refactored the cli and forensics codebases as classes and into seperate

folders for readability and consistent API access
This commit is contained in:
venus
2026-07-19 03:50:06 -05:00
parent 058b5c1eb5
commit 75614f6a21
19 changed files with 991 additions and 763 deletions

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@@ -1,6 +1,7 @@
# src/ctf/analysis.py
# {{{ imports
import re
from abc import ABC, abstractmethod
from dataclasses import dataclass
from pathlib import Path
# }}}
@@ -23,88 +24,132 @@ class AnalysisResult:
routes: list[RouteResult]
# }}}
# {{{ run_metadata_route
def run_metadata_route(file_path: Path) -> RouteResult:
"""Extracts file metadata and scans for potential flags or hints."""
from ctf.forensics import get_metadata
from ctf.decoding import check_for_flag
file_path = Path(file_path).resolve()
if not file_path.exists():
return RouteResult(
route_name="File Metadata Extraction",
executed=True,
success=False,
message=f"File not found: {file_path}"
)
# {{{ BaseRoute
class BaseRoute(ABC):
"""Abstract base class representing an analysis/solver route."""
def __init__(self, route_name: str):
self.route_name = route_name
@abstractmethod
def is_applicable(self, file_path: Path) -> bool:
"""Determines if this route is applicable to the given file."""
pass
@abstractmethod
def execute(self, file_path: Path) -> RouteResult:
"""Executes the analysis route on the target file."""
pass
# }}}
# {{{ MetadataRoute
class MetadataRoute(BaseRoute):
"""Route that extracts metadata and parses comments/EXIF for flags."""
def __init__(self):
super().__init__("File Metadata Extraction")
def is_applicable(self, file_path: Path) -> bool:
# Metadata parsing is applicable to any file
return True
def execute(self, file_path: Path) -> RouteResult:
from ctf.forensics import get_metadata
from ctf.decoding import check_for_flag
try:
meta = get_metadata(file_path)
extracted_flags = []
# Scan comment, EXIF attributes, and decoded hints
if meta.comment:
extracted_flags.extend(check_for_flag(meta.comment))
file_path = Path(file_path).resolve()
if not file_path.exists():
return RouteResult(
route_name=self.route_name,
executed=True,
success=False,
message=f"File not found: {file_path}"
)
for val in meta.exif_data.values():
if isinstance(val, str):
extracted_flags.extend(check_for_flag(val))
for dec_dict in meta.decoded_hints.values():
for dec_val in dec_dict.values():
extracted_flags.extend(check_for_flag(dec_val))
extracted_flags = list(set(extracted_flags))
success = True
if extracted_flags:
msg = f"Metadata inspected. Found {len(extracted_flags)} potential flag(s)."
else:
msg = "Metadata inspected. No obvious flags or decoded hints found."
try:
meta = get_metadata(file_path)
extracted_flags = []
details = {
"Filename": meta.filename,
"Size": f"{meta.size} bytes",
"Detected Type": meta.detected_type,
"Magic": meta.magic,
"Has EXIF": "Yes" if meta.exif_data else "No",
"Has Comment": "Yes" if meta.comment else "No",
"Has Hints": "Yes" if meta.decoded_hints else "No",
}
# Scan comment, EXIF attributes, and decoded hints
if meta.comment:
extracted_flags.extend(check_for_flag(meta.comment))
for val in meta.exif_data.values():
if isinstance(val, str):
extracted_flags.extend(check_for_flag(val))
for dec_dict in meta.decoded_hints.values():
for dec_val in dec_dict.values():
extracted_flags.extend(check_for_flag(dec_val))
extracted_flags = list(set(extracted_flags))
success = True
if extracted_flags:
msg = f"Metadata inspected. Found {len(extracted_flags)} potential flag(s)."
else:
msg = "Metadata inspected. No obvious flags or decoded hints found."
details = {
"Filename": meta.filename,
"Size": f"{meta.size} bytes",
"Detected Type": meta.detected_type,
"Magic": meta.magic,
"Has EXIF": "Yes" if meta.exif_data else "No",
"Has Comment": "Yes" if meta.comment else "No",
"Has Hints": "Yes" if meta.decoded_hints else "No",
}
return RouteResult(
route_name=self.route_name,
executed=True,
success=success,
message=msg,
details=details,
extracted_flags=extracted_flags
)
except Exception as e:
return RouteResult(
route_name=self.route_name,
executed=True,
success=False,
message=f"Error extracting metadata: {str(e)}"
)
# }}}
# {{{ RoutingEngine
class RoutingEngine:
"""Manages CTF challenge solvers and dynamic route execution."""
def __init__(self):
self.routes: list[BaseRoute] = []
def register_route(self, route: BaseRoute):
self.routes.append(route)
def run_all(self, file_path: Path | None) -> AnalysisResult:
executed_results = []
return RouteResult(
route_name="File Metadata Extraction",
executed=True,
success=success,
message=msg,
details=details,
extracted_flags=extracted_flags
)
except Exception as e:
return RouteResult(
route_name="File Metadata Extraction",
executed=True,
success=False,
message=f"Error extracting metadata: {str(e)}"
)
if not file_path:
# Add a non-executed default result for the metadata route
executed_results.append(RouteResult(
route_name="File Metadata Extraction",
executed=False,
success=False,
message="No file attached to analyze."
))
return AnalysisResult(success=False, routes=executed_results)
resolved_path = Path(file_path).resolve()
for route in self.routes:
if route.is_applicable(resolved_path):
executed_results.append(route.execute(resolved_path))
success = any(r.success and r.extracted_flags for r in executed_results)
return AnalysisResult(success=success, routes=executed_results)
# }}}
# {{{ run_analysis
def run_analysis(file_path: Path | None = None) -> AnalysisResult:
"""Executes all registered analysis routes to analyze and solve a challenge."""
routes = []
# Route 1: Metadata Extraction
if file_path:
routes.append(run_metadata_route(Path(file_path)))
else:
routes.append(RouteResult(
route_name="File Metadata Extraction",
executed=False,
success=False,
message="No file attached to analyze."
))
success = any(r.success and r.extracted_flags for r in routes)
return AnalysisResult(success=success, routes=routes)
"""Compatibility function that instantiates the RoutingEngine and runs all routes."""
engine = RoutingEngine()
engine.register_route(MetadataRoute())
return engine.run_all(file_path)
# }}}

34
src/ctf/cli/__init__.py Normal file
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@@ -0,0 +1,34 @@
# src/ctf/cli/__init__.py
# {{{ imports
import click
import sys
from ctf.cli.basic import basic_group
from ctf.cli.forensics import forensics_group
from ctf.cli.steg import steg_group
from ctf.cli.analyse import analyse_cmd
from ctf.cli.flag import flag_cmd
# }}}
# {{{ debug_exception_handler
def debug_exception_handler(type, value, tb):
"""Unhandled exception hook to start post-mortem debugging in pdb."""
import traceback
import pdb
traceback.print_exception(type, value, tb)
print("\n[!] Unhandled exception. Entering post-mortem debugger...")
pdb.post_mortem(tb)
# }}}
# {{{ cli
@click.group()
@click.option("-d", "--debug", is_flag=True, help="Enable post-mortem debugging on errors.")
def cli(debug):
if debug:
sys.excepthook = debug_exception_handler
cli.add_command(forensics_group)
cli.add_command(basic_group)
cli.add_command(flag_cmd)
cli.add_command(steg_group)
cli.add_command(analyse_cmd)
# }}}

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@@ -1,4 +1,4 @@
# src/ctf/cli_analyse.py
# src/ctf/cli/analyse.py
# {{{ imports
import click
from pathlib import Path

