MCP Server Auditor

guardbee-mcp

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guardbee.ai — AI Security Copilot for websites.

GuardBee's family of MCP (Model Context Protocol) servers — a single monorepo, independent npm packages.

Packages

Recent Changes (2026-10-06, cont'd 2)

AI-security MCP gap pass follow-up: shipped @guardbee/mcp-owasp-scan (unified OWASP MCP Top 10 path + live tools/list, A–F, SARIF), @guardbee/mcp-context-oversharing-auditor (MCP10 context oversharing distinct from toxic-flow), Python MCP05/OAuth patterns on mcp-server-auditor / oauth-auditor, and a reusable .github/actions/mcp-security-scan (+ workflow) that uploads SARIF for toxic-flow / audit-gap / context-oversharing / owasp-scan.

Recent Changes (2026-10-06, cont'd)

Gap pass against OWASP MCP Top 10 + github.com/topics/mcp-security: MCP05 and MCP08 had no dedicated coverage tags/packages. Shipped @guardbee/mcp-audit-gap-auditor for MCP08 and tagged mcp-server-auditor's shell/eval/SQL sinks as MCP05:2025. MCP09 Shadow MCP host discovery landed in mcp-config-auditor (discover CLI / discover_shadow_mcp tool): walks Cursor/Claude/Windsurf/VS Code well-known paths and flags servers missing from an organization allowlist.

Recent Changes (2026-10-06)

Bridged the industry detection standard into the monorepo: @guardbee/mcp-threat-rules wraps MIT-licensed Agent Threat Rules (ATR) as a GuardBee MCP server. ATR scores runtime agent/MCP events (prompt injection, tool poisoning, exfiltration); each match includes a follow-up hint to the matching GuardBee static auditor. Also tagged GuardBee/guardbee-mcp on GitHub with mcp-security / ai-security so the suite appears on github.com/topics/mcp-security.

Recent Changes (2026-09-30)

Added a new AI-security MCP after a gap pass against the current MCP/AI-security landscape (OWASP MCP Top 10, Simon Willison's lethal trifecta, competitor scanners that score individual tools but not combinations): @guardbee/mcp-toxic-flow-auditor. Every other GuardBee MCP auditor looks at one tool, one file, or one pattern at a time; this one asks whether the catalog as a whole can chain untrusted content + sensitive data + an exfil/destruct path — the failure mode where a prompt injection in a fetched page can reach vault/DB tools and then send_* / delete_*. Grades A–F, reports dangerous pairs when the full trifecta is absent, includes KVKK (tc_kimlik, müşteri) heuristics, CLI (audit / scan) + MCP tools + SARIF. Mapped to OWASP MCP10:2025.

Recent Changes (2026-09-27)

Completed and shipped work found sitting uncommitted in ai-code-scanner from an earlier session: custom rule packs (0.2.2 → 0.3.0, minor — new capability, no breaking change). Built-in patterns cover common AI/LLM integration mistakes, but field names and internal conventions (e.g. which prop carries KVKK-regulated data) are project-specific — rather than forking the package per customer, a project can now drop JSON rule files into .guardbee/rules/ (configurable via a new rules-dir key in guardbee.yml) that get merged with the built-ins at scan time, for both the CLI and the MCP server (list_patterns marks loaded custom rules (custom)). A rule id colliding with a built-in or another custom rule is rejected — reported on stderr, scan keeps running rather than crashing. 8 new tests (36 total): valid single-rule and multi-rule files, a rule that actually matches, and four rejection paths (id collision, missing field, invalid regex, invalid JSON) plus a missing-rules-dir case. Verified beyond the unit tests with a real end-to-end run: a genuine .guardbee/rules/kvkk.json file scanned against a real target file via the actual CLI binary, confirming the custom rule fires alongside the built-in patterns in the same run. tsc --noEmit and npm run build both clean.

