turbot/gcp_compliance

Control: 3.4 Ensure that RSASHA1 is not used for the key-signing key in Cloud DNS DNSSEC

Description

DNSSEC algorithm numbers in this registry may be used in CERT RRs. Zone signing (DNSSEC) and transaction security mechanisms (SIG(0) and TSIG) make use of particular subsets of these algorithms. The algorithm used for key signing should be a recommended one and it should be strong.

The algorithm used for key signing should be a recommended one and it should be strong. When enabling DNSSEC for a managed zone, or creating a managed zone with DNSSEC, the user can select the DNSSEC signing algorithms and the denial-of-existence type. Changing the DNSSEC settings is only effective for a managed zone if DNSSEC is not already enabled. If there is a need to change the settings for a managed zone where it has been enabled, turn DNSSEC off and then re-enable it with different settings.

Remediation

From Command Line

  1. Ensure the property algorithm for keyType keySigning is not using RSASHA1.
gcloud dns managed-zones describe ZONENAME --format="json(dnsName,dnssecConfig.state,dnssecConfig.defaultKeySpecs)"
  1. If it is necessary to change the settings for a managed zone where it has been enabled, NSSEC must be turned off and re-enabled with different settings. To turn off DNSSEC, run the following command:
gcloud dns managed-zones update ZONE_NAME --dnssec-state off
  1. To update key-signing for a reported managed DNS Zone, run the following command:
gcloud dns managed-zones update ZONE_NAME \
--dnssec-state on \
--ksk-algorithm KSK_ALGORITHM \
--ksk-key-length KSK_KEY_LENGTH \
--zsk-algorithm ZSK_ALGORITHM \
--zsk-key-length ZSK_KEY_LENGTH \
--denial-of-existence DENIAL_OF_EXISTENCE

For example the following command enables DNSSEC with 256-bit ECDSA and NSEC for the smallest DNSSEC-signed response packets possible using Cloud DNS:

gcloud dns managed-zones update EXAMPLE_ZONE \
--dnssec-state on \
--ksk-algorithm ECDSAP256SHA256 \
--ksk-key-length 256 \
--zsk-algorithm ECDSAP256SHA256 \
--zsk-key-length 256 \
--denial-of-existence NSEC

Note Supported algorithm options and key lengths are as follows.

Algorithm KSK Length ZSK Length
--------- ---------- ----------
RSASHA1 1024,2048 1024,2048
RSASHA256 1024,2048 1024,2048
RSASHA512 1024,2048 1024,2048
ECDSAP256SHA256 256 256
ECDSAP384SHA384 384 384

Usage

steampipe check gcp_compliance.control.cis_v120_3_4

SQL

This control uses a named query:

dns_managed_zone_key_signing_not_using_rsasha1

Tags