Application security testing (AST) is a set of processes designed to detect and address security gaps during the early phases of the software development lifecycle (SDLC). In other words, teams take steps in pre-production to identify and mitigate risks before applications are released into operational environments. By integrating application security testing into existing workflows, teams can catch issues early, avoid duplicating efforts, and reduce costly inefficiencies that come up when vulnerabilities surface after deployment.
That said, application security testing can feel like one more thing to keep track of. As the line between development and operations gets narrower, modern development teams often wear multiple hats: innovating, building features, using containerization, and writing infrastructure as code (IaC). As these responsibilities grow, manually checking for security vulnerabilities doesn’t cut it. The solution? Automated AST.
Read on to learn more about the different types of application security testing, best practices, and recommendations to help teams efficiently identify and remediate vulnerabilities before they reach production.
The State of Code Security Report [2025]
Open-source dependencies are a major attack surface. The State of Code Security Report 2025 found that NPM and PyPI were heavily targeted by supply chain attacks, with dependency confusion and malicious packages leading to severe breaches.
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Why AST matters: The importance of shift-left security
Identifying software security vulnerabilities late in the SDLC can cause widespread damage—costing you time, money, and the stress of an expanded blast radius. For example, the high-profile vulnerability at SolarWinds (CVE-2020-10148) cost approximately $90 million, which experts say could have been avoided with early detection. Attackers first accessed the SolarWinds network in September 2019 and injected their malicious code, known as the SUNBURST backdoor, starting in February 2020. But the vulnerability wasn’t discovered until December 2020, meaning attackers had been in the system for more than a year.
The 3CX attack is another example that highlights the danger and high cost of late detection in the software lifecycle. In this attack, the 3CX Desktop App platform was trojanized, resulting in what SecurityWeek called “the first known cascading supply chain attack.” Just like in the SolarWinds attack, the compromise was discovered only after the malicious updates had been distributed and were active for some time.
Attacks like these prove the critical importance of shift-left security, which is a fundamental aspect of application security posture management.
The most effective version of shift-left security is “start left security,” which is a term coined by Wiz to describe a key feature of Wiz Code. “Starting left” embeds security from the planning and design phases of the software development lifecycle. It allows teams to catch and fix security issues early on, reducing the delays when you have to backtrack to fix security flaws later.
Types of application security testing
So now that you know the stakes and you’re ready to shift left (or start left!), how do you jump in? The OWASP Web Security Testing Guide 4.2 is a great starting point for identifying different types of application security testing. For each type, some tools automate testing to reduce developer overhead while broadening test coverage.
Threat modeling
Threat modeling uses vulnerabilities, organizational values, and application needs to shape a clear security profile. This aids in making informed decisions throughout the designing, building, testing, and deployment stages. (The Threat Modeling Manifesto, developed in 2020, emphasizes the need for threat modeling during the earliest stages of the SDLC.)
Static application security testing (SAST)
SAST involves using automated code analysis tools to identify and report potential vulnerabilities. Because SAST tools don’t interact with applications externally but instead scan the application code (source code, binaries, byte code) to identify any known vulnerabilities, it’s considered a form of white-box testing / passive testing.
Static application security testing enables early detection because SAST tools can integrate into IDEs and CI/CD pipelines to catch issues early, though efficiency depends on rule tuning and reducing false positives.. Better yet? SAST is much faster than manual code review because these tools have access to a large database of syntactic and semantic flaws that lead to known vulnerabilities.
AI-enhanced SAST tools are evolving to reduce false positives and improve detection accuracy by learning from past vulnerabilities, refining their detection models based on historical security incidents. This advancement helps developers focus on high-impact security findings rather than sifting through large volumes of noisy results.
Popular open-source tools like Semgrep, SonarQube, and CodeQL are specifically built with SAST in mind. These tools support almost all modern programming languages and can integrate into a developer's favorite IDE, making the process seamless for them. (There are also some language-specific SAST tools, such as nodejsscan for JavaScript, Brakeman for Ruby, gosec for Go, and Bandit for Python.)
Another huge advantage of using advanced SAST tools? Their ability to analyze an application's control flows.