Recent Changes (2026-09-26, cont'd 4)

Follow-up to the dogfooding pass below: went further on secret-scanner's doc/placeholder noise, since the first suppression-comment fix alone only cut findings 28% (1,623 → 1,162) against IBM/mcp-context-forge — the fork's own report had flagged this as still noisy, and sampling the actual remaining findings turned up three more concrete, fixable patterns rather than vague "noise":

• bearer_token required no minimum length at all, so test fixtures like "Bearer alpha" and "Bearer test-token" (from that repo's own Rust test suite) matched just as readily as a real OAuth token — and turned out to be nearly the entire problem: 1,008 of 1,149 remaining findings, from a handful of literal test strings reused across hundreds of call sites. Real bearer tokens (JWTs, OAuth2 opaque tokens) are essentially never under 20 characters; added that floor to the pattern.
• Added a value-shape placeholder filter, applied across all patterns except connection strings (which have their own allowlist and can legitimately contain "example" in a hostname, e.g. example.com): an 8+ run of one repeated character, an 8+ ascending sequential run (abcdefgh, 01234567 — the exact shape this package's own test fixtures used as filler, which needed rewriting to realistic pseudo-random values as a result), or a dictionary placeholder word embedded in the value (EXAMPLE, PLACEHOLDER, CHANGEME, etc. — this is exactly why AWS's own officially-published example key, AKIAIOSFODNN7EXAMPLE, is a famous universal false positive across every secret scanner; it's now correctly recognized here too).
• Broadened the existing <UPPER_CASE> bracket-placeholder allowlist (already present in the connection-string and generic-secret patterns) to any bracketed text, since real docs write descriptive placeholders like <admin login password>, not just <UPPER_CASE> tokens.
• Split Stripe's secret/restricted key patterns into live (critical, unchanged) and test-mode (new, low severity) — Stripe's own documentation states test-mode keys are safe to embed in code samples, so treating every sk_test_... example in a docs-heavy repo as critical was itself a source of false alarm, not a real one.

Net effect on the same target repo: 1,623 → 173 findings (89%). 9 new/updated tests (33 total), covering both the new suppressions and explicit "must still detect a realistic-looking secret" cases so the fix can't regress into swallowing real positives. Verified against the real target repo, plus a monorepo-wide smoke test (21 findings, all pre-existing own-test-fixture matches). secret-scanner 0.2.3 → 0.2.4.

Recent Changes (2026-09-26, cont'd 3)

Dogfooding pass: ran the whole scanner family against 5 real, popular open-source MCP projects (modelcontextprotocol/servers, IBM/mcp-context-forge, cisco-ai-defense/mcp-scanner, semgrep/mcp, invariantlabs-ai/mcp-injection-experiments) to validate against code we don't control. No real vulnerabilities turned up — every medium+ finding was a false positive — but the exercise found two real bugs in our own patterns, both fixed here with regression tests:

• mcp-server-auditor's sql_injection_via_tool_input (0.1.2 → 0.1.3) matched JS's .delete(/.select(/.update(/.insert( method-call syntax as if it were SQL DML, case-insensitively — params.delete(prefix + "tags") next to an unrelated ${params.toString()} template literal was enough to trip it (IBM/mcp-context-forge's admin_ui/search.js, a plain browser URLSearchParams helper, zero SQL anywhere nearby). Tightened to require a real SQL clause keyword (FROM/INTO/SET/WHERE/VALUES) between the DML keyword and the interpolation, and added a negative lookbehind so a keyword preceded by . (a method call) never matches. Verified isolated before/after against both the real false positive and all existing positive fixtures; re-scanned the target repo (0 findings, was 1) and the whole monorepo (0 false positives across 247 files).
• secret-scanner's scanner had no suppression-comment support at all, so a mature codebase that already annotates known-safe matches (# pragma: allowlist secret, gitleaks:allow, nosec, etc. — 464 files' worth in IBM/mcp-context-forge alone) got flagged anyway. Added recognition of the common conventions (detect-secrets, gitleaks, trufflehog, plus a guardbee:allow/guardbee-ignore pair) checked against the same line as the match. Re-scanning the target repo dropped findings from 1,623 to 1,162 (28%) from this alone; still noisy from unrelated doc/placeholder content, which is a separate, larger fix not attempted here. 4 new tests (3 positive suppression cases + 1 negative — an annotation on an unrelated nearby line must not suppress a real secret). secret-scanner 0.2.2 → 0.2.3.

