10 leading open source application security testing tools

1. Semgrep

​Semgrep (derived from "semantic grep") Community Edition is a static application security testing (SAST) tool designed to identify patterns and potential vulnerabilities in source code.

Unlike traditional text-based search tools, such as grep, that operate on plain text, Semgrep understands the syntax and structure of code, enabling more precise and context-aware searches. This semantic awareness enables developers to write patterns that match specific code constructs, such as function calls with particular arguments or variable assignments, across multiple programming languages. Semgrep supports over 30 languages, including C#, C, C++, Go, Java, JavaScript, JSON, Python, PHP, Ruby and Scala.

One of Semgrep's distinguishing features is its flexibility. It enables developers to write custom rules using a syntax similar to the code they are analyzing, eliminating the need to learn a domain-specific language. This approach contrasts with commercial SAST tools, which often require users to master complex query languages or configurations or do not offer any configuration.

Semgrep is designed to be fast and lightweight, enabling it to run locally on a developer's machine without network access. This offline capability ensures code analysis can be integrated into the development workflow, providing immediate feedback during the coding process.

Pros:

• Easy to use and integrates into existing workflows.
• Users can write custom rules for specific security requirements.
• Scans are quicker than other static code analysis tools.
• Supports over 30 programming languages for diverse environments.

Cons:

• Writing and modifying custom rules has a learning curve.
• Can generate false positives or miss vulnerabilities.
• Running scans on large codebases can be resource-intensive.
• Open source version lacks a GUI.

2. ZAP by Checkmarx

Zed Attack Proxy by Checkmarx is a comprehensive tool for dynamic application security testing of web applications. Its core capability as an intercepting proxy enables practitioners to inspect, modify and analyze HTTP/HTTPS traffic between browsers and web applications. This enables security teams to perform detailed manual testing and get a deep understanding of application behaviors.

ZAP also has advanced web crawlers, including both traditional and Asynchronous JavaScript and XML (AJAX) spiders, designed to map application structures and effectively test even modern JavaScript-driven sites.

For automated vulnerability detection, ZAP combines active and passive scanning techniques. The active scanner proactively sends tailored requests to uncover vulnerabilities, such as SQL injection and cross-site scripting. The passive scanner quietly analyzes traffic without altering it, identifying potential threats based on known vulnerability patterns.

Additional features include fuzz testing, where ZAP delivers extensive and varied input payloads to detect vulnerabilities related to input handling, and comprehensive WebSocket support. These features are essential for analyzing real-time client-server communication and significantly enhance ZAP's versatility. The tool's extensibility is further improved through scripting support, enabling users to automate testing and customize scanning behavior using various scripting languages.

Pros:

• Intuitive interface suitable for beginners and experts.
• Offers wide-ranging features for thorough security assessments.
• Backed by a strong community providing updates and assistance.

Cons:

• Automated scans might generate false positives requiring verification.
• Active scanning can be resource-intensive and affect performance.
• Mastering all features requires time and experience.

3. SonarQube

​SonarQube is a static analysis platform developed by SonarSource that is primarily used to continuously inspect code quality. It performs automatic code scans to detect bugs, code smells, antipatterns and security vulnerabilities across 29 programming languages, including Java, C#, JavaScript and Python. ​

The platform offers reports on duplicated code, coding standards, unit tests, code coverage, code complexity, comments, bugs and security recommendations. It integrates seamlessly with build tools including Maven, Ant, Gradle and MSBuild, and continuous integration systems, such as Jenkins and Bamboo, facilitating automated analysis within development workflows.

SonarQube supports both on-premises and self-managed cloud deployment models, giving organizations complete control over their code analysis infrastructure.

SonarQube's extensibility is enhanced through a large plugin ecosystem, enabling users to add support for additional languages, integrate with external tools and customize analysis rules. The platform's community actively contributes to its development, providing plugins, sharing best practices and offering support through forums and documentation.

