Guide to the Secure Configuration of Red Hat Enterprise Linux 8
Rules, Groups, and Values defined within the XCCDF Benchmark
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Direct root Logins Not Allowed
To further limit access to the <code>root</code> account, administrators can disable root logins at the console by editing the <code>/etc/securetty</code> file. This file lists all devices the root...Rule Medium Severity -
Verify /boot/grub2/user.cfg User Ownership
The file <code>/boot/grub2/user.cfg</code> should be owned by the <code>root</code> user to prevent reading or modification of the file. To properly set the owner of <code>/boot/grub2/user.cfg</co...Rule Medium Severity -
All User Files and Directories In The Home Directory Must Have a Valid Owner
Either remove all files and directories from the system that do not have a valid user, or assign a valid user to all unowned files and directories. To assign a valid owner to a local interactive us...Rule Medium Severity -
All Interactive User Home Directories Must Be Group-Owned By The Primary Group
Change the group owner of interactive users home directory to the group found in <code>/etc/passwd</code>. To change the group owner of interactive users home directory, use the following command: ...Rule Medium Severity -
Ensure All User Initialization Files Have Mode 0740 Or Less Permissive
Set the mode of the user initialization files, including the <code>root</code> user, to <code>0740</code> with the following commands: <pre> $ sudo chmod 0740 /root/.<i>INIT_FILE</i> $ sudo chmod 0...Rule Medium Severity -
Ensure that User Home Directories are not Group-Writable or World-Readable
For each human user of the system, view the permissions of the user's home directory: <pre># ls -ld /home/<i>USER</i> </pre> Ensure that the directory is not group-writable and that...Rule Medium Severity -
Ensure the Default Bash Umask is Set Correctly
To ensure the default umask for users of the Bash shell is set properly, add or correct the <code>umask</code> setting in <code>/etc/bashrc</code> to read as follows: <pre>umask <xccdf-1.2:sub idre...Rule Medium Severity -
Ensure the Default C Shell Umask is Set Correctly
To ensure the default umask for users of the C shell is set properly, add or correct the <code>umask</code> setting in <code>/etc/csh.cshrc</code> to read as follows: <pre>umask <xccdf-1.2:sub idre...Rule Medium Severity -
Ensure the Default Umask is Set Correctly in login.defs
To ensure the default umask controlled by <code>/etc/login.defs</code> is set properly, add or correct the <code>UMASK</code> setting in <code>/etc/login.defs</code> to read as follows: <pre>UMASK ...Rule Medium Severity -
Disable Recovery Booting
Red Hat Enterprise Linux 8 systems support an "recovery boot" option that can be used to prevent services from being started. The <code>GRUB_DISABLE_RECOVERY</code> configuration option in <code>/e...Rule Medium Severity -
IOMMU configuration directive
On x86 architecture supporting VT-d, the IOMMU manages the access control policy between the hardware devices and some of the system critical units such as the memory. To ensure that <code>iomm...Rule Unknown Severity -
Verify /boot/grub2/grub.cfg Permissions
File permissions for <code>/boot/grub2/grub.cfg</code> should be set to 600. To properly set the permissions of <code>/boot/grub2/grub.cfg</code>, run the command: <pre>$ sudo chmod 600 /boot/grub...Rule Medium Severity -
Configure kernel to trust the CPU random number generator
There exist two ways how to ensure that the Linux kernel trusts the CPU hardware random number generator. If the option is configured during kernel compilation, e.g. the option <code>CONFIG_RANDOM_...Rule Medium Severity -
Configure L1 Terminal Fault mitigations
L1 Terminal Fault (L1TF) is a hardware vulnerability which allows unprivileged speculative access to data which is available in the Level 1 Data Cache when the page table entry isn't present. Sele...Rule High Severity -
Configure the confidence in TPM for entropy
The TPM security chip that is available in most modern systems has a hardware RNG. It is also used to feed the entropy pool, but generally not credited entropy. Use <code>rng_core.default_quality<...Rule Low Severity -
Disable merging of slabs with similar size
