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3 changed files with 53 additions and 33 deletions

43
iat.py
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@ -1,53 +1,70 @@
import json
import lief
lief.disable_leak_warning() # warnings to disable for the callback
dump_path = "rsc/wave-0001.dump"
# dump_path = "rsc/wave-0002.dump"
iat_json_path = "rsc/upx-hostname.exe.bin_iat_wave1.json"
# iat_json_path = "rsc/000155f2e0360f6ff6cd.exe_iat_wave2.json"
# Retrives all unique DLL names being imported
def get_used_dlls(calls: list[dict[str, str]]) -> set[str]:
res = set()
for call in calls:
res.add(call["name"].split('!')[0])
res.add(call["name"].split("!")[0])
return res
# Retrieves all unique function names used for a single DLL name
def get_used_functions_from_dll(dllname, calls):
res = set()
for [dll,func] in map(lambda x: x["name"].split('!'),calls):
for [dll, func] in map(lambda x: x["name"].split("!"), calls):
if dll == dllname:
res.add(func)
return res
def patch_call_to_new_IAT_entry(pe: lief.PE.Binary, call: dict[str, str], rva: int):
base = pe.imagebase
instruction_offset = int(call["adress"], 16) - base
# We can manually patch the instruction here: FF 15 08 10 00 01 represents `call [0x01001080]`
adress_size = 4 if pe.abstract.header.is_32 else 8
is_little_endian = pe.abstract.header.endianness == lief.Header.ENDIANNESS.LITTLE
new_value = [0x00] * adress_size
hex_adress = hex(rva + pe.imagebase)[::-1][:-2] # reversing order and stripping zero
hex_adress = hex(rva + pe.imagebase)[::-1][
:-2
] # reversing order and stripping zero
for i in range(0, adress_size):
byte_str = hex_adress[i * 2 : (i + 1) * 2][::-1]
new_value[i] += int(byte_str, 16)
if(not is_little_endian):
if not is_little_endian:
new_value = new_value[::-1] # reverse byte order for big endian
pe.patch_address(instruction_offset, [0xFF,0x15] + new_value, lief.Binary.VA_TYPES.RVA)
pe.patch_address(
instruction_offset, [0xFF, 0x15] + new_value, lief.Binary.VA_TYPES.RVA
)
def patch_calls_to_new_IAT(pe: lief.PE.Binary, imp: lief.PE.Import, entry:lief.PE.ImportEntry, rva: int):
def patch_calls_to_new_IAT(
pe: lief.PE.Binary, imp: lief.PE.Import, entry: lief.PE.ImportEntry, rva: int
):
# print(f"{imp.name}!{entry.name}: 0x{rva:010x}")
for call in filter(lambda x : x["name"] == f"{imp.name.upper()}!{entry.name}" ,calls):
for call in filter(
lambda x: x["name"] == f"{imp.name.upper()}!{entry.name}", calls
):
patch_call_to_new_IAT_entry(pe, call, rva)
# wave dump file to patch
with open("rsc/wave-0001.dump", "rb") as f:
with open(dump_path, "rb") as f:
pe = lief.parse(f)
assert isinstance(pe, lief.PE.Binary)
# JSON generated with the python reader files
with open("rsc/upx-hostname.exe.bin_iat_wave1.json", "r") as iat_json_input:
with open(iat_json_path, "r") as iat_json_input:
iat_data = json.load(iat_json_input)
calls: list[dict[str, str]] = iat_data["calls"]
wave_entry = int(iat_data["entry"], 16)
@ -76,6 +93,8 @@ for dll in get_used_dlls(calls):
# write result
config = lief.PE.Builder.config_t()
config.imports = True # allows the config of the writer to write a new IAT
config.resolved_iat_cbk = patch_calls_to_new_IAT # callback after the IAT has been written
config.resolved_iat_cbk = (
patch_calls_to_new_IAT # callback after the IAT has been written
)
pe.write("patched.exe", config)
print("Wrote the patched executable as patched.exe")

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