Pros:

• Automatic scans for vulnerabilities.
• Integrates with multiple build tools.
• Create custom plugins.

Cons:

• Free tier limits scanning and capabilities.

4. KICS by Checkmarx

​Keeping Infrastructure as Code Secure is a static code analysis tool designed to identify security vulnerabilities, compliance issues and misconfigurations in IaC templates. It supports a wide range of IaC platforms, including Terraform, Kubernetes, Docker, AWS CloudFormation, Ansible, Helm, Google Deployment Manager, AWS Serverless Application Model, Microsoft Azure Resources Manager, Azure Blueprints, OpenAPI 2.0 and 3.0, Pulumi, Crossplane, Knative and the Serverless Framework. ​

KICS offers more than 2,400 built-in queries to detect potential issues. Its architecture enables easy customization and extension of these rules to meet specific organizational requirements. The tool integrates seamlessly into continuous integration/continuous delivery (CI/CD) pipelines, enabling automated and continuous security testing within DevOps workflows.

Pros:

• Supports most IaC platforms used today.
• Provides thorough coverage for identifying vulnerabilities and misconfigurations.
• Users can tailor existing rules or create new ones for specific requirements.
• Benefits from community contributions as an open source tool.

Cons:

• Might generate false positives, requiring manual reviews.
• Maintaining custom rules to keep pace with evolving threats can be resource intensive.

5. Trivy

​Trivy is a vulnerability scanner developed by Aqua Security that is designed to detect security issues across various components of cloud-native applications. It supports scanning container images, file systems, Git repositories and IaC configurations, making it a versatile tool for comprehensive security assessments.

Trivy identifies vulnerabilities in OS packages, application dependencies and misconfigurations in IaC templates, supporting formats such as Dockerfiles, Kubernetes manifests, Terraform and AWS CloudFormation. ​

Key features of Trivy are its simplicity and speed. It performs fast scans, which is beneficial for integration into CI/CD pipelines. Trivy can integrate with various CI/CD tools, such as Jenkins, GitHub Actions, Travis CI and GitLab CI.

Pros:

• Performs rapid scans, maintaining development velocity in CI/CD pipelines.
• Supports scanning a wide range of targets and platforms.

Cons:

• Focuses on static analysis without runtime scanning capabilities.
• Effectiveness relies on regularly updated vulnerability databases.

6. Nmap

Nmap is a powerful network security scanner widely used for network discovery, vulnerability detection and security auditing. Primarily operating as a network-level security testing tool, Nmap scans networks to identify live hosts, open ports, running services and OSes. It uses various scanning techniques, including TCP and UDP scanning, stealth scans, OS fingerprinting and version detection.

Nmap is highly customizable and scriptable via the Nmap Scripting Engine (NSE), which provides hundreds of scripts for tasks such as vulnerability detection, exploit detection, malware identification and advanced network discovery. The community regularly contributes new scripts and updates, significantly enhancing its capabilities. Nmap integrates seamlessly with automation and security tools, facilitating its use in both manual assessments and automated workflows.

Pros:

• Supports detailed network enumeration, OS detection and vulnerability scanning.
• NSE scripts provide customizability for automating complex scanning tasks.
• A strong user base contributes scripts, support and documentation.
• Works on all major platforms, including Windows, Linux and macOS.

Cons:

• Advanced use and scripting require significant expertise.
• Aggressive scans can trigger defenses, disrupting systems or alerting administrators.
• Primarily network-focused with limited application-layer vulnerability assessment.
• Some techniques could produce false positives requiring manual verification.

7. OWASP Dependency-Check

OWASP Dependency-Check is a software composition analysis (SCA) tool designed to detect known vulnerabilities in third-party software libraries and application dependencies. SCA tools like Dependency-Check help organizations manage the risks associated with external components by scanning dependencies and cross-referencing them against vulnerability databases, such as the National Vulnerability Database (NVD). Dependency-Check supports multiple programming languages and build systems, including Java, .NET, Node.js, Python and Ruby, making it versatile across diverse development environments.

