mirror of
https://github.com/mandiant/capa.git
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1023 lines
29 KiB
Python
1023 lines
29 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 textwrap
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import pytest
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import capa.rules
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import capa.engine
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import capa.features.common
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from capa.features.file import FunctionName
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from capa.features.insn import Number, Offset
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from capa.features.common import (
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OS,
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OS_LINUX,
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ARCH_I386,
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FORMAT_PE,
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ARCH_AMD64,
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FORMAT_ELF,
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OS_WINDOWS,
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BITNESS_X32,
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BITNESS_X64,
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Arch,
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Format,
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String,
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Substring,
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)
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def test_rule_ctor():
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r = capa.rules.Rule("test rule", capa.rules.FUNCTION_SCOPE, Number(1), {})
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assert r.evaluate({Number(0): {1}}) == False
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assert r.evaluate({Number(1): {1}}) == True
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def test_rule_yaml():
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rule = textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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author: user@domain.com
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scope: function
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examples:
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- foo1234
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- bar5678
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features:
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- and:
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- number: 1
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- number: 2
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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assert r.evaluate({Number(0): {1}}) == False
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assert r.evaluate({Number(0): {1}, Number(1): {1}}) == False
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assert r.evaluate({Number(0): {1}, Number(1): {1}, Number(2): {1}}) == True
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assert r.evaluate({Number(0): {1}, Number(1): {1}, Number(2): {1}, Number(3): {1}}) == True
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def test_rule_yaml_complex():
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rule = textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- or:
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- and:
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- number: 1
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- number: 2
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- or:
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- number: 3
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- 2 or more:
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- number: 4
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- number: 5
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- number: 6
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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assert r.evaluate({Number(5): {1}, Number(6): {1}, Number(7): {1}, Number(8): {1}}) == True
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assert r.evaluate({Number(6): {1}, Number(7): {1}, Number(8): {1}}) == False
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def test_rule_descriptions():
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rule = textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- and:
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- description: and description
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- number: 1 = number description
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- string: mystring
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description: string description
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- string: '/myregex/'
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description: regex description
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- mnemonic: inc = mnemonic description
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# TODO - count(number(2 = number description)): 2
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- or:
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- description: or description
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- and:
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- offset: 0x50 = offset description
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- offset: 0x34 = offset description
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- description: and description
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- and:
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- description: and description
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- offset/x64: 0x50 = offset/x64 description
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- offset/x64: 0x30 = offset/x64 description
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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def rec(statement):
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if isinstance(statement, capa.engine.Statement):
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assert statement.description == statement.name.lower() + " description"
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for child in statement.get_children():
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rec(child)
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else:
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if isinstance(statement.value, str):
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assert "description" not in statement.value
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assert statement.description == statement.name + " description"
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rec(r.statement)
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def test_invalid_rule_statement_descriptions():
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# statements can only have one description
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with pytest.raises(capa.rules.InvalidRule):
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- or:
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- number: 1 = This is the number 1
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- description: description
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- description: another description (invalid)
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"""
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)
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)
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def test_rule_yaml_not():
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rule = textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- and:
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- number: 1
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- not:
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- number: 2
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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assert r.evaluate({Number(1): {1}}) == True
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assert r.evaluate({Number(1): {1}, Number(2): {1}}) == False
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def test_rule_yaml_count():
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rule = textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- count(number(100)): 1
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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assert r.evaluate({Number(100): {}}) == False
