Semgrep: Fast and Scalable Static Analysis for Code Security

Semgrep: Fast and Scalable Static Analysis for Code Security

In the fast-paced world of software development, maintaining code security without slowing down development velocity is a constant challenge. Semgrep emerges as a revolutionary solution, offering lightning-fast static analysis that combines traditional security testing with AI-powered intelligence to deliver accurate, actionable results.

What is Semgrep?

Semgrep is a fast, scalable static analysis tool that scans code for security vulnerabilities, code quality issues, and secrets. Unlike traditional static application security testing (SAST) tools, Semgrep uses a novel approach based on semantic grep patterns that are both powerful and easy to write.

Developed by r2c (now part of GitLab), Semgrep supports over 30 programming languages and integrates seamlessly into development workflows. Its AI-powered Assistant helps reduce false positives while providing contextual remediation guidance.

When to Use Semgrep

Semgrep should be integrated throughout your development lifecycle:

• Code Reviews: Automated scanning of pull requests and commits
• CI/CD Pipelines: Fast security gates without blocking development
• Pre-commit Hooks: Catch issues before code is committed
• Security Audits: Comprehensive codebase assessments
• Secrets Detection: Prevent accidental credential exposure
• Code Quality: Enforce coding standards and best practices
• Dependency Analysis: Identify vulnerable third-party components

How to Use Semgrep

Installation

Semgrep offers multiple installation methods:

# Via pip pip install semgrep # Via Docker docker run --rm -v "${PWD}:/src" semgrep/semgrep semgrep --help # Via Homebrew (macOS) brew install semgrep

Basic Usage

Scanning with Built-in Rules

The easiest way to get started:

semgrep --config auto

This uses Semgrep’s default ruleset to scan your codebase for common security issues.

Scanning Specific Directories

semgrep /path/to/code

Scanning with Custom Rules

semgrep --config path/to/rules.yaml

CI/CD Integration

Semgrep integrates with all major CI/CD platforms. GitHub Actions example:

name: Semgrep on: pull_request: {} push: branches: ["main", "master"] jobs: semgrep: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: semgrep/semgrep-action@v1 with: config: auto

Advanced Usage

Custom Rule Writing

Semgrep uses YAML-based rules that are easy to understand and write:

rules: - id: insecure-random patterns: - pattern: random.random() message: "Use cryptographically secure random instead of random.random()" severity: WARNING languages: [python]

Secrets Detection

semgrep --config secrets

This scans for accidentally committed secrets like API keys, passwords, and tokens.

Supply Chain Security

semgrep --config supply-chain

Detects vulnerable dependencies and supply chain risks.

Interfile Analysis

Semgrep can analyze relationships between files:

semgrep --config interfile

Output Formats

# Default terminal output semgrep # JSON for automation semgrep --json # SARIF for GitHub Security tab semgrep --sarif # JUnit XML for CI systems semgrep --junit-xml

Examples

Example 1: Basic Security Scan

$ semgrep --config auto Scanning 1 file with 1000+ rules... Findings: /src/app.py:15: sql-injection SQL injection vulnerability 15| cursor.execute(f"SELECT * FROM users WHERE id = {user_id}") Fix: Use parameterized queries

Example 2: Custom Rule for Python

# custom-rules.yaml rules: - id: hardcoded-password pattern: password = "$PASSWORD" message: "Hardcoded password detected" severity: ERROR languages: [python]

$ semgrep --config custom-rules.yaml Findings: /src/config.py:5: hardcoded-password Hardcoded password detected 5| password = "admin123"

Example 3: Secrets Detection

$ semgrep --config secrets Findings: /src/.env:10: generic-api-key Generic API key detected 10| API_KEY=sk-1234567890abcdef

Example 4: Supply Chain Analysis

$ semgrep --config supply-chain Findings: /requirements.txt:5: vulnerable-dependency Vulnerable version of requests library 5| requests==2.25.0 Fix: Upgrade to requests>=2.28.1

Example 5: Advanced Pattern Matching

rules: - id: unsafe-deserialization patterns: - pattern: pickle.loads(...) - pattern-not: pickle.loads(encrypted_data) message: "Unsafe pickle deserialization" severity: HIGH languages: [python]

What Semgrep Helps Mitigate

Semgrep addresses a wide range of security and quality issues:

1. Security Vulnerabilities (SAST)

• Injection Attacks: SQL injection, command injection, XSS
• Authentication Issues: Weak authentication, broken access control
• Cryptographic Failures: Weak encryption, improper key management
• Insecure Configuration: Misconfigured security settings
• Known Vulnerabilities: CWE Top 25, OWASP Top 10

