On the BIND 9.x server the private key corresponding to the ZSK, stored on name servers accepting dynamic updates, must be group owned by root.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-207590	SRG-APP-000516-DNS-000111	BIND-9X-001411	SV-207590r879887_rule	2024-02-15	2

Description
The private ZSK key must be protected from unauthorized access. This strategy is not feasible in situations in which the DNSSEC-aware name server has to support dynamic updates. To support dynamic update transactions, the DNSSEC-aware name server (which usually is a primary authoritative name server) has to have both the zone file master copy and the private key corresponding to the zone-signing key (ZSK-private) online to immediately update the signatures for the updated RRsets.

Description

The private ZSK key must be protected from unauthorized access. This strategy is not feasible in situations in which the DNSSEC-aware name server has to support dynamic updates. To support dynamic update transactions, the DNSSEC-aware name server (which usually is a primary authoritative name server) has to have both the zone file master copy and the private key corresponding to the zone-signing key (ZSK-private) online to immediately update the signatures for the updated RRsets.

ℹ️ Check
If the server is in a classified network, this is Not Applicable. Note: This check only verifies for ZSK key file ownership. Permissions for key files are required under V-72451, BIND-9X-001132 and V-72461, BIND-9X-001142. For each signed zone file, identify the ZSK "key id" number: # cat <signed_zone_file> \| grep -i "zsk" ZSK; alg = ECDSAP256SHA256; key id = 22335 Using the ZSK "key id", verify the private ZSK. Kexample.com.+008+22335.private Verify that the private ZSK is owned by root: # ls -l <ZSK_key_file> -r------- 1 root root 1776 Jul 3 17:56 Kexample.com.+008+22335.private If the key file is not group owned by root, this is a finding.

ℹ️ Check

If the server is in a classified network, this is Not Applicable. Note: This check only verifies for ZSK key file ownership. Permissions for key files are required under V-72451, BIND-9X-001132 and V-72461, BIND-9X-001142. For each signed zone file, identify the ZSK "key id" number: # cat <signed_zone_file> | grep -i "zsk" ZSK; alg = ECDSAP256SHA256; key id = 22335 Using the ZSK "key id", verify the private ZSK. Kexample.com.+008+22335.private Verify that the private ZSK is owned by root: # ls -l <ZSK_key_file> -r------- 1 root root 1776 Jul 3 17:56 Kexample.com.+008+22335.private If the key file is not group owned by root, this is a finding.

✔️ Fix
Change the group ownership of the ZSK private key to the root group account. # chgrp root <key_file>