mitigations.md

Mitigation Strategies Analysis for serverless/serverless

Mitigation Strategy: Input Validation and Sanitization within Functions

• Mitigation Strategy: Input Validation and Sanitization within Functions
• Description:
  1. Define Input Schemas: For each serverless function, clearly define the expected input data structure and data types, considering the event source and expected payloads.
  2. Implement Validation Logic within Functions: Crucially, implement validation logic inside each function's code to check incoming event data against defined schemas. This is vital as functions are often directly exposed to event sources and lack traditional application layers for input filtering.
  3. Sanitize Input Data within Functions: Sanitize data within the function before processing, especially data used in downstream services or databases. Serverless functions are often the first point of contact with external data.
  4. Handle Validation Errors within Functions: Functions should handle validation errors gracefully and return appropriate error responses, logging the invalid input for security monitoring.
  5. Regularly Review and Update Schemas for Function Events: Maintain and update input schemas as function logic and event sources evolve.
• Threats Mitigated:
  • Injection Attacks (SQL, NoSQL, Command Injection): Severity: High - Serverless functions, directly processing events, are vulnerable if input is not validated.
  • Cross-Site Scripting (XSS): Severity: Medium - If function output is used in web applications, sanitization within the function is crucial.
  • Data Corruption: Severity: Medium - Invalid data processed by functions can lead to data integrity issues.
  • Denial of Service (DoS): Severity: Medium - Functions can be targeted with malformed events to consume resources.
• Impact:
  • Injection Attacks: High - Directly mitigates injection risks by validating input at the function level.
  • Cross-Site Scripting: Medium - Reduces XSS risk by sanitizing output within the function's context.
  • Data Corruption: Medium - Prevents data corruption caused by invalid event data.
  • Denial of Service: Medium - Reduces DoS risk by rejecting invalid events early in the function execution.
• Currently Implemented: Partially implemented in API Gateway request validation for some endpoints using basic schema definitions in serverless.yml.
• Missing Implementation: Input validation and sanitization logic is missing within most serverless function code itself. Need to implement robust validation libraries and sanitization routines within each function, especially those processing event data from various sources.

Mitigation Strategy: Principle of Least Privilege for Function Permissions (IAM Roles)

• Mitigation Strategy: Principle of Least Privilege for Function Permissions (IAM Roles)
• Description:
  1. Identify Function-Specific Resource Needs: For each serverless function, precisely determine the minimum AWS resources (or cloud provider resources) it requires to function correctly. Serverless functions should only access what they absolutely need.
  2. Create Granular, Function-Specific IAM Roles: Design dedicated IAM roles per function or for tightly coupled groups of functions. Avoid broad, shared roles that violate least privilege in the serverless context.
  3. Grant Minimum Necessary Permissions in IAM Roles: Within each function's IAM role, grant only the essential permissions. Use specific resource ARNs to restrict access to precise resources. Wildcard permissions should be avoided in serverless function roles due to the potential for over-exposure.
  4. Regularly Audit and Refine Function IAM Roles: Serverless application architectures can evolve rapidly. Regularly review and refine function IAM roles to ensure they remain least privilege and aligned with current function needs.
  5. Automated IAM Policy Analysis for Serverless Functions: Utilize automated tools to analyze function IAM policies, specifically looking for overly permissive configurations in the serverless context.
• Threats Mitigated:
  • Privilege Escalation: Severity: High - Overly permissive function IAM roles are a major serverless security risk, enabling privilege escalation if a function is compromised.
  • Lateral Movement: Severity: High - Broad function permissions facilitate lateral movement within the serverless environment if a function is compromised.
  • Data Breaches: Severity: High - Excessive function permissions increase the potential scope of data breaches in serverless applications.
• Impact:
  • Privilege Escalation: High - Directly reduces privilege escalation risk by limiting function capabilities.
  • Lateral Movement: High - Significantly restricts lateral movement by confining function access.
  • Data Breaches: High - Minimizes the potential damage from data breaches by limiting function access to data.
• Currently Implemented: IAM roles are defined for functions, but some roles might be overly permissive and use wildcard permissions in certain areas.
• Missing Implementation: Granular, function-specific IAM roles with strict least privilege are not consistently implemented across all functions. Regular audits and automated analysis of function IAM roles are needed.

