Title

The DNS software administrator has not configured the DNS software to send all log data to either the system logging facility (e.g., UNIX syslog or Windows Application Event Log) or an alternative logging facility with security configuration equivalent to or more restrictive than the system logging facility. (Cat II impact)

Discussion

On name servers, DNS log data is typically more sensitive than system log data and, consequently, should benefit from security controls at least as restrictive as those for the system logging facility. DNS software administrators require DNS transaction logs for a wide variety of reasons including troubleshooting, intrusion detection, and forensics. These logs should be appropriately secured, having file permissions that restrict unauthorized changes or viewing, and archived, being appropriately backed-up and stored in order for them to be examined at a future time. Furthermore, it is required that the logs be reviewed daily.

Check Content

DNS software administrators need DNS transaction logs for a wide variety of reasons including troubleshooting, intrusion detection, and forensics. These logs should be appropriately secured, having file permissions that restrict unauthorized changes or viewing, and archived, being appropriately backed-up and stored so that they can be examined at a future time. BIND The DNS software administrator will configure the DNS software to send all log data to either the system logging facility (e.g., UNIX syslog or Windows Application Event Log) or an alternative logging facility with security configuration equivalent to or more restrictive than the system logging facility. Instruction: On an examination of the DNS configuration file (if BIND, named.conf), the reviewer can determine whether log data is sent to a facility other than the system logging facility. If this is the case, then the reviewer should do the following at a minimum: - Compare the file permissions of the operating system logs with the file permissions of the alternative logging facility for DNS (e.g., using ls –l). If the permissions on the alternative are weaker in any manner, this constitutes a finding. - Determine whether the system logs are transferred or copied to media on another machine (e.g., a cron job that periodically moves logs to another computer). If this is the case and there is not a similar technology in place for the DNS logs, then this constitutes a finding. The reviewer can identify other ways in which the security of the DNS logs may be weaker than the security of the system logs, and can generate a finding based on that discovery so long as the explanation of the weakness is clearly documented in the SRR results. Windows DNS Windows DNS software log files will be equivalent to the system logging facility by default. In addition, the DNS debug log file should be checked at %systemroot%\system32\dns\dns.log. The permissions should be restricted to the Administrators and/or Auditors group (in accordance with the Windows STIG permission settings for Windows Event Log settings) on the local computer or the Domain Admins group. In cases in which the name server is not running BIND or Windows DNS, the reviewer must still examine the configuration and its documentation to validate this requirement.

Fix Text

The DNS software administrator should either configure named.conf to utilize the system logging facility or place additional technical controls (e.g., more restrictive file permissions) on the alternative logging facility so that it is as least as secure as the system logging facility.

Additional Identifiers

Rule ID: SV-4489r2_rule

Vulnerability ID: V-4489

Group Title:

Expert Comments

CCIs tied to check.

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