Web Application Penetration Testing Services

A web application penetration test is an authorized security assessment that identifies and exploits vulnerabilities in a web application from an attacker’s perspective.

The goal goes beyond finding technical problems.

A thorough web application penetration test should help answer questions like:

“Can an unauthenticated attacker access information they should not reach?”

“Can one user access another user’s information?”

“Can an attacker bypass authentication or authorization controls?”

“Can someone manipulate business logic to perform an unauthorized action?”

To answer these questions, Tanner Security uses automated scans, manual testing, vulnerability confirmation checks, safe exploitation, and analysis of possible attack paths.

Web applications are now a key part of many business operations.

Customers use them to manage accounts, employees use them to access internal systems, businesses use them to process transactions, and applications exchange information with APIs, cloud platforms, databases, and third-party services.

This complexity can create security risks.

An application can enforce authentication correctly and still expose sensitive information through an authorization flaw. It can use strong encryption and still allow a user to manipulate the workflow in a way the developers never intended.

These vulnerabilities often require understanding how the application works, not simply which software components it uses.

This is a main drawback of relying only on automated scans.

Tanner’s recent web application penetration testing engagement illustrates this distinction. The team evaluated authentication, authorization, session management, input validation, access controls, business logic, and sensitive-information handling, including whether multiple weaknesses could combine into a more serious attack path.

Tanner Security can align web application penetration testing with the OWASP Web Security Testing Guide (WSTG) and current OWASP application-security practices.

OWASP describes the WSTG as a comprehensive testing framework for web applications and web services, not a rigid checklist. The guide covers information gathering, configuration, identity management, authentication, authorization, session management, input validation, error handling, cryptography, business logic, client-side testing, and API testing.

We also use the current OWASP Top 10:2025 as an important reference point when evaluating web application risk. The 2025 edition includes Broken Access Control, Security Misconfiguration, Software Supply Chain Failures, Cryptographic Failures, Injection, Insecure Design, Authentication Failures, Software or Data Integrity Failures, Security Logging and Alerting Failures, and Mishandling of Exceptional Conditions.

OWASP gives us a solid foundation for security testing. Tanner Security then customizes the assessment to fit your application’s technology, features, user roles, data, business processes, and specific risks.

The scope of testing depends on your application and what you want to achieve.

Authentication: We evaluate how the application identifies users and protects authentication. Testing can include login functionality, password controls, multifactor authentication, account recovery, authentication bypass, and other identity management controls.

Authorization and Access Control: Authentication tells the application who the user is. Authorization determines what that user can do. Tanner Security tests whether users can access functions, records, files, or administrative features that their roles should not permit. Broken access control represents the first category in the current OWASP Top 10:2025, reinforcing the importance of testing permissions rather than assuming that successful login means the application protects data correctly.

Session Management: A secure login does not always mean the entire session is safe. We evaluate session creation, session handling, expiration, logout behavior, session identifiers, and other controls that protect an authenticated user’s access.

Input Validation: We evaluate how the application handles data supplied by users and external systems. Testing can include injection risks, cross-site scripting, command injection, SQL injection, and other weaknesses that can arise when applications trust input, they should treat as untrusted.

Business Logic: Business logic testing focuses on how the application performs its intended functions. We may attempt to skip required steps, modify transaction values, repeat requests, manipulate parameters, change workflow sequences, or perform actions using a user role that should not have access. Automated scanners often miss these weaknesses. Each function might work as expected, but the overall workflow can still allow unintended actions.

APIs: Web applications often rely heavily on APIs. Tanner Security can assess REST APIs, GraphQL APIs, and other application interfaces for authentication, authorization, input validation, data exposure, business logic, and related security weaknesses.

Sensitive Information Exposure: We evaluate whether users or unauthenticated visitors can access information they should not see. The assessment may examine application responses, files, APIs, error messages, browser-side functionality, and other areas where sensitive information could unintentionally appear.

Security Configuration: We examine application and server configurations that could expose unnecessary functionality, administrative interfaces, debugging information, or other security weaknesses.

A thorough penetration test is most effective when we examine your application from several angles.

Unauthenticated Testing: Unauthenticated testing examines what an attacker can discover and exploit without legitimate credentials.

This angle helps us find weaknesses in public features, authentication, exposed data, APIs, and other areas attackers can reach before logging in.

Authenticated Testing: Authenticated testing examines what happens after an attacker obtains or legitimately receives application credentials.

This approach can uncover vulnerabilities that outside testing might miss, especially issues with authorization and user roles.

For example, Tanner Security can test whether a standard user can access another customer’s records, invoke administrative functions, manipulate another user’s transactions, or reach functionality outside the user’s intended privileges.

Testing Multiple User Roles: Applications often contain multiple levels of access.

A customer, employee, manager, administrator, and support representative may each have different permissions.

By testing different roles, we can find issues where users gain access they should not have, either at their own level or at a higher level.

Tanner’s recent web application penetration test specifically examined role-based access, authentication, authorization, business logic, and whether vulnerabilities could combine into more serious attack paths.

APIs have become central to modern web applications.

They connect front-end applications to backend services, mobile applications to databases, cloud systems to business applications, and internal systems to external platforms.

An API weakness can expose more than one part of your system.

Tanner Security can evaluate API authentication, authorization, input handling, data exposure, business logic, rate controls, and other applicable security mechanisms.

OWASP’s Web Security Testing Guide specifically includes API testing within its broader web application testing framework.

For businesses with extensive API infrastructure, Tanner can combine web application testing with dedicated API penetration testing.

