Currently, there are no protections to access the GRUB boot loader.
Any user with access to the console during boot may interrupt the boot sequence to enter
GRUB without authenticating.
When a user with access to the console
during boot interrupts the boot sequence to modify GRUB, the system prompts
for and validate a credentials before entering GRUB menu entries other than
default.
The following command configures grub bootloader password.
SLX(config-grub)# username root password fabos345
The GRUB credentials will be asked when accessing grub only, when the
feature is enabled via configuring the above CLI.