Title

The BIND 9.x authoritative name servers must be configured to only receive zone transfer requests from specified secondary name servers. (Cat II impact)

Discussion

Authoritative name servers (especially primary name servers) should be configured with an allow-transfer access control substatement designating the list of hosts from which zone transfer requests can be accepted. These restrictions address the denial-of-service threat and potential exploits from unrestricted dissemination of information about internal resources. Based on the need to know, the only name servers that need to refresh their zone files periodically are the secondary name servers. Zone transfer from primary name servers should be restricted to secondary name servers. The zone transfer should be completely disabled in the secondary name servers. The address match list argument for the allow-transfer substatement should consist of IP addresses of secondary name servers and stealth secondary name servers.

Check Content

Inspect the "named.conf" file for the following: allow-transfer { <ip>; <ip2>; }; If there is an "allow-transfer" statement, the IP's listed must be servers authorized to request transfers or this is a finding.

Fix Text

Remove unauthorized servers from the allow-transfer IP list in the "named.conf" file.

Additional Identifiers

Rule ID: SV-272398r1068033_rule

Vulnerability ID: V-272398

Group Title: SRG-APP-000516-DNS-000095

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.