Application Security Testing (AST): Technologies and Best Practices

What Is Application Security Testing?

Application security testing involves analyzing and evaluating software applications to identify vulnerabilities. The process includes techniques to find weaknesses in an application that attackers could exploit. Increasingly, this testing is done at early stages of the development lifecycle (a concept known as “shift left”), ensuring that security is embedded in the system from the onset. Methods can range from code scanning to real-world attack simulations.

Application security testing is crucial for protecting sensitive data and maintaining user trust. It helps prevent unauthorized access and data breaches by detecting and mitigating vulnerabilities before they can be exploited. As cyber threats evolve, application security testing adapts to identify new vulnerabilities.

Application security testing is commonly divided into three categories:

• Black-box testing (including methods like SAST and penetration testing) evaluates an application without any knowledge of its internal structures. Testers simulate attacks based on external inputs to find flaws.

• Gray-box testing (including methods like IAST and RASP) offers a partial understanding of the system, focusing on both functional testing and code locations with higher risks.

• White-box testing (including methods like DAST and SCA) provides full visibility into the application, analyzing code rigorously for vulnerabilities.

Application Security Testing Technologies: Common Solution Categories

Static Application Security Testing (SAST)

Static application security testing (SAST) is a white-box testing method performed early in the development cycle. SAST analyzes source code, bytecode, or binaries, seeking vulnerabilities without executing the code. By examining code syntax and structure, SAST identifies issues such as SQL injection and buffer overflows. This proactive approach facilitates immediate remediation, enhancing security at the foundational level.

SAST tools integrate easily into development environments, offering continuous feedback to developers on security defects as code is written. This early detection helps reduce the cost and time required to fix vulnerabilities. However, SAST can struggle with false positives, requiring human oversight to discern valid issues.

Dynamic Application Security Testing (DAST)

Dynamic application security testing (DAST) evaluates an application during runtime, focusing on external threats. Unlike SAST, DAST does not require access to the source code. Instead, it simulates cyberattacks to find vulnerabilities within running applications. Common targets include application logic flaws and security misconfigurations that could be exploited in production environments.

DAST is effective at identifying vulnerabilities visible once the application is deployed. This makes it useful for assessing potential security risks in real-world conditions. However, DAST requires more setup and time to execute, as it involves interacting with a live application.

Interactive Application Security Testing (IAST)

Interactive application security testing (IAST) combines features of SAST and DAST by interacting with applications in real-time. IAST tools operate within the running application, providing continuous feedback during active testing. This blend allows for detailed context on how vulnerabilities are exploited, improving detection and remediation accuracy.

IAST offers insights into both the code and behavior of applications, identifying vulnerabilities with less manual verification needed compared to SAST and DAST. It integrates well within Agile and DevOps workflows, supporting rapid development cycles. However, the complexity of IAST's setup may require significant resources.

Software Composition Analysis (SCA)

Software composition analysis (SCA) focuses on managing open-source and third-party components within software applications. It identifies vulnerable components by scanning for known weaknesses against databases like the National Vulnerability Database (NVD). Given the prevalent use of external libraries in modern software, SCA prevents risks posed by outdated or insecure packages.

SCA tools automate the identification of license compliance issues and security vulnerabilities, providing developers with actionable insights. By integrating SCA into development pipelines, organizations can maintain control over component security and align with compliance requirements. While effective, its reliance on existing vulnerability databases may miss emerging threats, making it important to supplement SCA with other testing methods.

Runtime Application Self-Protection (RASP)

Runtime application self-protection (RASP) enhances security by monitoring application behavior during runtime and responding to threats. RASP solutions integrate within the application, offering real-time protection from attacks such as SQL injection and unauthorized access. This method intervenes as threats emerge, blocking potential exploits dynamically.

RASP provides deeper protection by counteracting sophisticated attacks missed by traditional defenses, such as firewalls and intrusion detection systems. It complements other testing methods by fortifying runtime environments against both known and zero-day threats. However, RASP's dependence on runtime data may introduce performance overhead and requires careful integration into environments.

Mobile Application Security Testing (MAST)

Mobile application security testing (MAST) targets vulnerabilities specific to mobile apps across Android and iOS platforms. MAST encompasses a range of techniques, including static, dynamic, and interactive testing. Given the unique security challenges, such as device fragmentation and platform-specific threats, MAST addresses issues like data leakage, authentication flaws, and insecure data storage.

MAST tools identify and remediate mobile app vulnerabilities, enabling developers to build secure applications without sacrificing functionality. Their ability to handle multiple testing scenarios including network, client, and server-side security makes them versatile across diverse ecosystems.

API Security Testing

API security testing ensures that the application programming interfaces (APIs) within a system are free from vulnerabilities. APIs are critical for enabling communication between software components, making their security crucial. Testing involves evaluating authentication mechanisms, data validation, and access controls to ensure that APIs are resilient against attacks like data breaches and unauthorized access.

