Vulnerability Discussion

RHEL 9 systems handling data requiring "data at rest" protections must employ cryptographic mechanisms to prevent unauthorized disclosure and modification of the information at rest.

Selection of a cryptographic mechanism is based on the need to protect the integrity of organizational information. The strength of the mechanism is commensurate with the security category and/or classification of the information. Organizations have the flexibility to either encrypt all information on storage devices (i.e., full disk encryption) or encrypt specific data structures (e.g., files, records, or fields).

Satisfies: SRG-OS-000405-GPOS-00184, SRG-OS-000185-GPOS-00079, SRG-OS-000404-GPOS-00183

Check

Note: If there is a documented and approved reason for not having data-at-rest encryption at the operating system level, such as encryption provided by a hypervisor or a disk storage array in a virtualized environment, this requirement is Not Applicable.

Verify RHEL 9 prevents unauthorized disclosure or modification of all information requiring at-rest protection by using disk encryption.

Note: If there is a documented and approved reason for not having data-at-rest encryption, this requirement is Not Applicable.

List all block devices in tree-like format:

$ sudo lsblk --tree

NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
zram0 252:0 0 8G 0 disk [SWAP]
nvme0n1 259:0 0 476.9G 0 disk
|-nvme0n1p1 259:1 0 1G 0 part /boot/efi
|-nvme0n1p2 259:2 0 1G 0 part /boot
|-nvme0n1p3 259:3 0 474.9G 0 part
|-luks- 253:0 0 474.9G 0 crypt
|-rhel-root 253:1 0 16G 0 lvm /
|-rhel-varcache 253:2 0 8G 0 lvm /var/cache
|-rhel-vartmp 253:3 0 4G 0 lvm /var/tmp
|-rhel-varlog 253:4 0 4G 0 lvm /var/log
|-rhel-home 253:5 0 64G 0 lvm /home
|-rhel-varlogaudit 253:6 0 4G 0 lvm /var/log/audit

Verify that the block device tree for each persistent filesystem, excluding the /boot and /boot/efi filesystems, has at least one parent block device of type "crypt", and that the encryption type is LUKS:

$ sudo cryptsetup status luks-b74f6910-2547-4399-86b2-8b0252d926d7
/dev/mapper/luks-b74f6910-2547-4399-86b2-8b0252d926d7 is active and is in use.
type: LUKS2
cipher: aes-xts-plain64
keysize: 512 bits
key location: keyring
device: /dev/nvme0n1p3
sector size: 512
offset: 32768 sectors
size: 995986063 sectors
mode: read/write

If there are persistent filesystems (other than /boot or /boot/efi) whose block device trees do not have a crypt block device of type LUKS, ask the administrator to indicate how persistent filesystems are encrypted.

If there is no evidence that persistent filesystems are encrypted, this is a finding.

Fix

Configure RHEL 9 to prevent unauthorized modification of all information at rest by using disk encryption.

Encrypting a partition in an already installed system is more difficult, because existing partitions will need to be resized and changed.

To encrypt an entire partition, dedicate a partition for encryption in the partition layout.