Mitigation Strategy: Secure Event Source Configuration

• Mitigation Strategy: Secure Event Source Configuration
• Description:
  1. Authentication and Authorization for Serverless API Gateways: For API Gateway triggers, enforce robust authentication (OAuth 2.0, Cognito, API Keys with usage plans) and authorization (IAM authorizers, custom authorizers) to control access to serverless API endpoints.
  2. Access Controls for Serverless Message Queues (SQS, SNS): For SQS and SNS triggers, implement IAM policies to strictly control who can send messages to queues/topics and which functions can subscribe. Serverless event sources need explicit access control.
  3. Bucket Policies and ACLs for Serverless Cloud Storage (S3): For S3 triggers, meticulously configure bucket policies and ACLs to restrict access to buckets and objects. Serverless functions triggered by S3 events require secure bucket configurations.
  4. Network Security for Serverless VPC Endpoints: If functions are triggered by VPC-internal services, configure VPC endpoints and security groups to control network access, specifically for serverless function interactions within the VPC.
  5. Input Validation at Serverless API Gateway (WAF): For API Gateway event sources, leverage WAF to filter malicious requests before they reach serverless functions. WAF provides a crucial security layer at the serverless API entry point.
• Threats Mitigated:
  • Unauthorized Access to Serverless Functions: Severity: High - Insecure event sources can allow unauthorized invocation of serverless functions, bypassing intended access controls.
  • Data Tampering at Event Source: Severity: Medium - Unsecured serverless event sources can be exploited to tamper with event data before function processing.
  • Denial of Service (DoS) via Event Source Abuse: Severity: Medium - Unsecured serverless event sources can be abused to flood functions, causing DoS.
• Impact:
  • Unauthorized Access to Serverless Functions: High - Directly mitigates unauthorized function invocation by securing event sources.
  • Data Tampering at Event Source: Medium - Reduces risk of event data manipulation before function processing.
  • Denial of Service (DoS) via Event Source Abuse: Medium - Reduces DoS risk by controlling access and filtering traffic at event sources.
• Currently Implemented: API Gateway endpoints use API keys for basic authentication. S3 bucket policies are in place, but might not be fully restrictive.
• Missing Implementation: More robust authentication and authorization mechanisms (like OAuth 2.0 or Cognito) are needed for API Gateway. WAF is not configured for API Gateway. Explicit access controls for SQS/SNS triggers are lacking.

Mitigation Strategy: Secure Environment Variable Management (Serverless Context)

• Mitigation Strategy: Secure Environment Variable Management (Serverless Context)
• Description:
  1. Avoid Plaintext Secrets in Serverless Configuration: Never store sensitive secrets (API keys, database credentials) directly in serverless.yml or function environment variables. Serverless deployments can expose configuration.
  2. Utilize Serverless-Integrated Secrets Management Services: Leverage cloud provider secrets management services (AWS Secrets Manager, Azure Key Vault, Google Secret Manager) specifically designed for serverless environments.
  3. Retrieve Secrets at Serverless Function Runtime: Configure serverless functions to dynamically retrieve secrets from the secrets manager at runtime. Avoid embedding secrets in serverless deployment packages.
  4. Rotate Secrets Regularly in Serverless Environments: Implement automated secret rotation for secrets used by serverless functions, managed through the secrets management service.
  5. Restrict Access to Serverless Secrets Management Service: Control access to the secrets management service itself using IAM policies, ensuring only authorized serverless functions and services can retrieve secrets.
• Threats Mitigated:
  • Exposure of Secrets in Serverless Deployments: Severity: High - Plaintext secrets in serverless configurations are easily exposed in deployment artifacts and logs.
  • Hardcoded Credentials in Serverless Functions: Severity: High - Hardcoded secrets in serverless functions are a major vulnerability, easily discovered if code is compromised.
• Impact:
  • Exposure of Secrets in Serverless Deployments: High - Directly prevents secret exposure in serverless configurations and deployments.
  • Hardcoded Credentials in Serverless Functions: High - Eliminates hardcoded secrets by using secure, runtime secret retrieval in serverless functions.
• Currently Implemented: Some API keys are stored as environment variables in serverless.yml. Database credentials are partially managed using AWS Secrets Manager for some functions.
• Missing Implementation: Consistent use of AWS Secrets Manager for all sensitive credentials across all serverless functions. Automated secret rotation for serverless functions is not implemented. Access control to Secrets Manager for serverless functions needs explicit configuration.

Mitigation Strategy: Infrastructure-as-Code (IaC) Security Scanning (Serverless Framework)

• Mitigation Strategy: Infrastructure-as-Code (IaC) Security Scanning (Serverless Framework)
• Description:
  1. IaC Scanning Tools for Serverless Framework: Integrate IaC security scanning tools (Checkov, tfsec, CloudFormation Guard) specifically designed to analyze Serverless Framework serverless.yml files.
  2. Automated Scanning in Serverless CI/CD: Automate IaC scanning as a mandatory step in the serverless CI/CD pipeline. Fail serverless deployments if critical security issues are found in serverless.yml.
  3. Custom Security Policies for Serverless IaC: Configure IaC scanning tools with custom security policies tailored to serverless applications and Serverless Framework best practices.
  4. Regularly Update Serverless IaC Scanning Tools: Keep IaC scanning tools updated to ensure they have the latest security checks relevant to Serverless Framework and cloud provider updates.
  5. Remediate Serverless IaC Security Findings: Treat security issues identified by IaC scanning in serverless.yml as critical vulnerabilities and prioritize their remediation before deployment.
• Threats Mitigated:
  • Misconfigurations in Serverless Infrastructure (via IaC): Severity: High - Serverless IaC misconfigurations in serverless.yml can lead to critical security vulnerabilities (IAM, API Gateway, event sources).
  • Compliance Violations in Serverless Deployments: Severity: Medium - IaC scanning helps ensure serverless deployments comply with security standards defined in IaC.
• Impact:
  • Misconfigurations in Serverless Infrastructure (via IaC): High - Directly prevents security misconfigurations in serverless deployments by scanning IaC.
  • Compliance Violations in Serverless Deployments: Medium - Improves compliance posture of serverless deployments by enforcing security standards in IaC.
• Currently Implemented: No IaC security scanning is currently implemented for serverless.yml files.
• Missing Implementation: Need to integrate IaC scanning tools into the CI/CD pipeline to automatically scan serverless.yml configurations for security misconfigurations before serverless deployments.

