The output gate claimed LLM10 self-safety on the grounds that its patterns have
no nested quantifiers. True, and irrelevant: nesting is not what makes these
blow up. A run in front of a REQUIRED literal, reachable from a short anchor, is
enough -- crafted input repeats the anchor and never supplies the literal, so
every start position rescans the tail. Quadratic, not exponential, and the
max_scan_chars cap does not help: it bounds the input, and quadratic work on a
bounded input is still hours.
Measured, not argued. `<a:` x 100_000 took 23.4s in AUTOLINK_RE alone; the
composed gate on that payload took 458.7s, extrapolating to ~5.7 hours at the
1_000_000-char input the gate itself accepts. Size-matched ordinary prose runs
0.31s, so the separation is 18x-660x -- unlike the blob in the neighbouring
test, which is the *faster* side of prose and never exercised backtracking.
Two fixes, chosen per pattern rather than uniformly:
- active_content + lexicon JSON (15 runs): exclude the character that opens the
pattern's own anchor (`[` for markdown, `<` for tags), so a run cannot reach
past the next start position and the per-start costs telescope. Verified to
cost no recall: long URLs, long alt text, and `<` inside a quoted attribute
all still match. Bounding instead would have been linear too but wrong here --
the content is attacker-controlled, so padding past a bound would be a
one-line bypass of the EchoLeak class this table exists to catch.
- connstr egress (4 runs): bound the password at MAX_CONNSTR_VALUE. The
exclusion fix is unavailable -- the anchor character is `/` and passwords
containing `/` are the common case (measured: they match today). The residual
miss is a credential over 256 chars; a token that long is still caught by
egress:jwt-token.
hybrid-xss:script-tag had neither option: its run is the script BODY, which may
legitimately contain `<`. It now matches the opening tag and drops the
`</script>` requirement. That also closes a fail-open -- `<script>alert(1)`
unclosed was silently missed -- at the cost of flagging prose that merely
mentions `<script>`, now documented.
Found by the composed-gate test staying red after every individual scanner was
already linear: the lexicon's six html-obfuscation patterns were the remaining
813x. A per-scanner test alone would have shipped that.
662 passed (was 642), and faster than before the fix.
v0.3.0 made the untrusted upload path unusable: measured on both doors, an
ordinary remote image fail_secure'd and an ordinary link/autolink/refdef
quarantined, so only documents without external references persisted.
Two independent defects compounded; neither fix works alone:
1. `markdown-image: HIGH` fired on any external image. The exfil primitive is a
URL that moves bytes outward, not an image. `is_ordinary_url` now grades on
shape - http(s)/protocol-relative, no query, no userinfo, no percent-escape,
no opaque host label or path segment -> LOW; anything data-carrying keeps the
carrier's severity. raw-html and data: URIs stay HIGH unconditionally.
Opacity reuses entropy's primitives; floors calibrated against real doc URLs
(worst legit token H=4.08, exfil segments 4.36-4.54) and frozen in
calibration.
2. The quarantine_default floor fired on ANY finding, a premise that broke when
every ordinary link became a finding. It now fires at MEDIUM+ - a no-op for
every detector that shipped before 0.3.0 (no LOW/INFO exists), which is what
makes this a patch rather than a minor.
The corpus blind spot that let this pass 522 green tests is closed: the FP
corpus carries realistic markdown and is asserted on the OUTPUT gate under
PRESET_USER_UPLOAD, with a counter-corpus of exfil-shaped URLs that must still
block. Beaconing and short opaque segments are conceded in LIMITATIONS and
asserted by the coverage matrix rather than papered over.
No new public API; no new preset (0.4.0 work); allow_reserved default unchanged.
Session D: move every calibration constant (entropy floors 5.4/128, 5.1/64,
4.7/40 + shape floors; MAX_SCAN_CHARS; rot13-min; cognitive-load lengths
2000/2500; disposition ranks; active-content severities) into one documented
calibration.py, so a parallel Node/TS port can mirror exactly the same numbers.
Pure refactor, zero behavior change: calibration is a leaf module (imports only
report.Severity) that entropy/lexicon/disposition/active_content now source
their thresholds from. MAX_SCAN_CHARS is re-exported from lexicon so output.py
and existing callers are unaffected. The 347 pre-existing tests pass unmodified;
new test_calibration.py freezes the values and asserts each detector actually
reads its threshold from calibration (identity-checked, not a dead copy).