Also surfaced, not yet acted on: the whole family is JS/TS-pattern-oriented, so 3 of the 5 target repos (all-Python, including IBM/mcp-context-forge's actual OAuth/gateway logic — exactly what oauth-auditor targets) got no meaningful pattern coverage.

Recent Changes (2026-09-26, cont'd 2)

Added a 21st package, the last of three follow-on additions from a research pass on the current MCP/AI-security landscape: @guardbee/mcp-oauth-auditor — scans an MCP server's own authorization code for the exact anti-patterns the MCP specification's Security Considerations section names as the central authorization risks. Token passthrough: a client's token forwarded unchanged to a downstream API instead of being exchanged/re-scoped — the token was audienced for this server, not whatever it gets forwarded to. Missing audience validation: a jwt.verify() call that checks a token's signature but never its aud claim, so a token minted for a completely different resource server verifies successfully here too — the same confused-deputy substitution from the other direction. Three adjacent patterns round it out: an OAuth/OIDC discovery URL built from client-supplied input (the shape behind a real disclosed CVE), redirect_uri validated with startsWith/includes instead of exact match (open-redirect bypass), and a hardcoded client_secret. Two of the six checks (audience, PKCE) look for an absence near a call site rather than a fixed regex, extracting the full call/URL construction first. 18 tests; found and fixed a real regex bug during development (a trailing \b after a ] character can never match, since ] isn't a word character — silently missed the bracket-notation form of header access, req.headers['authorization']). End-to-end verified against a fixture with all 6 anti-patterns deliberately planted (caught all 6) and the entire monorepo (401 files — zero findings in real code; the only non-test matches were the scanner's own pattern-definition source textually containing the string jwt.verify( inside a regex literal, not actual vulnerable usage). New package, so no changeset added.

Recent Changes (2026-09-26, cont'd)

Added a 20th package: @guardbee/mcp-memory-poisoning-scanner — targets a gap prompt-injection-scanner doesn't cover: that package catches an injection payload sitting in content the model reads once (a document, a scraped page); this one catches the code pattern that lets a payload become part of what the model treats as its own long-term knowledge — the same gap between reflected and stored XSS, applied to an agent's memory. Deliberately scoped narrow: ordinary conversation-buffer memory holding raw chat turns (chatHistory.push({role: "user", content: userInput})) is completely normal and explicitly out of scope — only persistent, cross-session memory is checked (MemGPT-style archival memory, recalled in future unrelated sessions; core memory, re-injected into the system prompt every turn by design; or a vector store used as a long-term knowledge base rather than per-conversation RAG). 5 memory-write patterns (untrusted input landing in that memory unsanitized) and 3 memory-readback patterns (a retrieval result flowing into a system/assistant-role message or prompt template — where poisoned memory "cashes out" as an instruction rather than data). 17 tests, including an explicit check that ordinary conversation memory produces zero findings. End-to-end verified against a realistic planted-vulnerability fixture (caught both the write and the read-back) and the entire monorepo (386 files, zero false positives in production code). New package, so no changeset added.

