In this blog post, I will be addressing the differences between the three most popular Application Security (AppSec) testing types: SAST, DAST, and SCA. These 3 strategies alongside a range of other AppSec testing strategies are essential in modern day DevSecOps processes.
The role of Application Security in modern DevSecOps
Threat actors are increasingly targeting the software supply chain for security gaps. In particular, the ‘Shift-Left Security’ wave has strengthened security measures in the development phase, but has left the deployment phase behind to bear the brunt of cyber attacks.
This is a primary reason driving the adoption of AppSec practices at large enterprises. There are numerous AppSec testing strategies, but we will focus on the three most popular types in this blog. To read about the different types of AppSec testing and the corresponding DevSecOps tools for the same, click here.
What is Static Application Security Testing (SAST)?
Static Application Security Testing (SAST) is a method to analyze an application’s source code, bytecode, or binary code to identify security vulnerabilities without actually executing the program. By doing so, SAST tools detect a wide range of issues that might lead to security breaches, enabling developers to address these vulnerabilities early in the development lifecycle.
How do SAST tools analyze source code?
SAST tools parse the source code and construct an abstract syntax tree (AST) or other intermediate representations to systematically analyze the code’s structure and logic. They look for known vulnerabilities, coding errors, and insecure coding practices, such as:
- Buffer overflows
- SQL injection vulnerabilities
- Cross-site scripting (XSS)
- Hard-coded credentials
- Insecure use of cryptographic functions
Since SAST tools can follow recursion many steps deeper than a human mind, they are more effective and can find many more types of vulnerabilities than a human being in the absence of automated testing tools.
Benefits of SAST
- Early Detection: SAST detects vulnerabilities early in the SDLC, allowing developers to fix issues before they become complex and costly.
- Comprehensive Coverage: SAST analyzes all code paths and branches, uncovering vulnerabilities that manual reviews might miss.
- Automated Analysis: SAST automates code analysis, providing consistent, repeatable results, saving time and resources.
- Developer Empowerment: SAST tools offer immediate feedback, helping developers learn secure coding practices and avoid mistakes.
- Compliance and Standards: SAST ensures code adherence to security standards and regulations, aiding compliance efforts.
Limitations of SAST
- False Positives: SAST tools can flag benign code as vulnerable, leading to wasted time and effort.
- False Negatives: Some vulnerabilities may go undetected, especially if they require runtime information.
- Scalability: For large codebases, SAST tools can be resource-intensive and slow down the development process.
- Limited Scope: SAST may not detect vulnerabilities that only appear during runtime, like configuration issues or logic flaws.
- Manual Intervention: Due to the reasons mentioned above, SAST tools usually require a trained expert in order to use it to its full potential.
Tools used for SAST
Some of the popular open-source tools for Static Application Security Testing (SAST) are:
- SonarQube: A widely used tool that provides continuous inspection of code quality and security vulnerabilities.
- Bandit: Specializes in finding security issues in Python code.
- Brakeman: A static analysis tool for finding security vulnerabilities in Ruby on Rails applications.
- ESLint: Primarily a linting tool for JavaScript, but also includes security plugins to identify vulnerabilities.
What is Dynamic Application Security Testing (DAST)?
Dynamic Application Security Testing (DAST), also referred to as black-box testing, is a method used to test web applications while they are running in order to identify security vulnerabilities. Unlike SAST, DAST involves simulating attacks in real time to determine if the application is vulnerable to attacks such as SQL injections and cross-site scripting.
How do DAST tools test running applications in real time?
DAST tools test running applications in real-time by simulating attacks and monitoring responses to identify security vulnerabilities. They typically send various inputs to the running application and observe its responses to detect potential security issues. This usually follows a 3-step process:
- Scanning the Application: It first crawls the application to identify all possible entry points, such as forms, URLs, and other inputs.
- Sending Malicious Payloads: The tool then generates and sends malicious inputs, such as SQL injection strings, XSS scripts, and other attack vectors, to these entry points.
- Analyzing Responses: It then analyzes the application’s responses to these inputs to identify vulnerabilities based on unexpected or suspicious behavior.
DAST does not require access to the source code, making it language-agnostic and applicable to any application that can be accessed and interacted with via a network.
Benefits of DAST
- Realistic Testing: DAST mimics an attacker’s actions in real-time, providing a realistic assessment of application behavior under attack.
- No Source Code Required: Useful for testing third-party applications or components without access to source code.
- Runtime Analysis: Identifies issues that only appear during runtime, such as configuration errors and authentication flaws.
- Continuous Testing: Integrates into the CI/CD pipeline for continuous testing throughout development and deployment.
Limitations of DAST
- Limited to Running Applications: DAST requires deployed applications, making it less useful for early issue identification.
- Incomplete Coverage: Might not cover all paths and states, potentially missing some vulnerabilities.
- False Positives and Negatives: Can produce false positives and fail to detect some actual vulnerabilities.
- Performance Impact: Running DAST can affect application performance during testing.
Tools used for DAST
Some of the popular open-source tools for Dynamic Application Security Testing (DAST) are:
- OWASP ZAP (Zed Attack Proxy): A widely used tool for finding vulnerabilities in web applications.
- Nikto: A web server scanner that tests for a wide range of vulnerabilities.
- SQLMap: A tool that automates the detection and exploitation of SQL injection vulnerabilities in web applications.
- Arachni: A high-performance security scanner for web applications.
What is Software Composition Analysis (SCA)?
