feat(llm-security): v7.0.0 commit 7 — rule 18 (markdown image URL suppression)

E2E verification against content-heavy repo (`content-claude-code`) revealed
413 entropy findings (8 HIGH / 405 MEDIUM) from markdown image CDN URLs in
JSON content indexes — e.g., `![Image 1: Title](https://www-cdn.anthropic.com/images/.../cf1dd2167fcf12f5882333ddc58a5bc1f0026952.svg)`.
These are legitimate content-repo artifacts, not credentials. The 40-char
hash segment in the CDN URL trips Shannon entropy (H=5.29 over 300 chars),
and rule 13 (inline <svg>) doesn't match since there's no literal `<svg>`
tag — the `.svg` is just a URL path suffix.

Added rule 18 `MARKDOWN_IMAGE = /!\[[^\]]*\]\(\s*https?:\/\//` — matches
`![alt](http…)` / `![alt](https…)`. Line-level (not string-level) so URL
is not over-specific.

E2E impact on `content-claude-code`:
- Before: BLOCK / 65 / 8H 437M 0L
- After:  WARNING / 56 / 3H 427M 0L

Hyperframes unchanged: BLOCK / 80 / 1C 4H 92M — real CRITICAL SQL-injection
and HIGH findings still detected.

Tests: 2 new (positive + negative fixture) bringing entropy-context to 26,
total suite 1485 → 1487.

Docs updated to "rules 11-18" and "8 new line-suppression rules".

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
Kjell Tore Guttormsen 2026-04-19 22:37:39 +02:00
commit 765bc74f52
7 changed files with 43 additions and 9 deletions

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@ -1,11 +1,11 @@
# LLM Security Plugin (v7.0.0)
Security scanning, auditing, and threat modeling for Claude Code projects. 5 frameworks: OWASP LLM Top 10, Agentic AI Top 10 (ASI), Skills Top 10 (AST), MCP Top 10, AI Agent Traps (DeepMind). 1485 tests.
Security scanning, auditing, and threat modeling for Claude Code projects. 5 frameworks: OWASP LLM Top 10, Agentic AI Top 10 (ASI), Skills Top 10 (AST), MCP Top 10, AI Agent Traps (DeepMind). 1487 tests.
**v7.0.0 — Trustworthy scoring (BREAKING).** Three changes target the false-positive cascade on real codebases (hyperframes.com gave `BLOCK / Extreme / 100`, ~70% noise):
1. **Risk-score v2 formula** (`scanners/lib/severity.mjs`) — severity-dominated, log-scaled within tier. Replaces v1 sum-and-cap that collapsed every non-trivial scan to 100/Extreme. Tiers: critical → 7095, high only → 4065, medium only → 1535, low only → 111. Verdict cutoffs realigned to new bands (BLOCK ≥65, WARNING ≥15).
2. **Context-aware entropy scanner** — file-extension skip (`.glsl/.frag/.vert/.shader/.wgsl/.css/.scss/.sass/.less/.svg/.min.*/.map`) + 7 new line-suppression rules (GLSL keywords, CSS-in-JS, inline SVG, ffmpeg `filter_complex`, User-Agent strings, SQL DDL, `throw new Error(\`...\`)`). Configurable via `.llm-security/policy.json` `entropy` section (thresholds, `suppress_extensions`, `suppress_line_patterns`, `suppress_paths`). Envelope `calibration` block reports skip counters + effective thresholds + policy source.
2. **Context-aware entropy scanner** — file-extension skip (`.glsl/.frag/.vert/.shader/.wgsl/.css/.scss/.sass/.less/.svg/.min.*/.map`) + 8 new line-suppression rules (GLSL keywords, CSS-in-JS, inline SVG, ffmpeg `filter_complex`, User-Agent strings, SQL DDL, `throw new Error(\`...\`)`, markdown image URLs). Configurable via `.llm-security/policy.json` `entropy` section (thresholds, `suppress_extensions`, `suppress_line_patterns`, `suppress_paths`). Envelope `calibration` block reports skip counters + effective thresholds + policy source.
3. **DEP typosquat allowlist expansion** — 22 npm + 5 PyPI entries for short-name tools that tripped Levenshtein detection on every modern codebase (`knip`, `oxlint`, `tsx`, `nx`, `rimraf`, `uv`, `ruff`, etc.).
See `docs/security-hardening-guide.md` §6 for the calibration story.