Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.11/site-packages/unblob/handlers/archive/instar/instar_hd.py: 71%

1import mmap 

2import shutil 

3from pathlib import Path 

4 

5from structlog import get_logger 

6 

7from unblob.file_utils import File 

8from unblob.handlers.archive.zip import ZIPHandler 

9from unblob.models import Extractor, HandlerDoc, HandlerType, HexString 

10 

11logger = get_logger() 

12 

13LOCAL_FILE_HEADER_ZIP = b"\x50\x4b\x03\x04" 

14LOCAL_FILE_HEADER_INSTAR = b"\x50\x4b\x03\x07" 

15 

16EOCD_ZIP = b"\x50\x4b\x05\x06" 

17EOCD_INSTAR = b"\x50\x4b\x05\x09" 

18 

19CD_FILE_HEADER_ZIP = b"\x50\x4b\x01\x02" 

20CD_FILE_HEADER_INSTAR = b"\x50\x4b\x01\x08" 

21 

22 

23class InstarHDExtractor(Extractor): 

24 def extract(self, inpath: Path, outdir: Path): 

25 outfile = outdir / "instar_hd.deobfuscated" 

26 shutil.copyfile(inpath, outfile) 

27 with File.from_path(outfile, access=mmap.ACCESS_WRITE) as mm: 

28 replacements = { 

29 LOCAL_FILE_HEADER_INSTAR: LOCAL_FILE_HEADER_ZIP, 

30 EOCD_INSTAR: EOCD_ZIP, 

31 CD_FILE_HEADER_INSTAR: CD_FILE_HEADER_ZIP, 

32 } 

33 for pattern, replacement in replacements.items(): 

34 pos = mm.find(pattern) 

35 while pos != -1: 

36 mm[pos : pos + len(pattern)] = replacement 

37 pos = mm.find(pattern, pos + len(pattern)) 

38 

39 

40class InstarHDHandler(ZIPHandler): 

41 NAME = "instar_hd" 

42 

43 PATTERNS = [HexString("50 4b 03 07")] # match on the modified zip header 

44 

45 EXTRACTOR = InstarHDExtractor() 

46 

47 EOCD_RECORD_HEADER = 0x9054B50 

48 

49 DOC = HandlerDoc( 

50 name="Instar HD", 

51 description="Instar HD firmware files are modified ZIP archives with non-standard local file headers, central directory headers, and end-of-central-directory records. These modifications include custom magic bytes to differentiate them from standard ZIP files.", 

52 handler_type=HandlerType.ARCHIVE, 

53 vendor="Instar", 

54 references=[], 

55 limitations=[], 

56 )