Advanced Bandit Configuration: Custom Rules and Team Workflows

Three months into using Bandit on your team’s Python services, you hit a wall. The default configuration flags legitimate test files as security risks, misses domain-specific vulnerabilities, and generates too much noise for developers to take seriously. You need Bandit to understand your codebase like a team member, not like a generic security tool.

Bandit’s real power isn’t in its out-of-the-box rules-it’s in how you can customize it to fit your specific security requirements and development culture.

Creating Your Security Baseline

A baseline is a snapshot of your current security debt. Instead of trying to fix 200 existing vulnerabilities before you can start using Bandit effectively, create a baseline that acknowledges the current state while ensuring no new vulnerabilities get introduced.

# Create a baseline from current codebase
bandit -r . -f json -o baseline.json

# Future scans only show new issues
bandit -r . -b baseline.json

Configuration Files That Scale

As teams grow, ad-hoc security practices become organizational liabilities. Bandit configuration files encode security policies as code that can be version-controlled, reviewed, and deployed like any other critical infrastructure.

# .bandit
exclude_dirs:
  - tests
  - migrations
  - fixtures

skips:
  - B101  # Skip assert usage in test files
  
severity:
  B105: medium  # Hardcoded passwords - adjust severity
  
confidence:
  B608: high    # SQL injection - high confidence only

Custom Rules for Domain-Specific Security

Every industry has unique vulnerability patterns. Healthcare applications need to protect PHI data differently than e-commerce sites need to secure payment information. Custom rules let you extend Bandit’s detection capabilities to catch vulnerabilities specific to your domain.

Maybe you need to flag any code that processes social security numbers without proper encryption, or your organization has banned certain third-party libraries for compliance reasons. Custom rules codify institutional knowledge that would otherwise exist only in documentation.

The Art of False Positive Management

False positives are the enemy of effective security scanning. When developers see too many irrelevant warnings, they start ignoring all warnings, including the important ones. Advanced configuration helps minimize false positives through targeted exclusions and context-aware rules.

Be surgical rather than wholesale in your exclusions. Test files might legitimately use hardcoded passwords for test data. Development utilities might disable SSL verification when connecting to local services. Good configuration captures these nuances without creating security blind spots.

Team Adoption Strategies

The technical aspects of Bandit configuration are often easier than the human aspects. Successful adoption usually involves starting with minimal configuration and gradually increasing coverage.

Begin with high-severity rules that catch clear security mistakes, then add medium-severity rules as the team becomes comfortable. Use findings as teaching opportunities rather than gotcha moments. Start by running Bandit in advisory mode, then enable enforcement for new code while maintaining baselines for existing code.

Environment-Specific Configuration

Different environments have different security requirements. Development environments might need relaxed rules for experimentation. Staging environments could enforce stricter standards. Production deployments might have the most stringent requirements.

This layered approach prevents security scanning from becoming a development bottleneck while ensuring critical issues get caught before they reach sensitive environments.

Making Security Sustainable

The ultimate measure of successful Bandit configuration isn’t the number of vulnerabilities caught, it’s whether your security practices are sustainable over the long term. Can new team members understand and work with your security setup? Does your configuration evolve with your codebase and threat model? Are developers viewing security as a helpful constraint rather than an obstacle?

Advanced configuration transforms Bandit from a generic security tool into a custom security platform that understands your organization’s specific needs and constraints. The investment in setup pays dividends in reduced security debt, better developer education, and more sustainable security practices.