mirror of
https://github.com/mandiant/capa.git
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323 lines
17 KiB
Python
323 lines
17 KiB
Python
# Copyright (C) 2020 FireEye, Inc. All Rights Reserved.
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at: [package root]/LICENSE.txt
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# Unless required by applicable law or agreed to in writing, software distributed under the License
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# is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and limitations under the License.
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import os.path
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import collections
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try:
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from functools import lru_cache
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except ImportError:
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from backports.functools_lru_cache import lru_cache
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import pytest
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import capa.features
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import capa.features.file
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import capa.features.insn
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import capa.features.basicblock
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import capa.features.extractors.lancelot.file
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import capa.features.extractors.lancelot.insn
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import capa.features.extractors.lancelot.function
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import capa.features.extractors.lancelot.basicblock
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from capa.features import ARCH_X32, ARCH_X64
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CD = os.path.dirname(__file__)
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@lru_cache
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def extract_file_features(extractor):
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features = collections.defaultdict(set)
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for feature, va in extractor.extract_file_features():
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features[feature].add(va)
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return features
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@lru_cache
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def extract_function_features(extractor, f):
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features = collections.defaultdict(set)
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for bb in extractor.get_basic_blocks(f):
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for insn in extractor.get_instructions(f, bb):
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for feature, va in extractor.extract_insn_features(f, bb, insn):
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features[feature].add(va)
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for feature, va in extractor.extract_basic_block_features(f, bb):
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features[feature].add(va)
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for feature, va in extractor.extract_function_features(f):
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features[feature].add(va)
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return features
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@lru_cache
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def extract_basic_block_features(extractor, f, bb):
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features = collections.defaultdict(set)
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for insn in extractor.get_instructions(f, bb):
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for feature, va in extractor.extract_insn_features(f, bb, insn):
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features[feature].add(va)
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for feature, va in extractor.extract_basic_block_features(f, bb):
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features[feature].add(va)
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return features
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@lru_cache
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def get_lancelot_extractor(path):
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with open(path, "rb") as f:
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buf = f.read()
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return capa.features.extractors.lancelot.LancelotFeatureExtractor(buf)
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@pytest.fixture
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def sample(request):
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if request.param == "mimikatz":
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return os.path.join(CD, "data", "mimikatz.exe_")
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elif request.param == "kernel32":
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return os.path.join(CD, "data", "kernel32.dll_")
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elif request.param == "kernel32-64":
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return os.path.join(CD, "data", "kernel32-64.dll_")
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elif request.param == "pma12-04":
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return os.path.join(CD, "data", "Practical Malware Analysis Lab 12-04.exe_")
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elif request.param.startswith("a1982"):
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return os.path.join(CD, "data", "a198216798ca38f280dc413f8c57f2c2.exe_")
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elif request.param.startswith("39c05"):
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return os.path.join(CD, "data", "39c05b15e9834ac93f206bc114d0a00c357c888db567ba8f5345da0529cbed41.dll_")
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elif request.param.startswith("c9188"):
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return os.path.join(CD, "data", "c91887d861d9bd4a5872249b641bc9f9.exe_")
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else:
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raise ValueError("unexpected sample fixture")
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def get_function(extractor, fva):
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for f in extractor.get_functions():
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if f.__int__() == fva:
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return f
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raise ValueError("function not found")
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def get_basic_block(extractor, f, va):
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for bb in extractor.get_basic_blocks(f):
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if bb.__int__() == va:
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return bb
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raise ValueError("basic block not found")
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@pytest.fixture
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def scope(request):
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if request.param == "file":
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def inner(extractor):
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return extract_file_features(extractor)
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inner.__name__ = request.param
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return inner
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elif "bb=" in request.param:
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# like `function=0x401000,bb=0x40100A`
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fspec, _, bbspec = request.param.partition(",")
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fva = int(fspec.partition("=")[2], 0x10)
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bbva = int(bbspec.partition("=")[2], 0x10)
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def inner(extractor):
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f = get_function(extractor, fva)
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bb = get_basic_block(extractor, f, bbva)
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return extract_basic_block_features(extractor, f, bb)
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inner.__name__ = request.param
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return inner
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elif request.param.startswith("function"):
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# like `function=0x401000`
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va = int(request.param.partition("=")[2], 0x10)
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def inner(extractor):
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f = get_function(extractor, va)
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return extract_function_features(extractor, f)
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inner.__name__ = request.param
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return inner
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else:
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raise ValueError("unexpected scope fixture")
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def parametrize(params, values, **kwargs):
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"""
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extend `pytest.mark.parametrize` to pretty-print features.