Comprehensive API testing encompasses a variety of techniques, including automated scanning, fuzz testing, and penetration testing. This ensures a robust evaluation of potential vulnerabilities across all layers of API operations. API security testing is essential due to the growing reliance on cloud services and microservices architectures, where exposed APIs can become prime targets.

Penetration Testing

Penetration testing simulates real-world attacks to uncover vulnerabilities in applications. Security professionals, or ethical hackers, employ various techniques to exploit system weaknesses, presenting a report of findings for remediation. By mimicking the tactics of malicious actors, penetration testing generates actionable insights into potential threats and their impact on the system.

Conducted periodically, penetration testing offers a comprehensive evaluation of an organization's security posture. It complements automated security processes, providing a manual validation layer. However, it requires skilled professionals and can be time-consuming, necessitating strategic scheduling around business objectives to minimize disruption. Automated penetration testing as a service (PTaaS) offerings can mitigate many of these challenges.

Related content: Read our guide to continuous penetration testing

Tips From Our Experts

Mike Belton - Head of Service Delivery

With 25+ years in infosec, Michael excels in security, teaching, and leadership, with roles at Optiv, Rapid7, Pentera, and Madison College.

Leverage threat modeling as a foundation for testing

Start with threat modeling early in the design phase to identify potential attack vectors to your application. By mapping out high-risk areas, you can focus security testing on the most critical components, increasing efficiency and coverage across testing stages.

Use attack surface reduction to prioritize testing

Regularly analyze and minimize your application's attack surface, which includes exposed APIs, entry points, and external dependencies. By reducing these, you narrow the scope for both attackers and security testing, making tests more manageable and impactful.

Focus on API security hardening, especially for public-facing endpoints

With APIs increasingly targeted, emphasize testing for common vulnerabilities like broken object-level authorization (BOLA) and excessive data exposure. Use dedicated API security testing tools to analyze authorization and rate-limiting controls across different roles and environments

Perform dependency-based security assessments beyond SCA

While SCA tools scan for known vulnerabilities in open-source libraries, it's essential to also assess how your application uses those libraries. Code paths involving risky dependencies (e.g. those with privileged access) should be tested for any unintended escalation or exposure risks due to vulnerable components.

Optimize security test coverage with combinatorial testing for edge cases

Use combinatorial testing methods to ensure coverage of edge cases that can often be overlooked in security testing. This is particularly useful in complex applications with numerous input combinations, which could lead to unexpected security weaknesses.

Key Considerations for Security Testing of Cloud Applications

Shared Responsibility Model

Cloud environments operate under a shared responsibility model, where cloud providers secure the infrastructure, and users are responsible for securing their data, applications, and configurations. Security testing must account for this division, ensuring that application layers, data protection, and configurations within the user's control meet security standards.

Configuration and Access Management

Misconfigured settings, such as improperly set permissions or exposed endpoints, are common sources of cloud vulnerabilities. Security testing should include regular scans for misconfigurations and enforce strict access management policies. Testing for secure configurations, identity and access management (IAM) roles, and permissions can prevent unauthorized access.

Data Privacy and Compliance

Cloud applications often handle sensitive or regulated data. Testing should ensure that data is stored, processed, and transmitted in compliance with regulations like GDPR, HIPAA, or CCPA. This includes verifying encryption, secure data storage, and auditing logs to prevent data exposure and to meet compliance obligations.

Network Security and Segmentation

Security testing in the cloud requires evaluating network configurations to prevent lateral movement and unauthorized access. Techniques like network segmentation and virtual private cloud (VPC) setups can isolate workloads. Testing for network security involves assessing firewall configurations, access controls, and potential vulnerabilities in network paths.

Application Programming Interface (API) Security

Cloud applications heavily rely on APIs for interactions between services and components. Testing should focus on securing APIs from threats like unauthorized access, data leaks, and injection attacks. API security testing tools can validate access controls, ensure data validation, and prevent excessive data exposure across cloud services.

Resilience Against Distributed Denial of Service (DDoS) Attacks

Cloud applications are susceptible to DDoS attacks that can overwhelm resources. Security testing should include resilience assessments to ensure the application can handle unexpected spikes in traffic and potential attacks. Using cloud-native DDoS protection services and testing for scalability under stress can help prevent service disruptions.

Continuous Monitoring and Incident Response

Cloud environments are dynamic, with resources constantly being provisioned, modified, or deprovisioned. Security testing should involve setting up continuous monitoring for anomalies and potential threats. Integrating alerting mechanisms and an incident response plan allows for quick reaction to emerging security incidents.

