ANSSI-BP-028 (high)
Rules and Groups employed by this XCCDF Profile
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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 -
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 generate a check log entry, if an error cannot be c...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 since Linux kernel 3.7. But it could be disabled t...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 disabled through kernel boot parameters. Ensure tha...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 ensure that <code>pti=on</code> is added as a kerne...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 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 -
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 such cases, recent stores to the same memory loca...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 -
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 -
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 -
Verify /boot/grub2/user.cfg Permissions
File permissions for <code>/boot/grub2/user.cfg</code> should be set to 600. To properly set the permissions of <code>/boot/grub2/user.cfg</code>, run the command: <pre>$ sudo chmod 600 /boot/grub...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 -
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, generat...Rule High Severity -
Kernel Configuration
Contains rules that check the kernel configuration that was used to build it.Group -
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 -
Emulate Privileged Access Never (PAN)
Enabling this option prevents the kernel from accessing user-space memory directly by pointing TTBR0_EL1 to a reserved zeroed area and reserved ASID. The user access routines restore the valid TTBR...Rule Medium 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 -
Trigger a kernel BUG when data corruption is detected
This option makes the kernel BUG when it encounters data corruption in kernel memory structures when they get checked for validity. This configuration is available from kernel 4.10. The configurat...Rule Low 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 -
Warn on W+X mappings found at boot
Generate a warning if any W+X mappings are found at boot. This configuration is available from kernel 5.8. The configuration that was used to build kernel is available at <code>/boot/config-*</cod...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 -
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 -
Harden common str/mem functions against buffer overflows
Detect overflows of buffers in common string and memory functions where the compiler can determine and validate the buffer sizes. This configuration is available from kernel 4.13, but may be availa...Rule Medium Severity -
Harden memory copies between kernel and userspace
This option checks for obviously wrong memory regions when copying memory to/from the kernel (via copy_to_user() and copy_from_user() functions) by rejecting memory ranges that are larger than the ...Rule High Severity -
Do not allow usercopy whitelist violations to fallback to object size
This is a temporary option that allows missing usercopy whitelists to be discovered via a WARN() to the kernel log, instead of rejecting the copy, falling back to non-whitelisted hardened usercopy ...Rule High 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 -
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 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 -
Disable vsyscall emulation
The kernel traps and emulates calls into the fixed vsyscall address mapping. This configuration is available from kernel 5.3, but may be available if backported by distros. The configuration that ...Rule Medium Severity -
Disable vsyscall mapping
This config disables the vsyscall mapping at all. Attempts to use the vsyscalls will be reported to dmesg, so that either old or malicious userspace programs can be identified. This configuration i...Rule Medium Severity
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