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@@ -1,9 +1,8 @@
# functions for commands needed
# src/commands.py
# vim foldmethod=marker
# src/ctf/cli/basic.py
# {{{ imports
import click
from pathlib import Path
# }}}
# {{{ basic_group
# This defines a group with name basic which will nest other comands to be imported in the main loop
@@ -37,7 +36,7 @@ def set_flag_format(pattern: str, original: str):
You can either specify the regex PATTERN directly, or provide an example flag
via the -o/--original option to generate and select from a list of suggested patterns.
"""
from ctf.config import load_config, write_config
from ctf.config import Config
from ctf.utils import suggest_patterns
if pattern is None and original is None:
@@ -45,13 +44,12 @@ def set_flag_format(pattern: str, original: str):
if pattern is not None and original is not None:
raise click.UsageError("Cannot specify both PATTERN and --original/-o option.")
config_path = "/home/venus/code/ctf/config.toml"
config = load_config(config_path)
cfg = Config()
if "Competition" not in config:
config["Competition"] = {}
if "Competition" not in cfg.data:
cfg.data["Competition"] = {}
comp_name = config["Competition"].get("competition", "")
comp_name = cfg.data["Competition"].get("competition", "")
if original:
if not original.strip():
@@ -67,8 +65,8 @@ def set_flag_format(pattern: str, original: str):
val = click.prompt("Select a pattern index", type=click.IntRange(1, len(patterns)))
pattern = patterns[val - 1]
config["Competition"]["flag_format"] = pattern
write_config(config, config_path)
cfg.data["Competition"]["flag_format"] = pattern
cfg.save(cfg.data)
click.echo(f"Flag format set to: {pattern}")
# }}}
@@ -78,16 +76,13 @@ def set_flag_format(pattern: str, original: str):
@click.argument("name")
def set_competition(name: str):
"""Set the name of the active competition."""
from ctf.config import load_config, write_config
from ctf.config import Config
config_path = "/home/venus/code/ctf/config.toml"
config = load_config(config_path)
cfg = Config()
if "Competition" not in config:
config["Competition"] = {}
config["Competition"]["competition"] = name
write_config(config, config_path)
if "Competition" not in cfg.data:
cfg.data["Competition"] = {}
cfg.data["Competition"]["competition"] = name
cfg.save(cfg.data)
click.echo(f"Competition name set to: {name}")
# }}}

47
src/ctf/cli/flag.py Normal file
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@@ -0,0 +1,47 @@
# src/ctf/cli/flag.py
# {{{ imports
import click
from ctf.helpers import detector_state
# }}}
# {{{ flag_cmd
@click.command(name="flag")
@click.option("-p", "--plain", is_flag=True, help="Print raw flag without flavor text.")
@click.option("-l", "--list", "list_format", is_flag=True, help="List the current flag format.")
@click.option("-s", "--set", "set_format", type=str, help="Set the current flag format.")
@click.pass_context
def flag_cmd(ctx, plain, list_format, set_format):
"""Retrieve the last detected flag from config, or list/set flag format options."""
from ctf.config import Config
if list_format:
cfg = Config()
flag_format = cfg.data.get("Competition", {}).get("flag_format", "")
if plain:
click.echo(flag_format)
else:
click.echo(f"Current flag format: {flag_format}" if flag_format else "No flag format configured.")
return
if set_format is not None:
from ctf.commands import set_flag_format
ctx.invoke(set_flag_format, pattern=set_format, original=None)
return
# TODO add support for multiple flags and flag selection
if detector_state["active"] is not None:
detector_state["active"].detecting = False
try:
cfg = Config()
last_flag = cfg.data.get("Competition", {}).get("last_flag", "")
if not last_flag:
if not plain:
click.echo("No flag has been detected yet.")
return
if plain:
click.echo(last_flag)
else:
click.echo(f"Last detected flag: {last_flag}")
finally:
if detector_state["active"] is not None:
detector_state["active"].detecting = True
# }}}

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@@ -1,10 +1,9 @@
# src/ctf/cli_forensics.py
# CLI wrapper and rendering layer for forensics commands
# vim foldmethod=marker
# src/ctf/cli/forensics.py
# {{{ imports
import click
from pathlib import Path
from ctf.forensics import get_metadata, COMMON_SIGNATURES
# }}}
# {{{ forensics_group
@click.group(name="forensics")
@@ -140,4 +139,3 @@ def list_signatures():
console.print(table)
# }}}

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@@ -1,4 +1,4 @@
# src/ctf/cli_steg.py
# src/ctf/cli/steg.py
# {{{ imports
import click
from pathlib import Path

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@@ -1,30 +0,0 @@
# src/ctf/cli_helpers.py
# {{{ imports
import click
from ctf.helpers import detector_state
# }}}
# {{{ flag_cmd
@click.command(name="flag")
@click.option("-p", "--plain", is_flag=True, help="Print raw flag without flavor text.")
def flag_cmd(plain):
"""Retrieve the last detected flag from config."""
# TODO add support for multiple flags and flag selection
if detector_state["active"] is not None:
detector_state["active"].detecting = False
try:
from ctf.config import load_config
config = load_config("/home/venus/code/ctf/config.toml")
last_flag = config.get("Competition", {}).get("last_flag", "")
if not last_flag:
if not plain:
click.echo("No flag has been detected yet.")
return
if plain:
click.echo(last_flag)
else:
click.echo(f"Last detected flag: {last_flag}")
finally:
if detector_state["active"] is not None:
detector_state["active"].detecting = True
# }}}

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@@ -1,26 +1,38 @@
# src/ctf/config.py
# {{{ imports
import toml
import os
from pathlib import Path
from platformdirs import user_config_dir
# }}}
# {{{ load_config
def load_config(config = f"{user_config_dir()}/ctf-config.toml") -> dict:
p = Path(config)
if p.exists():
return toml.load(p)
return {}
# }}}
# {{{ write_config
def write_config(data: dict, config = f"{user_config_dir()}/ctf"):
with open(config, "w") as f:
toml.dump(data, f)
# {{{ Config
class Config:
"""Manages CTF challenge configuration loading and persistence."""
def __init__(self, path: str | Path | None = None):
if path is None:
# Check environment variable first, then fallback to hardcoded path
path = os.environ.get("CTF_CONFIG_PATH", "/home/venus/code/ctf/config.toml")
self.path = Path(path)
self.data = self._load()
def _load(self) -> dict:
if self.path.exists():
try:
return toml.load(self.path)
except Exception:
return {}
return {}
def save(self, data: dict):
self.data = data
self.path.parent.mkdir(parents=True, exist_ok=True)
with open(self.path, "w") as f:
toml.dump(self.data, f)
# }}}
# {{{ exports
config_data = load_config("/home/venus/code/ctf/config.toml")
competition = config_data.get("Competition", {})
enviroment = config_data.get("Enviroment", {})
# Load config instance to expose default values
_cfg = Config()
competition = _cfg.data.get("Competition", {})
enviroment = _cfg.data.get("Enviroment", {})
# }}}

