Web Application Security Testing
Identify security weaknesses across modern web applications before attackers exploit them.
Web applications carry authentication, user data, payments, administrative functionality and business logic. They are also the part of an organization that is permanently reachable from the internet, which makes them a natural starting point for both automated scanning and targeted attacks.
Our web application security testing looks past the issues a scanner can find. Automated tools are good at surfacing known patterns; they are considerably weaker at authorization flaws, business logic abuse and the chains where several low-severity findings combine into something that actually matters. See Business Logic Vulnerabilities for examples of what automated scanners miss.
A modern web application is several layers, each with its own failure modes.
- CLIENTBrowserClient-side logic, stored data, exposed configuration
- EDGEDelivery & WAFRouting, headers, caching, protective controls
- APPApplicationAuthentication, session handling, business logic
- APIInternal APIsAuthorization boundaries between components
- DATAData storesAccess paths, exposure, separation between tenants
Testing is performed against systems and scope you authorize in writing.
What is web application security testing?
Web application security testing is a manual, engagement-based assessment of a web application’s authentication, authorization, session handling, input validation, business logic, file handling, API interactions, data exposure and security configuration, looking for the kinds of flaws that automated scanners typically miss, such as one customer being able to reach another customer’s data. These map closely to the OWASP Top 10:2025 for Penetration Testers.
Who needs it? Organizations running SaaS platforms, fintech applications, healthcare portals, e-commerce sites, internal business applications and customer portals, most often before a public launch, after a major release, when an enterprise buyer is asking for evidence of testing, or once authorization rules have grown too complex to reason about internally.
How TMG Security helps. TMG Security tests these applications manually and with tooling through a recon, map, test, validate, report and retest process, and delivers a written report your team can act on, together with a retest to confirm remediation.
What we test
Testing approach
- 01RECONUnderstand the application, its users and the authorized scope.
- 02MAPEnumerate functionality, roles, endpoints and trust boundaries.
- 03TESTWork through the areas above, manually and with tooling.
- 04VALIDATEConfirm findings are real and reproducible, and remove false positives.
- 05REPORTEvidence, severity, business context and remediation guidance.
- 06RETESTVerify that addressed issues no longer reproduce.
Why web application security matters
A web application is usually the largest piece of custom code an organization exposes to the internet. Frameworks and platforms handle many classic vulnerability classes well, but they cannot know your authorization rules, your workflows or which combination of steps should never be possible.
That is where most of the meaningful findings sit. An authorization flaw that lets one customer read another customer’s records rarely shows up as a scanner alert; it shows up when someone deliberately tries it against a live application with the right context. This is the BOLA in API Security pattern, showing up at the application layer rather than the API alone.
Organizations this typically applies to.
Testing is scoped per engagement. Nothing here implies industry-specific certification or accreditation.
When Should You Test a Web Application?
A report your team can actually act on.
Exact deliverables and their format are confirmed during scoping.
What was assessed, what was found and what it means, written to be read by people who will not read the technical detail.
Each finding described with enough precision for an engineer to locate and understand it.
Reproduction detail and supporting evidence, so findings can be verified rather than taken on trust.
Severity considered against your environment, not only against a generic scoring table.
Practical direction on addressing each finding, including where a change belongs architecturally.
Verification that addressed findings no longer reproduce, within the agreed retest scope.
Adjacent parts of the attack surface.
How pricing and scope are determined
There is no published fixed price for web application testing. Each engagement is scoped and priced individually based on factors such as the number of applications in scope, the number of user roles that need authenticated testing, the size and complexity of the application, whether testing is scoped to staging or production, and whether a retest is included. These factors are discussed during an initial scoping conversation before a quote is provided.
Questions we get asked before an engagement.
A scan is automated and pattern-based; it is efficient at finding known issues across a broad surface. A penetration test adds a human working through your application’s specific roles, workflows and authorization rules, which is where business logic and access control findings tend to come from. Most engagements use both.
Either can work. Staging avoids any risk to live data and is often preferred, provided it genuinely mirrors production — a staging build with different roles, feature flags or data separation can hide the issues that matter. We agree the environment and its limitations before testing starts.
Testing is conducted within an agreed scope and rules of engagement, and the intent is to avoid disruption. Some checks carry inherent risk, so those are discussed and explicitly agreed — or excluded — before work begins rather than decided mid-test.
It depends on the goal. Unauthenticated testing shows what an anonymous attacker reaches. Authenticated testing across multiple roles is what reveals authorization and business logic flaws, so accounts at each privilege level are usually requested.
Retesting is part of how we scope engagements, because a finding is only closed once it has been verified as fixed. The retest window and what it covers are agreed as part of the engagement.
Duration depends on scope: the number of applications and user roles in scope, the size and complexity of the application, and whether a retest is included. Timelines are agreed as part of scoping, once these factors are known.
Request a Web Application Security Assessment
Tell us what the application does, who uses it and what would hurt most if it were compromised. We will work back from there to a scope that makes sense.