Guide to the Secure Configuration of Red Hat Enterprise Linux 9
Rules, Groups, and Values defined within the XCCDF Benchmark
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Confidence level on Hardware Random Number Generator
Defines the level of trust on the hardware random number generators available in the system and the percentage of entropy to credit.Value -
Spec Store Bypass Mitigation
This controls how the Speculative Store Bypass (SSB) vulnerability is mitigated.Value -
Disable Recovery Booting
Red Hat Enterprise Linux 9 systems support an "recovery boot" option that can be used to prevent services from being started. The <code>GRUB_DISABL...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 u...Rule Unknown Severity -
Configure kernel to zero out memory before allocation
To configure the kernel to zero out memory before allocating it, add the <code>init_on_alloc=1</code> argument to the default GRUB 2 command line. ...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...Rule Medium Severity -
daemons_dump_core SELinux Boolean
default - Default SELinux boolean setting.
on - SELinux boolean is enabled.
off - SELinux boolean is disabled.Value -
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 Ca...Rule High Severity -
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 -
Configure Microarchitectural Data Sampling mitigation
Microarchitectural Data Sampling (MDS) is a hardware vulnerability which allows unprivileged speculative access to data which is available in vario...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 -
Enable randomization of the page allocator
To enable randomization of the page allocator in the kernel, add the <code>page_alloc.shuffle=1</code> argument to the default GRUB 2 command line....Rule Medium Severity -
Enable Kernel Page-Table Isolation (KPTI)
To enable Kernel page-table isolation, add the argument <code>pti=on</code> to the default GRUB 2 command line for the Linux operating system. To e...Rule Low 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 -
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 -
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...Rule Medium Severity
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