Serverless Function Without Unique IAM Role

• Query id: 4ba74f01-aba5-4be2-83bc-be79ff1a3b92
• Query name: Serverless Function Without Unique IAM Role
• Platform: CloudFormation
• Severity: High
• Category: Insecure Configurations
• CWE: 269
• URL: Github

Description

AWS Serverless Function should not share IAM Role to ensure it will have the minimum privileges needed to perform the required tasks
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - yaml file

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: AWS SAM template with a simple API definition
Resources:
  Function1:
    Type: AWS::Serverless::Function
    Properties:
      PackageType: Image
      ImageUri: account-id.dkr.ecr.region.amazonaws.com/ecr-repo-name:image-name
      ImageConfig:
        Command:
          - "app.lambda_handler"
        EntryPoint:
          - "entrypoint1"
        WorkingDirectory: "workDir"
      Tags:
        - Key: Type
          Value: AWS Serverless Function
      Role: arn:aws:iam::123456789012:role/lambda-role
  Function2:
    Type: AWS::Serverless::Function
    Properties:
      PackageType: Image
      ImageUri: account-id.dkr.ecr.region.amazonaws.com/ecr-repo-name:image-name
      ImageConfig:
        Command:
          - "app.lambda_handler"
        EntryPoint:
          - "entrypoint1"
        WorkingDirectory: "workDir"
      Tags:
        - Key: Type
          Value: AWS Serverless Function
      Role: arn:aws:iam::123456789012:role/lambda-role

Positive test num. 2 - yaml file

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: AWS SAM template with a simple API definition
Resources:
  Function1:
    Type: AWS::Serverless::Function
    Properties:
      PackageType: Image
      ImageUri: account-id.dkr.ecr.region.amazonaws.com/ecr-repo-name:image-name
      ImageConfig:
        Command:
          - "app.lambda_handler"
        EntryPoint:
          - "entrypoint1"
        WorkingDirectory: "workDir"
      Tags:
        - Key: Type
          Value: AWS Serverless Function
      Role: !Ref Role
  Function2:
    Type: AWS::Serverless::Function
    Properties:
      PackageType: Image
      ImageUri: account-id.dkr.ecr.region.amazonaws.com/ecr-repo-name:image-name
      ImageConfig:
        Command:
          - "app.lambda_handler"
        EntryPoint:
          - "entrypoint1"
        WorkingDirectory: "workDir"
      Tags:
        - Key: Type
          Value: AWS Serverless Function
      Role: !Ref Role

Code samples without security vulnerabilities

Negative test num. 1 - yaml file

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: AWS SAM template with a simple API definition
Resources:
  Function3:
    Type: AWS::Serverless::Function
    Properties:
      PackageType: Image
      ImageUri: account-id.dkr.ecr.region.amazonaws.com/ecr-repo-name:image-name
      ImageConfig:
        Command:
          - "app.lambda_handler"
        EntryPoint:
          - "entrypoint1"
        WorkingDirectory: "workDir"
      Tags:
        - Key: Type
          Value: AWS Serverless Function
      Role: arn:aws:iam::123456789012:role/lambda-role

Negative test num. 2 - yaml file

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: AWS SAM template with a simple API definition
Resources:
  Function1:
    Type: AWS::Serverless::Function
    Properties:
      PackageType: Image
      ImageUri: account-id.dkr.ecr.region.amazonaws.com/ecr-repo-name:image-name
      ImageConfig:
        Command:
          - "app.lambda_handler"
        EntryPoint:
          - "entrypoint1"
        WorkingDirectory: "workDir"
      Tags:
        - Key: Type
          Value: AWS Serverless Function
      Role: !Ref Role2
  Function2:
    Type: AWS::Serverless::Function
    Properties:
      PackageType: Image
      ImageUri: account-id.dkr.ecr.region.amazonaws.com/ecr-repo-name:image-name
      ImageConfig:
        Command:
          - "app.lambda_handler"
        EntryPoint:
          - "entrypoint1"
        WorkingDirectory: "workDir"
      Tags:
        - Key: Type
          Value: AWS Serverless Function
      Role: !Ref Role4