Guide to the Secure Configuration of SUSE Linux Enterprise 15
Rules, Groups, and Values defined within the XCCDF Benchmark
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Force kernel panic on uncorrected MCEs
A Machine Check Exception is an error generated by the CPU itdetects an error in itself, memory or I/O devices. These errors may be corrected and g...Rule Medium Severity -
Ensure SMAP is not disabled during boot
The SMAP is used to prevent the supervisor mode from unintentionally reading/writing into memory pages in the user space, it is enabled by default ...Rule Medium Severity -
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 di...Rule Medium 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 cred...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 se...Rule Medium Severity -
zIPL bootloader configuration
During the boot process, the bootloader is responsible for starting the execution of the kernel and passing options to it. The default SUSE Linux E...Group -
net.ipv6.conf.all.max_addresses
Maximum number of autoconfigured IPv6 addressesValue -
Configure Speculative Store Bypass Mitigation
Certain CPUs are vulnerable to an exploit against a common wide industry wide performance optimization known as Speculative Store Bypass (SSB). In...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 int...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 e...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....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 pr...Rule Medium 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>,...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 passw...Rule High Severity -
UEFI GRUB2 bootloader configuration
UEFI GRUB2 bootloader configurationGroup -
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 re...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 —...Value -
Kernel panic timeout
The time, in seconds, to wait until a reboot occurs. If the value is <code>0</code> the system never reboots. If the value is less than <code>0</co...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 kerne...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 prog...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 c...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 c...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 segm...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 t...Rule Low Severity -
net.ipv6.conf.all.router_solicitations
Accept all router solicitations?Value -
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 wri...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>...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 unreg...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 conf...Rule Low 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, bu...Rule Medium 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 chec...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 ...Rule Medium Severity -
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/con...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...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 b...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...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 ...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 configur...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-...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_ha...Rule Medium Severity -
Specify module signing key to use
Setting this option to something other than its default of <code>certs/signing_key.pem</code> will disable the autogeneration of signing keys and a...Rule Medium 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 availab...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 config...Rule Medium Severity -
Use zero for poisoning instead of debugging value
Instead of using the existing poison value, fill the pages with zeros. This makes it harder to detect when errors are occurring due to sanitization...Rule Medium Severity -
net.ipv6.conf.default.accept_ra_defrtr
Accept default router in router advertisements?Value -
Remove the kernel mapping in user mode
This feature reduces the number of hardware side channels by ensuring that the majority of kernel addresses are not mapped into userspace. This con...Rule High Severity
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