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| from elftools.elf.elffile import ELFFile
from unicorn.arm64_const import *
from unicorn import *
from capstone.arm64_const import *
from capstone import *
import lief
SP_START = 0x80000000
SP_SIZE = 0x1000 * 0x1000 * 6
so_name = "xxxxxxxxxxx.so"
def load_elf(filename):
global img_size
global out_data
segs = []
with open(filename, 'rb') as f:
out_data = f.read()
elf_file = ELFFile(f)
for seg in elf_file.iter_segments():
if seg['p_type'] != 'PT_LOAD':
continue
print('file_off:%s, va: %s, size: %s' %(hex(seg['p_offset']), hex(seg['p_vaddr']), hex(seg['p_filesz'])))
segs.append((seg['p_offset'],seg['p_vaddr'], seg['p_filesz'], seg.data()))
img_size = segs[-1][1] + segs[-1][2]
byte_arr = bytearray([0] * img_size)
for seg in segs:
vaddr = seg[1]
size = seg[2]
data = seg[3]
byte_arr[vaddr: vaddr + size] = bytearray(data)
return byte_arr
def hook_code(uc : Uc, address, size, user_data):
bytes = uc.mem_read(address, size)
ins = list(cs.disasm(bytes, address))
if len(ins) == 0:
return
ins = ins[0]
print("%x : %s %s" % (address, ins.mnemonic, ins.op_str))
def set_sp():
uc.reg_write(UC_ARM64_REG_SP, SP_START + SP_SIZE)
def skip_ins(n = 1):
uc.reg_write(UC_ARM64_REG_PC, uc.reg_read(UC_ARM64_REG_PC) + 4 * n)
def init_unicorn(file_name):
global bin_data
global uc
bin_data = bytes(load_elf(file_name))
uc = Uc(UC_ARCH_ARM64, UC_MODE_ARM)
uc.mem_map(SP_START, SP_SIZE)
uc.mem_map(0, 8 * 0x1000 * 0x1000)
uc.mem_map(0x13370000, 0x100000)
uc.mem_write(0, bin_data)
set_sp()
uc.hook_add(UC_HOOK_MEM_WRITE, hook_mem_write)
def init_capstone():
global cs
cs = Cs(CS_ARCH_ARM64, CS_MODE_ARM)
cs.detail = True
sp_start = 0
sp_end = 0
chunk_start = 0
chunk_end = 0
def hook_mem_write(uc : Uc, access_type, address, size, value, user_data):
global sp_start, sp_end, chunk_start, chunk_end
if address <= 0x13470000 and address >= 0x13370000:
chunk_start = min(chunk_start, address)
chunk_end = max(chunk_end, address + size)
init_unicorn(so_name)
init_capstone()
init_proc_pattern = bytes.fromhex("FF 03 04 D1 E0 7B 00 A9 E0 07 01 A9 E2 0F 02 A9 E4 17 03 A9 E6 1F 04 A9 E8 27 05 A9 EA 2F 06 A9 EC 37 07 A9 EE 3F 08 A9 F0 47 09 A9 F2 4F 0A A9 F4 57 0B A9 F6 5F 0C A9 F8 67 0D A9 FA 6F 0E A9 FC 77 0F A9")
init_proc_offset = bin_data.find(init_proc_pattern)
print("init proc: %x" % (init_proc_offset))
init_block_offset = init_proc_offset + 0x44
uc.emu_start(init_block_offset, init_block_offset + 0x20, 0, 0)
option = uc.reg_read(UC_ARM64_REG_X0)
data = uc.reg_read(UC_ARM64_REG_X1)
print("option", hex(option))
print("data", hex(data))
offset = int.from_bytes(uc.mem_read(option + 0x1C, 4), "little")
print("offset", hex(offset))
dst = int.from_bytes(uc.mem_read(option + 0x24, 4), "little")
print("dst", hex(dst))
xor_key = int.from_bytes(uc.mem_read(option + 0x20, 4), "little", signed=True)
print("xor_key", hex(xor_key))
if xor_key != 0:
print("not supported")
exit()
length = int.from_bytes(uc.mem_read(option + 0x28, 4), "little", signed=True)
print("length", hex(length))
deflate_pattern = bytes.fromhex("FD 7B BE A9 E2 03 00 AA E0 03 01 AA FD 03 00 91 E1 03 03 2A A3 73 00 91")
deflate_offset = bin_data.find(deflate_pattern)
print("deflate offset: %x" % (deflate_offset))
chunk_start = 0x13470000
chunk_end = 0
uc.reg_write(UC_ARM64_REG_X0, 0x13370000)
uc.reg_write(UC_ARM64_REG_X1, data)
uc.reg_write(UC_ARM64_REG_X2, offset)
uc.reg_write(UC_ARM64_REG_X3, length)
uc.reg_write(UC_ARM64_REG_LR, 0)
uc.emu_start(deflate_offset, 0, 0, 0)
if uc.reg_read(UC_ARM64_REG_X0) != 0:
print("解密失败")
exit(0)
new_length = chunk_end - chunk_start
dst_data = uc.mem_read(chunk_start, new_length)
binary = lief.parse(so_name)
target_segment = None
for segment in binary.segments:
start = segment.virtual_address
end = start + segment.virtual_size
if dst >= start and dst < end:
target_segment = segment
print(target_segment)
break
if target_segment is None:
raise RuntimeError("没找到包含目标地址的段")
offset_in_segment = dst - target_segment.virtual_address
segment_data = bytearray(target_segment.content)
segment_data[offset_in_segment:offset_in_segment + len(dst_data)] = dst_data
target_segment.content = list(segment_data)
if target_segment.sections:
for section in target_segment.sections:
section.name = ".text"
binary.write(so_name+"_fix.so")
print("解密完成, 回填 %d 字节到 %s" % (len(dst_data), so_name))
del binary
|