\n\n[](https://github.com/cyanheads/attack-surface-mcp-server/releases/latest/download/attack-surface-mcp-server.mcpb) [](https://cursor.com/en/install-mcp?name=attack-surface-mcp-server&config=eyJjb21tYW5kIjoibnB4IiwiYXJncyI6WyIteSIsIkBjeWFuaGVhZHMvYXR0YWNrLXN1cmZhY2UtbWNwLXNlcnZlciJdfQ==) [](https://vscode.dev/redirect?url=vscode:mcp/install?%7B%22name%22%3A%22attack-surface-mcp-server%22%2C%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22-y%22%2C%22%40cyanheads%2Fattack-surface-mcp-server%22%5D%7D)\n\n[](https://www.npmjs.com/package/@cyanheads/mcp-ts-core)\n\n
\n\n---\n\n> [!IMPORTANT]\n> **Authorized, defensive use only.** Point this server only at assets you own or are explicitly authorized to assess. It performs **passive, non-intrusive** reconnaissance — it reads public records (Certificate Transparency logs, DNS, RDAP/WHOIS) and each target's *own* published surface (one TLS handshake and one HTTP GET per host). It does **not** port-scan, exploit, brute-force, fuzz, or probe for vulnerabilities; that capability is excluded from the surface by design, not gated behind a flag. Output is descriptive — what exists and what the security posture is — never an exploitation plan. Every outbound connection passes an SSRF guard that refuses private, loopback, link-local, and cloud-metadata targets.\n\n---\n\n## Tools\n\nEight tools organized around the recon workflow — `attacksurface_map_domain` orchestrates the full flow end to end, the per-aspect tools back it for targeted follow-up, and `attacksurface_recon_guidance` synthesizes findings into a defensive review plan. Seven are keyless; one (`attacksurface_lookup_host`) needs a Shodan key and degrades gracefully without it.\n\n| Tool | Description |\n|:---|:---|\n| `attacksurface_map_domain` | Flagship workflow. Maps a domain's external surface end to end: CT-log subdomain discovery → DNS liveness → (standard+) DNS records, TLS posture, HTTP headers/tech → optional RDAP/WHOIS → (thorough + key) per-IP Shodan enrichment. Returns a structured surface map and a defensive assessment of observable facts. |\n| `attacksurface_enumerate_subdomains` | Passive subdomain discovery from Certificate Transparency logs (crt.sh → Certspotter → TLS-SAN fallback chain), with DNS resolution to mark which names are live. Per-source provenance; no DNS brute-forcing. |\n| `attacksurface_resolve_dns` | Resolve and enumerate DNS records (A/AAAA/CNAME/MX/NS/TXT/CAA) for one or more hosts across multiple public resolvers, with optional reverse DNS (PTR). Per-resolver values surface propagation gaps. |\n| `attacksurface_inspect_tls` | Inspect TLS/SSL posture via a real read-only handshake: protocol, cipher, full certificate chain, SANs, validity window, days-to-expiry, issuer, validation status. Reports invalid/expired/self-signed certs instead of failing. |\n| `attacksurface_probe_http` | Passive HTTP(S) probe: one GET following redirects. Returns status, redirect chain, headers, a security-header audit (HSTS/CSP/X-Frame-Options/cookie flags/CORS reflection), and an evidence-bound technology fingerprint. |\n| `attacksurface_lookup_registration` | Registration and ownership lookup via RDAP (JSON; WHOIS fallback). A domain returns registrar, status, lifecycle events, nameservers, DNSSEC; an IP/CIDR returns netblock, allocation CIDRs, origin ASN, country. |\n| `attacksurface_lookup_host` | Infrastructure intelligence for a single IP (open ports, banners, software versions, ASN, geo) or a faceted internet-wide search, via Shodan. **Requires `SHODAN_API_KEY`** — returns a typed `source_unavailable` error when unset; the rest of the server is unaffected. |\n| `attacksurface_recon_guidance` | Offline synthesis over findings gathered so far. Returns a prioritized **defensive** review plan plus pre-filled follow-up calls (which certs to renew, which hosts to inspect, which software versions to check for CVEs against an external NVD/OSV server). No external calls. |\n\n### `attacksurface_map_domain`\n\nThe spine of most engagements — one call maps a domain end to end.\n\n- `depth` control: `quick` = subdomains + liveness only; `standard` = + DNS records, TLS, and HTTP posture; `thorough` = + Shodan enrichment (when a key is present, otherwise skipped with a note)\n- `includeRegistration` adds an RDAP/WHOIS lookup for the apex at standard+ depth\n- All per-host fan-out uses `Promise.allSettled` — one failed source or unreachable host degrades to a note, never tanks the call\n- Subdomain resolution is capped (`ATTACKSURFACE_MAX_SUBDOMAINS`, default 200) with the cap disclosed when hit\n- The `assessment` block synthesizes only observable facts — expiring certs, missing HSTS/CSP, weak TLS versions, failed chain validation — never an exploitation path\n\n---\n\n### `attacksurface_enumerate_subdomains`\n\nPassive subdomain discovery from public Certificate Transparency logs.