TL;DR
GitHub Copilot is trained on public code, so its suggestions can include both secure and insecure patterns. Review every suggestion for hardcoded secrets, SQL injection, and missing authentication. Use .copilotignore to exclude sensitive files. Business and Enterprise plans offer better privacy controls with no training on your code.
How GitHub Copilot Works
Copilot integrates directly into your IDE and provides real-time code suggestions. Here's what happens behind the scenes:
- Context collection: Copilot reads surrounding code to understand context
- Server processing: Context is sent to GitHub's servers for AI processing
- Suggestions: The model returns code completions based on patterns it learned
- Training data: Trained on public GitHub repositories (with licensing considerations)
Security Risks in Copilot Suggestions
Copilot learned from real code, including code with security flaws. Watch for these issues:
1. Insecure Code Patterns
Copilot may suggest patterns that were common but are now considered insecure:
- MD5 or SHA1 for password hashing (should use bcrypt or argon2)
- Synchronous crypto operations that can be timed
- Outdated authentication patterns
- Deprecated API usage
2. Hardcoded Credentials
If Copilot sees patterns like API initialization, it may suggest placeholder values that look like real credentials. Always replace with environment variables.
Important: Never accept Copilot suggestions that contain strings resembling API keys (sk_, pk_, api_, etc.) without replacing them with environment variable references.
3. Missing Security Controls
Copilot optimizes for completing your code, not for security. It may omit:
- Authentication middleware on routes
- Authorization checks (can user access this resource?)
- Input validation and sanitization
- Rate limiting
- CSRF protection
4. SQL Injection Vulnerabilities
Copilot might suggest string concatenation for SQL queries. Always verify it uses parameterized queries or an ORM.
Configuring .copilotignore
Prevent Copilot from accessing sensitive files by creating a .copilotignore file:
.copilotignore example: Add patterns like .env*, **/secrets/**, *.pem, and config/production.json to exclude sensitive files from Copilot's context.
Common patterns to include:
- Environment files:
.env,.env.local,.env.production - Key files:
*.pem,*.key,id_rsa* - Config with secrets:
config/secrets.js - Credential files:
**/credentials.json
Privacy Settings
Copilot offers different privacy levels based on your plan:
- Individual: Code snippets may be used to improve suggestions
- Business: Your code isn't used to train the model
- Enterprise: Additional controls, self-hosted options, audit logs
Organization Settings
Admins can configure Copilot policies:
- Enable/disable Copilot for the organization
- Allow/block suggestions matching public code
- Configure which repositories can use Copilot
- Set up audit logging
Secure Usage Patterns
Review Every Suggestion
Treat Copilot like a junior developer. It's helpful but needs supervision:
- Read the suggested code before accepting
- Understand what each line does
- Check for security implications
- Verify it matches your security requirements
Use Comments for Context
Guide Copilot with security-focused comments:
Example: Write comments like "// Authenticate user before allowing access" or "// Use parameterized query to prevent SQL injection" to guide Copilot toward secure patterns.
Enable Duplicate Detection
Copilot can filter suggestions that match public code verbatim. Enable this to reduce license and security risks from copying vulnerable code.
Code Review Checklist
Before committing Copilot-generated code:
- No hardcoded credentials or API keys
- Database queries are parameterized
- User input is validated
- Routes have appropriate authentication
- Authorization checks are in place
- Error handling doesn't leak sensitive info
- Dependencies are from trusted sources
- Crypto operations use modern algorithms
Is GitHub Copilot safe for proprietary code?
GitHub Copilot sends code context to GitHub's servers for processing. For Business and Enterprise plans, your code isn't used to train the model. Review your organization's Copilot settings and consider using .copilotignore for sensitive files.
Can Copilot suggestions contain security vulnerabilities?
Yes. Copilot is trained on public code, which includes both secure and insecure patterns. Always review suggestions for SQL injection, XSS, hardcoded secrets, and missing authentication before accepting them.
How do I exclude files from Copilot?
Create a .copilotignore file in your repository root. Add patterns for sensitive files like .env, config files with secrets, and proprietary algorithms. The syntax is the same as .gitignore.
Does Copilot store my code?
For Individual plans, snippets may be retained temporarily. Business and Enterprise plans have stronger privacy guarantees. Check GitHub's documentation for current data retention policies.