The /etc/resolv.conf file must not have an extended ACL.

From Oracle Linux 5 Security Technical Implementation Guide

Associated with: CCI-000225

SV-64513r1_rule The /etc/resolv.conf file must not have an extended ACL.

Vulnerability discussion

The resolv.conf (or equivalent) file configures the system's DNS resolver. DNS is used to resolve host names to IP addresses. If DNS configuration is modified maliciously, host name resolution may fail or return incorrect information. DNS may be used by a variety of system security functions such as time synchronization, centralized authentication, and remote system logging.

Check content

Verify /etc/resolv.conf has no extended ACL. # ls -l /etc/resolv.conf If the permissions include a '+', the file has an extended ACL. If the file has an extended ACL and it has not been documented with the IAO, this is a finding.

Fix text

Remove the extended ACL from the file. # setfacl --remove-all /etc/resolv.conf

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