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This script can patch macOS 10.12.2 amfid daemon on memory to allow arbitrary entitlements in Developer ID signed binaries.
#!/usr/bin/env python3
'''amfid_patch.py - Pedro José Pereira Vieito © 2016
This script can patch macOS 10.12.2 amfid daemon on memory
to allow arbitrary entitlements in Developer ID signed binaries.
Killing amfid will make the patch disapear:
$ sudo kill -9 `pgrep amfid`
You must run the script as a root (sudo) and with SIP disabled.
You can get the PyMach Python module from here:
PyMach: https://github.com/pvieito/PyMach
Usage:
amfid_patch.py [-h]
Options:
-h, --help Show this help
'''
import mach
import sys
import os
import binascii
from subprocess import check_output
from docopt import docopt
from distutils.util import strtobool
args = docopt(__doc__)
def get_pid(name):
try:
output = check_output(["pgrep", name])
return int(output)
except:
return None
def patch_mem(task, address, original_mem, patched_mem):
print("Patch Address:", hex(address))
patch_len = len(patched_mem)
mem = mach.vm_read(task, address, patch_len)
if mem == original_mem:
print("Correct process version!")
print("Patch:", binascii.hexlify(mem).decode(), "->",
binascii.hexlify(patched_mem).decode())
if strtobool(input('Continue patching? ')):
print("Patching amfid...")
mach.vm_protect(task, address, patch_len, 7)
mach.vm_write(task, address, patched_mem)
mem = mach.vm_read(amfid_task, address, patch_len)
if patched_mem == mem:
print("🎉 Patch Successfull!")
else:
print("Not patched :(")
else:
exit(0)
elif mem == patched_mem:
print("🎉 Already patched!")
else:
print("Memory:", binascii.hexlify(mem).decode(), "vs.",
binascii.hexlify(original_mem).decode())
print("Incorrect version of process or ASRL Offset")
if os.getuid() != 0:
print("This script should run as root.")
exit(0)
amfid_pid = get_pid("amfid")
if not amfid_pid:
print("Error: amfid not running, start some app to reload amfid")
exit(0)
try:
amfid_task = mach.task_for_pid(amfid_pid)
asrl_offset = mach.vm_asrl_offset(amfid_pid)
if asrl_offset:
print("PID:", amfid_pid)
asrl_offset = 0x0000000100000000 + asrl_offset
print("ASRL Offset:", hex(asrl_offset))
else:
print("Error getting the ASRL Offset")
exit(0)
# Convert `test r14, r14; je` -> `mov r14, r15; jno`
# So it always jump and r14 becomes 0
patch_mem(amfid_task, asrl_offset + 0x347D,
b"\x45\x85\xF6\x0F\x84", b"\x4D\x89\xFE\x0F\x81")
except SystemError as error:
print("Memory not accessible probably due to System Integrity Protection.")

Hi Pedro, Congratulation for the catch ! I just wonder if there's also option to disable amfid without disabling SIP first. do you think there's an option to write Kext that perform the same logic as you did just without task_for_pid ? thanks, Irad

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