Every Tanner Security engagement starts with defined authorization, scope, objectives, and rules of engagement.

1. Planning and Scoping: We identify the applications, environments, URLs, APIs, user roles, authentication requirements, integrations, and systems included in the assessment. We also identify production systems or functionality that require special testing limits.
2. Reconnaissance and Application Mapping: We examine the application from an attacker’s perspective and identify functionality, technologies, entry points, authentication mechanisms, APIs, user roles, and other components relevant to security testing.
3. Automated Testing: We use automated tools to identify common vulnerabilities and areas that deserve additional investigation. Automated tools help cover more ground, but they cannot replace manual testing.
4. Manual Testing: Our testers manually investigate authentication, authorization, session management, business logic, input validation, APIs, access controls, and other application functions.
5. Exploitation and Validation: Where the rules of engagement allow, we attempt controlled exploitation to determine whether a suspected vulnerability creates a meaningful security impact.
6. Attack-Path Analysis: We evaluate whether multiple vulnerabilities can combine to create a more serious compromise. This step often uncovers the most important issues, since several small weaknesses can lead to a serious risk.
7. Reporting: We document vulnerabilities, evidence, severity, potential business impact, and practical remediation recommendations.
8. Retesting: After your development or IT team addresses significant findings, Tanner Security can perform targeted retesting to determine whether the vulnerability remains exploitable.

These services complement each other, but they serve different purposes.

A vulnerability scan primarily uses automated tools to identify known weaknesses and potential vulnerabilities.

A website penetration test combines automated testing with manual analysis, exploitation, business-logic testing, authentication testing, authorization testing, and attack-path analysis.

• A scanner might identify a suspicious parameter.
• A penetration tester asks what happens when that parameter changes.
• A scanner might identify a potentially weak access-control endpoint.
• A penetration tester attempts to access another user’s information.
• A scanner might identify several vulnerabilities independently.
• A penetration tester evaluates whether those weaknesses can work together to create a larger compromise.

For this reason, Tanner recommends treating vulnerability scanning and penetration testing as complementary, not as substitutes. Vulnerability assessments are useful for ongoing monitoring, while penetration testing checks if vulnerabilities can actually be exploited.

The terms overlap, but the emphasis differs.

A website penetration test focuses on applications delivered through web technologies and the security risks associated with their functionality.

A custom application penetration test focuses on proprietary software where unique business logic, architecture, integrations, or application functionality may require deeper manual testing.

A custom application can also qualify as a web application.

The best approach depends on how your software works and what you want to achieve from the assessment.

Web application testing can support several cybersecurity and compliance programs, but the exact requirement depends on the applicable standard and environment.

PCI DSS includes application-layer penetration testing within its applicable penetration-testing requirements. Tanner’s PCI CDE penetration-testing service specifically addresses application testing when it falls within the approved PCI scope.

Businesses may also use application penetration testing to support broader security programs involving NIST, ISO 27001, HIPAA, CMMC, customer security requirements, or internal risk-management objectives.

A penetration test provides useful security evidence, but it does not guarantee compliance with every standard.

Tanner Security brings more than two decades of cybersecurity consulting experience to application security and penetration testing.

Our penetration-testing services include network, internal, external, cloud, OWASP, mobile application, custom application, authenticated, black box, gray box, white box, and PCI-CDE penetration testing services.

This experience is important because application vulnerabilities are rarely isolated.

Authentication connects to authorization.

Authorization connects to business logic.

Business logic connects to APIs.

APIs connect to databases and cloud services.

A small weakness in one part of the application can create a much larger attack path when combined with another weakness.

Tanner’s recent web application penetration testing case study demonstrates this approach. The team used authenticated and unauthenticated testing, manual analysis, business-logic testing, session testing, and attack-path analysis to determine what an attacker could realistically accomplish.

We also align our testing with established application-security resources such as the OWASP Web Security Testing Guide and current OWASP Top 10.

Most importantly, we explain our findings in ways IT teams and business leaders can both understand.

Web application security often involves more than just the application itself. Tanner Security offers other services to give you a full view of your security risks.

Website Penetration Testing: Evaluate API authentication, authorization, data exposure, input handling, and business logic.

Custom Application Penetration Testing: Assess proprietary software with complex workflows, integrations, user roles, and business logic that require deeper manual testing.

Mobile Application Penetration Testing: Test iOS and Android applications along with the APIs and backend systems that support them.

SQL Penetration Testing: Focus specifically on SQL injection and database-query manipulation within web applications and APIs.

Cloud Penetration Testing: Evaluate AWS, Azure, Microsoft, and hybrid cloud environments for exploitable security weaknesses and attack paths. Read more about the top 12 AWS misconfigurations.

External Network Penetration Testing: Test internet-facing infrastructure, remote-access systems, public services, and other external attack surfaces.

Internal Network Penetration Testing: Determine what an attacker could accomplish after gaining an initial foothold inside the network.

Network Vulnerability Assessment: Identify known vulnerabilities and configuration weaknesses between penetration-testing engagements.

PCI CDE Penetration Testing: Test web applications and related systems that fall within the Cardholder Data Environment and applicable PCI DSS scope.

Your application might look secure at first, but it could still have weaknesses that automated scans miss.

A web application penetration test shows your business how an attacker could exploit authentication, authorization, application logic, APIs, and other features to access sensitive data or perform actions they should not.

Tanner Security uses both automated testing and manual analysis, along with real-world attack techniques, to find vulnerabilities and explain what they mean for your business.