Amazon Simple Storage Service controls - AWS Security Hub

Amazon Simple Storage Service controls

These controls are related to Amazon S3 resources.

These controls may not be available in all AWS Regions. For more information, see Availability of controls by Region.

[S3.1] S3 general purpose buckets should have block public access settings enabled

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Related requirements: PCI DSS v3.2.1/1.2.1, PCI DSS v3.2.1/1.3.1, PCI DSS v3.2.1/1.3.2, PCI DSS v3.2.1/1.3.4, PCI DSS v3.2.1/1.3.6, CIS AWS Foundations Benchmark v1.4.0/2.1.5, NIST.800-53.r5 AC-21, NIST.800-53.r5 AC-3, NIST.800-53.r5 AC-3(7), NIST.800-53.r5 AC-4, NIST.800-53.r5 AC-4(21), NIST.800-53.r5 AC-6, NIST.800-53.r5 SC-7, NIST.800-53.r5 SC-7(11), NIST.800-53.r5 SC-7(16), NIST.800-53.r5 SC-7(20), NIST.800-53.r5 SC-7(21), NIST.800-53.r5 SC-7(3), NIST.800-53.r5 SC-7(4), NIST.800-53.r5 SC-7(9)

Category: Protect > Secure network configuration

Severity: Medium

Resource type: AWS::::Account

AWS Config rule: s3-account-level-public-access-blocks-periodic

Schedule type: Periodic

Parameters:

  • ignorePublicAcls: true (not customizable)

  • blockPublicPolicy: true (not customizable)

  • blockPublicAcls: true (not customizable)

  • restrictPublicBuckets: true (not customizable)

This control checks whether the preceding Amazon S3 block public access settings are configured at the account level for an S3 general purpose bucket. The control fails if one or more of the block public access settings are set to false.

The control fails if any of the settings are set to false, or if any of the settings are not configured.

Amazon S3 public access block is designed to provide controls across an entire AWS account or at the individual S3 bucket level to ensure that objects never have public access. Public access is granted to buckets and objects through access control lists (ACLs), bucket policies, or both.

Unless you intend to have your S3 buckets be publicly accessible, you should configure the account level Amazon S3 Block Public Access feature.

To learn more, see Using Amazon S3 Block Public Access in the Amazon Simple Storage Service User Guide.

Remediation

To enable Amazon S3 Block Public Access for your AWS account, see Configuring block public access settings for your account in the Amazon Simple Storage Service User Guide.

[S3.2] S3 general purpose buckets should block public read access

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Related requirements: PCI DSS v3.2.1/1.2.1, PCI DSS v3.2.1/1.3.1, PCI DSS v3.2.1/1.3.2, PCI DSS v3.2.1/1.3.6, PCI DSS v3.2.1/7.2.1, NIST.800-53.r5 AC-21, NIST.800-53.r5 AC-3, NIST.800-53.r5 AC-3(7), NIST.800-53.r5 AC-4, NIST.800-53.r5 AC-4(21), NIST.800-53.r5 AC-6, NIST.800-53.r5 SC-7, NIST.800-53.r5 SC-7(11), NIST.800-53.r5 SC-7(16), NIST.800-53.r5 SC-7(20), NIST.800-53.r5 SC-7(21), NIST.800-53.r5 SC-7(3), NIST.800-53.r5 SC-7(4), NIST.800-53.r5 SC-7(9)

Category: Protect > Secure network configuration

Severity: Critical

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-public-read-prohibited

Schedule type: Periodic and change triggered

Parameters: None

This control checks whether an Amazon S3 general purpose bucket permits public read access. It evaluates the block public access settings, the bucket policy, and the bucket access control list (ACL). The control fails if the bucket permits public read access.

Some use cases may require that everyone on the internet be able to read from your S3 bucket. However, those situations are rare. To ensure the integrity and security of your data, your S3 bucket should not be publicly readable.

Remediation

To block public read access on your Amazon S3 buckets, see Configuring block public access settings for your S3 buckets in the Amazon Simple Storage Service User Guide.

