Bootloader File Delivered via HTTP

This rule detects when a bootloader file is delivered via HTTP. It specifically looks for HTTP responses (flow:to_client) where the URI contains keywords like 'bootloader', 'grub', 'bootmgr', or 'mbr' (case-insensitive) and the file data contains the magic bytes '|55 AA|', which often indicate the end of a boot sector or a master boot record.