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CIS SUSE Linux Enterprise 15 Benchmark for Level 2 - Server

Rules and Groups employed by this XCCDF Profile

  • Disable Samba

    The smb service can be disabled with the following command:
    $ sudo systemctl mask --now smb.service
    Rule Low Severity
  • SNMP Server

    The Simple Network Management Protocol allows administrators to monitor the state of network devices, including computers. Older versions of SNMP were well-known for weak security, such as plaintex...
    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 is not needed, the software should be disabled an...
    Group
  • Uninstall net-snmp Package

    The net-snmp package provides the snmpd service. The net-snmp package can be removed with the following command:
    $ sudo zypper remove net-snmp
    Rule Unknown Severity
  • Disable snmpd Service

    The snmpd service can be disabled with the following command:
    $ sudo systemctl mask --now snmpd.service
    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 two systems, as well as server authentication, throu...
    Group
  • Verify Group Who Owns SSH Server config file

    To properly set the group owner of /etc/ssh/sshd_config, run the command:
    $ sudo chgrp root /etc/ssh/sshd_config
    Rule Medium Severity
  • Verify Owner on SSH Server config file

    To properly set the owner of /etc/ssh/sshd_config, run the command:
    $ sudo chown root /etc/ssh/sshd_config 
    Rule Medium Severity
  • Verify Permissions on SSH Server config file

    To properly set the permissions of /etc/ssh/sshd_config, run the command:
    $ sudo chmod 0600 /etc/ssh/sshd_config
    Rule Medium Severity
  • Verify Permissions on SSH Server Private *_key Key Files

    SSH server private keys - files that match the <code>/etc/ssh/*_key</code> glob, have to have restricted permissions. If those files are owned by the <code>root</code> user and the <code>root</code...
    Rule Medium Severity
  • Verify Permissions on SSH Server Public *.pub Key Files

    To properly set the permissions of /etc/ssh/*.pub, run the command:
    $ sudo chmod 0644 /etc/ssh/*.pub
    Rule Medium Severity
  • 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_config</code>. The following recommendations can be app...
    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 option <code>ClientAliveInterval</code> configures time...
    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 automatically logged out. <br> <br> To set this t...
    Rule Medium Severity
  • Disable Host-Based Authentication

    SSH's cryptographic host-based authentication is more secure than <code>.rhosts</code> authentication. However, it is not recommended that hosts unilaterally trust one another, even within an organ...
    Rule Medium 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 if no value is set for <code>PermitEmptyPasswords<...
    Rule High 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> files. <br> The default SSH configuration disables su...
    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 line in <code>/etc/ssh/sshd_config</code>: <pre>Pe...
    Rule Medium Severity
  • Disable SSH TCP Forwarding

    The <code>AllowTcpForwarding</code> parameter specifies whether TCP forwarding is permitted. To disable TCP forwarding, add or correct the following line in <code>/etc/ssh/sshd_config</code>: <p...
    Rule Medium Severity
  • Disable X11 Forwarding

    The X11Forwarding parameter provides the ability to tunnel X11 traffic through the connection to enable remote graphic connections. SSH has the capability to encrypt remote X11 connections when SSH...
    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 processing. The appropriate configuration is used if no v...
    Rule Medium Severity
  • Enable PAM

    UsePAM Enables the Pluggable Authentication Module interface. If set to “yes” this will enable PAM authentication using ChallengeResponseAuthentication and PasswordAuthentication in addition to PAM...
    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</code>: <pre>Banner /etc/issue</pre> Another section 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 and group can access the system via SSH. It is recom...
    Rule Unknown Severity
  • Ensure SSH LoginGraceTime is configured

    The <code>LoginGraceTime</code> parameter to the SSH server specifies the time allowed for successful authentication to the SSH server. The longer the Grace period is the more open unauthenticated ...
    Rule Medium Severity
  • Set SSH Daemon LogLevel to VERBOSE

    The <code>VERBOSE</code> parameter configures the SSH daemon to record login and logout activity. To specify the log level in SSH, add or correct the following line in <code>/etc/ssh/sshd_config<...
    Rule Medium Severity
  • Set SSH authentication attempt limit

