"origin": _meta.__package__,
"target": {
"type": "file",
"identifier": self.evidence
},
"match": {
"timestamp":
_rendering.timestamp(),
"rule":
match.rule,
"meta":
match.meta,
"namespace":
match.namespace,
"tags":
match.tags,
"hashes":
hashes,
"strings": [{
"offset":
string[0],
"reference":
string[1],
"litteral":
string[2].decode("utf-8",
"backslashreplace")
} for string in match.strings]
}
})
except yara.TimeoutError:
_log.warning("Timeout exceeded for evidence <{}>.".format(
self.evidence))
continue
except (yara.Error, Exception):
_log.exception(
"YARA exception raised during processing of evidence <{}>."
.format(self.evidence))
continue
def _process_evidence(self):
"""
.. py:function:: _process_evidence(self)
Main loop that processes the evidence(s) and formats the match(es).
:param self: current class instance
:type self: class
"""
for _, buffer in self.buffers.items():
try:
for match in buffer.match(pid=self.evidence,
timeout=_conf.YARA_MATCH_TIMEOUT,
fast=self.fast):
for action in [self.queue.put, self._invoke_callbacks]:
action({
"origin": _meta.__package__,
"target": {
"type": "process",
"identifier": self.evidence
},
"match": {
"timestamp":
pendulum.now().format(_conf.TIMESTAMP_FORMAT,
formatter="alternative"),
"rule":
match.rule,
"meta":
match.meta,
"namespace":
match.namespace,
"tags":
match.tags,
"hashes": [],
"strings": [{
"offset":
string[0],
"reference":
string[1],
"litteral":
string[2].decode("utf-8",
"backslashreplace")
} for string in match.strings]
}
})
except yara.TimeoutError:
_log.warning(
"Timeout exceeded for live process matching PID <{}>.".
format(self.evidence))
continue
except yara.Error:
_log.exception(
"YARA exception raised during processing of live process matching PID <{}>."
.format(self.evidence))
continue
except Exception:
_log.exception(
"YARA exception raised during processing of live process matching PID <{}>."
.format(self.evidence))
continue
def recursive_inflate(self,
archive,
output_directory,
level=0,
password=None):
if level > self.case.arguments._level:
_log.warning(
"Limit unpacking level <{}> exceeded. Stopped unpacking.".
format(self.case.arguments._level))
return
_log.debug(
"Inflating {}archive <{}> to temporary directory <{}>.".format(
"level {} sub".format(level) if level else "base ", archive,
output_directory))
sub_directory = os.path.join(output_directory,
os.path.basename(archive))
try:
with zipfile.ZipFile(archive) as z:
z.extractall(path=sub_directory,
pwd=(password.encode() if password else password))
except zipfile.BadZipFile:
_log.error(
"Bad file header. Cannot inflate evidence <{}>. Try to filter out non-zip file(s) using --include \"*.zip\" \".*.zip\"."
.format(archive))
return
except RuntimeError as exc:
if "password required" in str(exc):
_log.error(
"Archive <{}> seems to be encrypted. Please specify a password using --password or --inline-password."
.format(archive))
elif "Bad password" in str(exc):
_log.error(
"Password {}seems to be incorrect for archive <{}>. Please specify another password using --password or --inline-password."
.format(
"<{}> ".format(self.case.arguments._inline_password)
if not hasattr(self, "_password") else "", archive))
else:
_log.exception(
"Runtime exception raised while unpacking archive <{}>.".
format(archive))
return
except KeyboardInterrupt:
sys.stderr.write("\n")
_log.fault("Aborted due to manual user interruption.")
except Exception:
_log.exception(
"Exception raised while unpacking archive <{}>.".format(
archive))
if self.case.arguments._no_recursion:
return
for subarchive in _fs.enumerate_matching_files(
sub_directory,
wildcard_patterns=([
"*.{}".format(_)
for _ in self.__associations__["extensions"]
] + [
".*.{}".format(_)
for _ in self.__associations__["extensions"]
] if hasattr(self, "__associations__")
and "extensions" in self.__associations__
else None),
mime_types=(self.__associations__["mime"]
if hasattr(self, "__associations__")
and "mime" in self.__associations__ else None),
recursive=True):
self.recursive_inflate(subarchive,
sub_directory,
level=(level + 1),
password=password)
