The Windows DNS Server with a caching name server role must restrict recursive query responses to only the IP addresses and IP address ranges of known supported clients.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-259343	WDNS-22-000011	SV-259343r945244_rule		High

Description
A potential vulnerability of DNS is that an attacker can poison a name server's cache by sending queries that will cause the server to obtain host-to-IP address mappings from bogus name servers that respond with incorrect information. Once a name server has been poisoned, legitimate clients may be directed to nonexistent hosts (which constitutes a denial of service) or hosts that masquerade as legitimate ones to obtain sensitive data or passwords. To guard against poisoning, name servers specifically fulfilling the role of providing recursive query responses for external zones must be segregated from name servers authoritative for internal zones.

Description

A potential vulnerability of DNS is that an attacker can poison a name server's cache by sending queries that will cause the server to obtain host-to-IP address mappings from bogus name servers that respond with incorrect information. Once a name server has been poisoned, legitimate clients may be directed to nonexistent hosts (which constitutes a denial of service) or hosts that masquerade as legitimate ones to obtain sensitive data or passwords. To guard against poisoning, name servers specifically fulfilling the role of providing recursive query responses for external zones must be segregated from name servers authoritative for internal zones.

STIG	Date
Microsoft Windows Server Domain Name System (DNS) Security Technical Implementation Guide	2024-01-09

Details

Check Text ( C-63082r945242_chk )
Note: Sinkhole name servers host records that are manually added and for which the name server is not authoritative. It is configured and intended to block resolvers from reaching a destination by directing the query to a sinkhole. If the sinkhole name server is not authoritative for any zones and serves only as a caching/forwarding name server, this check is not applicable. The non-Active Directory (AD)-integrated, standalone, caching Windows DNS Server must be configured to be DNSSEC aware. When performing caching and lookups, the caching name server must be able to obtain a zone signing key (ZSK) DNSKEY record and corresponding RRSIG record for the queried record. It will use this information to compute the hash for the hostname being resolved. The caching name server decrypts the RRSIG record for the hostname being resolved with the zone's ZSK to get the RRSIG record hash. The caching name server compares the hashes and ensures they match. If the non-AD-integrated, standalone, caching Windows DNS Server is not configured to be DNSSEC aware, this is a finding.

Check Text ( C-63082r945242_chk )

Note: Sinkhole name servers host records that are manually added and for which the name server is not authoritative. It is configured and intended to block resolvers from reaching a destination by directing the query to a sinkhole. If the sinkhole name server is not authoritative for any zones and serves only as a caching/forwarding name server, this check is not applicable.

The non-Active Directory (AD)-integrated, standalone, caching Windows DNS Server must be configured to be DNSSEC aware. When performing caching and lookups, the caching name server must be able to obtain a zone signing key (ZSK) DNSKEY record and corresponding RRSIG record for the queried record. It will use this information to compute the hash for the hostname being resolved. The caching name server decrypts the RRSIG record for the hostname being resolved with the zone's ZSK to get the RRSIG record hash. The caching name server compares the hashes and ensures they match.

If the non-AD-integrated, standalone, caching Windows DNS Server is not configured to be DNSSEC aware, this is a finding.

Fix Text (F-62990r945243_fix)
Implement DNSSEC on all non-AD-integrated, standalone, caching Windows DNS Servers to ensure the caching server validates signed zones when resolving and caching.