    The <code>MaxAuthTries</code> parameter specifies the maximum number of authentication attempts permitted per connection. Once the number of failures reaches half this value, additional failures ar...
    Rule Medium Severity
  • Set SSH MaxSessions limit

    The <code>MaxSessions</code> parameter specifies the maximum number of open sessions permitted from a given connection. To set MaxSessions edit <code>/etc/ssh/sshd_config</code> as follows: <pre>Ma...
    Rule Medium Severity
  • Ensure SSH MaxStartups is configured

    The MaxStartups parameter specifies the maximum number of concurrent unauthenticated connections to the SSH daemon. Additional connections will be dropped until authentication succeeds or the Login...
    Rule Medium Severity
  • Use Only FIPS 140-2 Validated Ciphers

    Limit the ciphers to those algorithms which are FIPS-approved. Counter (CTR) mode is also preferred over cipher-block chaining (CBC) mode. The following line in <code>/etc/ssh/sshd_config</code> de...
    Rule Medium Severity
  • Use Only FIPS 140-2 Validated MACs

    Limit the MACs to those hash algorithms which are FIPS-approved. The following line in <code>/etc/ssh/sshd_config</code> demonstrates use of FIPS-approved MACs: <pre>MACs hmac-sha2-512,hmac-sha2-2...
    Rule Medium 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>/etc/ssh/sshd_config</code> demonstrates use of those...
    Rule Medium Severity
  • Use Only Strong Key Exchange algorithms

    Limit the Key Exchange to strong algorithms. The following line in <code>/etc/ssh/sshd_config</code> demonstrates use of those: <pre>KexAlgorithms <xccdf-1.2:sub idref="xccdf_org.ssgproject.content...
    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-1.2:sub idref="xccdf_org.ssgproject.content_value_...
    Rule Medium Severity
  • X Window System

    The X Window System implementation included with the system is called X.org.
    Group
  • Disable X Windows

    Unless there is a mission-critical reason for the system to run a graphical user interface, ensure X is not set to start automatically at boot and remove the X Windows software packages. There is u...
    Group
  • Remove the X Windows Package Group

    By removing the xorg-x11-server-common package, the system no longer has X Windows installed. If X Windows is not installed then the system cannot boot into graphical user mode. This prevents the s...
    Rule Medium Severity
  • Disable graphical user interface

    By removing the following packages, the system no longer has X Windows installed. <code>xorg-x11-server-Xorg xorg-x11-server-common xorg-x11-server-utils xorg-x11-server-Xwayland</code> If X Win...
    Rule Medium Severity
  • Configure Systemd Timer Execution of AIDE

    At a minimum, AIDE should be configured to run a weekly scan. To implement a systemd service and a timer unit to run the service periodically: For example, if a systemd timer is expected to be star...
    Rule Medium Severity
  • Record Attempts to perform maintenance activities

    The SUSE Linux Enterprise 15 operating system must generate audit records for privileged activities, nonlocal maintenance, diagnostic sessions and other system-level access. Verify the operating s...
    Rule Medium Severity
  • Dectivate firewalld Rules

    Firewalls can be used to separate networks into different zones based on the level of trust the user has decided to place on the devices and traffic within that network. Firewalls can be implemente...
    Group
  • Uninstall firewalld Package

    firewalld (Dynamic Firewall Manager) provides a dynamically managed firewall with support for network/firewall “zones” to assign a level of trust to a network and its associated connections, interf...
    Rule Medium Severity
  • Verify firewalld service disabled

    Firewalld (Dynamic Firewall Manager) provides a dynamically managed firewall with support for network/firewall “zones” to assign a level of trust to a network and its associated connections, interf...
    Rule Medium Severity
  • Configure Systemd Timesyncd Root Distance Servers

    <code>systemd-timesyncd</code> server configuration should have RootDistanceMaxSec is listed in accordance with local policy. This setting describes the maximum estimated time required for a packet...
    Rule Medium Severity

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