thanhnvandClaude Opus 4.8
ac40c0b281
A1 (V1): CASAN_SECURITY_STRICT=1 makes semantic classification REQUIRED and fail-closed — model unavailable/no-verdict → BLOCK, never a silent SKIP. Non-strict CASAN_SEMANTIC_CLASSIFY=1 keeps regex verdict but logs SEMANTIC_SKIPPED loudly (sourced casan-log.sh). Default (no flags) unchanged. A2 (V3/V4): unicode-normalize.py (NFKC + zero-width strip + Cyrillic/Greek homoglyph fold) and decode-suspicious.py (base64/hex decode + rescan, printable filter to avoid false positives) feed new match_either/secret_match haystacks. Blocks homoglyph, zero-width, fullwidth, base64/hex-smuggled injection & secrets. A3 (V7): tool-output-scan.sh scans tool output for injection/secret before it re-enters model context; wrapper runs it after H6-exec (mode off|warn|block, strict→block). warn is default to preserve benign-draft behaviour. Baseline preserved: run-casan4 35/35, adversarial 44/44. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
65 lines
2.0 KiB
Python
Executable File
65 lines
2.0 KiB
Python
Executable File
#!/usr/bin/env python3
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"""CASAN H4 — Suspicious base64/hex decoder (Track A, V4 encoding smuggling).
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Reads text on stdin. Finds embedded base64 and hex blobs, decodes them, and
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prints the decoded plaintext (one blob per line) on stdout so the caller can
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re-run its injection/secret pattern scan on the *decoded* content.
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Safety / no-false-positive design:
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* Only blobs >= MIN_LEN characters are considered (short words are ignored).
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* A decoded blob is emitted ONLY if it is mostly printable text. Random
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base64-looking words (e.g. "objectives", DER key bytes) decode to
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non-printable garbage and are dropped, so they can never trigger a match.
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* Output is advisory: the caller decides a decoded blob is malicious only if
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the decoded text itself matches a block/secret pattern.
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Deterministic: same input always yields the same output.
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"""
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import base64
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import binascii
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import re
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import sys
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MIN_LEN = 16
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PRINTABLE_RATIO = 0.8
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B64_RE = re.compile(r"[A-Za-z0-9+/]{%d,}={0,2}" % MIN_LEN)
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HEX_RE = re.compile(r"\b[0-9a-fA-F]{%d,}\b" % MIN_LEN)
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def _mostly_printable(text: str) -> bool:
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if not text:
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return False
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ok = sum(1 for c in text if c.isprintable() or c.isspace())
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return ok >= PRINTABLE_RATIO * len(text)
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def decode_blobs(data: str):
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out = []
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for m in B64_RE.findall(data):
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pad = m + "=" * ((4 - len(m) % 4) % 4)
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try:
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dec = base64.b64decode(pad, validate=True)
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except (binascii.Error, ValueError):
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continue
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txt = dec.decode("utf-8", "ignore")
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if _mostly_printable(txt):
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out.append(txt)
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for m in HEX_RE.findall(data):
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if len(m) % 2 != 0:
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continue
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try:
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dec = bytes.fromhex(m)
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except ValueError:
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continue
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txt = dec.decode("utf-8", "ignore")
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if _mostly_printable(txt):
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out.append(txt)
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return out
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if __name__ == "__main__":
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blobs = decode_blobs(sys.stdin.read())
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if blobs:
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sys.stdout.write("\n".join(blobs))
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