The Photon operating system must disable systemd fallback DNS.
An XCCDF Rule
Description
Systemd contains an ability to set fallback DNS servers, which 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 info unknowingly in the event DNS is absent or misconfigured at the system level.
- ID
- SV-258898r991589_rule
- Version
- PHTN-40-000236
- Severity
- Medium
- References
- Updated
Remediation Templates
A Manual Procedure
Navigate to and open:
/etc/systemd/resolved.conf
Add or update the "FallbackDNS" entry to the following: