HIGH
Source
Trivy
ID
AVD-AWS-0345

Disallow unrestricted s3:* IAM Policies

Ensure that the creation of the IAM policy ‘s3:*’ is disallowed.

Impact

Follow the appropriate remediation steps below to resolve the issue.

Create more restrictive S3 policies instead of using s3:*

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AWSTemplateFormatVersion: "2010-09-09"

Resources:
  GoodPolicy:
    Type: AWS::IAM::Policy
    Properties:
      PolicyName: good_policy
      PolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Action:
              - s3:GetObject
              - s3:PutObject
            Resource: arn:aws:s3:::examplebucket/*
      Roles:
        - !Ref GoodRole

  GoodRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: good_role
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service: ec2.amazonaws.com
            Action: sts:AssumeRole

Create more restrictive S3 policies instead of using s3:*

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resource "aws_iam_policy" "good_policy" {
  name = "good_policy"
  policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Effect = "Allow"
        Action = [
          "s3:GetObject",
          "s3:PutObject"
        ]
        Resource = "arn:aws:s3:::examplebucket/*"
      }
    ]
  })
}

resource "aws_iam_role" "good_role" {
  name = "good_role"
  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Effect = "Allow"
        Principal = {
          Service = "ec2.amazonaws.com"
        }
        Action = "sts:AssumeRole"
      }
    ]
  })
}

resource "aws_iam_role_policy_attachment" "good_role_policy_attachment" {
  role       = aws_iam_role.good_role.name
  policy_arn = aws_iam_policy.good_policy.arn
}