A BIND 9.x caching name server must implement DNSSEC validation to check all DNS queries for invalid input.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-72421	BIND-9X-001060	SV-87045r3_rule		Medium

Description
A common vulnerability of applications is unpredictable behavior when invalid inputs are received. This requirement guards against adverse or unintended system behavior caused by invalid inputs, where information system responses to the invalid input may be disruptive or cause the system to fail into an unsafe state. Attacks may be generated by entering invalid data into DNS transactions, in the hopes that the data will not be handled correctly and will allow a vulnerable condition to be exploited. To safeguard against this, all untrusted data entered in DNS transactions (e.g., DNS queries) should be checked for validity before being processed further.

Description

A common vulnerability of applications is unpredictable behavior when invalid inputs are received. This requirement guards against adverse or unintended system behavior caused by invalid inputs, where information system responses to the invalid input may be disruptive or cause the system to fail into an unsafe state. Attacks may be generated by entering invalid data into DNS transactions, in the hopes that the data will not be handled correctly and will allow a vulnerable condition to be exploited. To safeguard against this, all untrusted data entered in DNS transactions (e.g., DNS queries) should be checked for validity before being processed further.

STIG	Date
BIND 9.x Security Technical Implementation Guide	2019-01-07

Details

Check Text ( C-72621r3_chk )
If the server is not a caching name server, this is Not Applicable. If the server is in a classified network, this is Not Applicable. If the caching name server is only forwarding to the DISA ERS for query resolution and is not authoritative for any zones, DNSSEC awareness is not required since the ERS is validating. Verify that the server is configured to use DNSSEC validation for all DNS queries. Inspect the "named.conf" file for the following: options { dnssec-validation yes; }; managed-keys { "." initial-key 257 3 8 ""; }; If "dnssec-validation" is not set to "yes" or is missing, this is a finding. If the "managed-keys" statement is missing, this is a finding. Note: The should be replaced with the actual trust anchor.

Check Text ( C-72621r3_chk )

If the server is not a caching name server, this is Not Applicable.

If the server is in a classified network, this is Not Applicable.

If the caching name server is only forwarding to the DISA ERS for query resolution and is not authoritative for any zones, DNSSEC awareness is not required since the ERS is validating.
Verify that the server is configured to use DNSSEC validation for all DNS queries.

Inspect the "named.conf" file for the following:

options {
dnssec-validation yes;
};
managed-keys { "." initial-key 257 3 8 ""; };

If "dnssec-validation" is not set to "yes" or is missing, this is a finding.

If the "managed-keys" statement is missing, this is a finding.

Note: The should be replaced with the actual trust anchor.

Fix Text (F-78773r1_fix)
Enable DNSSEC validation on the name server. Set the "dnssec-validation" sub statement in the global options block to "yes". Configure the "managed-keys" statement to use the root domains trust anchor. Restart the BIND 9.x process.