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by default, it renders objects as an opaque value.
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ref: https://docs.pytest.org/en/2.9.0/example/parametrize.html#different-options-for-test-ids
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rendered ID might look something like:
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mimikatz-function=0x403BAC-api(CryptDestroyKey)-True
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"""
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ids = ["-".join(map(str, vs)) for vs in values]
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return pytest.mark.parametrize(params, values, ids=ids, **kwargs)
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@parametrize(
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"sample,scope,feature,expected",
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[
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# file/characteristic("embedded pe")
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("pma12-04", "file", capa.features.Characteristic("embedded pe"), True),
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# file/string
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("mimikatz", "file", capa.features.String("SCardControl"), True),
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("mimikatz", "file", capa.features.String("SCardTransmit"), True),
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("mimikatz", "file", capa.features.String("ACR > "), True),
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("mimikatz", "file", capa.features.String("nope"), False),
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# file/sections
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("mimikatz", "file", capa.features.file.Section(".rsrc"), True),
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("mimikatz", "file", capa.features.file.Section(".text"), True),
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("mimikatz", "file", capa.features.file.Section(".nope"), False),
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# file/exports
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("kernel32", "file", capa.features.file.Export("BaseThreadInitThunk"), True),
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("kernel32", "file", capa.features.file.Export("lstrlenW"), True),
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("kernel32", "file", capa.features.file.Export("nope"), False),
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# file/imports
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("mimikatz", "file", capa.features.file.Import("advapi32.CryptSetHashParam"), True),
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("mimikatz", "file", capa.features.file.Import("CryptSetHashParam"), True),
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("mimikatz", "file", capa.features.file.Import("kernel32.IsWow64Process"), True),
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("mimikatz", "file", capa.features.file.Import("msvcrt.exit"), True),
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("mimikatz", "file", capa.features.file.Import("cabinet.#11"), True),
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("mimikatz", "file", capa.features.file.Import("#11"), False),
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("mimikatz", "file", capa.features.file.Import("#nope"), False),
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("mimikatz", "file", capa.features.file.Import("nope"), False),
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# function/characteristic(loop)
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("mimikatz", "function=0x401517", capa.features.Characteristic("loop"), True),
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("mimikatz", "function=0x401000", capa.features.Characteristic("loop"), False),
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# bb/characteristic(tight loop)
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("mimikatz", "function=0x402EC4", capa.features.Characteristic("tight loop"), True),
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("mimikatz", "function=0x401000", capa.features.Characteristic("tight loop"), False),
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# bb/characteristic(stack string)
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("mimikatz", "function=0x4556E5", capa.features.Characteristic("stack string"), True),
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("mimikatz", "function=0x401000", capa.features.Characteristic("stack string"), False),
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# bb/characteristic(tight loop)
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("mimikatz", "function=0x402EC4,bb=0x402F8E", capa.features.Characteristic("tight loop"), True),
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("mimikatz", "function=0x401000,bb=0x401000", capa.features.Characteristic("tight loop"), False),
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# insn/mnemonic
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("mimikatz", "function=0x40105D", capa.features.insn.Mnemonic("push"), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Mnemonic("movzx"), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Mnemonic("xor"), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Mnemonic("in"), False),
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("mimikatz", "function=0x40105D", capa.features.insn.Mnemonic("out"), False),
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# insn/number
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("mimikatz", "function=0x40105D", capa.features.insn.Number(0xFF), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Number(0x3136B0), True),
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# insn/number: stack adjustments
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("mimikatz", "function=0x40105D", capa.features.insn.Number(0xC), False),
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("mimikatz", "function=0x40105D", capa.features.insn.Number(0x10), False),
