diff --git a/README.md b/README.md index 06f31d9..74bfa0f 100644 --- a/README.md +++ b/README.md @@ -138,9 +138,12 @@ configuration file and significant hardening is applied to a myriad of component Mitigations for known CPU vulnerabilities are enabled in their strictest form and simultaneous multithreading (SMT) is disabled. See the -`/etc/default/grub.d/40_cpu_mitigations.cfg` configuration file. Note, to achieve -complete protection for known CPU vulnerabilities, the latest security microcode -(BIOS/UEFI) updates must also be installed on the system. +`/etc/default/grub.d/40_cpu_mitigations.cfg` configuration file. + +Note, to achieve complete protection for known CPU vulnerabilities, the latest +security microcode (BIOS/UEFI) updates must be installed on the system. Furthermore, +if using Secure Boot, the Secure Boot Forbidden Signature Database (DBX) must be kept +up to date through [UEFI Revocation List](https://uefi.org/revocationlistfile) updates. Boot parameters relating to kernel hardening, DMA mitigations, and entropy generation are outlined in the `/etc/default/grub.d/40_kernel_hardening.cfg` diff --git a/etc/default/grub.d/40_cpu_mitigations.cfg b/etc/default/grub.d/40_cpu_mitigations.cfg index 06bcb88..9b29760 100644 --- a/etc/default/grub.d/40_cpu_mitigations.cfg +++ b/etc/default/grub.d/40_cpu_mitigations.cfg @@ -26,6 +26,13 @@ ## Note that incorrectly performing system BIOS/UEFI updates can potentially lead to serious functionality issues. ## The parameters below only provide (partial) protection at both the kernel and user space level. +## If using Secure Boot, users must also ensure the Secure Boot Forbidden Signature Database (DBX) is up to date. +## The UEFI Revocation List contains signatures of now revoked firmware and software used in booting systems. +## If using compatible hardware, the database can be updated directly in user space using fwupd. +## Note that incorrectly performing DBX updates can potentially lead to serious functionality issues. +## https://uefi.org/revocationlistfile +## https://github.com/fwupd/fwupd + ## Enable a subset of known mitigations for some CPU vulnerabilities and disable SMT. ## ## KSPP=yes