Software composition analysis (SCA)
SCA increases code visibility by indexing all dependencies and associated packages into an inventory known as a software bill of materials (SBOM). Modern applications rely on many open-source dependencies that may contain malicious code, making SCA (and SBOMs) crucial.
For example, in March 2022, the Spring4Shell vulnerability (CVE-2022-22965) was found in the popular Spring Framework with a 9.8/10 severity level. Integrating an SCA tool early in the SDLC would help you identify the use of a vulnerable version of the Spring Framework, which could lead to earlier detection, quicker remediation, and a smaller blast radius.
Popular open-source tools like OpenSCA and OWASP dependency-check are specifically built with SCA in mind. These tools support dependencies associated with modern programming languages, including JS, Java, Python, Ruby, .NET, Go, Scala, PHP, and many more. There are also some language-specific SCA tools such as Retire.js for JS and Bundler-audit for Ruby.
Dynamic application security testing (DAST)
DAST involves identifying application runtime vulnerabilities using a black box approach / active testing approach. (This means DAST doesn’t require access to the source code and other dependencies; instead, testing is conducted externally, on the running application.) Because it works on applications as they run, DAST often comes late in SDLC—after SAST and SCA. Michael Felderer, a pioneering security researcher, organizes DAST into four categories:
Penetration testing simulates an attack on a system similar to how a hacker would in order to discover and fix security vulnerabilities. Pen testing uses only the system’s public interfaces, so the target application has to be in a production/production-ready state. Open-source tools like Metasploit Framework are popular for penetration testing.
Vulnerability scanning tools can detect security weaknesses by systematically sending predefined attack payloads to an application. OpenVAS is one of many open-source vulnerability scanners for network services and software packages.
Dynamic taint analysis tracks how data from untrusted sources moves through the application and flags if there are any security vulnerabilities (e.g., cross-site scripting, SQL injection). Open-source tools like libdft are a good choice for tracking data flow in running applications.
Fuzzing involves feeding random data into a program to identify vulnerabilities by observing how the system handles unexpected or erroneous inputs. AFL is an open-source tool specifically built for fuzzing.
Interactive application security testing (IAST)
IAST involves monitoring the application testing process (both manual and automated) in real time to identify vulnerabilities in data flow, control flow, and the runtime environment—all at once. This is known as gray-box testing because, unlike SAST, which analyzes static code, or DAST, which tests externally, IAST works internally by monitoring an application as it runs in a test environment, using agents, to provide deeper insights into data flow and control logic.
While there are few open-source IAST tools such as Dongtai IAST, commercial tools like Wiz Code outpace them with the ability to integrate IAST directly into CI/CD pipelines. With IAST present in CI/CD pipelines, you can identify problems much earlier in the SDLC.
Wiz Code: A unified solution for application security testing
As we’ve seen, it takes a lot to cover all your testing bases. But having multiple tools for different stages of application development creates security silos, putting an extra burden on developers to manage complexity. Enter Wiz Code. Wiz Code offers a unified solution for all stages of the SDLC, covering threat modeling, SAST, SCA, DAST, and IAST:
Threat modeling: Wiz Code uses the Wiz Security Graph to connect to the infrastructure where the application will be hosted, mapping out cloud assets, configurations, and API security risks.
SAST: Wiz IDE Extension, WizCLI, and pull request scanning seamlessly integrate with developer workflows to automate code analysis with immediate, actionable remediation. Wiz’s SAST integration partners, such as Checkmarx, provide developers with real-time, prioritized feedback directly in their IDEs.
SCA: With agentless scanning and automated SBOM generation, Wiz gives you an inventory of all application dependencies at a glance.
DAST: Wiz Code ingests DAST findings from the Wiz Integration (WIN) Platform.
IAST: By seamlessly integrating into CI/CD pipelines, Wiz Code offers real-time monitoring of the application testing process. With the ability to ingest and consolidate findings from various application security testing tools, you’ll never have blind spots.
The bottom line? Wiz gives you detailed visibility across all stages of the application development lifecycle and all your infrastructure, going beyond traditional application security testing.
Want to see how Wiz Code can streamline your development process? Book a demo today!
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