PHTN-30-000245 - The Photon operating system must disable systemd fallback Domain Name System (DNS).

Information

Systemd contains an ability to set fallback DNS servers. This is used for DNS lookups in the event no system-level DNS servers are configured or other DNS servers are specified in the systemd 'resolved.conf' file. If uncommented, this configuration contains Google DNS servers by default and could result in DNS leaking information unknowingly in the event DNS is absent or misconfigured at the system level.

Solution

Navigate to and open:

/etc/systemd/resolved.conf

Add or update the 'FallbackDNS' entry to the following:

FallbackDNS=

Restart the systemd resolved service by running the following command:

# systemctl restart systemd-resolved

Note: If this option is not given, a compiled-in list of DNS servers is used instead, which is undesirable.

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_VMW_vSphere_7-0_Y24M01_STIG.zip

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b., CAT|II, CCI|CCI-000366, Rule-ID|SV-256590r887444_rule, STIG-ID|PHTN-30-000245, Vuln-ID|V-256590

Plugin: Unix

Control ID: 2ebee033c44f23ba0f329b8bb7067686952c712cc1a64b6f9a214681ce2c38e9