import logging
import struct
from abc import ABC
from typing import List, Optional, Generator, Tuple
from credsweeper.common.constants import MIN_DATA_LEN, UTF_8
from credsweeper.credentials.candidate import Candidate
from credsweeper.deep_scanner.abstract_scanner import AbstractScanner
from credsweeper.file_handler.data_content_provider import DataContentProvider
from credsweeper.utils.util import Util
logger = logging.getLogger(__name__)
[docs]
class DebScanner(AbstractScanner, ABC):
"""Implements deb (ar) scanning"""
__header_size = 60
[docs]
@staticmethod
def match(data: bytes | bytearray) -> bool:
"""According https://en.wikipedia.org/wiki/Deb_(file_format)"""
if data.startswith(b"!<arch>\n"):
return True
return False
[docs]
@staticmethod
def walk_deb(data: bytes) -> Generator[Tuple[int, str, bytes], None, None]:
"""Processes sequence of DEB archive and yields offset, name and data"""
offset = 8 # b"!<arch>\n"
data_limit = len(data) - DebScanner.__header_size
while offset <= data_limit:
_data = data[offset:offset + DebScanner.__header_size]
offset += DebScanner.__header_size
# basic header structure
_name, _, _size, __ = struct.unpack('16s32s10s2s', _data)
file_size = int(_size)
if MIN_DATA_LEN < file_size <= len(data) - offset:
_data = data[offset:offset + file_size]
yield offset, _name.decode(encoding=UTF_8).strip().rstrip('/'), _data
offset += file_size if 0 == 1 & file_size else file_size + 1
[docs]
def data_scan(
self, #
data_provider: DataContentProvider, #
depth: int, #
recursive_limit_size: int) -> Optional[List[Candidate]]:
"""Extracts data file from .ar (debian) archive and launches data_scan"""
try:
candidates: List[Candidate] = []
for offset, name, data in DebScanner.walk_deb(data_provider.data):
deb_content_provider = DataContentProvider(data=data,
file_path=data_provider.file_path,
file_type=Util.get_type(name),
info=f"{data_provider.info}|DEB:0x{offset:x}:{name}")
deb_candidates = self.recursive_scan(deb_content_provider, depth, recursive_limit_size)
candidates.extend(deb_candidates)
return candidates
except Exception as exc:
logger.warning(exc)
return None