\n\n- Three sources with a fallback chain: crt.sh (primary), Certspotter (fallback — crt.sh is frequently overloaded), and the apex's own TLS certificate SAN list (always available)\n- Every discovered name carries its source provenance\n- DNS resolution marks which names are live; `includeUnresolved: false` returns only live hosts\n- Reads public logs — it does not brute-force or probe the target's resolvers\n\n---\n\n### `attacksurface_resolve_dns`\n\nMulti-resolver DNS enumeration with propagation visibility.\n\n- Queries A, AAAA, CNAME, MX, NS, TXT, and CAA across multiple public resolvers (default `8.8.8.8`, `1.1.1.1`, `9.9.9.9`)\n- Reports per-resolver answers so propagation gaps and split-horizon DNS are visible\n- Optional reverse DNS (PTR) on resolved addresses\n- Each host passes the SSRF guard; private/loopback resolver IPs are rejected; one failing host degrades to a per-host error\n\n---\n\n### `attacksurface_inspect_tls`\n\nRead-only TLS posture inspection — surfacing problems is the point.\n\n- A real handshake per host reports negotiated protocol and cipher, the full certificate chain, SANs, validity window, days-to-expiry, issuer, and chain-validation status\n- Invalid, expired, and self-signed certificates are inspected and reported rather than throwing\n- Posture findings flag short expiry windows, deprecated protocols, and self-signed chains\n- One handshake per host; no application data is sent; SSRF-guarded\n\n---\n\n### `attacksurface_probe_http`\n\nA single passive HTTP(S) GET with a security read-out.\n\n- Follows redirects and reports the final status plus the full redirect chain\n- Security-header audit: HSTS, CSP, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy, cookie Secure/HttpOnly/SameSite flags, and CORS origin-reflection\n- Evidence-bound technology fingerprint (server, framework, CDN, WAF, CMS) — every detection names the header or body marker that triggered it\n- Strictly one request per host — no path traversal, parameter injection, or multi-method probing; every redirect hop is re-checked against the SSRF guard\n\n---\n\n### `attacksurface_lookup_registration`\n\nRegistration and ownership from public registries.\n\n- RDAP first (structured JSON, manual 302-follow with a fresh 5s timeout covering SSRF validation and the request for each hop, plus a five-redirect cap), WHOIS port-43 fallback for TLDs without RDAP or when a hop is unresponsive\n- Domain lookups return registrar, EPP status codes, registration/expiry/updated events, nameservers, and DNSSEC\n- IP/CIDR lookups return the netblock name, allocation CIDRs, origin ASN, and country\n- Registry data is frequently redacted or sparse — absent fields are reported as unknown, never inferred\n\n---\n\n### `attacksurface_lookup_host`\n\nShodan infrastructure intelligence — the one optional-key path.\n\n- `mode: \"host\"` (default) — a free single-IP lookup: open ports, service banners, software versions, hostnames, ASN, geo\n- `mode: \"search\"` — a faceted internet-wide query that consumes paid Shodan query credits\n- Requires `SHODAN_API_KEY`; without it the tool returns a typed `source_unavailable` error and every other tool keeps working\n- Shodan data reflects Shodan's last scan, not a live port state — the server itself never scans ports\n\n---\n\n### `attacksurface_recon_guidance`\n\nState-aware synthesis — no network calls, just reasoning over what you've found.\n\n- Takes the findings gathered so far (live hosts, TLS/cert state, missing headers, software versions, open ports) and returns a prioritized defensive review plan as markdown plus structured priority items\n- Pre-fills concrete follow-up calls — re-inspecting hosts that lack posture data, and chaining disclosed software versions to an external NVD (`nist-nvd-mcp-server`) or OSV (`osv-advisory-mcp-server`) server for CVE context\n- Output is a remediation/visibility plan, never an exploitation playbook\n\n## Resources\n\n| Type | Name | Description |\n|:---|:---|:---|\n| Resource | `attacksurface://surface/{domain}` | Read-once snapshot of a domain's mapped surface (subdomains, live hosts, per-host TLS/HTTP posture summary), equivalent to a standard-depth `attacksurface_map_domain` call. |\n\nAll resource data is also reachable via tools — tool-only clients lose nothing, since `attacksurface_map_domain` covers the same ground. Large maps disclose a truncation count rather than returning unbounded host detail. The server exposes no prompts; `attacksurface_recon_guidance` supplies the one \"structure the next steps\" pattern as a state-aware tool instead of a static template.