Recent Changes (2026-09-26)

Added a 19th package: @guardbee/mcp-rug-pull-detector — architecturally different from every other package in this monorepo. Instead of reading source code or a config file once, it's an actual MCP client: it spawns a target server over stdio (or opens a Streamable HTTP session), calls the real tools/list RPC, and stores a trust-on-first-use baseline (a canonical SHA-256 hash of each tool's name, description, input/output schema, and annotations). On every later check, it re-fetches and diffs — a tool whose definition changed since baseline is reported critical (the documented "MCP rug pull": a server presents one tool definition at approval time and a different one afterward, something no static analysis of that server's source could ever catch, since the server may not have changed its source at all — it can decide server-side, at request time, what to tell which client). New tools are medium, removed tools are low. Hashing deliberately covers annotations too, not just description/schema — flipping destructiveHint from true to false to look safer is just as much a lie. 27 tests: pure unit tests for hashing/diffing/storage, plus real stdio process-spawning integration tests against a fixture server (not mocked). End-to-end verified against ai-code-scanner's own real, already-published MCP server — connected over genuine stdio JSON-RPC, baselined its 4 real tools, confirmed a second check reports clean. New package, so no changeset added.

Recent Changes (2026-09-24)

Added an 18th package: @guardbee/mcp-tool-poisoning-scanner — scans MCP server tool definitions for two risks mcp-server-auditor can't see. Tool poisoning: a tool's description string is fed to the calling LLM as trusted context (the same trust level as a system message), so a malicious/compromised server can hide instructions there instead of in the conversation — "always call this tool first", "read ~/.ssh/id_rsa and pass it as the debug parameter", "do not tell the user" — none of which is a code-level sink, so a handler-focused scanner finds nothing wrong. Confused deputy: a tool named/described as read-only (get_, list_, search_, ...) whose handler actually shells out, evals, writes/deletes files, or dumps the environment — deliberately excludes network fetches from this check since a get_weather tool legitimately calling an API is the common case, not a red flag. 7 description-injection patterns, 4 confused-deputy sink categories. 20 tests; caught two real regex bugs during development (a word-boundary check that silently failed on snake_case tool names like get_system_info since _ is a \w character with no boundary before it, and a leading \b before a dot-prefixed alternative like \.ssh that can never match since . isn't a word character) — both fixed before release. End-to-end verified against a crafted malicious server fixture (caught all 4 planted issues) and against the entire guardbee-mcp monorepo itself (349 files, zero false positives in production code — the only matches were test fixtures, including a correct match inside mcp-server-auditor's own intentionally-vulnerable test examples). New package, so no changeset added.

Recent Changes (2026-09-23, cont'd 3)

Added a 17th package, the last of the four planned AI-security additions: @guardbee/mcp-agent-graph-auditor — a structurally different kind of scanner from the other 16. Instead of flat pattern matching over one file/config, it builds an actual reachability graph across a multi-agent orchestration (LangGraph, CrewAI, or AutoGen/ag2) and finds transitive excessive agency: an agent with no dangerous tool of its own that can still reach one — shell, code-exec, file-write, network, credentials — through another agent it's allowed to delegate to. That's a blind spot for every single-agent scanner in this monorepo (ai-code-scanner, mcp-server-auditor), which only see one agent's own tool list, not a two-hop delegation chain. LangGraph is the most reliable target since add_node/add_edge calls are the orchestration graph in the source; CrewAI (allow_delegation + Crew membership) and AutoGen (GroupChat co-membership, code_execution_config, register_function) require inferring delegation from framework semantics, so those are documented as heuristic. 31 tests, plus end-to-end verification against realistic fixtures for all three frameworks — correctly distinguished "direct" (single-agent) from "transitive" (delegation-crossing, always reported critical) in every case, and caught a real regex bug along the way (a constructor-extraction pattern that silently missed any Agent definition not followed by a trailing newline — fixed before release, not shipped broken). New package, so no changeset added.

