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Web Application Security

Web Application Penetration Testing

Manual, evidence-driven testing of the applications your customers rely on.

An authorized attacker, testing your application so you don't get hacked.

Web application penetration testing puts a skilled, authorized attacker in front of your application before a real attacker finds it. Our senior penetration testers work by hand: testing inputs, edge cases, and breaking assumptions behind each workflow. Small weaknesses get chained into a demonstrated compromise, and every finding is written up in the report with the proof and a specific fix.

90%+
Assessments uncovering critical findings
100%
senior-led testing
Tier 1
Banking & capital markets experience
200+
Penetration tests delivered

What a web application pentest covers

Authentication

Login, registration, password reset and MFA flows: credential handling, brute-force resistance, and the recovery paths attackers can slip through.

Session handling

Token generation and entropy, cookie flags, session fixation, concurrent sessions, and expiry and logout behaviour across devices.

Access control

Horizontal and vertical privilege escalation, insecure direct object references, and the role boundaries between customers, staff and administrators.

Business logic

Race conditions, negative values, skipped steps and order-of-operations flaws in the workflows that move money or approve requests.

Injection classes

SQL injection, cross-site scripting, command injection, template injection and file upload abuse, all tested manually.

APIs behind the frontend

The REST and GraphQL endpoints your browser and mobile app rely on, tested for broken object-level authorization and excessive data exposure among other flaws.

Testing follows the OWASP Web Security Testing Guide (WSTG), and the engagement structure (scoping, testing, reporting, retest) follows PTES and NIST SP 800-115 and is documented on our penetration testing methodology page.

The public standards set the coverage baseline. On top of them sits our in-house testing methodology, built through our testers' collective years of experience and adapted to the target in front of us.

Web application penetration testing: a tester reviewing application code for vulnerabilities

Every finding is backed by a proof of concept

Every finding in a ClarenSec report is verified by hand and carries a proof of concept: the exact request, the parameter we changed, and the response that proves the impact, with sensitive values redacted. Alongside it sit reproduction steps your developers can follow in minutes, a CVSS v3.1 severity, and a specific fix. If we could not demonstrate an issue within the test window, the report will indicate that and explain why.

Deliverables and the retest

You receive an executive summary written for management and a technical report your engineers can remediate from. Once your fixes are complete, a retest of the fixed findings is part of the engagement, and the retest report states which issues are closed and which remain open.

Executive summary for management and board review
Technical report with CVSS v3.1 scoring and proof-of-concept evidence
Prioritized remediation guidance per finding
Retest of fixed findings included in the engagement
OWASP WSTG and ASVS references where they help remediation
Post-assessment walkthrough call with your engineers

Web application pentest questions, answered

How long does a web application penetration test take?

It depends on the size and complexity of the application. A single application with a handful of user roles typically needs one to two weeks of testing plus reporting time; a large multi-tenant platform needs more. We confirm the timeline after a short scoping walkthrough of the application.

Should we test in production or staging?

A staging environment that mirrors production is the safest choice. Where only production exists, we test it with guardrails: dedicated test accounts, non-destructive payloads, agreed testing windows, and an emergency contact on both sides. 

What do we need to provide before testing starts?

The application URLs in scope, test accounts for each user role (ideally two per role), a technical contact who is reachable during the testing window, and written authorization to test. If the application sits behind a WAF or an allowlist, we agree in advance if our addresses will be whitelisted.

How is a web application penetration test different from a vulnerability scan?

A scan runs automated checks and lists possible issues, many of them being false positives. A penetration test is manual: a tester chains weaknesses together and proves the impact with a proof of concept. Access control and business logic flaws, where the real risk in a web application usually sits, only show up under manual testing.

Scope your web application pentest

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