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# insn/number: arch flavors
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("mimikatz", "function=0x40105D", capa.features.insn.Number(0xFF), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Number(0xFF, arch=ARCH_X32), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Number(0xFF, arch=ARCH_X64), False),
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# insn/offset
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("mimikatz", "function=0x40105D", capa.features.insn.Offset(0x0), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Offset(0x4), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Offset(0xC), True),
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# insn/offset: stack references
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("mimikatz", "function=0x40105D", capa.features.insn.Offset(0x8), False),
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("mimikatz", "function=0x40105D", capa.features.insn.Offset(0x10), False),
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# insn/offset: negative
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("mimikatz", "function=0x4011FB", capa.features.insn.Offset(-0x1), True),
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("mimikatz", "function=0x4011FB", capa.features.insn.Offset(-0x2), True),
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# insn/offset: arch flavors
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("mimikatz", "function=0x40105D", capa.features.insn.Offset(0x0), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Offset(0x0, arch=ARCH_X32), True),
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("mimikatz", "function=0x40105D", capa.features.insn.Offset(0x0, arch=ARCH_X64), False),
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# insn/api
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("mimikatz", "function=0x403BAC", capa.features.insn.API("advapi32.CryptAcquireContextW"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("advapi32.CryptAcquireContext"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("advapi32.CryptGenKey"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("advapi32.CryptImportKey"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("advapi32.CryptDestroyKey"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("CryptAcquireContextW"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("CryptAcquireContext"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("CryptGenKey"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("CryptImportKey"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("CryptDestroyKey"), True),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("Nope"), False),
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("mimikatz", "function=0x403BAC", capa.features.insn.API("advapi32.Nope"), False),
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# insn/api: thunk
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("mimikatz", "function=0x4556E5", capa.features.insn.API("advapi32.LsaQueryInformationPolicy"), True),
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("mimikatz", "function=0x4556E5", capa.features.insn.API("LsaQueryInformationPolicy"), True),
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# insn/api: x64
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("kernel32-64", "function=0x180001010", capa.features.insn.API("RtlVirtualUnwind"), True,),
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("kernel32-64", "function=0x180001010", capa.features.insn.API("RtlVirtualUnwind"), True),
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# insn/api: x64 thunk
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("kernel32-64", "function=0x1800202B0", capa.features.insn.API("RtlCaptureContext"), True,),
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("kernel32-64", "function=0x1800202B0", capa.features.insn.API("RtlCaptureContext"), True),
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# insn/api: resolve indirect calls
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("c91887...", "function=0x401A77", capa.features.insn.API("kernel32.CreatePipe"), True),
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("c91887...", "function=0x401A77", capa.features.insn.API("kernel32.SetHandleInformation"), True),
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("c91887...", "function=0x401A77", capa.features.insn.API("kernel32.CloseHandle"), True),
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("c91887...", "function=0x401A77", capa.features.insn.API("kernel32.WriteFile"), True),
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# insn/string
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("mimikatz", "function=0x40105D", capa.features.String("SCardControl"), True),
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("mimikatz", "function=0x40105D", capa.features.String("SCardTransmit"), True),
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("mimikatz", "function=0x40105D", capa.features.String("ACR > "), True),
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("mimikatz", "function=0x40105D", capa.features.String("nope"), False),
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# insn/string, pointer to string
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("mimikatz", "function=0x44EDEF", capa.features.String("INPUTEVENT"), True),
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# insn/bytes
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("mimikatz", "function=0x40105D", capa.features.Bytes("SCardControl".encode("utf-16le")), True),
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("mimikatz", "function=0x40105D", capa.features.Bytes("SCardTransmit".encode("utf-16le")), True),
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("mimikatz", "function=0x40105D", capa.features.Bytes("ACR > ".encode("utf-16le")), True),
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("mimikatz", "function=0x40105D", capa.features.Bytes("nope".encode("ascii")), False),
