106 lines
3.7 KiB
Python
106 lines
3.7 KiB
Python
import json
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import lief
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lief.disable_leak_warning() # warnings to disable for the callback
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dump_path = "rsc/wave-0001.dump"
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# dump_path = "rsc/wave-0002.dump"
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iat_json_path = "rsc/upx-hostname.exe.bin_iat_wave1.json"
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# iat_json_path = "rsc/000155f2e0360f6ff6cd.exe_iat_wave2.json"
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# Retrives all unique DLL names being imported
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def get_used_dlls(calls: list[dict[str, str]]) -> set[str]:
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res = set()
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for call in calls:
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res.add(call["name"].split("!")[0])
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return res
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# Retrieves all unique function names used for a single DLL name
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def get_used_functions_from_dll(dllname, calls):
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res = set()
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for [dll, func] in map(lambda x: x["name"].split("!"), calls):
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if dll == dllname:
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res.add(func)
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return res
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def patch_direct_adress_call(pe: lief.PE.Binary, rva: int, instruction_offset: int):
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# We can manually patch the instruction here: FF 15 08 10 00 01 represents `call [0x01001080]`
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adress_size = 4 if pe.abstract.header.is_32 else 8
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is_little_endian = pe.abstract.header.endianness == lief.Header.ENDIANNESS.LITTLE
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new_value = [0x00] * adress_size
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hex_adress = hex(rva + pe.imagebase)[::-1][
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:-2
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] # reversing order and stripping zero
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for i in range(0, adress_size):
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byte_str = hex_adress[i * 2 : (i + 1) * 2][::-1]
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new_value[i] += int(byte_str, 16)
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if not is_little_endian:
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new_value = new_value[::-1] # reverse byte order for big endian
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pe.patch_address(
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instruction_offset, [0xFF, 0x15] + new_value, lief.Binary.VA_TYPES.RVA
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)
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def patch_call_to_new_IAT_entry(pe: lief.PE.Binary, call: dict[str, str], rva: int):
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base = pe.imagebase
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instruction_offset = int(call["adress"], 16) - base
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memview = pe.get_content_from_virtual_address(instruction_offset,2)
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if([memview[0],memview[1]] == [0xFF,0x15]):
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patch_direct_adress_call(pe,rva, instruction_offset)
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def patch_calls_to_new_IAT(
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pe: lief.PE.Binary, imp: lief.PE.Import, entry: lief.PE.ImportEntry, rva: int
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):
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# print(f"{imp.name}!{entry.name}: 0x{rva:010x}")
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for call in filter(
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lambda x: x["name"] == f"{imp.name.upper()}!{entry.name}", calls
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):
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patch_call_to_new_IAT_entry(pe, call, rva)
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# wave dump file to patch
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with open(dump_path, "rb") as f:
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pe = lief.parse(f)
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assert isinstance(pe, lief.PE.Binary)
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# JSON generated with the python reader files
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with open(iat_json_path, "r") as iat_json_input:
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iat_data = json.load(iat_json_input)
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calls: list[dict[str, str]] = iat_data["calls"]
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wave_entry = int(iat_data["entry"], 16)
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# Define all sections as writeable, to help with some weird stuff we're seeing
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for section in pe.sections:
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section.characteristics_lists.append(lief.PE.Section.CHARACTERISTICS.MEM_WRITE)
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section.characteristics_lists.append(lief.PE.Section.CHARACTERISTICS.MEM_EXECUTE)
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# patch entrypoint
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entrypoint_format = int(hex(wave_entry)[-4:], 16)
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pe.optional_header.addressof_entrypoint = entrypoint_format
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# remove all current imports
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pe.remove_all_imports()
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# recreate all DLL imports
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for dll in get_used_dlls(calls):
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imported_dll = pe.add_import(dll.lower())
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# recreate all function calls related to that dll import
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for func in get_used_functions_from_dll(dll, calls):
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imported_dll.add_entry(func)
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# At this point, the new IAT will only be constructed when the PE is written. We therefore need to make a callback function to patch calls afterwards.
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# write result
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config = lief.PE.Builder.config_t()
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config.imports = True # allows the config of the writer to write a new IAT
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config.resolved_iat_cbk = (
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patch_calls_to_new_IAT # callback after the IAT has been written
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)
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pe.write("patched.exe", config)
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print("Wrote the patched executable as patched.exe")
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