Mitigation Strategy: Comprehensive Logging and Monitoring for Serverless Functions

• Mitigation Strategy: Comprehensive Logging and Monitoring for Serverless Functions
• Description:
  1. Centralized Logging for Serverless Functions: Configure all serverless functions to send logs to a centralized logging system (CloudWatch Logs, ELK, Splunk). Centralized logging is essential for managing ephemeral serverless function logs.
  2. Log Relevant Events within Serverless Functions: Log function invocations, errors, security events (authentication, authorization failures, input validation), and critical business events within each serverless function.
  3. Structured Logging in Serverless Functions: Use structured logging (JSON) in serverless functions for easier parsing and analysis of function logs. Include context like request IDs, function names, and event source details.
  4. Monitor Serverless Function Metrics: Monitor key function metrics (invocations, errors, latency, concurrency) specific to serverless environments. Set up dashboards and alerts for anomalies in serverless function behavior.
  5. Security Monitoring Dashboards for Serverless Applications: Create dedicated security dashboards focused on serverless function logs and metrics, monitoring for suspicious patterns and security events unique to serverless architectures.
• Threats Mitigated:
  • Security Incident Detection in Ephemeral Serverless Environments: Severity: High - Comprehensive logging is crucial for detecting incidents in serverless functions due to their ephemeral nature.
  • Anomaly Detection in Serverless Function Behavior: Severity: Medium - Monitoring function metrics and logs helps identify anomalies indicative of attacks targeting serverless functions.
  • Forensics and Incident Response for Serverless Applications: Severity: Medium - Logs are vital for forensics and incident response in serverless environments, providing insights into function execution and events.
• Impact:
  • Security Incident Detection in Ephemeral Serverless Environments: High - Significantly improves incident detection in serverless functions.
  • Anomaly Detection in Serverless Function Behavior: Medium - Enhances anomaly detection capabilities for serverless function security.
  • Forensics and Incident Response for Serverless Applications: Medium - Provides essential data for serverless security investigations.
• Currently Implemented: Basic logging to CloudWatch Logs is enabled for functions, but logging is not comprehensive, structured, or security-focused. Monitoring is limited to basic CloudWatch metrics.
• Missing Implementation: Need to implement structured logging within serverless functions, log security-relevant events, set up centralized logging and dedicated security monitoring dashboards for serverless applications, and configure alerts for serverless-specific security anomalies.

Mitigation Strategy: Security Alerting and Anomaly Detection for Serverless Applications

• Mitigation Strategy: Security Alerting and Anomaly Detection for Serverless Applications
• Description:
  1. Define Serverless-Specific Security Alerting Rules: Define alerting rules based on serverless function logs and metrics, focusing on serverless-specific security concerns (e.g., unusual function invocation patterns, IAM role violations, event source anomalies).
  2. Automated Alerting System for Serverless Security: Implement an automated alerting system that triggers notifications for serverless security alerts, enabling rapid response to potential incidents.
  3. Anomaly Detection Tools for Serverless Function Behavior: Utilize anomaly detection tools to automatically identify deviations from normal serverless function behavior in logs and metrics, detecting subtle serverless-specific threats.
  4. Prioritize and Investigate Serverless Security Alerts: Establish a clear process for prioritizing and investigating serverless security alerts, ensuring timely response and mitigation in the dynamic serverless environment.
  5. Regularly Review and Tune Serverless Alerting Rules: Periodically review and tune serverless security alerting rules to optimize for accuracy and effectiveness in detecting real serverless security threats, minimizing false positives.
• Threats Mitigated:
  • Delayed Incident Detection in Serverless Environments: Severity: High - Without alerting, security incidents in serverless applications can remain undetected longer due to their ephemeral nature.
  • Missed Serverless-Specific Security Events: Severity: Medium - Manual log analysis may miss subtle serverless-specific security events that automated alerting can detect.
• Impact:
  • Delayed Incident Detection in Serverless Environments: High - Significantly reduces delayed incident detection in serverless applications.
  • Missed Serverless-Specific Security Events: Medium - Improves detection of subtle serverless-specific security events through automation.
• Currently Implemented: No security alerting or anomaly detection is currently implemented for serverless applications.
• Missing Implementation: Need to define serverless-specific security alerting rules, implement an automated alerting system tailored for serverless environments, and explore anomaly detection tools to enhance serverless security monitoring and incident response.