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Guide to the Secure Configuration of Red Hat Enterprise Linux 9

Rules, Groups, and Values defined within the XCCDF Benchmark

  • Verify Permissions on cron.weekly

    To properly set the permissions of /etc/cron.weekly, run the command:
    $ sudo chmod 0700 /etc/cron.weekly
    Rule Medium Severity
  • Verify Permissions on crontab

    To properly set the permissions of /etc/crontab, run the command:
    $ sudo chmod 0600 /etc/crontab
    Rule Medium Severity
  • 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 del...
    Group
  • Ensure that /etc/at.deny does not exist

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

    The file /etc/cron.deny should not exist. Use /etc/cron.allow instead.
    Rule Medium Severity
  • 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>, ...
    Rule Medium Severity
  • Verify Group Who Owns /etc/cron.allow file

    If <code>/etc/cron.allow</code> exists, it must be group-owned by <code>root</code>. To properly set the group owner of <code>/etc/cron.allow</cod...
    Rule Medium Severity
  • Verify User Who Owns /etc/cron.allow file

    If <code>/etc/cron.allow</code> exists, it must be owned by <code>root</code>. To properly set the owner of <code>/etc/cron.allow</code>, run the ...
    Rule Medium Severity
  • Verify Permissions on /etc/at.allow file

    If <code>/etc/at.allow</code> exists, it must have permissions <code>0600</code> or more restrictive. To properly set the permissions of <code>/e...
    Rule Medium Severity
  • Verify Permissions on /etc/cron.allow file

    If <code>/etc/cron.allow</code> exists, it must have permissions <code>0600</code> or more restrictive. To properly set the permissions of <code>...
    Rule Medium Severity
  • Deprecated services

    Some deprecated software services impact the overall system security due to their behavior (leak of confidentiality in network exchange, usage as u...
    Group
  • Uninstall the inet-based telnet server

    The inet-based telnet daemon should be uninstalled.
    Rule High Severity
  • Uninstall the nis package

    The support for Yellowpages should not be installed unless it is required.
    Rule Low Severity
  • Uninstall the ntpdate package

    ntpdate is a historical ntp synchronization client for unixes. It sould be uninstalled.
    Rule Low Severity
  • Uninstall the ssl compliant telnet server

    The telnet daemon, even with ssl support, should be uninstalled.
    Rule High Severity
  • Uninstall the telnet server

    The telnet daemon should be uninstalled.
    Rule High Severity
  • DHCP

    The Dynamic Host Configuration Protocol (DHCP) allows systems to request and obtain an IP address and other configuration parameters from a server....
    Group
  • Configure DHCP Client if Necessary

    If DHCP must be used, then certain configuration changes can minimize the amount of information it receives and applies from the network, and thus ...
    Group
  • 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 obtain...
    Rule Unknown Severity
  • Configure DHCP Server

    If the system must act as a DHCP server, the configuration information it serves should be minimized. Also, support for other protocols and DNS-upd...
    Group
  • Minimize Served Information

    Edit /etc/dhcp/dhcpd.conf. Examine each address range section within the file, and ensure that the following options are not defined unless there i...
    Rule Unknown Severity
  • Disable DHCP Client

    DHCP is the default network configuration method provided by the system installer, and common on many networks. Nevertheless, manual management of ...
    Group
  • Disable DHCP Server

    The DHCP server <code>dhcpd</code> is not installed or activated by default. If the software was installed and activated, but the system does not n...
    Group
  • 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...
    Rule Medium Severity
  • Disable DHCP Service

    The <code>dhcpd</code> service should be disabled on any system that does not need to act as a DHCP server. The <code>dhcpd</code> service can be ...
    Rule Medium Severity
  • 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
  • Uninstall dnsmasq Package

    dnsmasq is a lightweight tool that provides DNS caching, DNS forwarding and DHCP (Dynamic Host Configuration Protocol) services. <br> The <code>dns...
    Rule Low Severity
  • 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
  • Disable named Service

    The named service can be disabled with the following command:
    $ sudo systemctl mask --now named.service
    Rule Medium Severity
  • Isolate DNS from Other Services

    This section discusses mechanisms for preventing the DNS server from interfering with other services. This is done both to protect the remainder of...
    Group
  • Run DNS Software in a chroot Jail

    Install the <code>bind-chroot</code> package: <pre>$ sudo yum install bind-chroot</pre> Place a valid named.conf file inside the chroot jail: <pre>...
    Group
  • Run DNS Software on Dedicated Servers

    Since DNS is a high-risk service which must frequently be made available to the entire Internet, it is strongly recommended that no other services ...
    Group
  • Protect DNS Data from Tampering or Attack

    This section discusses DNS configuration options which make it more difficult for attackers to gain access to private DNS data or to modify DNS data.
    Group
  • Use Views to Partition External and Internal Information

    If it is not possible to run external and internal nameservers on separate physical systems, run BIND9 and simulate this feature using views. Edit ...
    Group
  • Run Separate DNS Servers for External and Internal Queries

    Is it possible to run external and internal nameservers on separate systems? If so, follow the configuration guidance in this section. On the exter...
    Group
  • Docker Service

    The docker service is necessary to create containers, which are self-sufficient and self-contained applications using the resource isolation fe...
    Group
  • 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

    The fapolicyd 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
  • Configure Fapolicy Module to Employ a Deny-all, Permit-by-exception Policy to Allow the Execution of Authorized Software Programs.

    The Fapolicy module must be configured to employ a deny-all, permit-by-exception policy to allow the execution of authorized software programs and ...
    Rule Medium Severity
  • fapolicyd Must be Configured to Limit Access to Users Home Folders

    fapolicyd needs be configured so that users cannot give access to their home folders to other users.
    Rule Medium 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
  • 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, esp...
    Rule Low Severity
  • Disable vsftpd if Possible

    To minimize attack surface, disable vsftpd if at all possible.
    Group
  • Uninstall vsftpd Package

    The vsftpd package can be removed with the following command:
     $ sudo dnf erase vsftpd
    Rule High Severity
  • Disable vsftpd Service

    The vsftpd service can be disabled with the following command:
    $ sudo systemctl mask --now vsftpd.service
    Rule Medium Severity
  • Configure vsftpd to Provide FTP Service if Necessary

    The primary vsftpd configuration file is /etc/vsftpd.conf, if that file exists, or /etc/vsftpd/vsftpd.conf if it does not.
    Group
  • 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,...
    Rule Unknown Severity
  • Restrict the Set of Users Allowed to Access FTP

    This section describes how to disable non-anonymous (password-based) FTP logins, or, if it is not possible to do this entirely due to legacy applic...
    Group

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