qa-sec-scan-mcp-server

An MCP server that passively scans HAR files — the kind QA automation already produces (e.g. via Playwright's recordHar option) — for common security issues.

It never sends network requests of its own. It only analyzes HTTP traffic that already happened, captured in a .har file you point it at. That makes it safe to run against any environment, including production, since it can't cause side effects.

What it catches

Related MCP server: middleBrick

Setup

npm install
npm run build

Producing a HAR file from your test suite

This scanner needs response headers, cookies, and response bodies to work — so however you generate the HAR, make sure content isn't stripped out.

Playwright

const context = await browser.newContext({
  recordHar: { path: "test-results/network.har" },
  // defaults: mode "full", content "embed" for a .har path — includes headers, cookies, and bodies.
  // Don't override to mode: "minimal" or content: "omit", or the rules that inspect
  // response bodies (DATA-001, DATA-002, DATA-003) and cookies (COK-001) will have nothing to check.
});

// ... run your test, make requests via `context` or any page created from it ...

await context.close(); // the HAR is only written to disk once the context closes

If you're using the Playwright Test runner rather than driving browser/context by hand, the equivalent is setting recordHar in your project's use config, or per-test via test.use({ recordHar: { path: "..." } }).

Other tools that can emit HAR (mitmproxy, browser DevTools' "Save as HAR", har-recorder style middlewares) work too — harParser.ts reads the standard HAR 1.2 format, it isn't Playwright-specific.

Using this MCP with an AI client

For interactive, AI-assisted triage — asking an assistant to scan a HAR and explain what it finds, the way this project was built and tested — add the server to your MCP client's config (e.g. Claude Desktop):

{
  "mcpServers": {
    "qa-sec-scan": {
      "command": "node",
      "args": ["/absolute/path/to/qa-sec-scan-mcp-server/dist/index.js"]
    }
  }
}

Restart your client after any rebuild. MCP clients keep a long-lived server process running; a tsc rebuild overwrites the files on disk but does not restart the already-running process, so it'll keep serving stale code until you restart the client.

Tool: secscan_scan_har

Args:

• harFilePath (string) — absolute path to a .har file

• response_format ("markdown" | "json", default "markdown")

Returns a scan summary (counts by severity) plus a list of findings, each with the rule that fired, the offending request, evidence, and a remediation suggestion. Text responses are capped at the 50 highest-severity findings (worst first); the full, untruncated result set is always available via the tool's structured content, for any client reading that instead of the text.

In practice: point your AI client at a HAR file your test suite produced and ask it to scan for security issues — no manual invocation syntax needed, the assistant calls the tool for you.

Using this as a CI gate (no AI client needed)

If you want a deterministic pass/fail check in your pipeline instead — build fails if any critical finding shows up — use the bundled CLI, which runs the same scan logic directly without going through the MCP protocol at all:

npm run gate -- path/to/network.har

Exits 0 if there are no critical findings, 1 if there are (or if the HAR couldn't be scanned at all — the gate fails closed on errors rather than silently passing).

Example as a step in a CI workflow that already runs Playwright:

- name: Run Playwright tests
  run: npx playwright test

- name: Security gate on captured HAR
  run: npm run gate -- test-results/network.har

If your suite produces multiple HAR files (one per test, say), loop the gate command over each path rather than hardcoding one.

Development

npm run dev    # tsx watch — fast iteration, does NOT type-check
npm run build  # tsc — the real correctness gate for the code itself

Architecture

HAR file → harParser.ts → Transaction[] → rules/*.ts (each independent) → scanEngine.ts → ScanReport │ ┌─────────────────────┴─────────────────────┐ │ │ src/tools/scanHar.ts src/cli.ts (MCP tool, for AI clients) (deterministic CI gate)

Parsers translate raw formats into a normalized Transaction. Rules never touch raw HAR shapes — they only see Transaction. The scan engine and rule set are shared between both consumers (the MCP tool and the CLI gate); only the presentation and exit-code logic differ.