Recent Changes (2026-09-23, cont'd 2)

Added a 16th package, third of the four planned AI-security additions: @guardbee/mcp-prompt-leak-scanner — catches leaked credentials and PII in outbound LLM prompts, the moment before they leave your application, rather than in code at rest (secret-scanner's job). Detection uses real checksum algorithms where one exists — the actual 11-digit Turkish national ID (TC Kimlik No) algorithm, Luhn for credit cards, ISO 7064 MOD97-10 for IBANs — instead of bare digit-count regexes, which would otherwise flag order numbers and timestamps constantly. Findings never echo the real value back (maskedMatch shows only sk-…wx-style partial reveals). Beyond the usual scan_text/scan_file/scan_directory MCP tools, it also ships a scan_messages tool that understands OpenAI/Anthropic-style chat bodies (messages[].content, string or content-block array, plus system), and a standalone proxy CLI command — a real reverse proxy you point your app's baseURL at instead of the real LLM API, which inspects only the outbound request body (monitor/redact/block policies) and streams the upstream response back untouched, so SSE/streaming completions pass through unaffected. Audit events are credential-free by design — they record which pattern fired and where, never the matched text. 29 tests, including the proxy tested in all three modes via a real local HTTP client/server round trip (not just in-process mocks), plus a manual end-to-end run as an actual subprocess against a mock upstream confirming the redacted body — not the real key — was what got forwarded. New package, so no changeset added.

Recent Changes (2026-09-23, cont'd)

Added a 15th package, second of the four planned AI-security additions: @guardbee/mcp-vector-store-scanner — probes a vector-database endpoint for unauthenticated exposure, the same misconfiguration class behind repeated open-Elasticsearch/MongoDB/Redis incidents, now aimed at the RAG-era stack. Fingerprints Weaviate/Qdrant/Chroma/Elasticsearch via HTTP and escalates through three levels (instance info → schema/collection listing → actual stored data), so a "critical" finding always means real data was actually read back without credentials, not just that a port responded. Redis and Postgres/pgvector get from-scratch raw-protocol implementations instead of HTTP: a RESP PING for Redis, and a wire-protocol SSLRequest+StartupMessage handshake for Postgres that reads whether AuthenticationOk comes back with no password challenge — no client library, no real credentials ever sent. 22 tests against local mock HTTP/TCP servers, covering every probe's matched/unmatched fingerprint and each escalation level. New package, so no changeset added.

Recent Changes (2026-09-23)

Added a 14th package, the first of four planned additions to the AI-security family: @guardbee/mcp-model-scanner — unlike the other scanners, which look at your integration code or content flowing through a model, this one looks at the model file itself as a supply-chain artifact. A .pt/.pth/.pkl checkpoint is a pickle stream, and unpickling can execute arbitrary Python the instant it's loaded (torch.load()), not just deserialize data. The package implements a from-scratch pickle opcode disassembler (protocols 0–5, including protocol 4+'s STACK_GLOBAL encoding) that walks the byte stream to find every GLOBAL/STACK_GLOBAL/INST reference, then checks it against a 31-rule denylist (os, subprocess, socket, builtins.eval, ctypes, …) and an allowlist of legitimate ML-framework globals (numpy, torch, sklearn, …). For PyTorch's default zip-based checkpoint format, it reads the ZIP central directory directly off disk (with Zip64 support) to extract just the small data.pkl entry without loading a multi-gigabyte file into memory. Also validates .safetensors header structure (including detecting a pickle/zip disguised with a safe-looking extension), flags Keras .h5/.keras Lambda-layer RCE patterns, and flags ONNX external_data path-traversal references. 45 tests, end-to-end verified against fixtures produced by real CPython pickle/zipfile (not just hand-built byte buffers) — correctly caught os.system in both protocol-2 (GLOBAL) and protocol-4 (STACK_GLOBAL) pickle encodings, resolved to posix.system exactly as CPython's own pickler records it. New package, so no changeset added (existing project convention).

Recent Changes (2026-09-15)

Continued growing the AI Gateway (db-gateway) work:

• query_audit_log tool — the gateway's own audit history is now queryable, filterable by table/tool/operation/deniedOnly/since. It reads from an always-on in-memory ring buffer (audit.bufferSize, default 200) that is independent of the configured sink (console/file/http). This also fixed a bug where read and write tools each built their own AuditLogger, so write events would never have shown up in query results.
• SQLite adapter — createSqliteAdapter accepts a better-sqlite3 Database instance, following the same pattern as the pg/mysql2 adapters (identifiers validated against the live schema via PRAGMA table_info before being embedded in SQL).
• MongoDB adapter — createMongoAdapter accepts a MongoDB Db instance. Guards against a different risk class (not SQL injection, but "operator injection" — $-prefixed keys, dotted paths, operator-object filter values).

