V-285248

Discussion

If name server replies are invalid or cannot be validated, many networking functions and communications would be adversely affected. With DNS, the presence of Delegation Signer (DS) records associated with child zones informs clients of the security status of child zones. These records are crucial to the DNSSEC chain of trust model. Each parent domain's DS record is used to verify the DNSKEY record in its subdomain, from the top of the DNS hierarchy down. A DNS server is an example of an information system providing name/address resolution service. Digital signatures and cryptographic keys are examples of additional artifacts. DNS resource records are examples of authoritative data. Applications other than the DNS to map between host/service names and network addresses must provide other means to ensure the authenticity and integrity of response data. DNSSEC provides the means to verify integrity assurances for the host/service name to network address resolution information obtained through the service. By using the DS resource records in the DNS, the security status of a child domain can be validated. The DS resource record is used to identify the DNSSEC signing key of a delegated zone. Starting from a trusted name server (such as the root name server) and down to the current source of response through successive verifications of signature of the public key of a child by its parent, the chain of trust is established. The public key of the trusted name servers is called the trust anchor. After authenticating the source, the next process DNSSEC calls for is to authenticate the response. This requires that responses consist of not only the requested RRs but also an authenticator associated with them. In DNSSEC, this authenticator is the digital signature of a Resource Record (RR) Set. The digital signature of an RRSet is encapsulated through a special RRType called RRSIG. The DNS client using the trusted public key of the source (whose trust has just been established) then verifies the digital signature to detect if the response is valid or bogus. This control enables the DNS to obtain origin authentication and integrity verification assurances for the host/service name to network address resolution information obtained through the service. Without indication of the security status of a child domain and enabling verification of a chain of trust, integrity and availability of the DNS infrastructure cannot be ensured.

Check Content

Verify Infoblox DNS service members are configured to enable verification of a chain of trust among parent and child domains (if the child supports secure resolution services).

The Authoritative Check applies to external-facing authoritative zones:  

1. Navigate to the Data Management >> DNS >> Zones tab.

Note: To add the "Signed" column, select an existing column, click the down arrow, then select Columns >> Edit Columns. 

2. Set the "Signed" checkbox to "Visible" and select "Apply". DNSSEC signing status will be displayed in the "Zones" tab. 
3. Verify external authoritative zones are DNSSEC signed. 

Recursive Check: 

1. Navigate to Data Management >> DNS tab. 
2. Click "Grid DNS Properties" (Toolbar menu). 
3. Toggle "Advanced Mode", and select the DNSSEC tab. 
4. Validate that both "Enable DNSSEC" and "Enable DNSSEC Validation" checkboxes are selected. 
5. When complete, click "Cancel" to exit the "Properties" screen. 

Note: DNSSEC validation must be configured when all of the following conditions are met:
1. Root hints or custom root hints are used,
2. Default forwarding is disabled, and
3. Recursion is enabled for the DNS view or member.

If DNSSEC is not used for authoritative DNS and enabled for recursive clients, this is a finding.