[S3.3] S3 general purpose buckets should block public write access

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Related requirements: PCI DSS v3.2.1/1.2.1, PCI DSS v3.2.1/1.3.1, PCI DSS v3.2.1/1.3.2, PCI DSS v3.2.1/1.3.4, PCI DSS v3.2.1/1.3.6, PCI DSS v3.2.1/7.2.1, NIST.800-53.r5 AC-21, NIST.800-53.r5 AC-3, NIST.800-53.r5 AC-3(7), NIST.800-53.r5 AC-4, NIST.800-53.r5 AC-4(21), NIST.800-53.r5 AC-6, NIST.800-53.r5 SC-7, NIST.800-53.r5 SC-7(11), NIST.800-53.r5 SC-7(16), NIST.800-53.r5 SC-7(20), NIST.800-53.r5 SC-7(21), NIST.800-53.r5 SC-7(3), NIST.800-53.r5 SC-7(4), NIST.800-53.r5 SC-7(9)

Category: Protect > Secure network configuration

Severity: Critical

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-public-write-prohibited

Schedule type: Periodic and change triggered

Parameters: None

This control checks whether an Amazon S3 general purpose bucket permits public write access. It evaluates the block public access settings, the bucket policy, and the bucket access control list (ACL). The control fails if the bucket permits public write access.

Some use cases require that everyone on the internet be able to write to your S3 bucket. However, those situations are rare. To ensure the integrity and security of your data, your S3 bucket should not be publicly writable.

Remediation

To block public write access on your Amazon S3 buckets, see Configuring block public access settings for your S3 buckets in the Amazon Simple Storage Service User Guide.

[S3.5] S3 general purpose buckets should require requests to use SSL

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Related requirements: PCI DSS v3.2.1/4.1, CIS AWS Foundations Benchmark v1.4.0/2.1.2, NIST.800-53.r5 AC-17(2), NIST.800-53.r5 AC-4, NIST.800-53.r5 IA-5(1), NIST.800-53.r5 SC-12(3), NIST.800-53.r5 SC-13, NIST.800-53.r5 SC-23, NIST.800-53.r5 SC-23(3), NIST.800-53.r5 SC-7(4), NIST.800-53.r5 SC-8, NIST.800-53.r5 SC-8(1), NIST.800-53.r5 SC-8(2), NIST.800-53.r5 SI-7(6)

Category: Protect > Secure access management

Severity: Medium

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-ssl-requests-only

Schedule type: Change triggered

Parameters: None

This control checks whether an Amazon S3 general purpose bucket has a policy that requires requests to use SSL. The control fails if the bucket policy doesn't require requests to use SSL.

S3 buckets should have policies that require all requests (Action: S3:*) to only accept transmission of data over HTTPS in the S3 resource policy, indicated by the condition key aws:SecureTransport.

Remediation

To update an Amazon S3 bucket policy to deny nonsecure transport, see.Adding a bucket policy by using the Amazon S3 console in the Amazon Simple Storage Service User Guide.

Add a policy statement similar to the one in the following policy. Replace awsexamplebucket with the name of the bucket you're modifying.

{ "Id": "ExamplePolicy", "Version": "2012-10-17", "Statement": [ { "Sid": "AllowSSLRequestsOnly", "Action": "s3:*", "Effect": "Deny", "Resource": [ "arn:aws:s3:::awsexamplebucket", "arn:aws:s3:::awsexamplebucket/*" ], "Condition": { "Bool": { "aws:SecureTransport": "false" } }, "Principal": "*" } ] }

For more information, see the Knowledge Center article What S3 bucket policy should I use to comply with the AWS Config rule s3-bucket-ssl-requests-only?.

