Skip to main content

🛡️ AWS EFS File System is not encrypted with KMS CMK🟢

Logic​

Similar Policies​

Description​

Open File

Description​

This policy identifies AWS EFS file systems that are encrypted using AWS-managed keys rather than AWS KMS customer-managed keys (CMKs). Using CMKs provides greater control over encryption key management, access policies, and auditing capabilities compared to AWS-managed keys.

Rationale​

Encrypting data at rest adds an important layer of security by protecting stored data from unauthorized access to the underlying storage. Although AWS provides a default managed key (aws/elasticfilesystem) for EFS encryption, using customer-managed keys offers additional security and governance benefits:

  1. Enhanced Control: Full ownership of the key lifecycle, including creation, rotation, and permission management.
  2. Improved Auditing: Detailed key usage visibility through AWS CloudTrail, enabling precise tracking of when and how encryption keys are used.
  3. Configurable Rotation: Support for automatic or manual key rotation in alignment with organizational security requirements.
  4. Separation of Duties: Clear separation between encryption key administration and data or service administration responsibilities.

... see more

Remediation​

Open File

Remediation​

Encrypt EFS File System Using a KMS CMK​

Encryption at rest for Amazon EFS can only be enabled during the creation of the file system. It is not possible to enable encryption or change the KMS key for an existing file system.

From Command Line​

  1. Create a customer-managed KMS key:

    aws kms create-key \
        --region {{region-name}} \
        --description "CMK for EFS data encryption"

  2. (Optional) Create an alias for the CMK:

    aws kms create-alias \
        --region {{region-name}} \
        --alias-name {{alias/efs-cmk}} \
        --target-key-id {{cmk-arn}}

  3. Create a new EFS file system using the CMK:

    aws efs create-file-system \
        --region {{region-name}} \
        --creation-token {{unique-token}} \
        --encrypted \
        --kms-key-id {{cmk-arn}}

  4. Create mount targets for the new file system (repeat for each AZ):

    aws efs create-mount-target \
        --region {{region-name}} \
        --file-system-id {{new-file-system-id}} \

... see more

policy.yaml​

Open File

Linked Framework Sections​

SectionSub SectionsInternal RulesPoliciesFlagsCompliance
💼 AWS Foundational Security Best Practices v1.0.0 → 💼 [EFS.1] Elastic File System should be configured to encrypt file data at-rest using AWS KMS12no data
💼 AWS Well-Architected → 💼 SEC08-BP02 Enforce encryption at rest20no data
💼 Cloudaware Framework → 💼 Data Encryption70no data
💼 FedRAMP High Security Controls → 💼 CM-3(6) Cryptography Management (H)17no data
💼 FedRAMP High Security Controls → 💼 SC-7(10) Prevent Exfiltration (H)18no data
💼 FedRAMP High Security Controls → 💼 SC-13 Cryptographic Protection (L)(M)(H)1643no data
💼 FedRAMP High Security Controls → 💼 SC-28 Protection of Information at Rest (L)(M)(H)1736no data
💼 FedRAMP High Security Controls → 💼 SC-28(1) Cryptographic Protection (L)(M)(H)525no data
💼 FedRAMP Low Security Controls → 💼 SC-13 Cryptographic Protection (L)(M)(H)43no data
💼 FedRAMP Low Security Controls → 💼 SC-28 Protection of Information at Rest (L)(M)(H)136no data
💼 FedRAMP Low Security Controls → 💼 SC-28(1) Cryptographic Protection (L)(M)(H)25no data
💼 FedRAMP Moderate Security Controls → 💼 SC-13 Cryptographic Protection (L)(M)(H)43no data
💼 FedRAMP Moderate Security Controls → 💼 SC-28 Protection of Information at Rest (L)(M)(H)136no data
💼 FedRAMP Moderate Security Controls → 💼 SC-28(1) Cryptographic Protection (L)(M)(H)25no data
💼 NIST CSF v2.0 → 💼 PR.DS-01: The confidentiality, integrity, and availability of data-at-rest are protected187no data
💼 NIST CSF v2.0 → 💼 PR.DS-02: The confidentiality, integrity, and availability of data-in-transit are protected160no data
💼 NIST CSF v2.0 → 💼 PR.DS-10: The confidentiality, integrity, and availability of data-in-use are protected184no data
💼 NIST SP 800-53 Revision 5 → 💼 CA-9(1) Internal System Connections _ Compliance Checks54no data
💼 NIST SP 800-53 Revision 5 → 💼 CM-3(6) Configuration Change Control _ Cryptography Management17no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-7(10) Boundary Protection _ Prevent Exfiltration18no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-13 Cryptographic Protection432no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-28 Protection of Information at Rest31737no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-28(1) Protection of Information at Rest _ Cryptographic Protection1025no data
💼 NIST SP 800-53 Revision 5 → 💼 SI-7(6) Software, Firmware, and Information Integrity _ Cryptographic Protection27no data