open/llm-security
1
0
Fork 0
Code Issues Releases 1 Activity

refactor(llm-security): build the SIG ruleset from vendored commons (malware-signatures 0.1.0)

Browse source 
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
This commit is contained in:
Kjell Tore Guttormsen 2026-08-13 21:28:14 +02:00
commit bbada84e9f
12 changed files with 480 additions and 132 deletions
Download patch file Download diff file Expand all files Collapse all files

2
docs/scanner-reference.md
View file

@ -20,7 +20,7 @@ Toxic-flow (TFA) is a post-processing correlator that runs LAST — detects "let
Trigger-abuse (TRG) inspects command/agent/skill `name`+`description` frontmatter for activation-surface abuse: built-in shadowing (a name colliding with a built-in tool), activation baiting (maximally-activating description phrases), and overly broad triggers (generic name + universal-applicability claim → HIGH). Descriptions are run through the decode pipeline (zero-width strip, homoglyph fold, `normalizeForScan`) so obfuscated baiting still trips. Policy: `trg` section (`baiting_phrases`, `builtin_names`, `broad_single_words`). OWASP: LLM06, AST04.
Signature (SIG) is a known-bad-identity engine: a small, high-confidence, family-grouped ruleset (`knowledge/signatures.json` — webshell, reverse_shell, cryptominer, hacktool) tested against each file's decode pipeline (`normalizeForScan`/`foldHomoglyphs`/`rot13`), so obfuscated known-malware that a raw byte-matcher misses is still caught. Path-excludes `knowledge/`, `tests/`, `docs/`. Policy: `sig.enabled_families`. OWASP: LLM03, LLM02.
Signature (SIG) is a known-bad-identity engine: a small, high-confidence, family-grouped ruleset (`signatures/malware-signatures.json` in the vendored commons, built by `scanners/lib/malware-signatures.mjs` — webshell, reverse_shell, cryptominer, hacktool) tested against each file's decode pipeline (`normalizeForScan`/`foldHomoglyphs`/`rot13`), so obfuscated known-malware that a raw byte-matcher misses is still caught. Path-excludes `knowledge/`, `tests/`, `docs/`. Policy: `sig.enabled_families`. OWASP: LLM03, LLM02.
AST-taint (AST) shells out to a PARSE-ONLY python3 helper (`scanners/lib/py-ast-taint.py`) for scope-aware, variable-level Python taint analysis (sources → sinks), with graceful fallback to the regex taint-tracer when python3 is absent. The helper only `ast.parse`s the target — it never executes it. 5s timeout per file. Policy: `ast` section (`enabled`, `python_path`, `timeout_ms`). OWASP: LLM01, LLM02, AST02.