\n\n## Features\n\nBuilt on [`@cyanheads/mcp-ts-core`](https://www.npmjs.com/package/@cyanheads/mcp-ts-core):\n\n- Declarative tool and resource definitions — single file per primitive, framework handles registration and validation\n- Unified error handling — handlers throw, framework catches, classifies, and formats\n- Pluggable auth: `none`, `jwt`, `oauth`\n- Swappable storage backends: `in-memory`, `filesystem`, `Supabase`, `Cloudflare KV/R2/D1`\n- Structured logging with optional OpenTelemetry tracing\n- STDIO and Streamable HTTP transports\n\nAttack-surface-specific:\n\n- Passive and non-intrusive by mandate — public records plus each target's own single published response; active scanning, exploitation, and brute-forcing are excluded from the surface, not toggled by a flag\n- Keyless core — CT subdomain enumeration, DNS, TLS, HTTP/tech, and RDAP/WHOIS all work with zero API keys; Shodan is strictly additive depth\n- SSRF guard on every outbound connection — rejects private, loopback, link-local, cloud-metadata, and reserved IPv4/IPv6 ranges before connecting (opt out for trusted internal assessment via `ATTACKSURFACE_ALLOW_PRIVATE_TARGETS`)\n- Multi-source aggregation with fallback chains — CT discovery falls through crt.sh → Certspotter → TLS-SAN; registration falls through RDAP → WHOIS\n\nAgent-friendly output:\n\n- Provenance on every result — source labels (`source: crt.sh | certspotter | tls-san`, `source: rdap | whois`) and per-source status so agents can assess completeness and trust\n- Graceful partial failure — multi-target and multi-source tools return per-item/per-source `error` fields and operational `notes` instead of failing the whole call; only malformed input throws\n- Discriminated, typed contracts — typed error reasons (`source_unavailable`, `blocked_target`, `all_sources_failed`) and union output (`kind: domain | ip`) let callers branch on data, not string parsing\n- No fabricated signal — technology detections carry their triggering evidence; absent CT/DNS/RDAP fields are reported as unknown, never inferred\n\n## Getting started\n\nAdd the following to your MCP client configuration file. Every tool except `attacksurface_lookup_host` works with no configuration — the keyless core boots on an empty environment.\n\n```json\n{\n \"mcpServers\": {\n \"attack-surface-mcp-server\": {\n \"type\": \"stdio\",\n \"command\": \"bunx\",\n \"args\": [\"@cyanheads/attack-surface-mcp-server@latest\"],\n \"env\": {\n \"MCP_TRANSPORT_TYPE\": \"stdio\",\n \"MCP_LOG_LEVEL\": \"info\"\n }\n }\n }\n}\n```\n\nOr with npx (no Bun required):\n\n```json\n{\n \"mcpServers\": {\n \"attack-surface-mcp-server\": {\n \"type\": \"stdio\",\n \"command\": \"npx\",\n \"args\": [\"-y\", \"@cyanheads/attack-surface-mcp-server@latest\"],\n \"env\": {\n \"MCP_TRANSPORT_TYPE\": \"stdio\",\n \"MCP_LOG_LEVEL\": \"info\"\n }\n }\n }\n}\n```\n\nOr with Docker:\n\n```json\n{\n \"mcpServers\": {\n \"attack-surface-mcp-server\": {\n \"type\": \"stdio\",\n \"command\": \"docker\",\n \"args\": [\"run\", \"-i\", \"--rm\", \"-e\", \"MCP_TRANSPORT_TYPE=stdio\", \"ghcr.io/cyanheads/attack-surface-mcp-server:latest\"]\n }\n }\n}\n```\n\nTo enable Shodan host intelligence (`attacksurface_lookup_host`), add `SHODAN_API_KEY` to the `env` block.\n\nFor Streamable HTTP, set the transport and start the server:\n\n```sh\nMCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http\n# Server listens at http://localhost:3010/mcp\n```\n\nRefer to \"your MCP client configuration file\" generically — different clients use different config paths and this server isn't client-specific.\n\n### Prerequisites\n\n- [Bun v1.3.0](https://bun.sh/) or higher (or Node.js v24+).\n- No API key required for the core tools. Optional: a [Shodan API key](https://account.shodan.io/) for `attacksurface_lookup_host`, and a [Certspotter API key](https://sslmate.com/certspotter/api/) to raise CT-fallback rate limits.