OpenControls Logo

STIG Viewer

STIGViewer Support

The salt value for zones signed using NSEC3 RRs must be changed every time the zone is completely re-signed.

Overview

Finding IDVersionRule IDIA ControlsSeverity
V-205227SRG-APP-000516-DNS-000077SV-205227r961863_ruleCCI-000366medium
Description
NSEC3 RRs contain other options than just the (hashed) next name and RRType bitmap. There are also 2 values associated with the NSEC3 RR: the iterations (number of times each name is hashed) and the salt (string appended to each name before hashing). These values are configurable during signing and are used to increase the work necessary by an attacker. Both values should be changed on a regular basis to maintain protection against zone enumeration. The salt value should be changed every time the entire zone is re-signed. The salt value should be a random string with a length small enough to ensure that appending the salt value to the domain name does not result in a FQDN considered too long for the DNS protocol (a single label in the DNS protocol can be 256 octets). A value between 1 - 15 octets would be acceptable for the majority of cases. Note that zones that are dynamically re-signed as needed may not be able to change the salt for NSEC3 RRs as an automatic process. In these cases, the salt rollover procedure is similar to the key algorithm rollover procedure in that the NSEC3 RR chain with the new salt is generated first (ending with the NSEC3PARAM RR) before removing the old (outgoing) NSEC3 chain.
STIGDate
Domain Name System (DNS) Security Requirements Guide2024-07-02

Related Frameworks

1 mapping across 5 frameworks
SCF0 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (8) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

CFG-01Configuration Management Program
1.00
END-01Endpoint Device Management (EDM)
1.00
END-04Malicious Code Protection (Anti-Malware)
1.00
END-06Endpoint File Integrity Monitoring (FIM)
1.00
MON-01Continuous Monitoring
1.00
MON-01.7File Integrity Monitoring (FIM)
1.00
CFG-02Secure Baseline Configurations
0.50
CFG-02.7Approved Configuration Deviations
0.50
NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (100) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

AC-12Session Termination
1.00
AC-16(1)Dynamic Attribute Association
1.00
AC-17(1)Monitoring and Control
1.00
AC-2Account Management
1.00
AC-2(1)Automated System Account Management
1.00
AC-2(11)Usage Conditions
1.00
AC-2(3)Disable Accounts
1.00
AC-2(4)Automated Audit Actions
1.00
AC-24(1)Transmit Access Authorization Information
1.00
AC-25Reference Monitor
1.00

+90 more (top 10 by confidence shown)

NIST 800-1710 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (2) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

3.4.1
1.00
3.4.2
1.00
CCI1 mapping
CCI-000366
1.00
NIST CSF 2.00 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (5) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

DE.CM-09
1.00
PR.PS-01
1.00
PR.DS-10
0.50
PR.PSPlatform Security
0.50
PR.PS-05
0.50

Who does this work

10 NICE work roles and 9 EC-Council certifications.

This is an inference across published mappings, not a single claim by anyone. This check maps to a control, which maps to a Cybersecurity Framework outcome, which NIST assigns to the work roles below. EC-Council separately maps its certifications to those same roles.

A certification prepares someone for a role. It is not evidence that a holder is qualified, and neither NIST nor EC-Council has stated that any certification here addresses this check.

Work-role assignments published by NIST (NICE Framework Components 2.2.0 and the CSF 2.0 OLIR crosswalk). Certification mappings published by EC-Council.

Details

Check Text (C-205227r961863_chk)

Check the DNS configuration files and operational documentation. If the zone's RRs have been signed with NSEC3, the operational procedures should stipulate to change the salt value every time the zone is completely re-signed. If the operational procedures do not specify to change the salt value for RRs signed with NSEC3 every time the zone is completely re-signed, this is a finding.

Fix Text (F-5494r392595_fix)

Include instructions in the DNS operational procedures to change the salt value every time RRs signed by NSEC3 have been re-signed.