DRAFT - Australian Cyber Security Centre (ACSC) Essential Eight
Rules and Groups employed by this XCCDF Profile
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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 -
Xinetd
The <code>xinetd</code> service acts as a dedicated listener for some network services (mostly, obsolete ones) and can be used to provide access co...Group -
Uninstall xinetd Package
Thexinetd
package can be removed with the following command:$ sudo yum erase xinetd
Rule Low Severity -
Disable xinetd Service
Thexinetd
service can be disabled with the following command:$ sudo systemctl mask --now xinetd.service
Rule Medium Severity -
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 yum 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 yum 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 yum 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 yum 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 yum erase quagga
Rule Low Severity -
Disable Quagga Service
Thezebra
service can be disabled with the following command:$ sudo systemctl mask --now zebra.service
Rule Medium 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 -
Allow Only SSH Protocol 2
Only SSH protocol version 2 connections should be permitted. The default setting in <code>/etc/ssh/sshd_config</code> is correct, and can be verifi...Rule High Severity -
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 Support for Rhosts RSA Authentication
SSH can allow authentication through the obsolete rsh command through the use of the authenticating user's SSH keys. This should be disabled. <br><...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 -
Use Only Strong Ciphers
Limit the ciphers to strong algorithms. Counter (CTR) mode is also preferred over cipher-block chaining (CBC) mode. The following line in <code>/et...Rule Medium Severity -
Use Only Strong MACs
Limit the MACs to strong hash algorithms. The following line in <code>/etc/ssh/sshd_config</code> demonstrates use of those MACs: <pre>MACs <xccdf-...Rule Medium Severity
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