Guide to the Secure Configuration of Oracle Linux 8
Rules, Groups, and Values defined within the XCCDF Benchmark
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Ensure SMEP is not disabled during boot
The SMEP is used to prevent the supervisor mode from executing user space code, it is enabled by default since Linux kernel 3.0. But it could be disabled through kernel boot parameters. Ensure tha...Rule Medium 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 -
Enforce Spectre v2 mitigation
Spectre V2 is an indirect branch poisoning attack that can lead to data leakage. An exploit for Spectre V2 tricks the indirect branch predictor into executing code from a future indirect branch cho...Rule High Severity -
Ensure debug-shell service is not enabled during boot
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 -
Disable vsyscalls
To disable use of virtual syscalls, add the argument <code>vsyscall=none</code> to the default GRUB 2 command line for the Linux operating system. To ensure that <code>vsyscall=none</code> is added...Rule Medium Severity -
Non-UEFI GRUB2 bootloader configuration
Non-UEFI GRUB2 bootloader configurationGroup -
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 -
Verify /boot/grub2/grub.cfg User Ownership
The file <code>/boot/grub2/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/grub2/grub.cfg...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 -
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-protected superu...Rule Medium 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, generate a hash...Rule High Severity -
UEFI GRUB2 bootloader configuration
UEFI GRUB2 bootloader configurationGroup -
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 Password
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, generate a hash...Rule High Severity -
Sign kernel modules with SHA-512
This configures the kernel to build and sign modules using SHA512 as the hash function. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check th...Rule Medium Severity -
Enable poison without sanity check
Skip the sanity checking on alloc, only fill the pages with poison on free. This reduces some of the overhead of the poisoning feature. This configuration is available from kernel 4.6. The configu...Rule Medium Severity -
Protect Random-Number Entropy Pool
The I/O operations of the Linux kernel block layer due to their inherently unpredictable execution times have been traditionally considered as a reliable source to contribute to random-number entro...Group -
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 -
Kernel Configuration
Contains rules that check the kernel configuration that was used to build it.Group -
Hash function for kernel module signing
The hash function to use when signing modules during kernel build process.Value -
Key and certificate for kernel module signing
The private key and certificate to use when signing modules during kernel build process. On systems where the OpenSSL ENGINE_pkcs11 is functional — a PKCS#11 URI as defined by RFC7512 In the latter...Value -
Kernel panic timeout
The time, in seconds, to wait until a reboot occurs. If the value is0the system never reboots. If the value is less than0the system reboots immediately.Value -
Do not allow ACPI methods to be inserted/replaced at run time
This debug facility allows ACPI AML methods to be inserted and/or replaced without rebooting the system. This configuration is available from kernel 3.0. The configuration that was used to build k...Rule Low Severity -
Disable kernel support for MISC binaries
Enabling <code>CONFIG_BINFMT_MISC</code> makes it possible to plug wrapper-driven binary formats into the kernel. This is specially useful for programs that need an interpreter to run like Java, Py...Rule Medium Severity -
Enable support for BUG()
Disabling this option eliminates support for BUG and WARN, reducing the size of your kernel image and potentially quietly ignoring numerous fatal conditions. You should only consider disabling this...Rule Medium Severity -
Disable compatibility with brk()
Enabling compatiliby with <code>brk()</code> allows legacy binaries to run (i.e. those linked against libc5). But this compatibility comes at the cost of not being able to randomize the heap placem...Rule Medium Severity -
Disable the 32-bit vDSO
Certain buggy versions of glibc (2.3.3) will crash if they are presented with a 32-bit vDSO that is not mapped at the address indicated in its segment table. Setting <code>CONFIG_COMPAT_VDSO</code>...Rule Low Severity -
Enable checks on credential management
Enable this to turn on some debug checking for credential management. The additional code keeps track of the number of pointers from task_structs to any given cred struct, and checks to see that th...Rule Low Severity -
Disable kernel debugfs
<code>debugfs</code> is a virtual file system that kernel developers use to put debugging files into. Enable this option to be able to read and write to these files. The configuration that was use...Rule Low Severity -
Enable checks on linked list manipulation
Enable this to turn on extended checks in the linked-list walking routines. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check the configurat...Rule Low Severity -
Enable checks on notifier call chains
Enable this to turn on sanity checking for notifier call chains. This is most useful for kernel developers to make sure that modules properly unregister themselves from notifier chains. The config...Rule Low Severity -
Enable checks on scatter-gather (SG) table operations
Scatter-gather tables are mechanism used for high performance I/O on DMA devices. Enable this to turn on checks on scatter-gather tables. The configuration that was used to build kernel is availab...Rule Low Severity -
Disable /dev/kmem virtual device support
Disable support for the /dev/kmem device. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check the configuration value for <code>CONFIG_DEVKMEM...Rule Low Severity -
Disable hibernation
Enable the suspend to disk (STD) functionality, which is usually called "hibernation" in user interfaces. STD checkpoints the system and powers it off; and restores that checkpoint on reboot. The ...Rule Medium Severity -
cron_can_relabel SELinux Boolean
default - Default SELinux boolean setting.
on - SELinux boolean is enabled.
off - SELinux boolean is disabled.Value -
Disable IA32 emulation
Disables support for legacy 32-bit programs under a 64-bit kernel. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check the configuration value...Rule Medium Severity -
Disable the IPv6 protocol
Disable support for IP version 6 (IPv6). The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check the configuration value for <code>CONFIG_IPV6</co...Rule Medium Severity -
Disable kexec system call
<code>kexec</code> is a system call that implements the ability to shutdown your current kernel, and to start another kernel. It is like a reboot but it is independent of the system firmware. And l...Rule Low Severity -
Disable legacy (BSD) PTY support
Disable the Linux traditional BSD-like terminal names /dev/ptyxx for masters and /dev/ttyxx for slaves of pseudo terminals, and use only the modern ptys (devpts) interface. The configuration that ...Rule Medium Severity -
Enable module signature verification
Check modules for valid signatures upon load. Note that this option adds the OpenSSL development packages as a kernel build dependency so that the signing tool can use its crypto library. The conf...Rule Medium Severity -
Enable automatic signing of all modules
Sign all modules during make modules_install. Without this option, modules must be signed manually, using the scripts/sign-file tool. The configuration that was used to build kernel is available a...Rule Medium Severity -
Require modules to be validly signed
Reject unsigned modules or signed modules with an unknown key. The configuration that was used to build kernel is available at <code>/boot/config-*</code>. To check the configuration value for...Rule Medium Severity -
Specify the hash to use when signing modules
This configures the kernel to build and sign modules using <xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_kernel_config_module_sig_hash" use="legacy"></xccdf-1.2:sub> as the hash func...Rule Medium Severity
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