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Guide to the Secure Configuration of Oracle Linux 9

Rules, Groups, and Values defined within the XCCDF Benchmark

  • Verify Permissions On /etc/sysctl.d Directory

    To properly set the permissions of /etc/sysctl.d, run the command: 
    $ sudo chmod 0755 /etc/sysctl.d
    Rule Medium Severity
    Show

  • Verify that System Executables Have Root Ownership

    System executables are stored in the following directories by default: <pre>/bin /sbin /usr/bin /usr/libexec /usr/local/bin /usr/local/sbin /usr/sbin</pre> All files in these directories should be ...
    Rule Medium Severity
    Show

  • Verify that Shared Library Files Have Root Ownership

    System-wide shared library files, which are linked to executables during process load time or run time, are stored in the following directories by default: <pre>/lib /lib64 /usr/lib /usr/lib64 </pr...
    Rule Medium Severity
    Show

  • Disable the Automounter

    The <code>autofs</code> daemon mounts and unmounts filesystems, such as user home directories shared via NFS, on demand. In addition, autofs can be used to handle removable media, and the default c...
    Rule Medium Severity
    Show

  • Disable Mounting of cramfs

    To configure the system to prevent the <code>cramfs</code> kernel module from being loaded, add the following line to the file <code>/etc/modprobe.d/cramfs.conf</code>: <pre>install cramfs /bin/fa...
    Rule Low Severity
    Show

  • Disable Modprobe Loading of USB Storage Driver

    To prevent USB storage devices from being used, configure the kernel module loading system to prevent automatic loading of the USB storage driver. To configure the system to prevent the <code>usb-...
    Rule Medium Severity
    Show

  • Add nosuid Option to /boot/efi

    The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/boot/efi</code>. The SUID and SGID permissions should not be required on the boot partition. Add t...
    Rule Medium Severity
    Show

  • Disable storing core dumps

    To set the runtime status of the <code>kernel.core_pattern</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.core_pattern=|/bin/false</pre> To make sure that the sett...
    Rule Medium Severity
    Show

  • Restrict Access to Kernel Message Buffer

    To set the runtime status of the <code>kernel.dmesg_restrict</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.dmesg_restrict=1</pre> To make sure that the setting is...
    Rule Low Severity
    Show

  • Disable Kernel Image Loading

    To set the runtime status of the <code>kernel.kexec_load_disabled</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.kexec_load_disabled=1</pre> To make sure that the ...
    Rule Medium Severity
    Show

  • Disable loading and unloading of kernel modules

    To set the runtime status of the <code>kernel.modules_disabled</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.modules_disabled=1</pre> To make sure that the settin...
    Rule Medium Severity
    Show

  • Disable Access to Network bpf() Syscall From Unprivileged Processes

    To prevent unprivileged processes from using the <code>bpf()</code> syscall the <code>kernel.unprivileged_bpf_disabled</code> kernel parameter must be set to <code>1</code> or <code>2</code>. Writ...
    Rule Medium Severity
    Show

  • Harden the operation of the BPF just-in-time compiler

    To set the runtime status of the <code>net.core.bpf_jit_harden</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w net.core.bpf_jit_harden=2</pre> To make sure that the settin...
    Rule Medium Severity
    Show

  • Ensure No Device Files are Unlabeled by SELinux

    Device files, which are used for communication with important system resources, should be labeled with proper SELinux types. If any device files carry the SELinux type <code>device_t</code> or <cod...
    Rule Medium Severity
    Show

  • Disable Core Dumps

    A core dump file is the memory image of an executable program when it was terminated by the operating system due to errant behavior. In most cases, only software developers legitimately need to acc...
    Group
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  • Restrict Exposed Kernel Pointer Addresses Access

    To set the runtime status of the <code>kernel.kptr_restrict</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.kptr_restrict=<xccdf-1.2:sub idref="xccdf_org.ssgproject...
    Rule Medium Severity
    Show

  • Enable SLUB/SLAB allocator poisoning

    To enable poisoning of SLUB/SLAB objects, add the argument <code>slub_debug=<xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_slub_debug_options" use="legacy"></xccdf-1.2:sub> <...
    Rule Medium Severity
    Show

  • 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 programs should be limited in what files they can a...
    Group
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  • Install libselinux Package

    The libselinux package can be installed with the following command: 
    $ sudo yum install libselinux
    Rule High Severity
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  • Install policycoreutils Package

    The policycoreutils package can be installed with the following command: 
    $ sudo yum install policycoreutils
    Rule Low Severity
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  • Verify Group Who Owns /etc/selinux Directory

    To properly set the group owner of /etc/selinux, run the command: 
    $ sudo chgrp root /etc/selinux
    Rule Medium Severity
    Show

  • 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 configure the system to use this policy, add or correct ...
    Rule Medium Severity
    Show

  • Enable the auditadm_exec_content SELinux Boolean

    By default, the SELinux boolean <code>auditadm_exec_content</code> is enabled. If this setting is disabled, it should be enabled. To enable the <code>auditadm_exec_content</code> SELinux boolean, ...
    Rule Medium Severity
    Show

  • Disable the authlogin_nsswitch_use_ldap SELinux Boolean

    By default, the SELinux boolean <code>authlogin_nsswitch_use_ldap</code> is disabled. If this setting is enabled, it should be disabled. To disable the <code>authlogin_nsswitch_use_ldap</code> SEL...
    Rule Medium Severity
    Show

  • Disable the authlogin_radius SELinux Boolean

    By default, the SELinux boolean <code>authlogin_radius</code> is disabled. If this setting is enabled, it should be disabled. To disable the <code>authlogin_radius</code> SELinux boolean, run the ...
    Rule Medium Severity
    Show