Software Composition Analysis (SCA) is a method used to identify weaknesses in 3rd party and open-source components used in application code. Unlike SAST and DAST, the scope here is restricted to 3rd party and open source components – libraries, frameworks, packages, etc. and does not evaluate the security of the entire codebase.
How do SCA tools identify vulnerabilities in (open source) software components?
SCA tools scan the codebase to detect all open-source components and their dependencies. They then compare these components against a database of known vulnerabilities, license information, and other metadata. The process typically involves the following steps:
- Inventory Creation: Generation of a comprehensive inventory of all open-source components used in the application, including direct and transitive dependencies.
- Vulnerability Detection: The list of components is then cross-referenced against databases like the National Vulnerability Database (NVD) to identify known security vulnerabilities.
- License Compliance: Even the licenses of open-source components are verified to ensure compliance with the organization’s policies and to avoid potential legal issues.
- Risk Assessment: Each component is assessed, highlighting the potential security, legal, and quality risks.
- Remediation Guidance: SCA tools then offer guidance on how to remediate identified risks, such as upgrading to a safer version of the component or replacing it with a more secure alternative.
SCA tools are helpful because they do not perform static or dynamic analysis of the code, rather they report based on the already-documented list of vulnerabilities in dependencies, thus eliminating quality and licensing risks.
Benefits of SCA
- Software Bill of Materials (SBOM): Enables creation of an SBOM, detailing software dependencies for better supply chain management.
- Supply Chain Risks: Identifies supply chain risks by assessing component quality, licenses, versions, and vulnerabilities.
- Security Assurance: SCA identifies and mitigates security vulnerabilities in open-source components, reducing exploitation risks.
- License Compliance: Ensures open-source components comply with licensing requirements, avoiding legal complications.
- Automated Monitoring: Continuously monitors the codebase to promptly identify new vulnerabilities and compliance issues.
Limitations of SCA
- False Positives: SCA tools can flag non-critical issues, leading to false positives that require manual review.
- False Negatives: Some vulnerabilities may go undetected if component information is outdated or not documented.
- Complex Dependencies: Managing transitive dependencies can be challenging and may introduce hidden risks.
- Limited to Known Vulnerabilities: SCA tools only identify known vulnerabilities, missing new or undisclosed ones.
Tools used for SCA
Some of the popular open-source tools for Software Composition Analysis (SCA) are:
- OWASP Dependency-Check: This is a tool that Identifies vulnerabilities in project dependencies.
- Snyk: This provides vulnerability scanning and remediation for open-source dependencies
- Trivy: A comprehensive vulnerability scanner for container images, file systems, and Git repositories
Differences explained: SAST vs. DAST vs. SCA
While the detailed explanations provided above may help you understand the concepts individually, the below table compares the key differences and characteristics of SAST vs DAST vs and SCA side-by-side on the same set of parameters.
Feature | SAST | DAST | SCA |
Type of Analysis | Analyzes static code (when the code is at rest) | Analyzes a running application | Analyzes open source and 3rd party components in source code |
Primary Focus | Code quality and security flaws | Runtime vulnerabilities and behavior | Vulnerabilities in 3rd-party components |
Access to Code Repository | Requires access to source code/ bytecode | No access to source code required | Analyzes dependencies and libraries |
Timing in SDLC | Early in development (pre-build) | Post-deployment (running environment) | Throughout development and also post-deployment |
Types of Vulnerabilities it identifies | SQL injection, XSS, buffer overflows | SQL injection, XSS, authentication issues | Known vulnerabilities, license compliance |
Detection Method | Pattern matching, data flow analysis | Attack simulation, input manipulation | Database cross-referencing, dependency scanning |
Complexity of Implementation | Moderately complex to implement | Moderate to low complexity; doesn’t require prior knowledge | Low complexity; easy to implement |
False Positives / False Negatives | Can have false positives | Prone to false positives and negatives | Can have false positives and negatives |
Achieving ASPM: Integrating SAST, DAST, and SCA into DevSecOps
I hope I was able to clearly explain the differences between these three essential Application Security testing types in this blog. I would like to remind you readers that all of these three testing strategies offer unique benefits and help identify different vulnerabilities.
Performing SCA helps teams quickly identify popular vulnerabilities and CVEs in open source components. SAST helps developers nip it in the bud by identifying vulnerabilities in code even before it gets deployed to prod. DAST helps testers identify loopholes in a deployed application.
Conclusion
In modern-day DevSecOps processes, each of these play a crucial role in ensuring a healthy Application Security posture. Leading companies around the world rely on OpsMx to improve their DevSecOps workflows.
OpsMx helps integrate a number of AppSec tools with software delivery to:
- Continuously Monitor for Vulnerabilities (both pre and post deployment)
- Automate Approvals and Release Verifications
- Provide End-to-End Visibility from Development to Deployment
- Stay Compliant with organization and industry Policies
- Generate Audit reports
Talk to our AppSec experts for a demonstration on these capabilities!
About OpsMx
OpsMx is a leading innovator and thought leader in the Secure Continuous Delivery space. Leading technology companies such as Google, Cisco, Western Union, among others rely on OpsMx to ship better software faster.
OpsMx Secure CD is the industry’s first CI/CD solution designed for software supply chain security. With built-in compliance controls, automated security assessment, and policy enforcement, OpsMx Secure CD can help you deliver software quickly without sacrificing security.
OpsMx Delivery Shield adds DevSecOps to your existing CI/CD tools with application security orchestration, correlation, and posture management.
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