Web App Penetration Testing

Pentest a web application

Black-box (and optionally source-assisted) penetration testing of a running web app with Strix's autonomous agents. Every reported finding is validated with a working exploit, so there are no signature-based false positives to triage.

Install, LLM setup, all CLI flags, and the managed-cloud alternative are covered in the penetration-testing-with-strix skill — read it if the target is not a running web app, or if strix --version fails. This skill is the web-app-specific workflow.

1. Confirm authorization and scope

Before running anything, establish:

• The target is the user's (or they are explicitly authorized to test it). Never pentest a third-party site on a hunch.
• Which environment. Prefer staging over production; agents send real exploit payloads and will create/modify data.
• Out-of-scope paths — payment flows, mass-email endpoints, admin destructive actions, third-party SSO providers.
• Credentials. Most real vulnerabilities live behind login. Without a test account, the agents only ever see the marketing surface.

Ask for anything missing rather than guessing.

2. Run the scan

strix -n -t https://staging.example.com --max-budget 20 \
  --instruction "Test account: qa@example.com / <password>. In scope: /app/*, /api/*. Do not touch /billing or send email. Focus on access control between the two seeded orgs."

Notes that matter for web apps specifically:

• Give it credentials via --instruction (or --instruction-file for anything long), including how to log in if the flow is unusual (magic link, SSO, MFA-exempt test user).
• Two accounts beat one. Multi-tenant IDOR and broken-access-control bugs — consistently the highest-impact class in web apps — can only be proven when the agent can attempt cross-account access.
• Add the repo for white-box depth when you have the source: -t https://github.com/org/app -t https://staging.example.com (or a local path). Source access materially improves coverage of business-logic and authorization flaws.
• Localhost works. Point at http://host.docker.internal:3000 (Docker Desktop) so the sandbox can reach a dev server on the host.
• --scan-mode quick for a fast dev-loop pass, standard (~30 min) for a normal review, deep for pre-release assurance. Always set --max-budget.

For a hosted run with no Docker/LLM key, or when the user wants a shareable dashboard and an auditor-ready PDF, use the cloud path in managed-pentesting-with-strix instead — same engine, same findings.

3. Review results

Read strix_runs/<run>/penetration_test_report.md first, then per-finding files in vulnerabilities/. Each contains the PoC — re-run it yourself to confirm before reporting to the user.

Exit codes: 0 no validated vulns in what was analyzed, 2 vulnerabilities found, 1 fatal error. A 0 is not proof of full coverage — if the budget or turn cap was hit the scan wraps up early, so check run.json status and cost against --max-budget before calling the app clean.

4. Fix and verify

Hand findings to the fix-security-vulnerabilities-with-strix skill: patch the root cause, then re-run Strix against the same target to prove the exploit no longer works. Re-testing is the only reliable confirmation a fix landed.

To keep the app tested on every change rather than once, wire Strix into CI with ci-security-scanning-with-strix.