The kernel may merge similar slabs together to reduce overhead and increase cache hotness of objects. Disabling merging of slabs keeps the slabs separate and reduces the risk of kernel heap overflo...Rule Medium Severity -
Verify /boot/grub2/grub.cfg Group Ownership
The file <code>/boot/grub2/grub.cfg</code> should be group-owned by the <code>root</code> group to prevent destruction or modification of the file. To properly set the group owner of <code>/boot/g...Rule Medium Severity -
Verify /boot/grub2/user.cfg Group Ownership
The file <code>/boot/grub2/user.cfg</code> should be group-owned by the <code>root</code> group to prevent reading or modification of the file. To properly set the group owner of <code>/boot/grub2...Rule Medium Severity -
Set the Boot Loader Admin Username to a Non-Default Value
The grub2 boot loader should have a superuser account and password protection enabled to protect boot-time settings. <br> <br> To maximize the protection, select a password-protecte...Rule High Severity -
Boot Loader Is Not Installed On Removeable Media
The system must not allow removable media to be used as the boot loader. Remove alternate methods of booting the system from removable media. <code>usb0</code>, <code>cd</code>, <code>fd0</code>, e...Rule Medium Severity -
Set Boot Loader Password in grub2
The grub2 boot loader should have a superuser account and password protection enabled to protect boot-time settings. <br> <br> Since plaintext passwords are a security risk, generat...Rule High Severity -
Verify the UEFI Boot Loader grub.cfg Group Ownership
The file <code>/boot/efi/EFI/redhat/grub.cfg</code> should be group-owned by the <code>root</code> group to prevent destruction or modification of the file. To properly set the group owner of <cod...Rule Medium Severity -
Verify /boot/efi/EFI/redhat/user.cfg Group Ownership
The file <code>/boot/efi/EFI/redhat/user.cfg</code> should be group-owned by the <code>root</code> group to prevent reading or modification of the file. To properly set the group owner of <code>/b...Rule Medium Severity -
Verify the UEFI Boot Loader grub.cfg User Ownership
The file <code>/boot/efi/EFI/redhat/grub.cfg</code> should be owned by the <code>root</code> user to prevent destruction or modification of the file. To properly set the owner of <code>/boot/efi/E...Rule Medium Severity -
Verify /boot/efi/EFI/redhat/user.cfg User Ownership
The file <code>/boot/efi/EFI/redhat/user.cfg</code> should be owned by the <code>root</code> user to prevent reading or modification of the file. To properly set the owner of <code>/boot/efi/EFI/r...Rule Medium Severity -
Verify the UEFI Boot Loader grub.cfg Permissions
File permissions for <code>/boot/efi/EFI/redhat/grub.cfg</code> should be set to 700. To properly set the permissions of <code>/boot/efi/EFI/redhat/grub.cfg</code>, run the command: <pre>$ sudo ch...Rule Medium Severity -
Verify /boot/efi/EFI/redhat/user.cfg Permissions
File permissions for <code>/boot/efi/EFI/redhat/user.cfg</code> should be set to 600. To properly set the permissions of <code>/boot/efi/EFI/redhat/user.cfg</code>, run the command: <pre>$ sudo ch...Rule Medium Severity -
Set the UEFI Boot Loader Admin Username to a Non-Default Value
The grub2 boot loader should have a superuser account and password protection enabled to protect boot-time settings. <br> <br> To maximize the protection, select a password-protecte...Rule Medium Severity -
Ensure debug-shell service is not enabled in zIPL
systemd's <code>debug-shell</code> service is intended to diagnose systemd related boot issues with various <code>systemctl</code> commands. Once enabled and following a system reboot, the root she...Rule Medium Severity -
Ensure Solid State Drives Do Not Contribute To Random-Number Entropy Pool
For each solid-state drive on the system, run:# echo 0 > /sys/block/DRIVE/queue/add_random
Rule Medium Severity -
Configure Low Address Space To Protect From User Allocation
This is the portion of low virtual memory which should be protected from userspace allocation. This configuration is available from kernel 3.14, but may be available if backported by distros. The ...Rule Medium Severity -
Configure Syslog
The syslog service has been the default Unix logging mechanism for many years. It has a number of downsides, including inconsistent log format, lack of authentication for received messages, and lac...Group -