2. Secrets and Credentials

• API Keys: Accidental exposure of cloud service keys
• Passwords: Hardcoded credentials in source code
• Tokens: OAuth tokens, JWT secrets, SSH keys
• Certificates: Private keys and certificates

3. Supply Chain Security (SCA)

• Vulnerable Dependencies: Outdated or vulnerable third-party packages
• Malicious Packages: Typosquatting and dependency confusion attacks
• License Compliance: Incompatible or restrictive licenses

4. Code Quality Issues

• Best Practices: Enforcement of secure coding standards
• Performance: Identification of inefficient patterns
• Maintainability: Detection of code smells and anti-patterns

5. Compliance Requirements

• Regulatory Standards: PCI-DSS, HIPAA, SOC 2
• Industry Frameworks: NIST, ISO 27001
• Organizational Policies: Custom security rules

Integration with Government Cybersecurity Frameworks

Semgrep’s comprehensive scanning capabilities align well with the Australian Government’s Cybersecurity Assessment Framework (CAF), particularly in the areas of secure development practices and vulnerability management.

CAF Strategy 1: Patch Applications

Semgrep helps identify vulnerabilities that need patching and ensures secure coding practices prevent future issues.

CAF Strategy 2: Patch Operating Systems

Supports secure configuration and vulnerability detection in system-level code.

CAF Essential Eight Alignment

Semgrep directly supports several Essential Eight mitigation strategies:

• E1: Application Whitelisting: Ensures only approved, secure code patterns are used
• E2: Patching Applications: Identifies vulnerabilities requiring patches
• E3: Restrict Administrative Privileges: Detects privilege escalation vulnerabilities
• E4: Multi-Factor Authentication: Identifies weak authentication implementations
• E8: Daily Backups: Ensures backed-up code is free of known vulnerabilities

Additional CAF Benefits

• Secure Development: Enforces secure coding practices from the start
• Rapid Detection: Fast scanning enables shift-left security
• Compliance Automation: Automated checks reduce manual compliance efforts
• Risk Quantification: Provides severity ratings for prioritization

Best Practices

1. Rule Management

• Start with built-in rulesets (auto, secrets, supply-chain)
• Gradually add custom rules for organizational policies
• Regularly update rules to cover new threat patterns

2. CI/CD Integration

• Run scans on every pull request
• Fail builds on high-severity findings
• Use baseline scanning to avoid blocking legacy code

3. Performance Optimization

• Use --baseline to ignore existing issues
• Configure rules for specific file types
• Run incremental scans on changed files only

4. Team Collaboration

• Share custom rules across teams
• Use Semgrep Cloud for centralized rule management
• Integrate findings into development workflows

5. Continuous Improvement

• Monitor false positive rates and adjust rules
• Track security metrics over time
• Regularly review and update custom rules

Advanced Features

Semgrep Assistant

AI-powered analysis that:

• Reduces false positives by up to 98%
• Provides contextual remediation guidance
• Learns from triage patterns
• Suggests rule improvements

Semgrep Pro Engine

Advanced analysis capabilities:

• Inter-procedural analysis
• Data flow analysis
• Taint tracking
• Advanced pattern matching

Custom Rule Development

Create sophisticated rules using:

• Pattern matching with metavariables
• Logical operators (AND, OR, NOT)
• Regular expressions
• Context-aware matching

Integration Ecosystem

Semgrep integrates with:

• IDEs: VS Code, JetBrains, Vim
• CI/CD: GitHub Actions, GitLab CI, Jenkins, CircleCI
• Ticketing: Jira, Linear, GitHub Issues
• Security Platforms: Snyk, Dependabot, SonarQube

Troubleshooting

Common Issues

High False Positive Rate:

• Use Semgrep Assistant for AI-powered filtering
• Refine custom rules with more specific patterns
• Add exceptions for known safe patterns

Performance Issues:

• Limit scan scope to relevant directories
• Use --include and --exclude patterns
• Run scans in parallel for large codebases

Rule Conflicts:

• Use rule IDs to disable conflicting rules
• Organize rules in separate config files
• Use --config to combine multiple rule sets

Integration Problems:

• Check API tokens and permissions
• Verify webhook URLs and formats
• Test integrations in staging environments

Conclusion

Semgrep represents the future of static analysis, combining speed, accuracy, and AI-powered intelligence to deliver security insights that developers actually use. Its ability to scan codebases in seconds while providing actionable remediation guidance makes it an indispensable tool for modern development teams.

By integrating Semgrep into your development workflow, you not only catch security issues early but also establish a culture of security-aware development. When aligned with frameworks like the Australian Government’s CAF, Semgrep helps organizations achieve comprehensive security coverage without sacrificing development velocity.

Start using Semgrep today to elevate your code security posture and build more resilient software systems.