Ensure that S3 Bucket policy doesn't allow actions from all principals without a condition

Risk Level: Critical
Cloud Entity: Simple Storage Service (S3)
CloudGuard Rule ID: D9.AWS.IAM.40
Covered by Spectral: Yes
Category: Storage

GSL LOGIC

S3Bucket should not have policy.Statement with [Effect='Allow' and (Principal='*' or Principal.AWS='*') and Condition isEmpty()]

REMEDIATION

From Portal

1. Sign in to the AWS Management Console and open the Amazon S3 console at https://console.aws.amazon.com/s3/.
2. In the Buckets list, choose the name of the bucket that you want to create a bucket policy for or whose bucket policy you want to edit.
3. Choose Permissions.
4. Under Bucket policy, choose Edit. This opens the Edit bucket policy page.
5. In the Policy box, edit the existing policy.
6. Choose Save changes, which returns you to the Bucket Permissions page.

From TF
Add a policy document with required permissions and appropriate condition as needed as follows:

data "aws_iam_policy_document" "example" {
	...
	statement {
		effect = "Allow"
		
		actions = [
		REQUIRED_ACTIONS
		]
		principals {
			REQUIRED_PRINCIPALS
		}
		
		resources = [
		"S3_BUCKET_ARN",
		]
		
		condition {
			test     = TEST
			variable = CONTEXT_VARIABLE
			
			values = [
			VALUES
			]
		}
	}
	...
}

From Command Line
To add a policy with required permissions and appropriate condition as needed, run:

aws s3api put-bucket-policy --bucket BUCKET-NAME --policy file://policy.json

References

1. https://docs.aws.amazon.com/cli/latest/reference/s3api/put-bucket-policy.html
2. https://registry.terraform.io/providers/hashicorp/aws/3.3.0/docs/data-sources/iam_policy_document
3. https://docs.aws.amazon.com/AmazonS3/latest/userguide/example-bucket-policies.html
4. https://docs.aws.amazon.com/AmazonS3/latest/dev/using-iam-policies.html

Simple Storage Service (S3)

Companies today need the ability to simply and securely collect, store, and analyze their data at a massive scale. Amazon S3 is object storage built to store and retrieve any amount of data from anywhere ��� web sites and mobile apps, corporate applications, and data from IoT sensors or devices. It is designed to deliver 99.999999999% durability, and stores data for millions of applications used by market leaders in every indu

Compliance Frameworks

• AWS CCPA Framework
• AWS CSA CCM v.4.0.1
• AWS CloudGuard Best Practices
• AWS CloudGuard S3 Bucket Security
• AWS CloudGuard SOC2 based on AICPA TSC 2017
• AWS CloudGuard Well Architected Framework
• AWS HIPAA
• AWS HITRUST
• AWS HITRUST v11.0.0
• AWS ISO 27001:2013
• AWS ISO27001:2022
• AWS ITSG-33
• AWS LGPD regulation
• AWS MAS TRM Framework
• AWS MITRE ATT&CK Framework v10
• AWS MITRE ATT&CK Framework v11.3
• AWS NIST 800-171
• AWS NIST 800-53 Rev 4
• AWS NIST 800-53 Rev 5
• AWS NIST CSF v1.1
• AWS PCI-DSS 3.2
• AWS PCI-DSS 4.0
• AWS Security Risk Management
• CloudGuard AWS All Rules Ruleset
• CloudGuard AWS Default Ruleset