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@@ -1,80 +1,152 @@
# src/ctf/decoding.py
# {{{ imports
from abc import ABC, abstractmethod
from chepy import Chepy
import re
from typing import Dict, Set
from typing import Dict, Set, List
from ctf.helpers import check_for_flag, is_valid_flag
# }}}
# {{{ attempt_decode
def attempt_decode(val: str, name: str, pattern: str, method_name: str, len_check=None, validator=None) -> str | None:
"""Helper to run regex matching, dynamic Chepy decoding, and string printability checks."""
# Find all matches sequentially and try decoding
for match in re.finditer(pattern, val):
matched_val = match.group(0)
if len_check and not len_check(matched_val):
continue
try:
chepy_inst = Chepy(matched_val)
method = getattr(chepy_inst, method_name)
decoded = method().state
if isinstance(decoded, bytes):
dec_str = decoded.decode("utf-8")
elif isinstance(decoded, str):
dec_str = decoded
else:
dec_str = ""
# {{{ BaseDecoder
class BaseDecoder(ABC):
"""Abstract base class representing a Chepy-based metadata decoder."""
def __init__(self, name: str, pattern: str, method_name: str):
self.name = name
self.pattern = pattern
self.method_name = method_name
def is_applicable(self, matched_val: str) -> bool:
"""Determines if the matched substring is applicable for decoding (e.g. length checks)."""
return True
def validate(self, decoded_str: str, original_str: str) -> bool:
"""Validates if the decoded string is expected/correct (e.g. flag regex checks)."""
return True
def attempt_single(self, val: str) -> str | None:
"""Searches val for matches and returns the first successfully decoded printable string."""
for match in re.finditer(self.pattern, val):
matched_val = match.group(0)
if not self.is_applicable(matched_val):
continue
if dec_str.strip() and all(32 <= ord(c) < 127 or c in "\r\n\t" for c in dec_str):
if validator and not validator(dec_str, val):
continue
return dec_str
except Exception:
pass
return None
try:
chepy_inst = Chepy(matched_val)
method = getattr(chepy_inst, self.method_name)
decoded = method().state
if isinstance(decoded, bytes):
dec_str = decoded.decode("utf-8")
elif isinstance(decoded, str):
dec_str = decoded
else:
dec_str = ""
if dec_str.strip() and all(32 <= ord(c) < 127 or c in "\r\n\t" for c in dec_str):
if not self.validate(dec_str, val):
continue
return dec_str
except Exception:
pass
return None
# }}}
# {{{ Concrete Decoders
class HexDecoder(BaseDecoder):
def __init__(self):
super().__init__("hex", r"[0-9a-fA-F]{4,}", "from_hex")
def is_applicable(self, matched_val: str) -> bool:
return len(matched_val) % 2 == 0
class Base64Decoder(BaseDecoder):
def __init__(self):
super().__init__("base64", r"[A-Za-z0-9+/=]{4,}", "from_base64")
def is_applicable(self, matched_val: str) -> bool:
return len(matched_val) % 4 == 0
class Base32Decoder(BaseDecoder):
def __init__(self):
super().__init__("base32", r"[A-Za-z2-7=]{4,}", "from_base32")
def is_applicable(self, matched_val: str) -> bool:
return len(matched_val) % 8 == 0
class BinaryDecoder(BaseDecoder):
def __init__(self):
super().__init__("binary", r"[01]{8,}", "from_binary")
def is_applicable(self, matched_val: str) -> bool:
return len(matched_val) % 8 == 0
class UrlDecoder(BaseDecoder):
def __init__(self):
super().__init__("url", r"(?:%[0-9a-fA-F]{2})+", "from_url_encoding")
class Rot13Decoder(BaseDecoder):
def __init__(self):
super().__init__("rot13", r"[\x20-\x7E\s]{4,}", "rot_13")
def validate(self, decoded_str: str, original_str: str) -> bool:
return is_valid_flag(decoded_str, original_str)
class ReversedDecoder(BaseDecoder):
def __init__(self):
super().__init__("reversed", r"[\x20-\x7E\s]{4,}", "reverse")
def validate(self, decoded_str: str, original_str: str) -> bool:
return is_valid_flag(decoded_str, original_str)
# }}}
# {{{ DecodingRegistry
class DecodingRegistry:
"""Orchestrates decoding metadata using registered BaseDecoder classes."""
def __init__(self):
self.decoders: List[BaseDecoder] = []
def register_decoder(self, decoder: BaseDecoder):
self.decoders.append(decoder)
def try_decode(self, val: str, current_chain: str = "", max_depth: int = 10, seen: Set[str] = None) -> Dict[str, str]:
if seen is None:
seen = set()
results = {}
if not isinstance(val, str) or not val.strip() or max_depth <= 0:
return results
cleaned_val = val.strip()
if cleaned_val in seen:
return results
seen.add(cleaned_val)
for decoder in self.decoders:
decoded_val = decoder.attempt_single(cleaned_val)
if decoded_val is not None:
chain_name = f"{current_chain}->{decoder.name}" if current_chain else decoder.name
results[chain_name] = decoded_val
# Recurse
nested_results = self.try_decode(
decoded_val,
current_chain=chain_name,
max_depth=max_depth - 1,
seen=set(seen)
)
results.update(nested_results)
return results
@classmethod
def get_default_registry(cls) -> "DecodingRegistry":
registry = cls()
registry.register_decoder(HexDecoder())
registry.register_decoder(Base64Decoder())
registry.register_decoder(Base32Decoder())
registry.register_decoder(BinaryDecoder())
registry.register_decoder(UrlDecoder())
registry.register_decoder(Rot13Decoder())
registry.register_decoder(ReversedDecoder())
return registry
# }}}
# {{{ try_decode_metadata
def try_decode_metadata(val: str, current_chain: str = "", max_depth: int = 10, seen: Set[str] = None) -> Dict[str, str]:
"""Attempts to decode a metadata value using defined formats recursively."""
if seen is None:
seen = set()
results = {}
if not isinstance(val, str) or not val.strip() or max_depth <= 0:
return results
cleaned_val = val.strip()
if cleaned_val in seen:
return results
seen.add(cleaned_val)
# We define our decoders here using unanchored patterns. Note: for rot13 and reversed, we only allow them
# if they produce a valid flag to avoid spamming everyday metadata fields.
formats = [
("hex", r"[0-9a-fA-F]{4,}", "from_hex", lambda s: len(s) % 2 == 0, None),
("base64", r"[A-Za-z0-9+/=]{4,}", "from_base64", lambda s: len(s) % 4 == 0, None),
("base32", r"[A-Za-z2-7=]{4,}", "from_base32", lambda s: len(s) % 8 == 0, None),
("binary", r"[01]{8,}", "from_binary", lambda s: len(s) % 8 == 0, None),
("url", r"(?:%[0-9a-fA-F]{2})+", "from_url_encoding", None, None),
("rot13", r"[\x20-\x7E\s]{4,}", "rot_13", None, is_valid_flag),
("reversed", r"[\x20-\x7E\s]{4,}", "reverse", None, is_valid_flag),
]
for name, pattern, method, len_check, validator in formats:
decoded_val = attempt_decode(cleaned_val, name, pattern, method, len_check, validator)
if decoded_val is not None:
chain_name = f"{current_chain}->{name}" if current_chain else name
results[chain_name] = decoded_val
# Recurse with copy of seen to allow different branching paths to process same strings
nested_results = try_decode_metadata(
decoded_val,
current_chain=chain_name,
max_depth=max_depth - 1,
seen=set(seen)
)
results.update(nested_results)
return results
"""Compatibility wrapper that routes decoding requests to the default registry."""
registry = DecodingRegistry.get_default_registry()
return registry.try_decode(val, current_chain, max_depth, seen)
# }}}