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assert r.evaluate({Number(100): {1}}) == True
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assert r.evaluate({Number(100): {1, 2}}) == False
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def test_rule_yaml_count_range():
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rule = textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- count(number(100)): (1, 2)
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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assert r.evaluate({Number(100): {}}) == False
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assert r.evaluate({Number(100): {1}}) == True
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assert r.evaluate({Number(100): {1, 2}}) == True
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assert r.evaluate({Number(100): {1, 2, 3}}) == False
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def test_rule_yaml_count_string():
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rule = textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- count(string(foo)): 2
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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assert r.evaluate({String("foo"): {}}) == False
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assert r.evaluate({String("foo"): {1}}) == False
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assert r.evaluate({String("foo"): {1, 2}}) == True
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assert r.evaluate({String("foo"): {1, 2, 3}}) == False
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def test_invalid_rule_feature():
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with pytest.raises(capa.rules.InvalidRule):
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- foo: true
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"""
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)
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)
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with pytest.raises(capa.rules.InvalidRule):
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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scope: file
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features:
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- characteristic: nzxor
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"""
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)
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)
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with pytest.raises(capa.rules.InvalidRule):
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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scope: function
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features:
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- characteristic: embedded pe
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"""
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)
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)
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with pytest.raises(capa.rules.InvalidRule):
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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scope: basic block
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features:
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- characteristic: embedded pe
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"""
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)
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)
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def test_lib_rules():
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rules = capa.rules.RuleSet(
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[
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: a lib rule
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lib: true
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features:
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- api: CreateFileA
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"""
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)
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),
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: a standard rule
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lib: false
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features:
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- api: CreateFileW
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"""
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)
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),
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]
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)
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# lib rules are added to the rule set
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assert len(rules.function_rules) == 2
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def test_subscope_rules():
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rules = capa.rules.RuleSet(
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[
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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scope: file
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features:
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- and:
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- characteristic: embedded pe
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- function:
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- and:
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- characteristic: nzxor
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- characteristic: loop
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"""
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)
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)
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]
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)
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# the file rule scope will have one rules:
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# - `test rule`
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assert len(rules.file_rules) == 1
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# the function rule scope have one rule:
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# - the rule on which `test rule` depends
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assert len(rules.function_rules) == 1
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def test_duplicate_rules():
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with pytest.raises(capa.rules.InvalidRule):
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rules = capa.rules.RuleSet(
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[
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: rule-name
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features:
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- api: CreateFileA
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"""
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)
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),
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: rule-name
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features:
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- api: CreateFileW
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"""
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)
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),
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]
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)
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def test_missing_dependency():
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with pytest.raises(capa.rules.InvalidRule):
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rules = capa.rules.RuleSet(
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[
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capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: dependent rule
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features:
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- match: missing rule
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"""
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)
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),
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]
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)
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def test_invalid_rules():
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with pytest.raises(capa.rules.InvalidRule):
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r = capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- characteristic: number(1)