\n\n### Installation\n\n1. **Clone the repository:**\n\n```sh\ngit clone https://github.com/cyanheads/attack-surface-mcp-server.git\n```\n\n2. **Navigate into the directory:**\n\n```sh\ncd attack-surface-mcp-server\n```\n\n3. **Install dependencies:**\n\n```sh\nbun install\n```\n\n4. **Configure environment (optional):**\n\n```sh\ncp .env.example .env\n# edit .env only if you want Shodan, a Certspotter key, or non-default behavior\n```\n\n## Configuration\n\nAll variables are optional — the server boots and delivers its keyless core with an empty environment.\n\n| Variable | Description | Default |\n|:---------|:------------|:--------|\n| `SHODAN_API_KEY` | Enables `attacksurface_lookup_host`. Absent → that tool returns `source_unavailable`; every other tool keeps working. | — |\n| `CERTSPOTTER_API_KEY` | Raises Certspotter rate limits for the CT-log subdomain fallback. Absent → free unauthenticated tier (rate-limited but functional). | — |\n| `ATTACKSURFACE_DEFAULT_RESOLVERS` | Comma-separated default DNS resolver IPs for `attacksurface_resolve_dns`. | `8.8.8.8,1.1.1.1,9.9.9.9` |\n| `ATTACKSURFACE_HTTP_USER_AGENT` | Default User-Agent for `attacksurface_probe_http` (overridable per call). | identifies the server honestly |\n| `ATTACKSURFACE_MAX_SUBDOMAINS` | Cap on subdomains resolved during a `map_domain` run — bounds fan-out cost. | `200` |\n| `ATTACKSURFACE_RDAP_BOOTSTRAP_URL` | RDAP bootstrap base URL; override for a private/mirrored RDAP. | `https://rdap.org` |\n| `ATTACKSURFACE_ALLOW_PRIVATE_TARGETS` | Set `true` to disable the SSRF guard for internal-network assessment. **Leave `false` on any public deployment** — it is the safety boundary that keeps the server from being pointed at internal infrastructure. | `false` |\n| `MCP_TRANSPORT_TYPE` | Transport: `stdio` or `http`. | `stdio` |\n| `MCP_HTTP_PORT` | Port for HTTP server. | `3010` |\n| `MCP_AUTH_MODE` | Auth mode: `none`, `jwt`, or `oauth`. | `none` |\n| `MCP_LOG_LEVEL` | Log level (RFC 5424). | `info` |\n| `OTEL_ENABLED` | Enable [OpenTelemetry instrumentation](https://github.com/cyanheads/mcp-ts-core/tree/main/docs/telemetry). | `false` |\n\nSee [`.env.example`](./.env.example) for the full list of optional overrides.\n\n## Running the server\n\n### Local development\n\n- **Build and run:**\n\n ```sh\n # One-time build\n bun run rebuild\n\n # Run the built server\n bun run start:stdio\n # or\n bun run start:http\n ```\n\n- **Run checks and tests:**\n\n ```sh\n bun run devcheck # Lint, format, typecheck, security\n bun run test # Vitest test suite\n bun run lint:mcp # Validate MCP definitions against spec\n ```\n\n### Docker\n\n```sh\ndocker build -t attack-surface-mcp-server .\ndocker run --rm -e MCP_TRANSPORT_TYPE=http -p 3010:3010 attack-surface-mcp-server\n```\n\nThe Dockerfile defaults to HTTP transport, stateless session mode, and logs to `/var/log/attack-surface-mcp-server`. OpenTelemetry peer dependencies are installed by default — build with `--build-arg OTEL_ENABLED=false` to omit them.\n\n## Project structure\n\n| Directory | Purpose |\n|:----------|:--------|\n| `src/index.ts` | `createApp()` entry point — registers tools/resources and inits the six services. |\n| `src/config` | Server-specific environment variable parsing and validation with Zod. |\n| `src/mcp-server/tools` | Tool definitions (`*.tool.ts`). |\n| `src/mcp-server/resources` | Resource definitions (`*.resource.ts`). |\n| `src/services` | Domain service integrations (`ct`, `dns`, `tls`, `http`, `registration`, `shodan`). |\n| `src/utils` | SSRF guard and input validation. |\n| `tests/` | Unit and integration tests mirroring `src/`. |\n\n## Development guide\n\nSee [`CLAUDE.md`/`AGENTS.md`](./CLAUDE.md) for development guidelines and architectural rules. The short version:\n\n- Handlers throw, framework catches — no `try/catch` in tool logic\n- Use `ctx.log` for request-scoped logging, `ctx.state` for tenant-scoped storage\n- Register new tools and resources via the barrels in `src/mcp-server/*/definitions/index.ts`\n- Every outbound connection to a user-supplied target must pass the SSRF guard (`assertSafeDomain` / `assertSafeUrl` / `assertSafeResolverIp`) before connecting\n- Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields\n\n## Contributing\n\nIssues and pull requests are welcome. Run checks and tests before submitting:\n\n```sh\nbun run devcheck\nbun run test\n```\n\n## License\n\nApache-2.0 — see [LICENSE](LICENSE) for details.\n",
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