rules:
- id: aws-lambda-environment-unencrypted
  patterns:
  - pattern-inside: |
      resource "aws_lambda_function" $ANYTHING {
        ...
      }
  - pattern-either:
    - patterns:
      - pattern: |
          environment { ... }
      - pattern-not-inside: |
          resource $A $B {
            ...
            kms_key_arn = ...
            ...
          }
    - patterns:
      - pattern: |
          kms_key_arn = ...
      - pattern-not-inside: |
          resource $A $B {
            ...
            environment { ... }
            ...
          }
    - pattern: kms_key_arn = ""
  message: >-
    By default, the AWS Lambda Environment is encrypted using AWS-managed keys.
    However, for added security, it's recommended to configure your own AWS KMS encryption key to protect your environment variables in Lambda.
    You can either create a new aws_kms_key resource or use the ARN of an existing key in your AWS account to do so.
  languages: [hcl]
  severity: WARNING
  metadata:
    owasp:
    - A03:2017 - Sensitive Data Exposure
    cwe:
    - 'CWE-320: CWE CATEGORY: Key Management Errors'
    technology:
    - aws
    - terraform
    category: security
    references:
    - https://owasp.org/Top10/A02_2021-Cryptographic_Failures
    subcategory:
    - audit
    likelihood: LOW
    impact: LOW
    confidence: LOW