[Tutorial] ME cleaner still working for newer platforms

[c0d3z3r0]

I've been experimenting hours on IFWI image cleaning and finally found out, that IFWI support is not required for me_cleaner to work (#213, #242). The trick is to apply me_cleaner to just the ME subregion of the IFWI image. That can be achieved in this way:

• Get the FIT tool for your ME version
• Open your image with FIT
• Save the project via File>Save
• Apply me_cleaner to //Decom/ME Sub Partition.bin
• Reopen the project (the previously saved xml file, not the original image!)
• Click Build
• Flash the new image and pray ;-)

This was tested with CSME 14.0.11.1205, FIT 14.0.11.1205.

Note: Most modules seem to be mandatory on newer ME versions and the system will reset instantly when one of those gets cleaned (for me at least fpf,maestro,pm,crypto,heci,policy,storage,...). At least I could clean touch_fw,fwupdate,ptt. So, there is not much left to be cleaned and thus, this is not yet a real alternative to #282.

Note 2: you will need the modules whitelist patch from #160

mv "ME Sub Partition.bin" "ME Sub Partition.bin.orig"
me_cleaner.py -O "ME Sub Partition.bin" "ME Sub Partition.bin.orig" -w PSVN,UEP,IVBP,MFS,UTOK,HVMP,RSTR,FLOG,IMDP,RBEP,FTPR,NFTP,DLMP -R touch_fw,ptt,fwupdate

[Yannik]

Hi @c0d3z3r0, thanks for the guide.

Where can I get this "FIT" tool?

[steelpuxnastik]

Hi @c0d3z3r0, thanks for the guide.

Where can I get this "FIT" tool?

FIT - Flash image tool. Find the one that compitable with your processor.

[Nephiel]

FWIW, this is what worked for me on a Comet Lake with Intel ME 14.x. Do this at your own risk.

• Get me_cleaner.py from #282 and ensure it reports your original dump.bin as generation 4 at least. Mine was falling into gen 3 as the default case so I arbitrarily added a gen 5 if branch to catch it.
• Use the FIT tool compatible with your processor platform to open your original dump.bin
• In the ME Kernel section of FIT, find the Reserved value (this is the HAP bit, see reference) and toggle it to Yes. Do not change anything else.
• Build the image using FIT but do NOT flash that.
• Instead, use ifdtool -d on both the original dump and the one built with FIT, and diff the outputs. Only one bit should have changed, and this will tell you the offset. Let's say it looks like this:

< PCHSTRP28 : 0x801001b8
---
> PCHSTRP28 : 0x801101b8

So the HAP bit is the 5th on PCHSTRP28.

With this information, we can modify me_cleaner.py, editing the fspba offset on the gen 4 (or 5) branches to replace PCHSTRP32 with PCHSTRP28 and fspba offset 0x80 with 28x4 = 112 = 0x70. In my case, as the fipped bit was still the 5th most significant one, the mask was still 16, no need to change that.

• Use this me_cleaner.py on the original dump, to flip the HAP bit.
• Now, just to check, hexdump and diff both the original dump and the one just cleaned. Only that single bit should have changed between them.
  • (diffing with the one built with FIT should show more changes, this is why we don't want to flash that).
• Flash the dump modified with me_cleaner.py and check that ME is disabled sucessfully.

[c0d3z3r0]

@Nephiel sorry for the late response :D Well, what you describe is actually the soft-disable strap. What I described initially was actual cleaning/wiping of modules to prevent their code to run, even if HAP would had a backdoor. That's what clean(er) in me_cleaner stands for.

So, this feature of me_cleaner could be implemented for platforms >= 9th Gen by extracting the CSME partition from the IFWI image, apply the cleaning stuff just like on < 9th Gen platforms and repackage the cleaned partition into the IFWI image.

[Nephiel]

Right, I only flipped the soft-disable bit, so the rest of the ME code is still in there, and there is no guarantee it can't be invoked some other way.

But, IIRC, I tried more complete cleaning and ran into issues during boot. May have cleaned some module that turned out to be mandatory on that machine... So I had to settle for soft-disabling.