CCN Red Hat Enterprise Linux 9 - Intermediate
Rules and Groups employed by this XCCDF Profile
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Ensure SELinux State is Enforcing
The SELinux state should be set to <code><xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_selinux_state" use="legacy"></xccdf-1.2:sub><...Rule High Severity -
Services
The best protection against vulnerable software is running less software. This section describes how to review the software which Red Hat Enterpris...Group -
DNS Server
Most organizations have an operational need to run at least one nameserver. However, there are many common attacks involving DNS server software, a...Group -
Disable DNS Server
DNS software should be disabled on any systems which does not need to be a nameserver. Note that the BIND DNS server software is not installed on R...Group -
Uninstall bind Package
The <code>named</code> service is provided by the <code>bind</code> package. The <code>bind</code> package can be removed with the following comman...Rule Low Severity -
FTP Server
FTP is a common method for allowing remote access to files. Like telnet, the FTP protocol is unencrypted, which means that passwords and other data...Group -
Disable vsftpd if Possible
To minimize attack surface, disable vsftpd if at all possible.Group -
Uninstall vsftpd Package
Thevsftpd
package can be removed with the following command:$ sudo dnf erase vsftpd
Rule High Severity -
IMAP and POP3 Server
Dovecot provides IMAP and POP3 services. It is not installed by default. The project page at <a href="http://www.dovecot.org">http://www.dovec...Group -
Disable Cyrus IMAP
If the system does not need to operate as an IMAP or POP3 server, the Cyrus IMAP software should be removed.Group -
Uninstall cyrus-imapd Package
Thecyrus-imapd
package can be removed with the following command:$ sudo dnf erase cyrus-imapd
Rule Unknown Severity -
Disable Dovecot
If the system does not need to operate as an IMAP or POP3 server, the dovecot software should be disabled and removed.Group -
Uninstall dovecot Package
Thedovecot
package can be removed with the following command:$ sudo dnf erase dovecot
Rule Unknown Severity -
Network Time Protocol
The Network Time Protocol is used to manage the system clock over a network. Computer clocks are not very accurate, so time will drift unpredictabl...Group -
The Chrony package is installed
System time should be synchronized between all systems in an environment. This is typically done by establishing an authoritative time server or se...Rule Medium Severity -
Ensure that chronyd is running under chrony user account
chrony is a daemon which implements the Network Time Protocol (NTP). It is designed to synchronize system clocks across a variety of systems and us...Rule Medium Severity -
A remote time server for Chrony is configured
<code>Chrony</code> is a daemon which implements the Network Time Protocol (NTP). It is designed to synchronize system clocks across a variety of s...Rule Medium Severity -
Obsolete Services
This section discusses a number of network-visible services which have historically caused problems for system security, and for which disabling or...Group -
Telnet
The telnet protocol does not provide confidentiality or integrity for information transmitted on the network. This includes authentication informat...Group -
Uninstall telnet-server Package
Thetelnet-server
package can be removed with the following command:$ sudo dnf erase telnet-server
Rule High Severity -
TFTP Server
TFTP is a lightweight version of the FTP protocol which has traditionally been used to configure networking equipment. However, TFTP provides littl...Group -
Uninstall tftp-server Package
Thetftp-server
package can be removed with the following command:$ sudo dnf erase tftp-server
Rule High Severity -
Proxy Server
A proxy server is a very desirable target for a potential adversary because much (or all) sensitive data for a given infrastructure may flow throug...Group -
Disable Squid if Possible
If Squid was installed and activated, but the system does not need to act as a proxy server, then it should be disabled and removed.Group -
Uninstall squid Package
Thesquid
package can be removed with the following command:$ sudo dnf erase squid
Rule Unknown Severity -
SNMP Server
The Simple Network Management Protocol allows administrators to monitor the state of network devices, including computers. Older versions of SNMP w...Group -
Disable SNMP Server if Possible
The system includes an SNMP daemon that allows for its remote monitoring, though it not installed by default. If it was installed and activated but...Group -
Uninstall net-snmp Package
The <code>net-snmp</code> package provides the snmpd service. The <code>net-snmp</code> package can be removed with the following command: <pre> $...Rule Unknown Severity -
SSH Server
The SSH protocol is recommended for remote login and remote file transfer. SSH provides confidentiality and integrity for data exchanged between tw...Group -
Configure OpenSSH Server if Necessary
If the system needs to act as an SSH server, then certain changes should be made to the OpenSSH daemon configuration file <code>/etc/ssh/sshd_confi...Group -
Set SSH Client Alive Count Max
The SSH server sends at most <code>ClientAliveCountMax</code> messages during a SSH session and waits for a response from the SSH client. The optio...Rule Medium Severity -
Set SSH Client Alive Interval
SSH allows administrators to set a network responsiveness timeout interval. After this interval has passed, the unresponsive client will be automat...Rule Medium Severity -
Enable SSH Warning Banner
To enable the warning banner and ensure it is consistent across the system, add or correct the following line in <code>/etc/ssh/sshd_config.d/00-c...Rule Medium Severity -
Limit Users' SSH Access
By default, the SSH configuration allows any user with an account to access the system. There are several options available to limit which users an...Rule Unknown Severity -
USBGuard daemon
The USBGuard daemon enforces the USB device authorization policy for all USB devices.Group -
Install usbguard Package
Theusbguard
package can be installed with the following command:$ sudo dnf install usbguard
Rule Medium Severity -
Enable the USBGuard Service
The USBGuard service should be enabled. The <code>usbguard</code> service can be enabled with the following command: <pre>$ sudo systemctl enable ...Rule Medium Severity -
Generate USBGuard Policy
By default USBGuard when enabled prevents access to all USB devices and this lead to inaccessible system if they use USB mouse/keyboard. To prevent...Rule Medium Severity
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