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"""
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)
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)
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with pytest.raises(capa.rules.InvalidRule):
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r = capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- characteristic: count(number(100))
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"""
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)
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)
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# att&ck and mbc must be lists
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with pytest.raises(capa.rules.InvalidRule):
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r = capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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att&ck: Tactic::Technique::Subtechnique [Identifier]
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features:
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- number: 1
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"""
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)
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)
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with pytest.raises(capa.rules.InvalidRule):
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r = capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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mbc: Objective::Behavior::Method [Identifier]
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features:
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- number: 1
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"""
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)
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)
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def test_number_symbol():
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rule = textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- and:
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- number: 1
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- number: 0xFFFFFFFF
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- number: 2 = symbol name
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- number: 3 = symbol name
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- number: 4 = symbol name = another name
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- number: 0x100 = symbol name
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- number: 0x11 = (FLAG_A | FLAG_B)
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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children = list(r.statement.get_children())
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assert (Number(1) in children) == True
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assert (Number(0xFFFFFFFF) in children) == True
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assert (Number(2, description="symbol name") in children) == True
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assert (Number(3, description="symbol name") in children) == True
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assert (Number(4, description="symbol name = another name") in children) == True
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assert (Number(0x100, description="symbol name") in children) == True
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def test_count_number_symbol():
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rule = textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- or:
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- count(number(2 = symbol name)): 1
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- count(number(0x100 = symbol name)): 2 or more
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- count(number(0x11 = (FLAG_A | FLAG_B))): 2 or more
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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assert r.evaluate({Number(2): {}}) == False
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assert r.evaluate({Number(2): {1}}) == True
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assert r.evaluate({Number(2): {1, 2}}) == False
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assert r.evaluate({Number(0x100, description="symbol name"): {1}}) == False
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assert r.evaluate({Number(0x100, description="symbol name"): {1, 2, 3}}) == True
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def test_invalid_number():
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with pytest.raises(capa.rules.InvalidRule):
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r = capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- number: "this is a string"
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"""
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)
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)
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with pytest.raises(capa.rules.InvalidRule):
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r = capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- number: 2=
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"""
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)
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)
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with pytest.raises(capa.rules.InvalidRule):
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r = capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- number: symbol name = 2
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"""
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)
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)
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def test_number_bitness():
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r = capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- number/x32: 2
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"""
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)
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)
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assert r.evaluate({Number(2, bitness=BITNESS_X32): {1}}) == True
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assert r.evaluate({Number(2): {1}}) == False
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assert r.evaluate({Number(2, bitness=BITNESS_X64): {1}}) == False
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|
|
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def test_number_bitness_symbol():
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r = capa.rules.Rule.from_yaml(
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textwrap.dedent(
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"""
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rule:
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meta:
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name: test rule
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features:
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- number/x32: 2 = some constant
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"""
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)
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)
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assert r.evaluate({Number(2, bitness=BITNESS_X32, description="some constant"): {1}}) == True
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|
|
|
|
def test_offset_symbol():
|
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rule = textwrap.dedent(
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"""
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rule:
|
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meta:
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name: test rule
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features:
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- and:
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- offset: 1
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- offset: 2 = symbol name
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- offset: 3 = symbol name
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- offset: 4 = symbol name = another name
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- offset: 0x100 = symbol name
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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children = list(r.statement.get_children())
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assert (Offset(1) in children) == True
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assert (Offset(2, description="symbol name") in children) == True