Configure Logwatch HostLimit Line
On a central logserver, you want Logwatch to summarize all syslog entries, including those which did not originate on the logserver itself. The <code>HostLimit</code> setting tells Logwatch to repo...Rule Unknown Severity -
Configure Logwatch SplitHosts Line
If <code>SplitHosts</code> is set, Logwatch will separate entries by hostname. This makes the report longer but significantly more usable. If it is not set, then Logwatch will not report which host...Rule Unknown Severity -
Ensure Proper Configuration of Log Files
The file <code>/etc/rsyslog.conf</code> controls where log message are written. These are controlled by lines called <i>rules</i>, which consist of a <i>selector</i> and an <i>action</i>. These rul...Group -
Ensure Rsyslog Encrypts Off-Loaded Audit Records
Rsyslogd is a system utility providing support for message logging. Support for both internet and UNIX domain sockets enables this utility to support both local and remote logging. Couple this uti...Rule Medium Severity -
Ensure Log Files Are Owned By Appropriate Group
The group-owner of all log files written by <code>rsyslog</code> should be <code>root</code>. These log files are determined by the second part of each Rule line in <code>/etc/rsyslog.conf</code> a...Rule Medium Severity -
Ensure System Log Files Have Correct Permissions
The file permissions for all log files written by <code>rsyslog</code> should be set to 640, or more restrictive. These log files are determined by the second part of each Rule line in <code>/etc/r...Rule Medium Severity -
Ensure remote access methods are monitored in Rsyslog
Logging of remote access methods must be implemented to help identify cyber attacks and ensure ongoing compliance with remote access policies are being audited and upheld. An examples of a remote a...Rule Medium Severity -
Ensure All Logs are Rotated by logrotate
Edit the file <code>/etc/logrotate.d/syslog</code>. Find the first line, which should look like this (wrapped for clarity): <pre>/var/log/messages /var/log/secure /var/log/maillog /var/log/spoole...Group -
Rsyslog Logs Sent To Remote Host
If system logs are to be useful in detecting malicious activities, it is necessary to send logs to a remote server. An intruder who has compromised the root account on a system may delete the log e...Group -
Disable Zeroconf Networking
Zeroconf networking allows the system to assign itself an IP address and engage in IP communication without a statically-assigned address or even a DHCP server. Automatic address assignment via Zer...Rule Unknown Severity -
Prevent non-Privileged Users from Modifying Network Interfaces using nmcli
By default, non-privileged users are given permissions to modify networking interfaces and configurations using the <code>nmcli</code> command. Non-privileged users should not be making configurati...Rule Medium Severity -
Strengthen the Default Ruleset
The default rules can be strengthened. The system scripts that activate the firewall rules expect them to be defined in configuration files under the <code>/etc/firewalld/services</code> and <code>...Group -
Configure the Firewalld Ports
Configure the <code>firewalld</code> ports to allow approved services to have access to the system. To configure <code>firewalld</code> to open ports, run the following command: <pre>firewall-cmd -...Rule Medium Severity -
Configure Firewalld to Restrict Loopback Traffic
Configure <code>firewalld</code> to restrict loopback traffic to the <code>lo</code> interface. The loopback traffic must be trusted by assigning the <code>lo</code> interface to the <code>firewal...Rule Medium Severity -
Verify Group Who Owns /etc/ipsec.d Directory
To properly set the group owner of/etc/ipsec.d, run the command:$ sudo chgrp root /etc/ipsec.d
Rule Medium Severity -
Verify User Who Owns /etc/ipsec.d Directory
To properly set the owner of/etc/ipsec.d, run the command:$ sudo chown root /etc/ipsec.d
Rule Medium Severity -
Verify Permissions On /etc/ipsec.d Directory
To properly set the permissions of/etc/ipsec.d, run the command:$ sudo chmod 0700 /etc/ipsec.d
Rule Medium Severity -
Verify Group Who Owns /etc/ipsec.conf File
To properly set the group owner of/etc/ipsec.conf, run the command:$ sudo chgrp root /etc/ipsec.conf
Rule Medium Severity
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