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@@ -0,0 +1,32 @@
# src/ctf/forensics/__init__.py
# {{{ imports
from ctf.forensics.base import FileMetadata, FormatParser, ParserFactory, FallbackParser, COMMON_SIGNATURES
from ctf.forensics.jpeg import JpegParser
from ctf.forensics.png import PngParser
from ctf.forensics.gif import GifParser
from ctf.forensics.metadata import get_metadata
from pathlib import Path
from typing import Dict, Any
# }}}
# {{{ get_exif
def get_exif(path: Path) -> Dict[str, Any]:
"""Compatibility wrapper for extracting EXIF tags."""
try:
with open(path, "rb") as f:
data = f.read()
return ParserFactory.get_parser(data).get_exif_tags(data)
except Exception:
return {}
# }}}
# {{{ get_comment
def get_comment(path: Path) -> str:
"""Compatibility wrapper for extracting comments."""
try:
with open(path, "rb") as f:
data = f.read()
return ParserFactory.get_parser(data).get_comment(data)
except Exception:
return ""
# }}}

114
src/ctf/forensics/base.py Normal file
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@@ -0,0 +1,114 @@
# src/ctf/forensics/base.py
# {{{ imports
from abc import ABC, abstractmethod
from dataclasses import dataclass, field
from typing import Dict, Any
# }}}
# {{{ Common Signatures
COMMON_SIGNATURES = {
b"\x89PNG\r\n\x1a\n": ("PNG Image", [".png"]),
b"\xff\xd8\xff": ("JPEG Image", [".jpg", ".jpeg"]),
b"%PDF": ("PDF Document", [".pdf"]),
b"PK\x03\x04": ("ZIP Archive", [".zip"]),
b"\x7fELF": ("ELF Executable", [".elf"]),
b"MZ": ("PE Executable", [".exe", ".dll"]),
b"GIF87a": ("GIF Image", [".gif"]),
b"GIF89a": ("GIF Image", [".gif"]),
b"7z\xbc\xaf\x27\x1c": ("7-Zip Archive", [".7z"]),
b"\x1f\x8b": ("GZIP Archive", [".gz"]),
b"Rar!\x1a\x07\x00": ("RAR Archive", [".rar"]),
b"Rar!\x1a\x07\x01\x00": ("RAR Archive", [".rar"]),
b"BZh": ("BZIP2 Archive", [".bz2"]),
b"BM": ("BMP Image", [".bmp"]),
b"ID3": ("MP3 Audio", [".mp3"]),
}
# }}}
# {{{ FileMetadata
@dataclass
class FileMetadata:
filename: str
size: int
magic: str
extension: str
detected_type: str
# POSIX Permissions
permissions_octal: str
permissions_symbolic: str
# Ownership Identity
owner_uid: int
owner_username: str
owner_gid: int
owner_groupname: str
# Allocation Metrics
allocated_size: int
# Hard Links
hard_links: int
# Inode & Device Identifiers
inode: int
device: int
# Extended Attributes
extended_attributes: Dict[str, str] = field(default_factory=dict)
# EXIF Data
exif_data: Dict[str, Any] = field(default_factory=dict)
# Physical Image Data
physical_data: Dict[str, Any] = field(default_factory=dict)
# Decoded metadata hints
decoded_hints: Dict[str, Dict[str, str]] = field(default_factory=dict)
# JPEG/PNG Comments
comment: str = ""
# }}}
# {{{ FormatParser
class FormatParser(ABC):
"""Abstract base class representing a file format metadata parser."""
@abstractmethod
def is_matching(self, data: bytes) -> bool:
pass
@abstractmethod
def parse_physical(self, data: bytes) -> Dict[str, Any]:
pass
@abstractmethod
def get_comment(self, data: bytes) -> str:
pass
@abstractmethod
def get_exif_tags(self, data: bytes) -> Dict[str, Any]:
pass
# }}}
# {{{ FallbackParser
class FallbackParser(FormatParser):
def is_matching(self, data: bytes) -> bool:
return True
def parse_physical(self, data: bytes) -> Dict[str, Any]:
return {}
def get_comment(self, data: bytes) -> str:
return ""
def get_exif_tags(self, data: bytes) -> Dict[str, Any]:
return {}
# }}}
# {{{ ParserFactory
class ParserFactory:
@staticmethod
def get_parser(data: bytes) -> FormatParser:
from ctf.forensics.jpeg import JpegParser
from ctf.forensics.png import PngParser
from ctf.forensics.gif import GifParser
parsers = [JpegParser(), PngParser(), GifParser()]
for parser in parsers:
if parser.is_matching(data):
return parser
return FallbackParser()
# }}}

98
src/ctf/forensics/gif.py Normal file
View File

@@ -0,0 +1,98 @@
# src/ctf/forensics/gif.py
# {{{ imports
import struct
from typing import Dict, Any
from ctf.forensics.base import FormatParser
# }}}
# {{{ GifParser
class GifParser(FormatParser):
def is_matching(self, data: bytes) -> bool:
return data.startswith(b"GIF87a") or data.startswith(b"GIF89a")
def parse_physical(self, data: bytes) -> Dict[str, Any]:
return get_gif_physical(data)
def get_comment(self, data: bytes) -> str:
return extract_gif_comments(data)
def get_exif_tags(self, data: bytes) -> Dict[str, Any]:
return {}
# }}}
# {{{ get_gif_physical
def get_gif_physical(data: bytes) -> Dict[str, Any]:
"""Parses GIF logical screen descriptor for physical size."""
physical = {}
if not (data.startswith(b"GIF87a") or data.startswith(b"GIF89a")):
return physical
if len(data) >= 10:
width = struct.unpack("<H", data[6:8])[0]
height = struct.unpack("<H", data[8:10])[0]
physical["Image Size"] = f"{width}x{height}"
mp = (width * height) / 1000000.0
physical["Megapixels"] = f"{mp:.1f}"
physical["Encoding Process"] = "LZW"
return physical
# }}}
# {{{ extract_gif_comments
def extract_gif_comments(data: bytes) -> str:
"""Extracts comments from GIF comment extensions (\x21\xfe) sequentially."""
if not (data.startswith(b"GIF87a") or data.startswith(b"GIF89a")):
return ""
comments = []
idx = 6
if idx + 7 > len(data):
return ""
packed_byte = data[idx+4]
global_color_table_present = bool(packed_byte & 0x80)
global_color_table_size = 2 ** ((packed_byte & 0x07) + 1)
idx += 7
if global_color_table_present:
idx += 3 * global_color_table_size
while idx < len(data) - 2:
intro = data[idx]
if intro == 0x21: # Extension Introducer
ext_label = data[idx+1]
idx += 2
if ext_label == 0xfe: # Comment Extension
comment_parts = []
while idx < len(data):
block_len = data[idx]
idx += 1
if block_len == 0:
break
if idx + block_len <= len(data):
comment_parts.append(data[idx:idx+block_len].decode("utf-8", errors="ignore"))
idx += block_len
else:
break
comments.append("".join(comment_parts))
else:
while idx < len(data):
block_len = data[idx]
idx += 1
if block_len == 0:
break
idx += block_len
elif intro == 0x2c: # Image Descriptor
if idx + 10 > len(data):
break
packed = data[idx+9]
local_table = bool(packed & 0x80)
local_table_size = 2 ** ((packed & 0x07) + 1)
idx += 10
if local_table:
idx += 3 * local_table_size
idx += 1
while idx < len(data):
block_len = data[idx]
idx += 1
if block_len == 0:
break
idx += block_len
elif intro == 0x3b: # Trailer
break
else:
idx += 1
return "\n".join(comments)
# }}}

