The Windows 2008 DNS Server authoritative for local zones must only point root hints to the DNS servers that host the internal root domain.

From Microsoft Windows 2008 Server Domain Name System Security Technical Implementation Guide

Part of SRG-APP-000516-DNS-000102

Associated with: CCI-000366

SV-83287r1_rule The Windows 2008 DNS Server authoritative for local zones must only point root hints to the DNS servers that host the internal root domain.

Vulnerability discussion

All caching name servers must be authoritative for the root zone because, without this starting point, they would have no knowledge of the DNS infrastructure and thus would be unable to respond to any queries. The security risk is that an adversary could change the root hints and direct the caching name server to a bogus root server. At that point, every query response from that name server is suspect, which would give the adversary substantial control over the network communication of the name servers' clients. When authoritative servers are sent queries for zones that they are not authoritative for, and they are configured as a non-caching server (as recommended), they can either be configured to return a referral to the root servers or they can be configured to refuse to answer the query. The recommendation is to configure authoritative servers to refuse to answer queries for any zones for which they are not authoritative. This is more efficient for the server and allows it to spend more of its resources doing what its intended purpose is, answering authoritatively for its zone.

Check content

Log on to the authoritative DNS server using the Domain Admin or Enterprise Admin account. Press Windows Key + R, execute dnsmgmt.msc. Right-click the DNS server, select “Properties”. Select the "Root Hints" tab. Verify the "Root Hints" is either empty or only has entries for internal zones under "Name servers:". All Internet root server entries must be removed. If "Root Hints" is not empty and the entries on the "Root Hints" tab under "Name servers:" are external to the local network, this is a finding.

Fix text

Log on to the authoritative DNS server using the Domain Admin or Enterprise Admin account. Press Windows Key + R, execute dnsmgmt.msc. Right-click the DNS server, select “Properties”. Select the "Root Hints" tab. Remove all entries under "Name servers:" which are for name servers outside of the internal network.

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