Dependency-Check creates detailed reports in formats including HTML, XML and JSON, providing clear insights into identified vulnerabilities and their severity and suggested remediation actions. It also integrates seamlessly into CI/CD pipelines to automate dependency analysis and promote continuous visibility into security risks. The tool also provides a CLI that enables easy automation and integration into build scripts and development workflows.

Pros:

• Integrates with NVD to offer up-to-date information on known vulnerabilities.
• A user-friendly interface and detailed reporting simplify identification and remediation.
• Seamlessly integrates with CI/CD pipelines for continuous security assessments.

Cons:

• It might generate false positives, requiring manual verification.
• Can only identify known vulnerabilities listed in the NVD, not zero-days.
• Scanning large projects with extensive dependencies leads to longer scan times.
• Mastering all features and configurations requires additional time and effort.

8. Sqlmap

Sqlmap is a penetration testing tool that specializes in detecting and exploiting SQL injection vulnerabilities in web applications and APIs. It automates complex injection techniques to help security professionals quickly identify weaknesses in databases. It supports various database systems, including MySQL, Oracle Database, PostgreSQL, Microsoft SQL Server and SQLite, and offers techniques such as error-based, time-based, Boolean-based and union-based injections.

Sqlmap can extract data from vulnerable databases, revealing tables, columns and specific entries. It integrates well with other pen testing tools and frameworks, provides detailed reporting and operates primarily via a CLI.

Pros:

• Rapidly identifies and exploits SQL injection vulnerabilities.
• Works across multiple database management systems.
• A strong open source community provides regular updates and support.

Cons:

• Primarily command-line driven, limiting ease of use.
• Users must understand SQL injection techniques to use it effectively.
• Powerful capabilities require responsible, ethical usage.

9. The OWASP Amass

The OWASP Amass Project is a reconnaissance toolkit designed to streamline network mapping and asset discovery during pen testing. It excels at subdomain enumeration and DNS record gathering, quickly uncovering assets, hostnames, IP addresses and associated services to reveal a target's attack surface.

Amass correlates intelligence from diverse sources, such as DNS databases, certificate transparency logs and public APIs, to provide thorough visibility into external infrastructure. Its visualization capabilities simplify analysis by clearly illustrating asset relationships and potential vulnerabilities, making it a powerful tool for proactive security assessments.

Pros:

• Offers extensive features for thorough network mapping and information gathering.
• Utilizes various data sources, enhancing reconnaissance depth.
• It can be integrated with other tools and frameworks to streamline processes.

Cons:

• New users require time to familiarize themselves with functionalities and the CLI.
• Comprehensive scans can be resource-intensive, especially for large targets.

10. TruffleHog

TruffleHog is a security tool designed to detect secrets, API and encryption keys, credentials and other sensitive information that has been inadvertently committed to source code repositories.

Primarily used in DevSecOps workflows, TruffleHog scans git repositories -- including historical commits -- to discover secrets by using pattern matching, regular expressions, entropy analysis and custom detectors. It integrates smoothly into CI/CD pipelines. It can scan repositories hosted on GitHub, GitLab, Bitbucket and local Git repositories to identify leaked credentials and secrets before potential exploitation.

Pros:

• Discovers sensitive secrets, credentials and API keys efficiently.
• Integrates simply into automated CI/CD workflows.
• Offers flexible pattern matching and entropy checks for potential secrets.
• Supports scanning historical commit data for sensitive information.

Cons:

• Primarily CLI-driven with limited graphical interfaces.
• Requires proper tuning of detection rules to minimize false alerts.
• Detects already committed secrets rather than blocking commits proactively.

Colin Domoney is a software security consultant who evangelizes DevSecOps and helps developers secure their software. He previously worked for Veracode and 42Crunch and authored a book on API security. He is currently a CTO and co-founder, and an independent security consultant.