View File

@@ -1,225 +1,35 @@
# src/ctf/forensics.py
# Library for forensic analysis (pure functions only)
# vim foldmethod=marker
from dataclasses import dataclass, field
from pathlib import Path
import stat
import os
import sys
# src/ctf/forensics/jpeg.py
# {{{ imports
import struct
import xml.etree.ElementTree as ET
from typing import List, Dict, Any
try:
import pwd
import grp
except ImportError:
pwd = None
grp = None
# {{{ Common Signatures
COMMON_SIGNATURES = {
b"\x89PNG\r\n\x1a\n": ("PNG Image", [".png"]),
b"\xff\xd8\xff": ("JPEG Image", [".jpg", ".jpeg"]),
b"%PDF": ("PDF Document", [".pdf"]),
b"PK\x03\x04": ("ZIP Archive", [".zip"]),
b"\x7fELF": ("ELF Executable", [".elf"]),
b"MZ": ("PE Executable", [".exe", ".dll"]),
b"GIF87a": ("GIF Image", [".gif"]),
b"GIF89a": ("GIF Image", [".gif"]),
b"7z\xbc\xaf\x27\x1c": ("7-Zip Archive", [".7z"]),
b"\x1f\x8b": ("GZIP Archive", [".gz"]),
b"Rar!\x1a\x07\x00": ("RAR Archive", [".rar"]),
b"Rar!\x1a\x07\x01\x00": ("RAR Archive", [".rar"]),
b"BZh": ("BZIP2 Archive", [".bz2"]),
b"BM": ("BMP Image", [".bmp"]),
b"ID3": ("MP3 Audio", [".mp3"]),
}
from typing import Dict, Any
from ctf.forensics.base import FormatParser
# }}}
# {{{ FileMetadata
@dataclass
class FileMetadata:
filename: str
size: int
magic: str
extension: str
detected_type: str
# Task 1: POSIX Permissions
permissions_octal: str
permissions_symbolic: str
# Task 2: Ownership Identity
owner_uid: int
owner_username: str
owner_gid: int
owner_groupname: str
# Task 3: Allocation Metrics
allocated_size: int
# Task 4: Hard Links
hard_links: int
# Task 5: Inode & Device Identifiers
inode: int
device: int
# Task 6: Extended Attributes
extended_attributes: Dict[str, str] = field(default_factory=dict)
# EXIF Data
exif_data: Dict[str, Any] = field(default_factory=dict)
# Physical Image Data
physical_data: Dict[str, Any] = field(default_factory=dict)
# Decoded metadata hints
decoded_hints: Dict[str, Dict[str, str]] = field(default_factory=dict)
# JPEG/PNG Comments
comment: str = ""
# }}}
# {{{ get_metadata
def get_metadata(path: Path) -> FileMetadata:
"""Extracts metadata attributes from a file without any console rendering."""
p = Path(path)
if not p.exists():
raise FileNotFoundError(f"File not found: {p}")
stat_info = p.stat()
# Apparent size & extension
size = stat_info.st_size
extension = p.suffix
# Magic bytes
try:
with open(p, 'rb') as f:
magic = f.read(8).hex().upper()
except Exception:
magic = ""
detected_type = "Unknown"
try:
magic_bytes = bytes.fromhex(magic)
for signature, (type_name, exts) in COMMON_SIGNATURES.items():
if magic_bytes.startswith(signature):
detected_type = type_name
break
except Exception:
pass
# POSIX Permissions
mode = stat_info.st_mode
permissions_octal = oct(stat.S_IMODE(mode))
permissions_symbolic = stat.filemode(mode)
# Ownership Identity
owner_uid = stat_info.st_uid
owner_gid = stat_info.st_gid
owner_username = str(owner_uid)
owner_groupname = str(owner_gid)
if pwd is not None:
# {{{ JpegParser
class JpegParser(FormatParser):
def is_matching(self, data: bytes) -> bool:
return data.startswith(b"\xff\xd8\xff")
def parse_physical(self, data: bytes) -> Dict[str, Any]:
return get_jpeg_physical(data)
def get_comment(self, data: bytes) -> str:
return extract_jpeg_comment(data)
def get_exif_tags(self, data: bytes) -> Dict[str, Any]:
tags = {}
exif_data = extract_jpeg_exif(data)
if exif_data:
try:
tags.update(parse_tiff(exif_data))
except Exception: pass
xmp_str = extract_jpeg_xmp(data)
if xmp_str:
try:
tags.update(parse_xmp(xmp_str))
except Exception: pass
try:
owner_username = pwd.getpwuid(owner_uid).pw_name
except KeyError:
pass
if grp is not None:
try:
owner_groupname = grp.getgrgid(owner_gid).gr_name
except KeyError:
pass
# Allocation Metrics
if hasattr(stat_info, "st_blocks"):
allocated_size = stat_info.st_blocks * 512
else:
allocated_size = size
# Hard Links
hard_links = stat_info.st_nlink
# Inode & Device Identifiers
inode = stat_info.st_ino
device = stat_info.st_dev
# Extended Attributes
extended_attributes = {}
if hasattr(os, "listxattr") and hasattr(os, "getxattr"):
try:
attrs = os.listxattr(p)
for attr in attrs:
try:
val = os.getxattr(p, attr)
extended_attributes[attr] = val.decode("utf-8", errors="ignore")
except OSError:
pass
except OSError:
pass
exif_data = get_exif(p)
comment = get_comment(p)
physical_data = {}
try:
with open(p, "rb") as f:
file_bytes = f.read()
if file_bytes.startswith(b"\xff\xd8\xff"):
physical_data = get_jpeg_physical(file_bytes)
elif file_bytes.startswith(b"\x89PNG\r\n\x1a\n"):
physical_data = get_png_physical(file_bytes)
elif file_bytes.startswith(b"GIF87a") or file_bytes.startswith(b"GIF89a"):
physical_data = get_gif_physical(file_bytes)
except Exception:
pass
decoded_hints = {}
try:
from ctf.decoding import try_decode_metadata
if comment:
dec = try_decode_metadata(comment)
if dec:
decoded_hints["Comment"] = dec
for tag, val in exif_data.items():
if isinstance(val, str):
dec = try_decode_metadata(val)
if dec:
decoded_hints[f"EXIF:{tag}"] = dec
for attr, val in extended_attributes.items():
if isinstance(val, str):
dec = try_decode_metadata(val)
if dec:
decoded_hints[f"xattr:{attr}"] = dec
except Exception:
pass
return FileMetadata(
filename=p.name,
size=size,
magic=magic,
extension=extension,
detected_type=detected_type,
permissions_octal=permissions_octal,
permissions_symbolic=permissions_symbolic,
owner_uid=owner_uid,
owner_username=owner_username,
owner_gid=owner_gid,
owner_groupname=owner_groupname,
allocated_size=allocated_size,
hard_links=hard_links,
inode=inode,
device=device,
extended_attributes=extended_attributes,
exif_data=exif_data,
physical_data=physical_data,
decoded_hints=decoded_hints,
comment=comment
)
tags.update(extract_jpeg_iptc(data))
except Exception: pass
return tags
# }}}
# {{{ EXIF tags
@@ -260,7 +70,8 @@ EXIF_TAGS = {
0xa403: "WhiteBalance",
0xa405: "FocalLengthIn35mmFilm",
0xa406: "SceneCaptureType",
}# }}}
}
# }}}
# {{{ parse_tiff
def parse_tiff(data: bytes) -> Dict[str, Any]:
@@ -371,7 +182,6 @@ def extract_jpeg_exif(data: bytes) -> bytes:
marker = data[idx+1]
if marker == 0xd9: # EOI
break
# Markers without length parameters
if marker in (0xd8, 0xd9, 0x00) or 0xd0 <= marker <= 0xd7:
idx += 2
continue
@@ -386,75 +196,6 @@ def extract_jpeg_exif(data: bytes) -> bytes:
return b""
# }}}
# {{{ extract_png_exif
def extract_png_exif(data: bytes) -> bytes:
"""Extracts raw Exif/TIFF payload from PNG eXIf chunks."""
if not data.startswith(b"\x89PNG\r\n\x1a\n"):
return b""
idx = 8
while idx < len(data) - 8:
length = struct.unpack(">I", data[idx:idx+4])[0]
chunk_type = data[idx+4:idx+8]
if chunk_type == b"eXIf":
return data[idx+8:idx+8+length]
elif chunk_type == b"IEND":
break
idx += 12 + length
return b""
# }}}
# {{{ get_exif
def get_exif(path: Path) -> Dict[str, Any]:
"""Reads file, extracts Exif and XMP segments, and parses them to a tag dictionary."""
try:
with open(path, "rb") as f:
data = f.read()
except Exception:
return {}
tags = {}
# 1. Parse standard EXIF
exif_data = b""
if data.startswith(b"\xff\xd8\xff"):
exif_data = extract_jpeg_exif(data)
elif data.startswith(b"\x89PNG\r\n\x1a\n"):
exif_data = extract_png_exif(data)
if exif_data:
try:
tags.update(parse_tiff(exif_data))
except Exception:
pass
# 2. Parse XMP (Adobe)
xmp_str = ""
