new RegExp(pattern, 'i') never throws when pattern is a truthy non-string
(e.g. an object) — it ToString-coerces it first. The truthy-only guard
(`!rule.pattern`) let such a rule through as a real, compiled RegExp,
bypassing the try/catch meant to drop malformed rules. Worse than a silent
drop: `new RegExp("[object Object]", "i")` is parsed as a character class
over o/b/j/e/c/t/space, so the "dropped" rule instead becomes a
near-universal false-positive matcher. Same path for the built-in
commons-backed ruleset and the operator's sig.custom_rules_path (both
route through compileRules).
Fix: require typeof rule.pattern === 'string' before compiling. Verified
the golden dump pins no rule that exists only because of this coercion —
it regenerates byte-identically after the fix.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019iWrdLSVgRhgPzTB29rQGD
Fifth and last consumer swap of v8 Phase 5 step 4. The seven known-bad-identity
signatures stop living in knowledge/signatures.json and are built from the
vendored commons artifact signatures/malware-signatures.json instead.
Measured before the swap over all seven positions -- id, family, severity,
pattern, description, provenance, key order, and recompilation identity under
the engine's unconditional `i` flag: zero divergences over 56 checks, in order.
The commons copy was extracted from this repository's own file at b0de0ca and
had not drifted.
knowledge/signatures.json is REMOVED rather than left in place. Keeping it would
have left two files spelling one table with nothing gating the drift, and its
golden `file:` pin would have gone on passing while pinning bytes no scanner
reads -- a gate reporting success without running. The pin is replaced by a
walked-module anchor over SIGNATURE_RULES, which is strictly stronger: the pin
covered the bytes on disk, the walk covers what `new RegExp` made of them.
Golden diff was exactly that and nothing else: 7 ADDED, 1 REMOVED, 0 CHANGED
(102/7/5 -> 109/7/4), each added source verified equal to the recompiled commons
pattern.
compileRules() moves into the new lib module and is exported, so the built-in
ruleset and the operator's sig.custom_rules_path path keep one implementation
rather than two copies of the defaulting logic.
Coverage by construction, not by memory: the probe table in the scanner test is
asserted against the LOADED ruleset, so a rule commons adds cannot arrive
without an end-to-end probe. Mutation of the vendored JSON fires in three
directions -- under-match (xmrig alternative dropped) reddens two scanner tests
plus golden; over-match (webshell rule widened to a bare `shell`) reddens the
clean-fixture false-positive probe plus golden; reorder reddens the declared-
order test plus golden.
Loud failure is contract: an unresolvable commons writes one line to stderr
rather than silently disabling known-malware detection, and never throws.
Suite 2247 / 2241 pass / 6 skipped / 0 fail. suite-counts.json untouched.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0151x4FVg9Mn55C2LvHLpHKo