[S3.6] S3 general purpose bucket policies should restrict access to other AWS accounts

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Related requirements: NIST.800-53.r5 CA-9(1), NIST.800-53.r5 CM-2

Category: Protect > Secure access management > Sensitive API operations actions restricted

Severity: High

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-blacklisted-actions-prohibited

Schedule type: Change triggered

Parameters:

  • blacklistedactionpatterns: s3:DeleteBucketPolicy, s3:PutBucketAcl, s3:PutBucketPolicy, s3:PutEncryptionConfiguration, s3:PutObjectAcl (not customizable)

This control checks whether an Amazon S3 general purpose bucket policy prevents principals from other AWS accounts from performing denied actions on resources in the S3 bucket. The control fails if the bucket policy allows one or more of the preceding actions for a principal in another AWS account.

Implementing least privilege access is fundamental to reducing security risk and the impact of errors or malicious intent. If an S3 bucket policy allows access from external accounts, it could result in data exfiltration by an insider threat or an attacker.

The blacklistedactionpatterns parameter allows for successful evaluation of the rule for S3 buckets. The parameter grants access to external accounts for action patterns that are not included in the blacklistedactionpatterns list.

Remediation

To update an Amazon S3 bucket policy to remove permissions, see.Adding a bucket policy by using the Amazon S3 console in the Amazon Simple Storage Service User Guide.

On the Edit bucket policy page, in the policy editing text box, take one of the following actions:

  • Remove the statements that grant other AWS accounts access to denied actions.

  • Remove the permitted denied actions from the statements.

[S3.7] S3 general purpose buckets should use cross-Region replication

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Related requirements: PCI DSS v3.2.1/2.2, NIST.800-53.r5 AU-9(2), NIST.800-53.r5 CP-10, NIST.800-53.r5 CP-6, NIST.800-53.r5 CP-6(1), NIST.800-53.r5 CP-6(2), NIST.800-53.r5 CP-9, NIST.800-53.r5 SC-36(2), NIST.800-53.r5 SC-5(2), NIST.800-53.r5 SI-13(5)

Category: Protect > Secure access management

Severity: Low

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-replication-enabled

Schedule type: Change triggered

Parameters:

  • ReplicationType: CROSS-REGION (not customizable)

This control checks whether an Amazon S3 general purpose bucket has cross-Region replication enabled. The control fails if the bucket doesn't have cross-Region replication enabled.

Replication is the automatic, asynchronous copying of objects across buckets in the same or different AWS Regions. Replication copies newly created objects and object updates from a source bucket to a destination bucket or buckets. AWS best practices recommend replication for source and destination buckets that are owned by the same AWS account. In addition to availability, you should consider other systems hardening settings.

Remediation

To enable Cross-Region Replication on an S3 bucket, see Configuring replication for source and destination buckets owned by the same account in the Amazon Simple Storage Service User Guide. For Source bucket, choose Apply to all objects in the bucket.

[S3.8] S3 general purpose buckets should block public access

Related requirements: CIS AWS Foundations Benchmark v1.4.0/2.1.5, NIST.800-53.r5 AC-21, NIST.800-53.r5 AC-3, NIST.800-53.r5 AC-3(7), NIST.800-53.r5 AC-4, NIST.800-53.r5 AC-4(21), NIST.800-53.r5 AC-6, NIST.800-53.r5 SC-7, NIST.800-53.r5 SC-7(11), NIST.800-53.r5 SC-7(16), NIST.800-53.r5 SC-7(20), NIST.800-53.r5 SC-7(21), NIST.800-53.r5 SC-7(3), NIST.800-53.r5 SC-7(4), NIST.800-53.r5 SC-7(9)

Category: Protect > Secure access management > Access control

Severity: High

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-level-public-access-prohibited

Schedule type: Change triggered

Parameters:

  • excludedPublicBuckets (not customizable) – A comma-separated list of known allowed public S3 bucket names

This control checks whether an Amazon S3 general purpose bucket blocks public access at the bucket level. The control fails if any of the following settings are set to false:

  • ignorePublicAcls

  • blockPublicPolicy

  • blockPublicAcls

  • restrictPublicBuckets

Block Public Access at the S3 bucket level provides controls to ensure that objects never have public access. Public access is granted to buckets and objects through access control lists (ACLs), bucket policies, or both.