if data.startswith(b"\xff\xd8\xff"):
xmp_str = extract_jpeg_xmp(data)
if xmp_str:
try:
tags.update(parse_xmp(xmp_str))
except Exception:
pass
# 3. Parse IPTC (Photoshop APP13) if JPEG
if data.startswith(b"\xff\xd8\xff"):
try:
tags.update(extract_jpeg_iptc(data))
except Exception:
pass
# 4. Parse PNG text chunks if PNG
if data.startswith(b"\x89PNG\r\n\x1a\n"):
try:
tags.update(parse_png_text_chunks(data))
except Exception:
pass
return tags
# }}}
# {{{ extract_jpeg_comment
def extract_jpeg_comment(data: bytes) -> str:
"""Extracts raw comment string from JPEG COM (0xfe) segments."""
@@ -479,23 +220,7 @@ def extract_jpeg_comment(data: bytes) -> str:
return ""
# }}}
# {{{ get_comment
def get_comment(path: Path) -> str:
"""Reads file, checks headers, and extracts JPEG COM / GIF comments."""
try:
with open(path, "rb") as f:
data = f.read()
except Exception:
return ""
if data.startswith(b"\xff\xd8\xff"):
return extract_jpeg_comment(data)
elif data.startswith(b"GIF87a") or data.startswith(b"GIF89a"):
return extract_gif_comments(data)
return ""
# }}}
#{{{ NS_map
# {{{ NS_map
NS_MAP = {
"http://www.w3.org/1999/02/22-rdf-syntax-ns#": "rdf",
"http://creativecommons.org/ns#": "cc",
@@ -504,7 +229,7 @@ NS_MAP = {
"http://ns.adobe.com/exif/1.0/": "exif",
"http://ns.adobe.com/tiff/1.0/": "tiff",
}
#}}}
# }}}
# {{{ parse_xmp
def parse_xmp(xmp_str: str) -> Dict[str, Any]:
@@ -654,84 +379,6 @@ def get_jpeg_physical(data: bytes) -> Dict[str, Any]:
return physical
# }}}
# {{{ get_png_physical
def get_png_physical(data: bytes) -> Dict[str, Any]:
"""Parses PNG IHDR and pHYs chunks for physical properties."""
physical = {}
if not data.startswith(b"\x89PNG\r\n\x1a\n"):
return physical
idx = 8
while idx < len(data) - 8:
length = struct.unpack(">I", data[idx:idx+4])[0]
chunk_type = data[idx+4:idx+8]
chunk_data = data[idx+8:idx+8+length]
if chunk_type == b"IHDR":
if len(chunk_data) >= 13:
width = struct.unpack(">I", chunk_data[0:4])[0]
height = struct.unpack(">I", chunk_data[4:8])[0]
bit_depth = chunk_data[8]
color_type = chunk_data[9]
compression = chunk_data[10]
filter_method = chunk_data[11]
interlace = chunk_data[12]
physical["Image Size"] = f"{width}x{height}"
mp = (width * height) / 1000000.0
physical["Megapixels"] = f"{mp:.1f}"
physical["Bit Depth"] = f"{bit_depth} bits/sample"
color_types = {
0: "Grayscale",
2: "Truecolor",
3: "Indexed-color",
4: "Grayscale with Alpha",
6: "Truecolor with Alpha"
}
physical["Color Type"] = color_types.get(color_type, f"Unknown ({color_type})")
if compression == 0:
physical["Encoding Process"] = "Deflate/Inflate"
else:
physical["Encoding Process"] = f"Unknown compression ({compression})"
interlace_methods = {
0: "Noninterlaced",
1: "Adam7 Interlace"
}
physical["Interlace Method"] = interlace_methods.get(interlace, f"Unknown ({interlace})")
elif chunk_type == b"pHYs":
if len(chunk_data) >= 9:
x_res = struct.unpack(">I", chunk_data[0:4])[0]
y_res = struct.unpack(">I", chunk_data[4:8])[0]
unit = chunk_data[8]
unit_str = " meters" if unit == 1 else " (unknown unit)"
physical["Pixels Per Unit X"] = f"{x_res}{unit_str}"
physical["Pixels Per Unit Y"] = f"{y_res}{unit_str}"
elif chunk_type == b"IEND":
break
idx += 12 + length
return physical
# }}}
# {{{ get_gif_physical
def get_gif_physical(data: bytes) -> Dict[str, Any]:
"""Parses GIF logical screen descriptor for physical size."""
physical = {}
if not (data.startswith(b"GIF87a") or data.startswith(b"GIF89a")):
return physical
if len(data) >= 10:
width = struct.unpack("<H", data[6:8])[0]
height = struct.unpack("<H", data[8:10])[0]
physical["Image Size"] = f"{width}x{height}"
mp = (width * height) / 1000000.0
physical["Megapixels"] = f"{mp:.1f}"
physical["Encoding Process"] = "LZW"
return physical
# }}}
# {{{ extract_jpeg_iptc
def extract_jpeg_iptc(data: bytes) -> Dict[str, str]:
"""Extracts IPTC/NAA metadata (Record 2) from Photoshop APP13 segments."""
@@ -819,132 +466,3 @@ def extract_jpeg_iptc(data: bytes) -> Dict[str, str]:
return iptc_metadata
# }}}
# {{{ parse_png_text_chunks
def parse_png_text_chunks(data: bytes) -> Dict[str, str]:
"""Decompresses and extracts standard tEXt/zTXt/iTXt PNG text metadata."""
import zlib
text_metadata = {}
if not data.startswith(b"\x89PNG\r\n\x1a\n"):
return text_metadata
idx = 8
while idx < len(data) - 8:
length = struct.unpack(">I", data[idx:idx+4])[0]
chunk_type = data[idx+4:idx+8]
chunk_data = data[idx+8:idx+8+length]
if chunk_type == b"tEXt":
parts = chunk_data.split(b"\x00", 1)
if len(parts) == 2:
key = parts[0].decode("utf-8", errors="ignore")
val = parts[1].decode("utf-8", errors="ignore")
text_metadata[key] = val
elif chunk_type == b"zTXt":
parts = chunk_data.split(b"\x00", 1)
if len(parts) == 2:
key = parts[0].decode("utf-8", errors="ignore")
remaining = parts[1]
if len(remaining) > 1:
comp_method = remaining[0]
comp_text = remaining[1:]
if comp_method == 0:
try:
val = zlib.decompress(comp_text).decode("utf-8", errors="ignore")
text_metadata[key] = val
except Exception:
pass
elif chunk_type == b"iTXt":
parts = chunk_data.split(b"\x00", 1)
if len(parts) == 2:
key = parts[0].decode("utf-8", errors="ignore")
remaining = parts[1]
if len(remaining) >= 2:
comp_flag = remaining[0]
comp_method = remaining[1]
rem = remaining[2:]
parts2 = rem.split(b"\x00", 1)
if len(parts2) == 2:
lang_tag = parts2[0].decode("utf-8", errors="ignore")
rem = parts2[1]
parts3 = rem.split(b"\x00", 1)
if len(parts3) == 2:
trans_key = parts3[0].decode("utf-8", errors="ignore")
text_bytes = parts3[1]
if comp_flag == 1 and comp_method == 0:
try:
val = zlib.decompress(text_bytes).decode("utf-8", errors="ignore")
text_metadata[key] = val
except Exception:
pass
else:
val = text_bytes.decode("utf-8", errors="ignore")
text_metadata[key] = val
elif chunk_type == b"IEND":
break
idx += 12 + length
return text_metadata
# }}}
# {{{ extract_gif_comments
def extract_gif_comments(data: bytes) -> str:
"""Extracts comments from GIF comment extensions (\x21\xfe) sequentially."""
if not (data.startswith(b"GIF87a") or data.startswith(b"GIF89a")):
return ""
comments = []
idx = 6
if idx + 7 > len(data):
return ""
packed_byte = data[idx+4]
global_color_table_present = bool(packed_byte & 0x80)
global_color_table_size = 2 ** ((packed_byte & 0x07) + 1)
idx += 7
if global_color_table_present:
idx += 3 * global_color_table_size
while idx < len(data) - 2:
intro = data[idx]
if intro == 0x21: # Extension Introducer
ext_label = data[idx+1]
idx += 2
if ext_label == 0xfe: # Comment Extension
comment_parts = []
while idx < len(data):
block_len = data[idx]
idx += 1
if block_len == 0:
break
if idx + block_len <= len(data):
comment_parts.append(data[idx:idx+block_len].decode("utf-8", errors="ignore"))
idx += block_len
else:
break
comments.append("".join(comment_parts))
else:
while idx < len(data):
block_len = data[idx]
idx += 1
if block_len == 0:
break
idx += block_len
elif intro == 0x2c: # Image Descriptor
if idx + 10 > len(data):
break
packed = data[idx+9]
local_table = bool(packed & 0x80)
local_table_size = 2 ** ((packed & 0x07) + 1)
idx += 10
if local_table:
idx += 3 * local_table_size
idx += 1
while idx < len(data):
block_len = data[idx]
idx += 1
if block_len == 0:
break
idx += block_len
elif intro == 0x3b: # Trailer
break
else:
idx += 1
return "\n".join(comments)
# }}}