  • Configure the deny_execmem SELinux Boolean

    By default, the SELinux boolean <code>deny_execmem</code> is disabled. This setting should be configured to <xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_deny_execmem" use="legacy"><...
    Rule Medium Severity
    Show

  • Enable the kerberos_enabled SELinux Boolean

    By default, the SELinux boolean <code>kerberos_enabled</code> is enabled. If this setting is disabled, it should be enabled to allow confined applications to run with Kerberos. To enable the <code...
    Rule Medium Severity
    Show

  • Disable the ssh_sysadm_login SELinux Boolean

    By default, the SELinux boolean <code>ssh_sysadm_login</code> is disabled. If this setting is enabled, it should be disabled. To disable the <code>ssh_sysadm_login</code> SELinux boolean, run the ...
    Rule Medium Severity
    Show

  • Disable Avahi Publishing

    To prevent Avahi from publishing its records, edit <code>/etc/avahi/avahi-daemon.conf</code> and ensure the following line appears in the <code>[publish]</code> section: <pre>disable-publishing=yes...
    Rule Low Severity
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  • Disable Avahi Server Software

    The avahi-daemon service can be disabled with the following command: 
    $ sudo systemctl mask --now avahi-daemon.service
    Rule Medium Severity
    Show

  • Enable cron Service

    The <code>crond</code> service is used to execute commands at preconfigured times. It is required by almost all systems to perform necessary maintenance tasks, such as notifying root of system acti...
    Rule Medium Severity
    Show

  • Disable At Service (atd)

    The <code>at</code> and <code>batch</code> commands can be used to schedule tasks that are meant to be executed only once. This allows delayed execution in a manner similar to cron, except that it ...
    Rule Medium Severity
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  • Restrict at and cron to Authorized Users if Necessary

    The <code>/etc/cron.allow</code> and <code>/etc/at.allow</code> files contain lists of users who are allowed to use <code>cron</code> and at to delay execution of processes. If these files exist an...
    Group
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  • Ensure that /etc/at.deny does not exist

    The file /etc/at.deny should not exist. Use /etc/at.allow instead.
    Rule Medium Severity
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  • Ensure that /etc/cron.deny does not exist

    The file /etc/cron.deny should not exist. Use /etc/cron.allow instead.
    Rule Medium Severity
    Show

  • Verify Group Who Owns /etc/at.allow file

    If <code>/etc/at.allow</code> exists, it must be group-owned by <code>root</code>. To properly set the group owner of <code>/etc/at.allow</code>, run the command: <pre>$ sudo chgrp root /etc/at.al...
    Rule Medium Severity
    Show

  • Verify Permissions on /etc/at.allow file

    If <code>/etc/at.allow</code> exists, it must have permissions <code>0640</code> or more restrictive. To properly set the permissions of <code>/etc/at.allow</code>, run the command: <pre>$ sudo c...
    Rule Medium Severity
    Show

  • Verify Permissions on /etc/cron.allow file

    If <code>/etc/cron.allow</code> exists, it must have permissions <code>0640</code> or more restrictive. To properly set the permissions of <code>/etc/cron.allow</code>, run the command: <pre>$ su...
    Rule Medium Severity
    Show

  • Minimize the DHCP-Configured Options

    Create the file <code>/etc/dhcp/dhclient.conf</code>, and add an appropriate setting for each of the ten configuration settings which can be obtained via DHCP. For each setting, do one of the follo...
    Rule Unknown Severity
    Show

  • Uninstall DHCP Server Package

    If the system does not need to act as a DHCP server, the dhcp package can be uninstalled. The <code>dhcp-server</code> package can be removed with the following command: <pre> $ sudo yum erase dhc...
    Rule Medium Severity
    Show

  • Uninstall bind Package

    The named service is provided by the bind package. The bind package can be removed with the following command: 
    $ sudo yum erase bind
    Rule Low Severity
    Show

  • 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 transmitted during the session can be captured an...
    Group
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  • Remove ftp Package

    FTP (File Transfer Protocol) is a traditional and widely used standard tool for transferring files between a server and clients over a network, especially where no authentication is necessary (perm...
    Rule Low Severity
    Show

  • Configure Firewalls to Protect the FTP Server

    By default, <code>iptables</code> blocks access to the ports used by the web server. To configure <code>iptables</code> to allow port 21 traffic, one must edit <code>/etc/sysconfig/iptables</code>...
    Rule Unknown Severity
    Show

  • Mail Server Software

    Mail servers are used to send and receive email over the network. Mail is a very common service, and Mail Transfer Agents (MTAs) are obvious targets of network attack. Ensure that systems are not r...
    Group
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  • The s-nail Package Is Installed

    A mail server is required for sending emails. The s-nail package can be installed with the following command: 
    $ sudo yum install s-nail
    Rule Medium Severity
    Show

  • Configure System to Forward All Mail For The Root Account

    Make sure that mails delivered to root user are forwarded to a monitored email address. Make sure that the address <xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_postfix_root_mail_ali...
    Rule Medium Severity
    Show

  • Configure System to Forward All Mail through a specific host

    Set up a relay host that will act as a gateway for all outbound email. Edit the file <code>/etc/postfix/main.cf</code> to ensure that only the following <code>relayhost</code> line appears: <pre>re...
    Rule Medium Severity
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  • Uninstall nfs-utils Package

    The nfs-utils package can be removed with the following command: 
    $ sudo yum erase nfs-utils
    Rule Low Severity
    Show

  • Mount Remote Filesystems with Restrictive Options

    Edit the file <code>/etc/fstab</code>. For each filesystem whose type (column 3) is <code>nfs</code> or <code>nfs4</code>, add the text <code>,nodev,nosuid</code> to the list of mount options in co...
    Group
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