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assert (Offset(3, description="symbol name") in children) == True
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assert (Offset(4, description="symbol name = another name") in children) == True
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assert (Offset(0x100, description="symbol name") in children) == True
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|
|
|
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def test_count_offset_symbol():
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rule = textwrap.dedent(
|
|
"""
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rule:
|
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meta:
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name: test rule
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features:
|
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- or:
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- count(offset(2 = symbol name)): 1
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- count(offset(0x100 = symbol name)): 2 or more
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- count(offset(0x11 = (FLAG_A | FLAG_B))): 2 or more
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"""
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)
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r = capa.rules.Rule.from_yaml(rule)
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assert r.evaluate({Offset(2): {}}) == False
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assert r.evaluate({Offset(2): {1}}) == True
|
|
assert r.evaluate({Offset(2): {1, 2}}) == False
|
|
assert r.evaluate({Offset(0x100, description="symbol name"): {1}}) == False
|
|
assert r.evaluate({Offset(0x100, description="symbol name"): {1, 2, 3}}) == True
|
|
|
|
|
|
def test_offset_bitness():
|
|
r = capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- offset/x32: 2
|
|
"""
|
|
)
|
|
)
|
|
assert r.evaluate({Offset(2, bitness=BITNESS_X32): {1}}) == True
|
|
|
|
assert r.evaluate({Offset(2): {1}}) == False
|
|
assert r.evaluate({Offset(2, bitness=BITNESS_X64): {1}}) == False
|
|
|
|
|
|
def test_offset_bitness_symbol():
|
|
r = capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- offset/x32: 2 = some constant
|
|
"""
|
|
)
|
|
)
|
|
assert r.evaluate({Offset(2, bitness=BITNESS_X32, description="some constant"): {1}}) == True
|
|
|
|
|
|
def test_invalid_offset():
|
|
with pytest.raises(capa.rules.InvalidRule):
|
|
r = capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- offset: "this is a string"
|
|
"""
|
|
)
|
|
)
|
|
|
|
with pytest.raises(capa.rules.InvalidRule):
|
|
r = capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- offset: 2=
|
|
"""
|
|
)
|
|
)
|
|
|
|
with pytest.raises(capa.rules.InvalidRule):
|
|
r = capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- offset: symbol name = 2
|
|
"""
|
|
)
|
|
)
|
|
|
|
|
|
def test_invalid_string_values_int():
|
|
with pytest.raises(capa.rules.InvalidRule):
|
|
r = capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- string: 123
|
|
"""
|
|
)
|
|
)
|
|
|
|
with pytest.raises(capa.rules.InvalidRule):
|
|
r = capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- string: 0x123
|
|
"""
|
|
)
|
|
)
|
|
|
|
|
|
def test_explicit_string_values_int():
|
|
rule = textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- or:
|
|
- string: "123"
|
|
- string: "0x123"
|
|
"""
|
|
)
|
|
r = capa.rules.Rule.from_yaml(rule)
|
|
children = list(r.statement.get_children())
|
|
assert (String("123") in children) == True
|
|
assert (String("0x123") in children) == True
|
|
|
|
|
|
def test_string_values_special_characters():
|
|
rule = textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- or:
|
|
- string: "hello\\r\\nworld"
|
|
- string: "bye\\nbye"
|
|
description: "test description"
|
|
"""
|
|
)
|
|
r = capa.rules.Rule.from_yaml(rule)
|
|
children = list(r.statement.get_children())
|
|
assert (String("hello\r\nworld") in children) == True
|
|
assert (String("bye\nbye") in children) == True
|
|
|
|
|
|
def test_substring_feature():
|
|
rule = textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- or:
|
|
- substring: abc
|
|
- substring: "def"
|
|
- substring: "gh\\ni"
|
|
"""
|
|
)
|
|
r = capa.rules.Rule.from_yaml(rule)
|
|
children = list(r.statement.get_children())
|
|
assert (Substring("abc") in children) == True
|
|
assert (Substring("def") in children) == True
|
|
assert (Substring("gh\ni") in children) == True
|
|
|
|
|
|
def test_substring_description():
|
|
rule = textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
features:
|
|
- or:
|
|
- substring: abc
|
|
description: the start of the alphabet
|
|
"""
|
|
)
|
|
r = capa.rules.Rule.from_yaml(rule)
|
|
children = list(r.statement.get_children())
|
|
assert (Substring("abc") in children) == True
|
|
|
|
|
|
|
|
|
|
def test_filter_rules():
|
|
rules = capa.rules.RuleSet(
|
|
[
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 1
|
|
author: joe
|
|
features:
|
|
- api: CreateFile
|
|
"""
|
|
)
|
|
),
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 2
|
|
features:
|
|
- string: joe
|
|
"""
|
|
)
|
|
),
|
|
]
|
|
)
|
|
rules = rules.filter_rules_by_meta("joe")
|
|
assert len(rules) == 1
|
|
assert "rule 1" in rules.rules
|
|
|
|
|
|
def test_filter_rules_dependencies():
|
|
rules = capa.rules.RuleSet(
|
|
[
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 1
|
|
features:
|
|
- match: rule 2
|
|
"""
|
|
)
|
|
),
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 2
|
|
features:
|
|
- match: rule 3
|
|
"""
|
|
)
|
|
),
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 3
|
|
features:
|
|
- api: CreateFile
|
|
"""
|
|
)
|
|
),
|
|
]
|
|
)
|
|
rules = rules.filter_rules_by_meta("rule 1")
|
|
assert len(rules.rules) == 3
|
|
assert "rule 1" in rules.rules
|
|
assert "rule 2" in rules.rules
|
|
assert "rule 3" in rules.rules
|
|
|
|
|
|
def test_filter_rules_missing_dependency():
|
|
with pytest.raises(capa.rules.InvalidRule):
|
|
capa.rules.RuleSet(
|
|
[
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 1
|
|
author: joe
|
|
features:
|
|
- match: rule 2
|
|
"""
|
|
)
|
|
),
|
|
]
|
|
)
|
|
|
|
|
|
def test_rules_namespace_dependencies():
|
|
rules = [
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 1
|
|
namespace: ns1/nsA
|
|
features:
|
|
- api: CreateFile
|
|
"""
|
|
)
|
|
),
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 2
|
|
namespace: ns1/nsB
|
|
features:
|
|
- api: CreateFile
|
|
"""
|
|
)
|
|
),
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 3
|
|
features:
|
|
- match: ns1/nsA
|
|
"""
|
|
)
|
|
),
|
|
capa.rules.Rule.from_yaml(
|
|
textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: rule 4
|
|
features:
|
|
- match: ns1
|
|
"""
|
|
)
|
|
),
|
|
]
|
|
|
|
r3 = set(map(lambda r: r.name, capa.rules.get_rules_and_dependencies(rules, "rule 3")))
|
|
assert "rule 1" in r3
|
|
assert "rule 2" not in r3
|
|
assert "rule 4" not in r3
|
|
|
|
r4 = set(map(lambda r: r.name, capa.rules.get_rules_and_dependencies(rules, "rule 4")))
|
|
assert "rule 1" in r4
|
|
assert "rule 2" in r4
|
|
assert "rule 3" not in r4
|
|
|
|
|
|
def test_function_name_features():
|
|
rule = textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
scope: file
|
|
features:
|
|
- and:
|
|
- function-name: strcpy
|
|
- function-name: strcmp = copy from here to there
|
|
- function-name: strdup
|
|
description: duplicate a string
|
|
"""
|
|
)
|
|
r = capa.rules.Rule.from_yaml(rule)
|
|
children = list(r.statement.get_children())
|
|
assert (FunctionName("strcpy") in children) == True
|
|
assert (FunctionName("strcmp", description="copy from here to there") in children) == True
|
|
assert (FunctionName("strdup", description="duplicate a string") in children) == True
|
|
|
|
|
|
def test_os_features():
|
|
rule = textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
scope: file
|
|
features:
|
|
- and:
|
|
- os: windows
|
|
"""
|
|
)
|
|
r = capa.rules.Rule.from_yaml(rule)
|
|
children = list(r.statement.get_children())
|
|
assert (OS(OS_WINDOWS) in children) == True
|
|
assert (OS(OS_LINUX) not in children) == True
|
|
|
|
|
|
def test_format_features():
|
|
rule = textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
scope: file
|
|
features:
|
|
- and:
|
|
- format: pe
|
|
"""
|
|
)
|
|
r = capa.rules.Rule.from_yaml(rule)
|
|
children = list(r.statement.get_children())
|
|
assert (Format(FORMAT_PE) in children) == True
|
|
assert (Format(FORMAT_ELF) not in children) == True
|
|
|
|
|
|
def test_arch_features():
|
|
rule = textwrap.dedent(
|
|
"""
|
|
rule:
|
|
meta:
|
|
name: test rule
|
|
scope: file
|
|
features:
|
|
- and:
|
|
- arch: amd64
|
|
"""
|
|
)
|
|
r = capa.rules.Rule.from_yaml(rule)
|
|
children = list(r.statement.get_children())
|
|
assert (Arch(ARCH_AMD64) in children) == True
|
|
assert (Arch(ARCH_I386) not in children) == True
|