View File

@@ -0,0 +1,139 @@
# src/ctf/forensics/metadata.py
# {{{ imports
from pathlib import Path
import os
import stat
from ctf.forensics.base import FileMetadata, COMMON_SIGNATURES, ParserFactory
try:
import pwd
import grp
except ImportError:
pwd = None
grp = None
# }}}
# {{{ get_metadata
def get_metadata(path: Path) -> FileMetadata:
"""Extracts metadata attributes from a file without any console rendering."""
p = Path(path)
if not p.exists():
raise FileNotFoundError(f"File not found: {p}")
stat_info = p.stat()
size = stat_info.st_size
extension = p.suffix
try:
with open(p, 'rb') as f:
magic = f.read(8).hex().upper()
except Exception:
magic = ""
detected_type = "Unknown"
try:
magic_bytes = bytes.fromhex(magic)
for signature, (type_name, exts) in COMMON_SIGNATURES.items():
if magic_bytes.startswith(signature):
detected_type = type_name
break
except Exception:
pass
mode = stat_info.st_mode
permissions_octal = oct(stat.S_IMODE(mode))
permissions_symbolic = stat.filemode(mode)
owner_uid = stat_info.st_uid
owner_gid = stat_info.st_gid
owner_username = str(owner_uid)
owner_groupname = str(owner_gid)
if pwd is not None:
try:
owner_username = pwd.getpwuid(owner_uid).pw_name
except KeyError:
pass
if grp is not None:
try:
owner_groupname = grp.getgrgid(owner_gid).gr_name
except KeyError:
pass
if hasattr(stat_info, "st_blocks"):
allocated_size = stat_info.st_blocks * 512
else:
allocated_size = size
hard_links = stat_info.st_nlink
inode = stat_info.st_ino
device = stat_info.st_dev
extended_attributes = {}
if hasattr(os, "listxattr") and hasattr(os, "getxattr"):
try:
attrs = os.listxattr(p)
for attr in attrs:
try:
val = os.getxattr(p, attr)
extended_attributes[attr] = val.decode("utf-8", errors="ignore")
except OSError:
pass
except OSError:
pass
try:
with open(p, "rb") as f:
file_bytes = f.read()
parser = ParserFactory.get_parser(file_bytes)
exif_data = parser.get_exif_tags(file_bytes)
comment = parser.get_comment(file_bytes)
physical_data = parser.parse_physical(file_bytes)
except Exception:
exif_data = {}
comment = ""
physical_data = {}
decoded_hints = {}
try:
from ctf.decoding import try_decode_metadata
if comment:
dec = try_decode_metadata(comment)
if dec:
decoded_hints["Comment"] = dec
for tag, val in exif_data.items():
if isinstance(val, str):
dec = try_decode_metadata(val)
if dec:
decoded_hints[f"EXIF:{tag}"] = dec
for attr, val in extended_attributes.items():
if isinstance(val, str):
dec = try_decode_metadata(val)
if dec:
decoded_hints[f"xattr:{attr}"] = dec
except Exception:
pass
return FileMetadata(
filename=p.name,
size=size,
magic=magic,
extension=extension,
detected_type=detected_type,
permissions_octal=permissions_octal,
permissions_symbolic=permissions_symbolic,
owner_uid=owner_uid,
owner_username=owner_username,
owner_gid=owner_gid,
owner_groupname=owner_groupname,
allocated_size=allocated_size,
hard_links=hard_links,
inode=inode,
device=device,
extended_attributes=extended_attributes,
exif_data=exif_data,
physical_data=physical_data,
decoded_hints=decoded_hints,
comment=comment
)
# }}}

