Australian Cyber Security Centre (ACSC) Essential Eight
Rules and Groups employed by this XCCDF Profile
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Enable Randomized Layout of Virtual Address Space
To set the runtime status of the <code>kernel.randomize_va_space</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.r...Rule Medium Severity -
SELinux
SELinux is a feature of the Linux kernel which can be used to guard against misconfigured or compromised programs. SELinux enforces the idea that p...Group -
Configure SELinux Policy
The SELinux <code>targeted</code> policy is appropriate for general-purpose desktops and servers, as well as systems in many other roles. To config...Rule Medium Severity -
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 -
Avahi Server
The Avahi daemon implements the DNS Service Discovery and Multicast DNS protocols, which provide service and host discovery on a network. It allows...Group -
Disable Avahi Server if Possible
Because the Avahi daemon service keeps an open network port, it is subject to network attacks. Disabling it can reduce the system's vulnerability t...Group -
Disable Avahi Server Software
Theavahi-daemon
service can be disabled with the following command:$ sudo systemctl mask --now avahi-daemon.service
Rule Medium Severity -
Application Whitelisting Daemon
Fapolicyd (File Access Policy Daemon) implements application whitelisting to decide file access rights. Applications that are known via a reputatio...Group -
Install fapolicyd Package
Thefapolicyd
package can be installed with the following command:$ sudo dnf install fapolicyd
Rule Medium Severity -
Enable the File Access Policy Service
The File Access Policy service should be enabled. The <code>fapolicyd</code> service can be enabled with the following command: <pre>$ sudo system...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 -
NIS
The Network Information Service (NIS), also known as 'Yellow Pages' (YP), and its successor NIS+ have been made obsolete by Kerberos, LDAP, and oth...Group -
Remove NIS Client
The Network Information Service (NIS), formerly known as Yellow Pages, is a client-server directory service protocol used to distribute system conf...Rule Unknown Severity -
Rlogin, Rsh, and Rexec
The Berkeley r-commands are legacy services which allow cleartext remote access and have an insecure trust model.Group -
Uninstall rsh-server Package
Thersh-server
package can be removed with the following command:$ sudo dnf erase rsh-server
Rule High Severity -
Uninstall rsh Package
Thersh
package contains the client commands for the rsh servicesRule Unknown Severity -
Chat/Messaging Services
The talk software makes it possible for users to send and receive messages across systems through a terminal session.Group -
Uninstall talk-server Package
Thetalk-server
package can be removed with the following command:$ sudo dnf erase talk-server
Rule Medium Severity -
Uninstall talk Package
The <code>talk</code> package contains the client program for the Internet talk protocol, which allows the user to chat with other users on differe...Rule Medium Severity -
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 -
Remove telnet Clients
The telnet client allows users to start connections to other systems via the telnet protocol.Rule Low Severity -
Disable telnet Service
Make sure that the activation of the <code>telnet</code> service on system boot is disabled. The <code>telnet</code> socket can be disabled with t...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 -
Disable Squid
Thesquid
service can be disabled with the following command:$ sudo systemctl mask --now squid.service
Rule Unknown Severity -
Network Routing
A router is a very desirable target for a potential adversary because they fulfill a variety of infrastructure networking roles such as access to ...Group -
Disable Quagga if Possible
If Quagga was installed and activated, but the system does not need to act as a router, then it should be disabled and removed.Group -
Uninstall quagga Package
Thequagga
package can be removed with the following command:$ sudo dnf erase quagga
Rule Low 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 -
Disable SSH Access via Empty Passwords
Disallow SSH login with empty passwords. The default SSH configuration disables logins with empty passwords. The appropriate configuration is used ...Rule High Severity -
Disable GSSAPI Authentication
Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like GSSAPI. <br> The default SSH configuration disallows ...Rule Medium Severity -
Disable SSH Support for .rhosts Files
SSH can emulate the behavior of the obsolete rsh command in allowing users to enable insecure access to their accounts via <code>.rhosts</code> fil...Rule Medium Severity -
Disable SSH Root Login
The root user should never be allowed to login to a system directly over a network. To disable root login via SSH, add or correct the following lin...Rule Medium Severity -
Disable SSH Support for User Known Hosts
SSH can allow system users to connect to systems if a cache of the remote systems public keys is available. This should be disabled. <br><br> To e...Rule Medium Severity -
Do Not Allow SSH Environment Options
Ensure that users are not able to override environment variables of the SSH daemon. <br> The default SSH configuration disables environment process...Rule Medium Severity -
Enable Use of Strict Mode Checking
SSHs <code>StrictModes</code> option checks file and ownership permissions in the user's home directory <code>.ssh</code> folder before accepting l...Rule Medium Severity -
Enable SSH Print Last Log
Ensure that SSH will display the date and time of the last successful account logon. <br> The default SSH configuration enables print of the date a...Rule Medium Severity -
Set LogLevel to INFO
The INFO parameter specifices that record login and logout activity will be logged. <br> The default SSH configuration sets the log level to INFO. ...Rule Low Severity -
Distribute the SSH Server configuration to multiple files in a config directory.
Make sure to have the <code>Include /etc/ssh/sshd_config.d/*.conf</code> line in the <code>/etc/ssh/sshd_config</code> file. Ideally, don't have an...Rule Medium Severity
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