Unless you intend to have your S3 buckets publicly accessible, you should configure the bucket level Amazon S3 Block Public Access feature.

Remediation

For information on how to remove public access at a bucket level, see Blocking public access to your Amazon S3 storage in the Amazon S3 User Guide.

[S3.9] S3 general purpose buckets should have server access logging enabled

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Related requirements: NIST.800-53.r5 AC-2(4), NIST.800-53.r5 AC-4(26), NIST.800-53.r5 AC-6(9), NIST.800-53.r5 AU-10, NIST.800-53.r5 AU-12, NIST.800-53.r5 AU-2, NIST.800-53.r5 AU-3, NIST.800-53.r5 AU-6(3), NIST.800-53.r5 AU-6(4), NIST.800-53.r5 CA-7, NIST.800-53.r5 SC-7(9), NIST.800-53.r5 SI-3(8), NIST.800-53.r5 SI-4(20), NIST.800-53.r5 SI-7(8)

Category: Identify > Logging

Severity: Medium

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-logging-enabled

Schedule type: Change triggered

Parameters: None

This control checks whether server access logging is enabled for an Amazon S3 general purpose bucket. The control fails if server access logging isn't enabled. When logging is enabled, Amazon S3 delivers access logs for a source bucket to a chosen target bucket. The target bucket must be in the same AWS Region as the source bucket and must not have a default retention period configured. The target logging bucket does not need to have server access logging enabled, and you should suppress findings for this bucket.

Server access logging provides detailed records of requests made to a bucket. Server access logs can assist in security and access audits. For more information, see Security Best Practices for Amazon S3: Enable Amazon S3 server access logging.

Remediation

To enable Amazon S3 server access logging, see Enabling Amazon S3 server access logging in the Amazon S3 User Guide.

[S3.10] S3 general purpose buckets with versioning enabled should have Lifecycle configurations

Important

On March 12, 2024, the title of this control changed to the title shown. Security Hub retired this control in April 2024 from the AWS Foundational Security Best Practices standard, but it is still included in the NIST SP 800-53 Rev. 5 standard. For more information, see Change log for Security Hub controls.

Related requirements: NIST.800-53.r5 CP-10, NIST.800-53.r5 CP-6(2), NIST.800-53.r5 CP-9, NIST.800-53.r5 SC-5(2), NIST.800-53.r5 SI-13(5)

Category: Identify > Logging

Severity: Medium

Resource type: AWS::S3::Bucket

AWS Config rule: s3-version-lifecycle-policy-check

Schedule type: Change triggered

Parameters: None

This control checks whether an Amazon S3 general purpose versioned bucket has a Lifecycle configuration. The control fails if the bucket doesn't have a Lifecycle configuration.

We recommended creating a Lifecycle configuration for your S3 bucket to help you define actions that you want Amazon S3 to take during an object's lifetime.

Remediation

For more information on configuring lifecycle on an Amazon S3 bucket, see Setting lifecycle configuration on a bucket and Managing your storage lifecycle.

[S3.11] S3 general purpose buckets should have event notifications enabled

Important

On March 12, 2024, the title of this control changed to the title shown. Security Hub retired this control in April 2024 from the AWS Foundational Security Best Practices standard, but it is still included in the NIST SP 800-53 Rev. 5 standard:. For more information, see Change log for Security Hub controls.

Related requirements: NIST.800-53.r5 CA-7, NIST.800-53.r5 SI-3(8), NIST.800-53.r5 SI-4, NIST.800-53.r5 SI-4(4)

Category: Identify > Logging

Severity: Medium

Resource type: AWS::S3::Bucket

AWS Config rule: s3-event-notifications-enabled

Schedule type: Change triggered

Parameters:

Parameter Description Type Allowed custom values Security Hub default value

eventTypes

List of preferred S3 event types

EnumList (maximum of 28 items)

s3:IntelligentTiering, s3:LifecycleExpiration:*, s3:LifecycleExpiration:Delete, s3:LifecycleExpiration:DeleteMarkerCreated, s3:LifecycleTransition, s3:ObjectAcl:Put, s3:ObjectCreated:*, s3:ObjectCreated:CompleteMultipartUpload, s3:ObjectCreated:Copy, s3:ObjectCreated:Post, s3:ObjectCreated:Put, s3:ObjectRemoved:*, s3:ObjectRemoved:Delete, s3:ObjectRemoved:DeleteMarkerCreated, s3:ObjectRestore:*, s3:ObjectRestore:Completed, s3:ObjectRestore:Delete, s3:ObjectRestore:Post, s3:ObjectTagging:*, s3:ObjectTagging:Delete, s3:ObjectTagging:Put, s3:ReducedRedundancyLostObject, s3:Replication:*, s3:Replication:OperationFailedReplication, s3:Replication:OperationMissedThreshold, s3:Replication:OperationNotTracked, s3:Replication:OperationReplicatedAfterThreshold, s3:TestEvent

No default value

This control checks whether S3 Event Notifications are enabled on an Amazon S3 general purpose bucket. The control fails if S3 Event Notifications are not enabled on the bucket. If you provide custom values for the eventTypes parameter, the control passes only if event notifications are enabled for the specified types of events.

When you enable S3 Event Notifications, you receive alerts when specific events occur that impact your S3 buckets. For example, you can be notified of object creation, object removal, and object restoration. These notifications can alert relevant teams to accidental or intentional modifications that may lead to unauthorized data access.

Remediation

For information about detecting changes to S3 buckets and objects, see Amazon S3 Event Notifications in the Amazon S3 User Guide.

[S3.12] ACLs should not be used to manage user access to S3 general purpose buckets

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Related requirements: NIST.800-53.r5 AC-2(1), NIST.800-53.r5 AC-3, NIST.800-53.r5 AC-3(15), NIST.800-53.r5 AC-3(7), NIST.800-53.r5 AC-6

Category: Protect > Secure access management > Access control

Severity: Medium

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-acl-prohibited

Schedule type: Change triggered

Parameters: None

This control checks whether an Amazon S3 general purpose bucket provides user permissions with an access control list (ACL). The control fails if an ACL is configured for managing user access on the bucket.

ACLs are legacy access control mechanisms that predate IAM. Instead of ACLs, we recommend using S3 bucket policies or AWS Identity and Access Management (IAM) policies to manage access to your S3 buckets.

Remediation

To pass this control, you should disable ACLs for your S3 buckets. For instructions, see Controlling ownership of objects and disabling ACLs for your bucket in the Amazon Simple Storage Service User Guide.

To create an S3 bucket policy, see Adding a bucket policy by using the Amazon S3 console. To create an IAM user policy on an S3 bucket, see Controlling access to a bucket with user policies.

[S3.13] S3 general purpose buckets should have Lifecycle configurations

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Related requirements: NIST.800-53.r5 CP-10, NIST.800-53.r5 CP-6(2), NIST.800-53.r5 CP-9, NIST.800-53.r5 SC-5(2), NIST.800-53.r5 SI-13(5)

Category: Protect > Data protection

Severity: Low

Resource type: AWS::S3::Bucket

AWS Config rule: s3-lifecycle-policy-check

Schedule type: Change triggered

Parameters:

Parameter Description Type Allowed custom values Security Hub default value

targetTransitionDays

Number of days after object creation when objects are transitioned to a specified storage class

Integer

1 to 36500

No default value

targetExpirationDays

Number of days after object creation when objects are deleted

Integer

1 to 36500

No default value

targetTransitionStorageClass

Destination S3 storage class type

Enum

STANDARD_IA, INTELLIGENT_TIERING, ONEZONE_IA, GLACIER, GLACIER_IR, DEEP_ARCHIVE

No default value

This control checks whether an Amazon S3 general purpose bucket has a Lifecycle configuration. The control fails if the bucket doesn't have a Lifecycle configuration. If you provide custom values for one or more of the preceding parameters, the control passes only if the policy includes the specified storage class, deletion time, or transition time.