Full write-up: packages/db-gateway/README.md#recent-changes-2026-09-15.

Also added a new package: @guardbee/mcp-server-auditor — follows ai-code-scanner's architecture (a regex pattern list, scanText/scanFile/scanDirectory, SARIF, guardbee.yml) but points it at a different target: not general LLM integration code, but an MCP server's own tool definitions. Does a tool name registered via server.tool(...) imply shell/SQL execution, does its handler pass raw tool input straight into an exec/eval/fetch/SQL sink, is a parameter typed z.any(), does it leak the entire process.env — 10 patterns, 5 categories, 32 tests.

And a third: @guardbee/mcp-prompt-injection-scanner — reuses the same engine (scanText/scanFile/scanDirectory/SARIF) but scans data, not code: a RAG chunk, a scraped web page, a document. Unlike classic prompt injection, indirect prompt injection never talks to the model directly — it embeds instructions in content the model will later read (via RAG retrieval or a web fetch). Detects override phrases ("ignore previous instructions"), spoofed System:/<|im_start|> role tokens, text hidden from a human reviewer via zero-width characters or display:none while a scraper still extracts it, phrasing that addresses "the AI" directly, and instructions to leak the system prompt or send data to an external URL. 10 patterns, 5 categories, 30 tests — with explicit negative tests against known false-positive sources like emoji ZWJ sequences and ordinary display:none modals.

And a fourth, a different kind of tool entirely: @guardbee/mcp-llm-redteam — while the other three scan code or content at rest, this one actively probes a live LLM endpoint or chatbot you control (OpenAI-compatible, Anthropic, or your own webhook) with known jailbreak/extraction/obfuscation/refusal-suppression techniques. Every probe is canary-based, not harm-based: it never asks the target to produce genuinely harmful content — success is a deterministic check for whether the target reproduced a random, single-use token, proving an override instruction was obeyed. 12 probes, 5 categories, 29 tests (target adapters tested against a mocked fetch), verified end-to-end via the CLI against local fake chatbot servers (a naive one that leaked 5/6 canaries, a safe one that leaked none).

Telemetry

Every package sends usage telemetry to GuardBee via @guardbee/mcp-telemetry, enabled by default: which tool is called, how often, and how long it takes. A one-time notice is printed to stderr on first use.

• To disable: GUARDBEE_TELEMETRY=0 (or false/off)
• What's sent: tool name, short (≤40 character) parameter values (e.g. table: "users", limit: 50), success/failure, duration
• What's NEVER sent: values under keys like content/text/data/filter/password/email/apiKey/token, and any string longer than 40 characters — all replaced with "[redacted: ...]" by redactParams() in packages/telemetry/src/redact.ts. So the full content of scanned files/code, or the real row data from an insert_row/update_row call, is never sent.

Details: packages/telemetry/README.md.

Development

pnpm install
pnpm build     # turbo run build — all packages, in dependency order
pnpm test      # turbo run test

To work on a single package:

pnpm --filter @guardbee/mcp-ssl-inspector dev

Versioning and publishing

Packages are versioned independently (Changesets). If you changed something in a PR:

pnpm changeset

After merging to main, CI automatically opens a version PR; merging that PR publishes the changed packages to npm (see .github/workflows/release.yml).

Structure

• pnpm workspaces — packages/*, real workspace:* dependencies (e.g. security-suite depends on the other 4 packages directly from the workspace, not a registry version)
• Turborepo — build/test/type-check pipeline, dependency-graph-aware ordering and caching
• Shared config — tsconfig.base.json and vitest.shared.ts at the root; each package layers its own settings on top