171
src/ctf/forensics/png.py Normal file
View File

@@ -0,0 +1,171 @@
# src/ctf/forensics/png.py
# {{{ imports
import struct
from typing import Dict, Any
from ctf.forensics.base import FormatParser
# }}}
# {{{ PngParser
class PngParser(FormatParser):
def is_matching(self, data: bytes) -> bool:
return data.startswith(b"\x89PNG\r\n\x1a\n")
def parse_physical(self, data: bytes) -> Dict[str, Any]:
return get_png_physical(data)
def get_comment(self, data: bytes) -> str:
return ""
def get_exif_tags(self, data: bytes) -> Dict[str, Any]:
tags = {}
exif_data = extract_png_exif(data)
if exif_data:
try:
from ctf.forensics.jpeg import parse_tiff
tags.update(parse_tiff(exif_data))
except Exception: pass
try:
tags.update(parse_png_text_chunks(data))
except Exception: pass
return tags
# }}}
# {{{ extract_png_exif
def extract_png_exif(data: bytes) -> bytes:
"""Extracts raw Exif/TIFF payload from PNG eXIf chunks."""
if not data.startswith(b"\x89PNG\r\n\x1a\n"):
return b""
idx = 8
while idx < len(data) - 8:
length = struct.unpack(">I", data[idx:idx+4])[0]
chunk_type = data[idx+4:idx+8]
if chunk_type == b"eXIf":
return data[idx+8:idx+8+length]
elif chunk_type == b"IEND":
break
idx += 12 + length
return b""
# }}}
# {{{ get_png_physical
def get_png_physical(data: bytes) -> Dict[str, Any]:
"""Parses PNG IHDR and pHYs chunks for physical properties."""
physical = {}
if not data.startswith(b"\x89PNG\r\n\x1a\n"):
return physical
idx = 8
while idx < len(data) - 8:
length = struct.unpack(">I", data[idx:idx+4])[0]
chunk_type = data[idx+4:idx+8]
chunk_data = data[idx+8:idx+8+length]
if chunk_type == b"IHDR":
if len(chunk_data) >= 13:
width = struct.unpack(">I", chunk_data[0:4])[0]
height = struct.unpack(">I", chunk_data[4:8])[0]
bit_depth = chunk_data[8]
color_type = chunk_data[9]
compression = chunk_data[10]
filter_method = chunk_data[11]
interlace = chunk_data[12]
physical["Image Size"] = f"{width}x{height}"
mp = (width * height) / 1000000.0
physical["Megapixels"] = f"{mp:.1f}"
physical["Bit Depth"] = f"{bit_depth} bits/sample"
color_types = {
0: "Grayscale",
2: "Truecolor",
3: "Indexed-color",
4: "Grayscale with Alpha",
6: "Truecolor with Alpha"
}
physical["Color Type"] = color_types.get(color_type, f"Unknown ({color_type})")
if compression == 0:
physical["Encoding Process"] = "Deflate/Inflate"
else:
physical["Encoding Process"] = f"Unknown compression ({compression})"
interlace_methods = {
0: "Noninterlaced",
1: "Adam7 Interlace"
}
physical["Interlace Method"] = interlace_methods.get(interlace, f"Unknown ({interlace})")
elif chunk_type == b"pHYs":
if len(chunk_data) >= 9:
x_res = struct.unpack(">I", chunk_data[0:4])[0]
y_res = struct.unpack(">I", chunk_data[4:8])[0]
unit = chunk_data[8]
unit_str = " meters" if unit == 1 else " (unknown unit)"
physical["Pixels Per Unit X"] = f"{x_res}{unit_str}"
physical["Pixels Per Unit Y"] = f"{y_res}{unit_str}"
elif chunk_type == b"IEND":
break
idx += 12 + length
return physical
# }}}
# {{{ parse_png_text_chunks
def parse_png_text_chunks(data: bytes) -> Dict[str, str]:
"""Decompresses and extracts standard tEXt/zTXt/iTXt PNG text metadata."""
import zlib
text_metadata = {}
if not data.startswith(b"\x89PNG\r\n\x1a\n"):
return text_metadata
idx = 8
while idx < len(data) - 8:
length = struct.unpack(">I", data[idx:idx+4])[0]
chunk_type = data[idx+4:idx+8]
chunk_data = data[idx+8:idx+8+length]
if chunk_type == b"tEXt":
parts = chunk_data.split(b"\x00", 1)
if len(parts) == 2:
key = parts[0].decode("utf-8", errors="ignore")
val = parts[1].decode("utf-8", errors="ignore")
text_metadata[key] = val
elif chunk_type == b"zTXt":
parts = chunk_data.split(b"\x00", 1)
if len(parts) == 2:
key = parts[0].decode("utf-8", errors="ignore")
remaining = parts[1]
if len(remaining) > 1:
comp_method = remaining[0]
comp_text = remaining[1:]
if comp_method == 0:
try:
val = zlib.decompress(comp_text).decode("utf-8", errors="ignore")
text_metadata[key] = val
except Exception:
pass
elif chunk_type == b"iTXt":
parts = chunk_data.split(b"\x00", 1)
if len(parts) == 2:
key = parts[0].decode("utf-8", errors="ignore")
remaining = parts[1]
if len(remaining) >= 2:
comp_flag = remaining[0]
comp_method = remaining[1]
rem = remaining[2:]
parts2 = rem.split(b"\x00", 1)
if len(parts2) == 2:
lang_tag = parts2[0].decode("utf-8", errors="ignore")
rem = parts2[1]
parts3 = rem.split(b"\x00", 1)
if len(parts3) == 2:
trans_key = parts3[0].decode("utf-8", errors="ignore")
text_bytes = parts3[1]
if comp_flag == 1 and comp_method == 0:
try:
val = zlib.decompress(text_bytes).decode("utf-8", errors="ignore")
text_metadata[key] = val
except Exception:
pass
else:
val = text_bytes.decode("utf-8", errors="ignore")
text_metadata[key] = val
elif chunk_type == b"IEND":
break
idx += 12 + length
return text_metadata
# }}}

View File

@@ -18,9 +18,9 @@ def check_for_flag(text: str, pattern: str | None = None) -> list[str]:
patterns.append(pattern.strip("^$"))
else:
try:
from ctf.config import load_config
config = load_config()
flag_format = config.get("Competition", {}).get("flag_format", "")
from ctf.config import Config
cfg = Config()
flag_format = cfg.data.get("Competition", {}).get("flag_format", "")
except Exception:
flag_format = ""
if flag_format:
@@ -74,13 +74,12 @@ class FlagDetectorStream:
for match in matches:
self.original_stream.write(f" \033[1;32m✓ {match}\033[0m\n")
try:
from ctf.config import load_config, write_config
config_path = "/home/venus/code/ctf/config.toml"
config = load_config(config_path)
if "Competition" not in config:
config["Competition"] = {}
config["Competition"]["last_flag"] = match
write_config(config, config_path)
from ctf.config import Config
cfg = Config()
if "Competition" not in cfg.data:
cfg.data["Competition"] = {}
cfg.data["Competition"]["last_flag"] = match
cfg.save(cfg.data)
except Exception:
pass
self._flag_buffer = ""

View File

@@ -1,31 +1,15 @@
# src/main.py
# Parses and calls commands
from ctf.commands import basic_group
from ctf.cli_forensics import forensics_group
from ctf.cli_steg import steg_group
from ctf.cli_analyse import analyse_cmd
from ctf.cli_helpers import flag_cmd
from ctf.helpers import FlagDetectorStream, detector_state
import click
import sys
# {{{ cli
@click.group()
def cli(): pass
cli.add_command(forensics_group)
cli.add_command(basic_group)
cli.add_command(flag_cmd)
cli.add_command(steg_group)
cli.add_command(analyse_cmd)
# }}}
from ctf.cli import cli
from ctf.helpers import FlagDetectorStream, detector_state
# {{{ main
def main():
from ctf.config import load_config
config = load_config("/home/venus/code/ctf/config.toml")
flag_format = config.get("Competition", {}).get("flag_format", "")
from ctf.config import Config
cfg = Config()
flag_format = cfg.data.get("Competition", {}).get("flag_format", "")
if flag_format:
detector = FlagDetectorStream(sys.stdout, flag_format)

View File

@@ -2,7 +2,7 @@
# basic utilities
from pathlib import Path
from ctf.config import load_config, competition, enviroment
from ctf.config import competition, enviroment
# return a list of path objects for each catagory in a competition
def active_categories(p: Path) -> list: