anti
19ceff4417
Seven instrumenters that mutate operator-supplied artifacts to
embed the callback URL:
- passthrough — bytes unchanged; only DNS-callback tokens trip
detection, with the slug embedded in the placement path
- plain — substitutes {{CANARY_URL}}/{{CANARY_HOST}} placeholders;
falls back to appending a comment line whose prefix adapts to the
apparent file syntax (#, //, ;)
- html — injects a 1x1 tracking pixel before </body>, appends
if the close tag is missing
- docx — direct zipfile manipulation (no python-docx dep):
inserts an external-image Relationship into word/_rels/document.xml.rels
and a matching <w:drawing> element before </w:body>
- xlsx — sibling of docx; injects an external-image relationship
into xl/_rels/workbook.xml.rels (orphan rels are still fetched on
open by most viewers)
- pdf — uses pikepdf to install /OpenAction /URI on the catalog;
rejects with a clear message when pikepdf isn't installed
- image — uses Pillow to embed slug + URL in PNG tEXt / JPEG
comment; rejects with a clear message when Pillow isn't installed
DOCX and XLSX share the rId allocator + relationship injector via
the docx module; both work on stdlib zipfile only.
Tests synthesise minimal real DOCX/XLSX fixtures inline, round-trip
each instrumenter, and assert the callback URL ends up in the
mutated bytes while the file still parses.
38 lines
1.4 KiB
Python
38 lines
1.4 KiB
Python
"""Passthrough instrumenter — bytes go to disk unchanged.
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Used as the dispatch fallback for content types we can't safely
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mutate (random binary blobs, container images, archives we don't
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recognise). In passthrough mode the only callback surface is the
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:attr:`CanaryToken.placement_path` itself: the operator must use a
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DNS-callback token whose slug appears in the filename, so a
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listing/access at the OS level resolves the slug as part of the
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path (e.g. ``/etc/<slug>.canary.example.test/secrets.bin``) when
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the attacker greps for hostnames in their loot.
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The instrumenter does not enforce that — the API does, when it sees
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``instrumenter=passthrough`` with ``kind=http`` it returns 400.
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"""
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from __future__ import annotations
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from decnet.canary.base import CanaryArtifact, CanaryContext, CanaryInstrumenter
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class PassthroughInstrumenter(CanaryInstrumenter):
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name = "passthrough"
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mime_prefixes = () # dispatched by fallback in pick_instrumenter_for_mime
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def instrument(
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self, blob: bytes, ctx: CanaryContext, *, target_path: str,
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) -> CanaryArtifact:
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return CanaryArtifact(
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path=target_path,
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content=blob,
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mode=0o644,
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mtime_offset=-86400 * 7,
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instrumenter=self.name,
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notes=[
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"passthrough: bytes unchanged — only DNS-callback tokens "
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"trip detection (slug must live in the placement path)",
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],
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)
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