Container and Microservices Security

Many cloud applications utilize containerized microservices architectures. Security testing in these environments requires assessing each container’s security configuration, including image scanning, network policies, and runtime monitoring. Tools specifically designed for container security can help identify vulnerabilities and misconfigurations in these components.

Challenges in Application Security Testing

Dealing with Complex Architectures

Complex architectures, such as microservices and cloud-native applications, present significant challenges for security testing. These environments often involve numerous interacting components, making comprehensive security assessments difficult. As systems scale, the challenge increases due to distributed and heterogeneous components which may require distinct security measures.

Managing security within complex architectures necessitates tools that can handle diverse environments. This might include automated security testing frameworks capable of continuous integration, accommodating rapid deployment cycles common in agile development.

Managing False Positives and Negatives

Managing false positives and negatives is a persistent challenge in application security testing. False positives refer to benign issues falsely identified as vulnerabilities, while false negatives occur when actual vulnerabilities go undetected. Both issues can disrupt development processes, with false positives wasting resources on non-issues, and false negatives leaving weaknesses exposed.

Reducing these inaccuracies requires fine-tuning testing mechanisms, setting precise security policies, and incorporating expert analysis where possible. Balancing automated tools with manual inspection promotes robust identification of threats. Continuous monitoring and refinement of testing parameters ensure more accurate results.

Integrating Security into Agile and DevOps Workflows

Integrating security into agile and DevOps workflows is essential but challenging due to the rapid pace and iterative nature of these methodologies. Traditional security practices can struggle to keep up with quick development sprints, often resulting in security being sidelined. This disconnect can lead to vulnerabilities being introduced or missed in the final product.

To align security with agile and DevOps, organizations adopt DevSecOps practices which embed security as a shared responsibility. Security becomes a part of everyday processes with automated tests, continuous monitoring, and collaboration between teams. This integration requires cultural changes, necessitating a shift in mindset and equipping teams with the tools and knowledge to prioritize security.

Best Practices for Effective Application Security Testing

1. Shift Security Testing Left

Shifting security testing left means incorporating security early in the development process. By detecting vulnerabilities early, developers can address them before they become more significant issues. This strategy reduces the cost and time of remediation, as problems are easier and quicker to fix before they propagate through development stages.

Practices like code reviews, static analysis, and developer training are critical components of shifting security left. By making security an integral part of the coding process, organizations foster a proactive approach. This ensures that security knowledge is distributed across teams, creating a security-aware culture that identifies and resolves issues efficiently.

2. Automate Security Testing Processes

Automation in security testing streamlines the identification and remediation of vulnerabilities. Automated tools can conduct repetitive and complex testing quickly, freeing up human resources for higher-order security tasks. Automated testing enables continuous integration with minimal manual intervention, allowing organizations to scale security measures alongside development efforts.

By employing automated solutions, organizations can maintain security assessments during rapid releases prevalent in agile and DevOps environments. Automation reduces the risk of human error and ensures consistency in testing procedures.

3. Integrate Security into the CI/CD Pipeline

Integrating security into the continuous integration/continuous deployment (CI/CD) pipeline ensures that security checks are part of every step in the software delivery process. Automated security tests within CI/CD pipelines identify vulnerabilities early, facilitating immediate remediation before production deployment. This approach dovetails with rapid development cycles typical of modern software engineering workflows.

CI/CD integration requires selecting appropriate security testing tools that support automation while blending into existing workflows. This process ensures that security assessments occur in tandem with code changes, maintaining developer efficiency without compromising security standards. Effective CI/CD integration builds a robust feedback loop, continuously enhancing security posture.

4. Ensure Comprehensive Testing Across All Layers

Ensuring comprehensive testing across all layers means addressing each component of an application, from front-end interfaces to back-end services. This approach considers security vulnerabilities across diverse elements like APIs, databases, and network communications. Comprehensive testing encompasses various testing methods, including SAST, DAST, and penetration testing.

Adopting a multi-layered security testing strategy helps detect intricate vulnerabilities that single-method approaches may miss. Each layer requires tailored security assessments that align with specific risks, contributing to an overarching protective framework. Striking the right balance between depth and breadth in testing optimizes resource allocation and enhances overall security resilience.

5. Regularly Train and Educate Development Teams

Regular training and education for development teams are crucial for maintaining high security standards. Knowledgeable teams are better equipped to identify security risks and implement secure coding practices. Training transforms developers from potential security liabilities into essential security stakeholders, fostering an organizational culture that prioritizes protection.

Organizations should facilitate regular workshops, encourage knowledge sharing, and provide access to resources for continuous learning. By keeping teams informed about the latest threats and security practices, organizations ensure adaptability to the evolving cyber landscape. Encouraging a security-minded mindset among development teams enhances the collective security skills, benefiting the entire development workflow.

Application Security Testing with Sprocket Security