Files

86 lines
3.8 KiB
Python

# This file is Copyright 2019 Volatility Foundation and licensed under the Volatility Software License 1.0
# which is available at https://www.volatilityfoundation.org/license/vsl-v1.0
#
import logging
from typing import Iterable, Tuple, List
from volatility.framework import interfaces, renderers
from volatility.framework.configuration import requirements
from volatility.framework.interfaces import plugins
from volatility.framework.layers import resources
from volatility.framework.renderers import format_hints
vollog = logging.getLogger(__name__)
try:
import yara
except ImportError:
vollog.info("Python Yara module not found, plugin (and dependent plugins) not available")
raise
class YaraScanner(interfaces.layers.ScannerInterface):
# yara.Rules isn't exposed, so we can't type this properly
def __init__(self, rules) -> None:
super().__init__()
self._rules = rules
def __call__(self, data: bytes, data_offset: int) -> Iterable[Tuple[int, str]]:
for match in self._rules.match(data = data):
for offset, name, value in match.strings:
yield (offset + data_offset, name)
class YaraScan(plugins.PluginInterface):
"""Scans kernel memory using yara rules (string or file)."""
@classmethod
def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]:
return [
requirements.TranslationLayerRequirement(name = 'primary',
description = "Memory layer for the kernel",
architectures = ["Intel32", "Intel64"]),
requirements.BooleanRequirement(name = "insensitive",
description = "Makes the search case insensitive",
default = False,
optional = True),
requirements.BooleanRequirement(name = "wide",
description = "Match wide (unicode) strings",
default = False,
optional = True),
requirements.StringRequirement(name = "yara_rules",
description = "Yara rules (as a string)",
optional = True),
requirements.URIRequirement(name = "yara_file", description = "Yara rules (as a file)", optional = True),
requirements.IntRequirement(name = "max_size",
default = 0x40000000,
description = "Set the maximum size (default is 1GB)",
optional = True)
]
def _generator(self):
layer = self.context.layers[self.config['primary']]
rules = None
if self.config.get('yara_rules', None) is not None:
rule = self.config['yara_rules']
if rule[0] not in ["{", "/"]:
rule = '"{}"'.format(rule)
if self.config.get('case', False):
rule += " nocase"
if self.config.get('wide', False):
rule += " wide ascii"
rules = yara.compile(sources = {'n': 'rule r1 {{strings: $a = {} condition: $a}}'.format(rule)})
elif self.config.get('yara_file', None) is not None:
rules = yara.compile(file = resources.ResourceAccessor().open(self.config['yara_file'], "rb"))
else:
vollog.error("No yara rules, nor yara rules file were specified")
for offset, name in layer.scan(context = self.context, scanner = YaraScanner(rules = rules)):
yield (0, (format_hints.Hex(offset), name))
def run(self):
return renderers.TreeGrid([('Offset', format_hints.Hex), ('Rule', str)], self._generator())