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# insn/bytes, pointer to bytes
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("mimikatz", "function=0x44EDEF", capa.features.Bytes("INPUTEVENT".encode("utf-16le")), True),
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# insn/characteristic(nzxor)
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("mimikatz", "function=0x410DFC", capa.features.Characteristic("nzxor"), True),
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("mimikatz", "function=0x40105D", capa.features.Characteristic("nzxor"), False),
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# insn/characteristic(nzxor): no security cookies
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("mimikatz", "function=0x46B67A", capa.features.Characteristic("nzxor"), False),
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# insn/characteristic(peb access)
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("kernel32-64", "function=0x180001068", capa.features.Characteristic("peb access"), True),
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("mimikatz", "function=0x46B67A", capa.features.Characteristic("peb access"), False),
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# insn/characteristic(gs access)
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("kernel32-64", "function=0x180001068", capa.features.Characteristic("gs access"), True),
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("mimikatz", "function=0x46B67A", capa.features.Characteristic("gs access"), False),
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# insn/characteristic(cross section flow)
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("a1982...", "function=0x4014D0", capa.features.Characteristic("cross section flow"), True),
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# insn/characteristic(cross section flow): imports don't count
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("kernel32-64", "function=0x180001068", capa.features.Characteristic("cross section flow"), False),
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("mimikatz", "function=0x46B67A", capa.features.Characteristic("cross section flow"), False),
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# insn/characteristic(recursive call)
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("39c05...", "function=0x10003100", capa.features.Characteristic("recursive call"), True),
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("mimikatz", "function=0x46B67A", capa.features.Characteristic("recursive call"), False),
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# insn/characteristic(indirect call)
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("mimikatz", "function=0x4175FF", capa.features.Characteristic("indirect call"), True),
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("mimikatz", "function=0x46B67A", capa.features.Characteristic("indirect call"), False),
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# insn/characteristic(calls from)
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("mimikatz", "function=0x46B67A", capa.features.Characteristic("calls from"), True),
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("mimikatz", "function=0x40E51B", capa.features.Characteristic("calls from"), False),
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# function/characteristic(calls to)
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("mimikatz", "function=0x40105D", capa.features.Characteristic("calls to"), True),
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("mimikatz", "function=0x46C0D2", capa.features.Characteristic("calls to"), False),
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("mimikatz", "function=0x40E51B", capa.features.Characteristic("calls to"), False),
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],
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indirect=["sample", "scope"],
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)
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def test_lancelot_features(sample, scope, feature, expected):
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extractor = get_lancelot_extractor(sample)
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features = scope(extractor)
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if expected:
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msg = "%s should be found in %s" % (str(feature), scope.__name__)
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else:
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msg = "%s should not be found in %s" % (str(feature), scope.__name__)
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assert feature.evaluate(features) == expected, msg
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@parametrize(
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"sample,scope,feature,expected",
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[
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("mimikatz", "function=0x40E51B", capa.features.basicblock.BasicBlock(), 1),
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("mimikatz", "function=0x40E5C2", capa.features.basicblock.BasicBlock(), 7),
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("mimikatz", "function=0x40E5C2", capa.features.Characteristic("calls from"), 3),
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],
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indirect=["sample", "scope"],
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)
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def test_lancelot_feature_counts(sample, scope, feature, expected):
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extractor = get_lancelot_extractor(sample)
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features = scope(extractor)
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msg = "%s should be found %d times in %s" % (str(feature), expected, scope.__name__)
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assert len(features[feature]) == expected, msg
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