Creating a Lifecycle configuration for your S3 bucket defines actions that you want Amazon S3 to take during an object's lifetime. For example, you can transition objects to another storage class, archive them, or delete them after a specified period of time.

Remediation

For information about configuring lifecycle policies on an Amazon S3 bucket, see Setting lifecycle configuration on a bucket and see Managing your storage lifecycle in the Amazon S3 User Guide.

[S3.14] S3 general purpose buckets should have versioning enabled

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Category: Protect > Data protection > Data deletion protection

Related requirements: NIST.800-53.r5 AU-9(2), NIST.800-53.r5 CP-10, NIST.800-53.r5 CP-6, NIST.800-53.r5 CP-6(1), NIST.800-53.r5 CP-6(2), NIST.800-53.r5 CP-9, NIST.800-53.r5 SC-5(2), NIST.800-53.r5 SI-12, NIST.800-53.r5 SI-13(5)

Severity: Low

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-versioning-enabled

Schedule type: Change triggered

Parameters: None

This control checks whether an Amazon S3 general purpose bucket has versioning enabled. The control fails if versioning is suspended for the bucket.

Versioning keeps multiple variants of an object in the same S3 bucket. You can use versioning to preserve, retrieve, and restore earlier versions of an object stored in your S3 bucket. Versioning helps you recover from both unintended user actions and application failures.

Tip

As the number of objects increases in a bucket because of versioning, you can set up a Lifecycle configuration to automatically archive or delete versioned objects based on rules. For more information, see Amazon S3 Lifecycle Management for Versioned Objects.

Remediation

To use versioning on an S3 bucket, see Enabling versioning on buckets in the Amazon S3 User Guide.

[S3.15] S3 general purpose buckets should have Object Lock enabled

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Category: Protect > Data protection > Data deletion protection

Related requirements: NIST.800-53.r5 CP-6(2)

Severity: Medium

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-default-lock-enabled

Schedule type: Change triggered

Parameters:

Parameter Description Type Allowed custom values Security Hub default value

mode

S3 Object Lock retention mode

Enum

GOVERNANCE, COMPLIANCE

No default value

This control checks whether an Amazon S3 general purpose bucket has Object Lock enabled. The control fails if Object Lock isn't enabled for the bucket. If you provide a custom value for the mode parameter, the control passes only if S3 Object Lock uses the specified retention mode.

You can use S3 Object Lock to store objects using a write-once-read-many (WORM) model. Object Lock can help prevent objects in S3 buckets from being deleted or overwritten for a fixed amount of time or indefinitely. You can use S3 Object Lock to meet regulatory requirements that require WORM storage, or add an extra layer of protection against object changes and deletion.

Remediation

To configure Object Lock for new and existing S3 buckets, see Configuring S3 Object Lock in the Amazon S3 User Guide.

[S3.17] S3 general purpose buckets should be encrypted at rest with AWS KMS keys

Important

On March 12, 2024, the title of this control changed to the title shown. For more information, see Change log for Security Hub controls.

Category: Protect > Data protection > Encryption of data at rest

Related requirements: NIST.800-53.r5 SC-12(2), NIST.800-53.r5 CM-3(6), NIST.800-53.r5 SC-13, NIST.800-53.r5 SC-28, NIST.800-53.r5 SC-28(1), NIST.800-53.r5 SC-7(10), NIST.800-53.r5 CA-9(1), NIST.800-53.r5 SI-7(6), NIST.800-53.r5 AU-9

Severity: Medium

Resource type: AWS::S3::Bucket

AWS Config rule: s3-default-encryption-kms

Schedule type: Change triggered

Parameters: None

This control checks whether an Amazon S3 general purpose bucket is encrypted with an AWS KMS key (SSE-KMS or DSSE-KMS). The control fails if the bucket is encrypted with default encryption (SSE-S3).

