Application security
Application Penetration Testing
Find the flaws that put your users, data and business at risk. GDF combines hands-on application testing, AI-assisted analysis and source-code review to expose weaknesses and give developers clear fixes.
Test what an attacker could do to your application
Could a user read another customer's records, bypass an approval or gain administrative access? GDF examines how your application actually behaves. We test the web interface, APIs, user roles and business rules to find weaknesses that affect your customers and operations.
Our testers combine manual examination with selected tools and AI-assisted analysis. We reproduce the findings, explain the affected data or action and give your developers the evidence needed to correct the problem. Testing can cover a new release, an existing application or a wider network and application penetration test.
Go beyond the login screen
- Web applications: examine authenticated and public features, input handling and server-side behavior.
- APIs: test object access, authorization, data exposure and workflow enforcement directly.
- Authentication and sessions: assess login, account recovery, multifactor flows, tokens and session handling.
- Roles and customer separation: test access between ordinary users, privileged accounts and different customer organizations.
- Business logic: examine approval, transaction and state changes, including actions performed out of their intended sequence.
- Mobile application connections: include supported mobile clients, local storage and API interactions where relevant to the scope.
Put your testing priorities on the table
Tell us what you need tested and when. We can discuss the approach, deliverables and price.
Choose the access that fits the question
Black-box application testing
We assess the application from an outside perspective with limited internal information. This can show what the public-facing application exposes and which behaviors an unauthenticated user can reach.
Gray-box application testing
Selected test accounts, role details and API documentation help us examine authenticated features and permission boundaries. We can compare what different users are allowed to do with what the application actually permits.
White-box testing and source-code review
Source access lets us inspect the code behind a finding and review security-sensitive functions directly. We can examine authorization decisions, input handling, data flows and business rules, then validate relevant behavior in the running application. Learn more about source-code security review.
AI assistance with a tester accountable for the finding
We can use approved AI tools to help organize application information, correlate observations and develop test cases. The tester directs the work, checks the results and documents the evidence. Your team gets findings it can reproduce and discuss with the person who examined the application.
Application and network testing can also support a wider red-team objective. The combined penetration testing offering explains how we assess attack paths, detection and response across the agreed environment.
The decisions the application makes when no one is watching
An application can encrypt every byte in transit and still show one customer another customer's invoices. It can enforce strong passwords and still let a user approve their own expense report. Application penetration testing at GDF targets the permission checks, the APIs behind the interface and the business workflows that decide what a user can actually do. Developers get findings they can reproduce and fix with confidence.
We start by learning the application: who the users are, which data is sensitive, which transactions would hurt if they went wrong. A customer portal, a payments workflow, a partner API and an internal admin console fail in different ways and deserve different test priorities. Early input from your product owner keeps testing focused on the decisions and workflows that matter.
Authorization checks, including the ones only the API sees
Authorization is the application's decision about what an authenticated user is allowed to do. We compare the intended permissions with the actual behavior, including behavior reached only through application programming interfaces (APIs) that the browser never shows.
The classic case is an insecure direct object reference, or IDOR. A request carries a record identifier. The tester changes it to another user's identifier. If the server independently checks that the requesting user is entitled to that record, the control holds. If the server trusts that the user would never have seen that identifier, it fails. A hidden button or an unguessable identifier is no substitute for that server-side check, so we test the server directly.
When the scope covers multiple customer organizations, we test the walls between tenants. We also look at administrative roles, service accounts, impersonation features and anything that exports or shares data, since those are where tenant separation most often leaks. Test accounts and representative data let us probe those boundaries without pulling production records into the report.
Following the whole transaction, out of order
Business logic testing asks whether a workflow stays secure when steps are repeated, skipped, delayed or performed by the wrong role. Account recovery, approval chains, refunds, invitations and file sharing are the usual suspects. Before we can call an odd result a defect, we have to know what the business rule was supposed to be, which is another reason the scoping conversation includes someone who owns the product.
Some of the worst problems live between components. The interface revokes a user's access. A background export job, or a token issued yesterday, keeps working for another day. We follow the agreed workflow far enough to explain the real exposure and the conditions required to trigger it.
Evidence a developer can reproduce
Every finding identifies the build and environment, the affected function, the user role required, the exact test sequence and the observed result. Supporting requests and responses, or code references where we have them, let the developer go straight to the failed control. Sensitive payloads stay out of the executive summary.
We discuss the fix in terms of the intended permission or business rule, because patching the one request we found while leaving the pattern in place just moves the problem. Retesting checks the original condition and the related cases we agreed on. Leadership reads a plain language account of why the finding matters. The development team reads the reproduction steps and gets to work.
Make the results useful to developers and leadership
Developers receive the affected feature, user role, reproduction steps, observed impact and recommended correction. Security leaders receive a prioritized view of the application's exposure and how the findings affect the business.
We agree on test accounts, data handling, operating constraints and escalation contacts before work starts. For a pre-release assessment, we can test a stable staging build and plan the appropriate follow-up. Retesting checks the agreed fixes against the original findings and relevant variants.
- Application and API test scope
- Validated findings with supporting evidence
- Code references where source review is included
- Remediation guidance for the development team
- Executive summary and retest record
Frequently asked
Common questions
Can you test before a release?
Yes, and it is the best time. A stable test build, representative roles and a clear release boundary make the results more useful. If the code changes materially after testing, plan on a follow-up.
Is a scanner enough for this work?
A scanner will find missing headers and known library versions. It cannot know that a sales rep should never see another rep's pipeline or that a refund must not exceed the original charge. Business rules and user relationships need a human who understands them and tests them on purpose.
Can a focused test address one critical workflow?
Yes. Scope can concentrate on one new feature or one high-consequence transaction, with the limits stated plainly in the report.
Can you test our APIs as well as the web application?
Yes. We test API access and behavior directly, including permissions, object access, data exposure and business workflows.
Do we have to provide source code?
Black-box and gray-box testing can proceed with the agreed application access. Source-code review is an additional option when you want deeper implementation analysis.
Can you test different user roles?
Yes. Providing selected test accounts lets us examine ordinary users, privileged roles and the separation of data between customers or business units.
Can testing happen before a release?
Yes. We can assess a stable staging build, report findings to developers and plan retesting as fixes are delivered.
Can application testing be combined with a network pen test?
Yes. We can scope the application, APIs, identities and connected infrastructure together so the assessment examines the paths between them.
Bring GDF into the release conversation
Bring GDF into the release conversation before the application goes live or a sensitive workflow changes. Tell us what the application does, who uses it, which data or transactions matter most and what timeline your team is working toward. We can scope application penetration testing, API penetration testing, remediation support and retesting around the findings your developers need. Your initial consultation is free.
Bring GDF into the release conversation
Related services and resources: source code review, cybersecurity penetration testing, vulnerability assessments.
Connect application testing with your wider security plan
For connected infrastructure and detection exercises, explore network penetration testing and red teaming. For implementation analysis, see source-code review.
Plan your application assessment
Tell us about the application, its users and your next release or assessment deadline. We can discuss test access, source review and the findings your developers need.