What is SAST? A Complete Guide to Static Application Security Testing
Learn how Static Application Security Testing works, what vulnerabilities it finds, and how to integrate SAST into your CI/CD pipeline before code reaches production.
By Scantis
Secure Your Code Before It Runs
Modern software development moves fast. Developers commit code multiple times a day, CI/CD pipelines deploy automatically, and applications are expected to be secure from the very first release.
One of the most effective ways to identify security vulnerabilities early is through Static Application Security Testing (SAST).
Rather than waiting until an application is running, SAST analyses source code, bytecode, or binaries to detect security issues before the software is deployed.
What is SAST?
Static Application Security Testing (SAST) is a white-box security testing technique that scans an application's source code without executing it.
By analysing the code itself, SAST tools can identify vulnerabilities such as:
- SQL Injection
- Cross-Site Scripting (XSS)
- Command Injection
- Hardcoded passwords and API keys
- Insecure cryptographic implementations
- Buffer overflows
- Path traversal vulnerabilities
- Insecure deserialization
- Weak authentication logic
Because the code doesn't need to be compiled or running, SAST can be integrated directly into a developer's workflow.
Why SAST Matters
The earlier a vulnerability is discovered, the less expensive it is to fix.
Finding a security issue during development may take only a few minutes to resolve. Finding the same issue after deployment could require emergency patches, production outages, or incident response.
Benefits of SAST include:
- Detect vulnerabilities early in development
- Reduce remediation costs
- Improve code quality
- Enforce secure coding standards
- Meet compliance requirements
- Shift security left within the SDLC
How SAST Works
A SAST scanner parses your application's source code and builds an internal representation of how the application behaves.
It then compares the code against thousands of security rules and known insecure coding patterns.
Typical workflow:
- Developer writes code.
- Code is committed to Git.
- CI/CD pipeline triggers a SAST scan.
- Vulnerabilities are reported.
- Developers remediate issues before merging.
This allows security to become an automated part of the development lifecycle rather than a final-stage activity.
Common Vulnerabilities Detected
A quality SAST solution can identify many common security weaknesses, including:
Injection Attacks
Unsanitised user input reaching databases, operating systems, or interpreters.
Example:
Statement stmt = conn.createStatement();
stmt.execute("SELECT * FROM users WHERE id=" + userInput);Cross-Site Scripting (XSS)
Unescaped user input rendered directly into HTML pages.
Hardcoded Secrets
Passwords, API tokens, AWS credentials, and encryption keys accidentally committed to source control.
Insecure Cryptography
Use of weak algorithms such as MD5 or SHA-1 instead of modern cryptographic standards.
Path Traversal
Improper validation allowing attackers to access arbitrary files.
Advantages of SAST
Fast Feedback
Developers receive immediate feedback while writing code.
CI/CD Integration
SAST integrates seamlessly into GitHub Actions, GitLab CI, Jenkins, Azure DevOps, and other build pipelines.
Language Support
Most enterprise SAST tools support multiple programming languages including:
- Java
- JavaScript
- TypeScript
- Python
- C#
- Go
- C/C++
- PHP
- Kotlin
- Swift
Secure Coding Education
Many SAST tools explain why a vulnerability exists and provide recommendations for fixing it, helping developers improve their security knowledge over time.
Limitations of SAST
While SAST is extremely valuable, it is not a complete security solution.
Common limitations include:
- False positives
- Difficulty analysing dynamic runtime behaviour
- Limited visibility into third-party infrastructure
- Cannot detect runtime configuration issues
- May miss business logic vulnerabilities
This is why SAST should be combined with other security testing techniques.
SAST vs Other Security Testing
A mature DevSecOps program uses multiple scanning techniques together.
| Technique | What it scans | When it runs |
|---|---|---|
| SAST | Source code | Before deployment |
| DAST | Running application | Against a live or staging environment |
| SCA | Dependencies & libraries | During build or CI |
| Secrets scanning | Repositories & configs | On commit or in CI |
Scantis combines SAST (Semgrep), dependency scanning (Trivy), secrets detection (Gitleaks), and IaC checks (Checkov) in one Docker image — see the scan product guide to run them all with --scanners all.
Popular SAST Tools
Several mature SAST solutions are available, including:
- Semgrep
- SonarQube
- Checkmarx
- Fortify
- Veracode
- CodeQL
- Coverity
Each offers different strengths depending on your programming languages, compliance requirements, and development workflow.
Best Practices
To maximise the value of SAST:
- Scan every pull request
- Integrate scans into CI/CD pipelines
- Define severity thresholds
- Prioritise high-risk findings
- Regularly update security rules
- Combine SAST with dependency and secrets scanning
- Educate developers on secure coding practices
Security works best when it becomes part of everyday development rather than a separate process.
Conclusion
Static Application Security Testing is one of the foundational components of modern application security. By identifying vulnerabilities before software reaches production, organisations can reduce risk, lower remediation costs, and build more secure applications.
While no single tool can catch every security issue, integrating SAST into your development pipeline is an essential first step toward a mature DevSecOps practice.
Whether you're building a startup application or managing enterprise-scale software, automated SAST scanning helps ensure security is built into every commit — not added as an afterthought.