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112 lines
5.3 KiB
Python
112 lines
5.3 KiB
Python
# This file is Copyright 2019 Volatility Foundation and licensed under the Volatility Software License 1.0
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# which is available at https://www.volatilityfoundation.org/license/vsl-v1.0
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#
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import logging
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from typing import Any, Dict, Iterable, List, Tuple
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from volatility3.framework import interfaces, renderers
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from volatility3.framework.configuration import requirements
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from volatility3.framework.interfaces import plugins
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from volatility3.framework.layers import resources
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from volatility3.framework.renderers import format_hints
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vollog = logging.getLogger(__name__)
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try:
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import yara
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if tuple([int(x) for x in yara.__version__.split('.')]) < (3, 8):
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raise ImportError
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except ImportError:
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vollog.info("Python Yara (>3.8.0) module not found, plugin (and dependent plugins) not available")
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raise
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class YaraScanner(interfaces.layers.ScannerInterface):
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_version = (2, 0, 0)
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# yara.Rules isn't exposed, so we can't type this properly
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def __init__(self, rules) -> None:
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super().__init__()
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if rules is None:
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raise ValueError("No rules provided to YaraScanner")
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self._rules = rules
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def __call__(self, data: bytes, data_offset: int) -> Iterable[Tuple[int, str, str, bytes]]:
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for match in self._rules.match(data = data):
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for offset, name, value in match.strings:
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yield (offset + data_offset, match.rule, name, value)
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class YaraScan(plugins.PluginInterface):
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"""Scans kernel memory using yara rules (string or file)."""
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_required_framework_version = (2, 0, 0)
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_version = (1, 1, 0)
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# TODO: When the major version is bumped, take the opportunity to rename the yara_rules config to yara_string
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# or something that makes more sense
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@classmethod
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def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]:
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return [
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requirements.TranslationLayerRequirement(name = 'primary',
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description = "Memory layer for the kernel",
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architectures = ["Intel32", "Intel64"]),
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requirements.BooleanRequirement(name = "insensitive",
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description = "Makes the search case insensitive",
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default = False,
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optional = True),
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requirements.BooleanRequirement(name = "wide",
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description = "Match wide (unicode) strings",
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default = False,
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optional = True),
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requirements.StringRequirement(name = "yara_rules",
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description = "Yara rules (as a string)",
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optional = True),
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requirements.URIRequirement(name = "yara_file", description = "Yara rules (as a file)", optional = True),
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# This additional requirement is to follow suit with upstream, who feel that compiled rules could potentially be used to execute malicious code
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# As such, there's a separate option to run compiled files, as happened with yara-3.9 and later
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requirements.URIRequirement(name = "yara_compiled_file",
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description = "Yara compiled rules (as a file)",
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optional = True),
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requirements.IntRequirement(name = "max_size",
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default = 0x40000000,
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description = "Set the maximum size (default is 1GB)",
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optional = True)
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]
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@classmethod
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def process_yara_options(cls, config: Dict[str, Any]):
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rules = None
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if config.get('yara_rules', None) is not None:
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rule = config['yara_rules']
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if rule[0] not in ["{", "/"]:
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rule = f'"{rule}"'
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if config.get('case', False):
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rule += " nocase"
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if config.get('wide', False):
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rule += " wide ascii"
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rules = yara.compile(sources = {'n': f'rule r1 {{strings: $a = {rule} condition: $a}}'})
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elif config.get('yara_source', None) is not None:
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rules = yara.compile(source = config['yara_source'])
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elif config.get('yara_file', None) is not None:
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rules = yara.compile(file = resources.ResourceAccessor().open(config['yara_file'], "rb"))
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elif config.get('yara_compiled_file', None) is not None:
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rules = yara.load(file = resources.ResourceAccessor().open(config['yara_compiled_file'], "rb"))
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else:
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vollog.error("No yara rules, nor yara rules file were specified")
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return rules
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def _generator(self):
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rules = self.process_yara_options(dict(self.config))
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layer = self.context.layers[self.config['primary']]
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for offset, rule_name, name, value in layer.scan(context = self.context, scanner = YaraScanner(rules = rules)):
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yield 0, (format_hints.Hex(offset), rule_name, name, value)
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def run(self):
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return renderers.TreeGrid([('Offset', format_hints.Hex), ('Rule', str), ('Component', str), ('Value', bytes)],
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self._generator())
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