Secure Serverless Workflows
Secure Serverless Workflows focus on mitigating security risks
inherent in event-driven, microservice-based architecture. Because the cloud
provider handles server provisioning, patching, and OS maintenance, security
efforts shift primarily toward application logic, access control, data
protection, and event handling.
Core Principles for Securing Serverless Workflows
1. Principle of Least Privilege (IAM)
- Granular Roles: Assign single, dedicated
Identity and Access Management (IAM) roles per serverless function (e.g.,
AWS Lambda, Azure Functions, Google Cloud Functions) rather than sharing
broad roles across services.
- Minimal Resource Scope: Scope function permissions
strictly to the resources required (e.g., read-only access to a specific
S3 bucket or DynamoDB table).
2. Event Input Validation & Sanitization
- Prevent Event Injection: Validate and sanitize all
incoming payloads before processing. Serverless functions process event
triggers from diverse sources (APIs, SQS queues, S3 uploads, webhooks, or
IoT streams). Unsanitized inputs can lead to command injection or
SQL/NoSQL injection.
- Schema Enforcement: Use strict API Gateway schemas
(OpenAPI/JSON schema validation) to reject malformed requests before they
reach your function execution layer.
3. Secrets & Configuration Management
- Avoid Hardcoded Secrets: Never store passwords, API
keys, or database credentials directly in environment variables or
application code.
- Managed Secret Stores: Fetch secrets dynamically at
runtime from dedicated stores like AWS Secrets Manager, HashiCorp Vault,
or Azure Key Vault using IAM roles.
4. Dependency & Vulnerability Management
- Scan 3rd-Party Libraries: Serverless functions often rely
heavily on open-source packages (npm, PyPI, Maven). Continually scan
dependencies for known vulnerabilities using tools like Snyk or GitHub
Dependabot.
- Minimal Function Footprint: Include only necessary
dependencies to keep function execution packages small, reducing the
attack surface and execution cold-start overhead.
5. Network & Perimeters
- Virtual Private Clouds (VPC): Place serverless functions
handling sensitive data inside private subnets/VPCs with restricted
outbound internet egress.
- API Gateways & WAFs: Deploy Web Application
Firewalls (WAF) in front of public API endpoints to filter out malicious
traffic, rate limit requests, and block DDoS or OWASP Top 10 vectors.
6. Observability, Logging, & Auditing
- Centralized Logging: Aggregate execution logs and
trace outputs (e.g., AWS CloudWatch, Datadog, AWS X-Ray) to correlate
distributed function calls across event streams.
- Avoid Sensitive Data Leakage: Ensure logs never capture
sensitive payloads like credentials, PII (Personally Identifiable
Information), or payment details.
- Runtime Anomaly Detection: Set up alerts for unexpected
spikes in invocation rate, elevated error rates, runtime duration
anomalies, or unexpected egress connections.
7. Timeouts & Concurrency Limits
- Strict Timeouts: Set conservative execution
timeout limits for each function to prevent infinite loops, Groundhog Day
persistence attacks, or excessive cloud charges.
- Reserved Concurrency: Set concurrency throttles to
prevent runaway scaling attacks from exhausting downstream databases or
backend infrastructure.