The BIND 9.x server implementation must utilize separate TSIG key-pairs when securing server-to-server transactions.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-72431	BIND-9X-001106	SV-87055r1_rule		Medium

Description
Server-to-server (zone transfer) transactions are provided by TSIG, which enforces mutual server authentication using a key that is unique to each server pair (TSIG), thus uniquely identifying the other server. Enforcing separate TSIG key-pairs provides another layer of protection for the BIND implementation in the event that a TSIG key is compromised. This additional layer of security provides the DNS administrators with the ability to change a compromised TSIG key with a minimal disruption to DNS operations. Failure to identify devices and authenticate devices can lead to malicious activity, such as a Man-In-The-Middle attack where an attacker could pose as an authorized name server, and redirect legitimate customers to malicious websites. A failure on this part could also lead to a Denial of Service of any and all DNS services provided to an organizations network infrastructure.

Description

Server-to-server (zone transfer) transactions are provided by TSIG, which enforces mutual server authentication using a key that is unique to each server pair (TSIG), thus uniquely identifying the other server. Enforcing separate TSIG key-pairs provides another layer of protection for the BIND implementation in the event that a TSIG key is compromised. This additional layer of security provides the DNS administrators with the ability to change a compromised TSIG key with a minimal disruption to DNS operations. Failure to identify devices and authenticate devices can lead to malicious activity, such as a Man-In-The-Middle attack where an attacker could pose as an authorized name server, and redirect legitimate customers to malicious websites. A failure on this part could also lead to a Denial of Service of any and all DNS services provided to an organizations network infrastructure.

STIG	Date
BIND 9.x Security Technical Implementation Guide	2018-04-03

Details

Check Text ( C-72631r1_chk )
Verify that the BIND 9.x server is configured to utilize separate TSIG key-pairs when securing server-to-server transactions. Inspect the "named.conf" file for the presence of TSIG key statements: On the master name server, this is an example of a configured key statement: key tsig_example. { algorithm hmac-SHA1; include "tsig-example.key"; }; zone "disa.mil" { type master; file "db.disa.mil"; allow-transfer { key tsig_example.; }; }; On the slave name server, this is an example of a configured key statement: key tsig_example. { algorithm hmac-SHA1; include "tsig-example.key"; }; server { keys { tsig_example }; }; zone "disa.mil" { type slave; masters { ; }; file "db.disa.mil"; }; Verify that each TSIG key-pair listed is only used by a single key statement: # cat If any TSIG key-pair is being used by more than one key statement, this is a finding.

Check Text ( C-72631r1_chk )

Verify that the BIND 9.x server is configured to utilize separate TSIG key-pairs when securing server-to-server transactions.
Inspect the "named.conf" file for the presence of TSIG key statements:

On the master name server, this is an example of a configured key statement:

key tsig_example. {
algorithm hmac-SHA1;
include "tsig-example.key";
};

zone "disa.mil" {
type master;
file "db.disa.mil";
allow-transfer { key tsig_example.; };
};

On the slave name server, this is an example of a configured key statement:

key tsig_example. {
algorithm hmac-SHA1;
include "tsig-example.key";
};

server {
keys { tsig_example };
};

zone "disa.mil" {
type slave;
masters { ; };
file "db.disa.mil";
};

Verify that each TSIG key-pair listed is only used by a single key statement:
# cat

If any TSIG key-pair is being used by more than one key statement, this is a finding.

Fix Text (F-78783r1_fix)
Create a separate TSIG key-pair for each key statement listed in the named.conf file. Configure the name server to utilize separate TSIG key-pairs for each key statement listed in the named.conf file. Restart the BIND 9.x process.