STIGQter: STIG Summary: Oracle Linux 7 Security Technical Implementation Guide Version: 2 Release: 3 Benchmark Date: 23 Apr 2021:

For Oracle Linux operating systems using DNS resolution, at least two name servers must be configured.

DISA Rule

SV-221872r603260_rule

Vulnerability Number

V-221872

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

OL07-00-040600

Severity

CAT III

CCI(s)

• CCI-000366 - The organization implements the security configuration settings.

Weight

10

Fix Recommendation

Configure the operating system to use two or more name servers for DNS resolution.

Edit the "/etc/resolv.conf" file to uncomment or add the two or more "nameserver" option lines with the IP address of local authoritative name servers. If local host resolution is being performed, the "/etc/resolv.conf" file must be empty. An empty "/etc/resolv.conf" file can be created as follows:

# echo -n > /etc/resolv.conf

And then make the file immutable with the following command:

# chattr +i /etc/resolv.conf

If the "/etc/resolv.conf" file must be mutable, the required configuration must be documented with the Information System Security Officer (ISSO) and the file must be verified by the system file integrity tool.

Check Contents

Determine whether the system is using local or DNS name resolution with the following command:

# grep hosts /etc/nsswitch.conf
hosts: files dns

If the DNS entry is missing from the host's line in the "/etc/nsswitch.conf" file, the "/etc/resolv.conf" file must be empty.

Verify the "/etc/resolv.conf" file is empty with the following command:

# ls -al /etc/resolv.conf
-rw-r--r-- 1 root root 0 Aug 19 08:31 resolv.conf

If local host authentication is being used and the "/etc/resolv.conf" file is not empty, this is a finding.

If the DNS entry is found on the host's line of the "/etc/nsswitch.conf" file, verify the operating system is configured to use two or more name servers for DNS resolution.

Determine the name servers used by the system with the following command:

# grep nameserver /etc/resolv.conf
nameserver 192.168.1.2
nameserver 192.168.1.3

If less than two lines are returned that are not commented out, this is a finding.

Verify the "/etc/resolv.conf" file is immutable with the following command:

# sudo lsattr /etc/resolv.conf

----i----------- /etc/resolv.conf

If the file is mutable and has not been documented with the Information System Security Officer (ISSO), this is a finding.

Vulnerability Number

V-221872

Documentable

False

Rule Version

OL07-00-040600

Severity Override Guidance

Determine whether the system is using local or DNS name resolution with the following command:

# grep hosts /etc/nsswitch.conf
hosts: files dns

If the DNS entry is missing from the host's line in the "/etc/nsswitch.conf" file, the "/etc/resolv.conf" file must be empty.

Verify the "/etc/resolv.conf" file is empty with the following command:

# ls -al /etc/resolv.conf
-rw-r--r-- 1 root root 0 Aug 19 08:31 resolv.conf

If local host authentication is being used and the "/etc/resolv.conf" file is not empty, this is a finding.

If the DNS entry is found on the host's line of the "/etc/nsswitch.conf" file, verify the operating system is configured to use two or more name servers for DNS resolution.

Determine the name servers used by the system with the following command:

# grep nameserver /etc/resolv.conf
nameserver 192.168.1.2
nameserver 192.168.1.3

If less than two lines are returned that are not commented out, this is a finding.

Verify the "/etc/resolv.conf" file is immutable with the following command:

# sudo lsattr /etc/resolv.conf

----i----------- /etc/resolv.conf

If the file is mutable and has not been documented with the Information System Security Officer (ISSO), this is a finding.

Check Content Reference

M

Target Key

4089

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