mirror of
https://github.com/mandiant/capa.git
synced 2026-01-14 13:56:49 -08:00
3cd97ae9f2
Replace the header from source code files using the following script:
```Python
for dir_path, dir_names, file_names in os.walk("capa"):
for file_name in file_names:
# header are only in `.py` and `.toml` files
if file_name[-3:] not in (".py", "oml"):
continue
file_path = f"{dir_path}/{file_name}"
f = open(file_path, "rb+")
content = f.read()
m = re.search(OLD_HEADER, content)
if not m:
continue
print(f"{file_path}: {m.group('year')}")
content = content.replace(m.group(0), NEW_HEADER % m.group("year"))
f.seek(0)
f.write(content)
```
Some files had the copyright headers inside a `"""` comment and needed
manual changes before applying the script. `hook-vivisect.py` and
`pyinstaller.spec` didn't include the license in the header and also
needed manual changes.
The old header had the confusing sentence `All rights reserved`, which
does not make sense for an open source license. Replace the header by
the default Google header that corrects this issue and keep capa
consistent with other Google projects.
Adapt the linter to work with the new header.
Replace also the copyright text in the `web/public/index.html` file for
consistency.
150 lines
4.9 KiB
Python
150 lines
4.9 KiB
Python
# Copyright 2021 Google LLC
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#
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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
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# 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
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# limitations under the License.
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import io
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import re
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import logging
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import binascii
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import contextlib
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from typing import Iterator
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import pefile
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import capa.features
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import capa.features.extractors.elf
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import capa.features.extractors.pefile
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import capa.features.extractors.strings
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from capa.features.common import (
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OS,
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OS_ANY,
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OS_AUTO,
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ARCH_ANY,
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FORMAT_PE,
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FORMAT_ELF,
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OS_WINDOWS,
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FORMAT_FREEZE,
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FORMAT_RESULT,
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Arch,
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Format,
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String,
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Feature,
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)
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from capa.features.freeze import is_freeze
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from capa.features.address import NO_ADDRESS, Address, FileOffsetAddress
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logger = logging.getLogger(__name__)
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# match strings for formats
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MATCH_PE = b"MZ"
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MATCH_ELF = b"\x7fELF"
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MATCH_RESULT = b'{"meta":'
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MATCH_JSON_OBJECT = b'{"'
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def extract_file_strings(buf: bytes, **kwargs) -> Iterator[tuple[String, Address]]:
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"""
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extract ASCII and UTF-16 LE strings from file
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"""
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for s in capa.features.extractors.strings.extract_ascii_strings(buf):
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yield String(s.s), FileOffsetAddress(s.offset)
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for s in capa.features.extractors.strings.extract_unicode_strings(buf):
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yield String(s.s), FileOffsetAddress(s.offset)
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def extract_format(buf: bytes) -> Iterator[tuple[Feature, Address]]:
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if buf.startswith(MATCH_PE):
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yield Format(FORMAT_PE), NO_ADDRESS
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elif buf.startswith(MATCH_ELF):
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yield Format(FORMAT_ELF), NO_ADDRESS
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elif is_freeze(buf):
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yield Format(FORMAT_FREEZE), NO_ADDRESS
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elif buf.startswith(MATCH_RESULT):
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yield Format(FORMAT_RESULT), NO_ADDRESS
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elif re.sub(rb"\s", b"", buf[:20]).startswith(MATCH_JSON_OBJECT):
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# potential start of JSON object data without whitespace
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# we don't know what it is exactly, but may support it (e.g. a dynamic CAPE sandbox report)
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# skip verdict here and let subsequent code analyze this further
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return
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else:
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# we likely end up here:
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# 1. handling a file format (e.g. macho)
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#
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# for (1), this logic will need to be updated as the format is implemented.
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logger.debug("unknown file format: %s", buf[:4].hex())
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return
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def extract_arch(buf) -> Iterator[tuple[Feature, Address]]:
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if buf.startswith(MATCH_PE):
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yield from capa.features.extractors.pefile.extract_file_arch(pe=pefile.PE(data=buf))
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elif buf.startswith(MATCH_RESULT):
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yield Arch(ARCH_ANY), NO_ADDRESS
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elif buf.startswith(MATCH_ELF):
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with contextlib.closing(io.BytesIO(buf)) as f:
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arch = capa.features.extractors.elf.detect_elf_arch(f)
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if arch not in capa.features.common.VALID_ARCH:
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logger.debug("unsupported arch: %s", arch)
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return
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yield Arch(arch), NO_ADDRESS
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else:
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# we likely end up here:
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# 1. handling shellcode, or
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# 2. handling a new file format (e.g. macho)
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#
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# for (1) we can't do much - its shellcode and all bets are off.
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# we could maybe accept a further CLI argument to specify the arch,
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# but i think this would be rarely used.
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# rules that rely on arch conditions will fail to match on shellcode.
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#
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# for (2), this logic will need to be updated as the format is implemented.
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logger.debug("unsupported file format: %s, will not guess Arch", binascii.hexlify(buf[:4]).decode("ascii"))
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return
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def extract_os(buf, os=OS_AUTO) -> Iterator[tuple[Feature, Address]]:
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if os != OS_AUTO:
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yield OS(os), NO_ADDRESS
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if buf.startswith(MATCH_PE):
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yield OS(OS_WINDOWS), NO_ADDRESS
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elif buf.startswith(MATCH_RESULT):
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yield OS(OS_ANY), NO_ADDRESS
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elif buf.startswith(MATCH_ELF):
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with contextlib.closing(io.BytesIO(buf)) as f:
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os = capa.features.extractors.elf.detect_elf_os(f)
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if os not in capa.features.common.VALID_OS:
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logger.debug("unsupported os: %s", os)
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return
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yield OS(os), NO_ADDRESS
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else:
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# we likely end up here:
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# 1. handling shellcode, or
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# 2. handling a new file format (e.g. macho)
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#
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# for (1) we can't do much - its shellcode and all bets are off.
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# rules that rely on OS conditions will fail to match on shellcode.
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#
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# for (2), this logic will need to be updated as the format is implemented.
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logger.debug("unsupported file format: %s, will not guess OS", binascii.hexlify(buf[:4]).decode("ascii"))
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return
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