Server-side encryption (SSE) is the encryption of data at its destination by the application or service that receives it. Unless you specify otherwise, S3 buckets use Amazon S3 managed keys (SSE-S3) by default for server-side encryption. However, for added control, you can choose to configure buckets to use server-side encryption with AWS KMS keys (SSE-KMS or DSSE-KMS) instead. Amazon S3 encrypts your data at the object level as it writes it to disks in AWS data centers and decrypts it for you when you access it.

Remediation

To encrypt an S3 bucket using SSE-KMS, see Specifying server-side encryption with AWS KMS (SSE-KMS) in the Amazon S3 User Guide. To encrypt an S3 bucket using DSSE-KMS, see Specifying dual-layer server-side encryption with AWS KMS keys (DSSE-KMS) in the Amazon S3 User Guide.

[S3.19] S3 access points should have block public access settings enabled

Related requirements: NIST.800-53.r5 AC-21, NIST.800-53.r5 AC-3, NIST.800-53.r5 AC-3(7), NIST.800-53.r5 AC-4, NIST.800-53.r5 AC-4(21), NIST.800-53.r5 AC-6, NIST.800-53.r5 SC-7, NIST.800-53.r5 SC-7(11), NIST.800-53.r5 SC-7(16), NIST.800-53.r5 SC-7(20), NIST.800-53.r5 SC-7(21), NIST.800-53.r5 SC-7(3), NIST.800-53.r5 SC-7(4), NIST.800-53.r5 SC-7(9)

Category: Protect > Secure access management > Resource not publicly accessible

Severity: Critical

Resource type: AWS::S3::AccessPoint

AWS Config rule: s3-access-point-public-access-blocks

Schedule type: Change triggered

Parameters: None

This control checks whether an Amazon S3 access point has block public access settings enabled. The control fails if block public access settings aren't enabled for the access point.

The Amazon S3 Block Public Access feature helps you manage access to your S3 resources at three levels: the account, bucket, and access point levels. The settings at each level can be configured independently, allowing you to have different levels of public access restrictions for your data. The access point settings can't individually override the more restrictive settings at higher levels (account level or bucket assigned to the access point). Instead, the settings at the access point level are additive, meaning they complement and work alongside the settings at the other levels. Unless you intend an S3 access point to be publicly accessible, you should enable block public access settings.

Remediation

Amazon S3 currently doesn't support changing an access point's block public access settings after the access point has been created. All block public access settings are enabled by default when you create a new access point. We recommend that you keep all settings enabled unless you know that you have a specific need to disable any of them. For more information, see Managing public access to access points in the Amazon Simple Storage Service User Guide.

[S3.20] S3 general purpose buckets should have MFA delete enabled

Related requirements: CIS AWS Foundations Benchmark v1.4.0, NIST.800-53.r5 CA-9(1), NIST.800-53.r5 CM-2, NIST.800-53.r5 CM-2(2), NIST.800-53.r5 CM-3, NIST.800-53.r5 SC-5(2)

Category: Protect > Data protection > Data deletion protection

Severity: Low

Resource type: AWS::S3::Bucket

AWS Config rule: s3-bucket-mfa-delete-enabled

Schedule type: Change triggered

Parameters: None

This control checks whether multi-factor authentication (MFA) delete is enabled on an Amazon S3 general purpose bucket. The control fails if MFA delete is not enabled on the bucket.

When working with S3 Versioning in Amazon S3 buckets, you can optionally add another layer of security by configuring a bucket to enable MFA delete. When you do this, the bucket owner must include two forms of authentication in any request to delete a version or change the versioning state of the bucket. MFA delete provides added security if your security credentials are compromised. MFA delete can also help prevent accidental bucket deletions by requiring the user who initiates the delete action to prove physical possession of an MFA device with an MFA code and adding an extra layer of friction and security to the delete action.

Note

The MFA delete feature requires bucket versioning as a dependency. Bucket versioning is a method of keeping multiple variations of an S3 object in the same bucket. In addition, only the bucket owner who is logged in as a root user can enable MFA delete and perform delete actions on S3 buckets.

Remediation

To enable S3 Versioning and configure MFA delete on a bucket, see Configuring MFA delete in the Amazon Simple Storage Service User Guide.