Web Application and API Penetration Testing

Your web applications and APIs are where customers, data and business logic meet the internet. We test them the way a determined attacker would, and show you what to fix before someone else finds it.

What we test

  • Authentication and sessions. Login, multi-factor flows, password reset, token handling and session lifetime.
  • Access control. Whether one user can reach another user’s records or an administrator’s functions, including object-level and function-level checks on every API endpoint.
  • Input handling. Injection, cross-site scripting, unsafe file upload and unsafe deserialization.
  • Business logic. Abuse of legitimate workflows such as payments, approvals, refunds and account recovery, which scanners cannot judge.
  • API-specific risks. Excessive data in responses, mass assignment, missing limits on requests and resources, and undocumented endpoints.
  • Configuration. Transport security, security headers, verbose errors and exposed administration or debugging interfaces.

Standards we work from

We organize coverage around recognized references instead of a private checklist: the OWASP Top 10 and OWASP API Security Top 10 for risk categories, the OWASP Application Security Verification Standard (ASVS) for depth, and PTES and NIST SP 800-115 for how the engagement is planned and run. Automated scanning helps with breadth, but the findings that matter most usually come from an analyst reading how the application behaves and testing what it assumes.

How an engagement works

  1. Scope. Which applications and environments, which user roles, which test accounts, and what is off limits, all agreed in writing as rules of engagement.
  2. Test. Mapping the application, then authenticated and unauthenticated testing with controlled exploitation. If we find something serious, we tell you right away rather than waiting for the report.
  3. Report. Each finding comes with evidence, reproduction steps, risk rating and a fix your developers can act on.
  4. Retest. When fixes are made, we retest the findings so you can show they are closed.

Test accounts and environments

The best results come from testing with an account for each role, so we can check what each role can and cannot do. Where possible we test a staging copy that mirrors production. If testing must happen in production, we agree handling of data and timing beforehand.

What you receive

  • Executive summary for leadership
  • Technical findings with evidence and reproduction steps
  • Findings prioritized by risk and effort
  • Remediation guidance written for developers
  • Retest confirmation

When to test

  • Before a new application or major release goes live
  • After significant changes to authentication, payments or data handling
  • When you expose an API to customers or partners
  • When a customer, insurer or framework asks for independent testing

Testing a wider environment? See all penetration testing services. Our team has delivered hundreds of assessments, has worked with large enterprises including Fortune 50 organizations, and has experience with HIPAA, FISMA and ISO frameworks and with nation-state and APT-level threat actors.

Book a scoping call

Tell us what you want tested and why, and we will talk through scope, timing and what a useful report looks like for your team. Prefer to write? Email info@core-infosec.com or use the contact form. We reply to form and email enquiries by the next business day.

Penetration testing is performed only with written authorization.