AWS Organizations service control policies (SCPs) are designed to enforce preventive guardrails across accounts without requiring application-level changes. According to the AWS Certified Security – Specialty documentation, SCPs can restrict specific API actions or require certain condition keys to enforce security standards centrally. AWS Lambda function URLs support two authentication modes: AWS_IAM and NONE. When the authentication type is set to NONE, the function URL becomes publicly accessible, which introduces a significant security risk in production environments.
By using an SCP that explicitly denies the lambda:CreateFunctionUrlConfig and lambda:UpdateFunctionUrlConfig actions when the lambda:FunctionUrlAuthType condition key equals NONE, the organization ensures that unauthenticated function URLs cannot be created or modified in production accounts. This enforcement occurs at the AWS Organizations level and applies automatically to all accounts within the specified organizational units (OUs). Developers are not required to change their workflows or add additional controls, satisfying the requirement of no additional developer effort.
Option A relates to browser-based access controls and does not provide authentication or authorization enforcement. Option B is not valid because AWS WAF cannot be attached directly to AWS Lambda function URLs. Option C is incorrect because SCPs do not grant permissions; they only limit permissions. AWS documentation clearly states that SCPs define maximum available permissions and are evaluated before IAM policies.
This approach aligns with AWS best practices for centralized governance, least privilege, and preventive security controls.
Referenced AWS Specialty Documents:
AWS Certified Security – Specialty Official Study Guide
AWS Organizations Service Control Policies Documentation
AWS Lambda Security and Function URL Authentication Overview
