ron minnich wrote:
you may or may not have seen them
http://eecue.com/log_archive/eecue-log-724-Black_Hat_2007___Day_2___John_Hea...
"There are many ways to get code into the EFI environment. An attacker can modify the bootlader directly, modify bootloader varibles in NVRAM, modify and reflash firmware or exploit an implementation flaw in the driver. Once the attacher is in, they can shim a boot service, modify an ACPI table like in the tradition BIOS attack, load an SMM driver, or hook interrup handlers. Modifying the boot loader is actually quite simple in Mac OSX as the bootloader binary is located in user disk space: /System/Library/CoreSerbvice.boot.efi. This isn't very stealthy as you are modifying a file on disk which could easily be detected by verifying checksums with an application like tripwire."
Our goal, too, is not being stealthy.
Which is why I was quite surprised that not using the locked away memory areas for my SMM handler was considered a knock-out criterionfor that approach.
now we've been trying to get this message across for eitght years now and it's good to see people are independently figuring it out.
The one thing that transports our message best, in my opinion, is ports to new chipsets and ports to new boards.
Stefan