Vulnerability Discussion

Operating 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).

Check

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

Verify the Ubuntu operating system prevents unauthorized disclosure or modification of all information requiring at-rest protection by using disk encryption.

Determine the partition layout for the system with the following command:

$ sudo fdisk -l
(..)
Disk /dev/vda: 15 GiB, 16106127360 bytes, 31457280 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 83298450-B4E3-4B19-A9E4-7DF147A5FEFB

Device Start End Sectors Size Type
/dev/vda1 2048 4095 2048 1M BIOS boot
/dev/vda2 4096 2101247 2097152 1G Linux filesystem
/dev/vda3 2101248 31455231 29353984 14G Linux filesystem
(...)

Verify that the system partitions are all encrypted with the following command:

$ more /etc/crypttab

Every persistent disk partition present must have an entry in the file.

If any partitions other than the boot partition or pseudo file systems (such as /proc or /sys) are not listed, this is a finding.

Fix

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

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