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EFI Memory Scanner

NOTE: This utility is work in progress.

Scan for memory data structures as known from UEFI PI firmware, i.e., EDK2 and derivatives.

You can access EFI memory e.g. using a Linux kernel with full access to /dev/mem.

Strategy

Invoke ems --file /dev/mem to locate occurrences of known EFI data structures, via their tags and also by providing a custom --pattern. Use the --offset and --limit arguments to narrow down the search. It is recommended to get a copy of that memory for offline analysis.

For example, a Lenovo ThinkPad X270's EFI memory starts at 0xb56e4000. That is the first address where an EFI memory "pool head" is found. Dumping it with u-root's dd:

dd if=/dev/mem bs=4096 skip=0xb56e4 count=43292 of=/tmp/memdump

The above example will dump about 190 MB. Put the resulting file on a USB drive or copy it over network to continue.

Rerun ems with --file again, passing the path to your copy.

TODO

  • pass the --base to resolve references/links
  • reconstruct the memory to access the data