peacestone/obfu_block.py

591 lines
19 KiB
Python

from qiling import *
from qiling.const import *
from capstone import *
from keystone import *
import pefile
import json
import re
# Set to binary name
BIN_NAME = "sppsvc.exe"
REG_NAMES = {
19: "EAX",
20: "EBP",
21: "EBX",
22: "ECX",
23: "EDI",
24: "EDX",
29: "ESI"
}
NOP = b"\x90"
with open("syms.json", "r") as f:
sym_data = json.loads(f.read())
sym_data = {int(a, 16): b for a, b in sym_data.items()}
sym_data_inv = {b: a for a, b in sym_data.items()}
sym_addrs = sorted(sym_data)
ks = Ks(KS_ARCH_X86, KS_MODE_32)
md = Cs(CS_ARCH_X86, CS_MODE_32)
md.detail = True
md.skipdata = True
ql = Qiling(["./rootfs/sppsvc.exe"], "./rootfs", verbose=QL_VERBOSE.OFF)
image_start = ql.loader.images[0].base
image_end = ql.loader.images[0].end
image_size = image_end - image_start
pe = pefile.PE(data=ql.mem.read(image_start, image_size))
scratch_base = ql.mem.map_anywhere(0x1000)
def mem_read_int(addr):
return ql.unpack(ql.mem.read(addr, 4))
def array_read_int(array, offset):
return int.from_bytes(array[offset:offset+4], "little")
def array_write_int(array, offset, val):
arr_copy = list(array)
val_bytes = val.to_bytes(4, "little")
for i in range(4):
arr_copy[offset + i] = val_bytes[i]
return arr_copy
def assemble(instrs):
return bytes(ks.asm(instrs)[0])
num_obd = mem_read_int(sym_data_inv["?g_nNumObfuscatedBlockData@WARBIRD@@3KA"])
obd_addr = sym_data_inv["?g_ObfuscatedBlockData@WARBIRD@@3PAU_OBFUSCATED_BLOCK_DATA@1@A"]
obd = []
for i in range(num_obd):
obf_block = []
for j in range(5):
obf_block.append(mem_read_int(obd_addr + 4*(5*i + j)))
obd.append(obf_block)
num_relocs = mem_read_int(sym_data_inv["?g_PrivateRelocationsTable@WARBIRD@@3VCPrivateRelocationsTable@1@B"])
reloc_addr = sym_data_inv["?g_PrivateRelocationsTable@WARBIRD@@3VCPrivateRelocationsTable@1@B"] + 4
private_relocs = []
for i in range(num_relocs):
private_relocs.append(mem_read_int(reloc_addr + 4*i))
obfu_code_table = {}
obfu_ctrlflow = []
for target in range(num_obd):
first = 0
first_prev = 0
last = num_obd - 1
last_prev = num_obd - 1
sum_diff = 0
while True:
index = (first + last) // 2
xor_value = obd[index][0] ^ sum_diff
if index <= target:
if index != target:
first = index + 1
last = last_prev
first_prev = first
sum_diff = (obd[index][0] - obd[index][3]) % (1 << 32)
else:
break
else:
last = index - 1
last_prev = last
sum_diff = (obd[index][0] + obd[index][3]) % (1 << 32)
if first > last:
raise Exception("???")
addr = image_start + xor_value
val1 = (obd[index][1] + obd[index][0]) % (1 << 32)
val2 = (obd[index][2] - obd[index][0]) % (1 << 32)
val3 = (obd[index][4] + obd[index][3]) % (1 << 32)
unk3 = obd[index][3]
cont_mode = (unk3 >> 12) & 0x7F
data_size = unk3 & 0xfff
if cont_mode in [0x0B, 0x10, 0x13, 0x16, 0x33, 0x38, 0x45, 0x74]:
# INDIRECT JUMP
param1 = (unk3 >> 18) & 0x3F00 | (unk3 >> 12) & 0x80 | cont_mode & 0xFFF0007F | ((unk3 & 0x100000 | ((unk3 & 0x1E00000 | (unk3 >> 5) & 0x100000) >> 5)) >> 1)
param2 = val3
obfu_ctrlflow.append((-1, -1))
elif cont_mode in [0x19, 0x2F, 0x58, 0x63]:
# RETURN
obfu_ctrlflow.append((addr, 0, 0))
else:
# DIRECT JUMP
addr0 = image_start + xor_value + data_size
addr1 = image_start + val3
obfu_ctrlflow.append((addr, addr0, addr1))
obfu_code_table[addr] = (index, val1, val2, val3, unk3)
def decrypt_code(ecstart, start_offset=0):
print("DECRYPTING CODE @ " + hex(ecstart) + " OFFSET " + hex(start_offset))
ecstart_offset = ecstart - image_start
index, val1, val2, val3, unk3 = obfu_code_table[ecstart]
data_size = unk3 & 0xfff
enc_bytes = ql.mem.read(ecstart, data_size + 1)
dec_bytes = [0] * data_size
chksum = 0xa5
if val2 & 0x1000000 == 0:
print("DERIVING KEY FROM MAC")
mac_func = mem_read_int(sym_data_inv["?g_apMacFuncs@WARBIRD@@3PAP6AXAA_JPBE1ABU_CBCKey2@1@@ZA"] + (val2 >> 25) * 4)
for instr in md.disasm(ql.mem.read(mac_func, 0x100), mac_func):
if instr.mnemonic == "ret":
mac_end = instr.address
break
ql.mem.write(scratch_base, b"\x00\x01\x02\x03\x04\x05")
ql.mem.write(scratch_base + 0x10, ql.pack(ecstart_offset))
ql.mem.write(scratch_base + 0x14, ql.pack(0))
ql.arch.stack_push(scratch_base)
ql.arch.stack_push(val1 + image_start + (val2 & 0xffff))
ql.arch.stack_push(val1 + image_start)
ql.arch.stack_push(0x10)
ql.arch.stack_push(0x69696969)
old_sp = ql.arch.regs.esp
ql.run(begin=mac_func, end=mac_end)
ql.arch.regs.esp = old_sp
key1 = ql.mem.read(0x10, 4)
key2 = ql.mem.read(0x14, 2)
else:
print("USING BLOCK VALUES AS KEY")
key1 = val1.to_bytes(4, "little")
key2 = (val2 & 0xFFFF).to_bytes(2, "little")
for i in range(data_size - 1, -1, -1):
enc_byte = enc_bytes[i]
if i > 0:
b = enc_bytes[i - 1]
else:
b = 0
if i % 2 == 1:
if (enc_byte ^ key1[3]) % 2 == 1:
a = (enc_byte ^ key1[3] ^ key1[2] ^ 0x100) >> 1
else:
a = (enc_byte ^ key1[3]) >> 1
if (a ^ b) % 2 == 1:
dec_byte = (a ^ b ^ key2[1] ^ 0x100) >> 1
else:
dec_byte = (a ^ b) >> 1
else:
if (enc_byte ^ key1[1]) % 2 == 1:
a = (enc_byte ^ key1[1] ^ key1[0] ^ 0x100) >> 1
else:
a = (enc_byte ^ key1[1]) >> 1
if (a ^ b) % 2 == 1:
dec_byte = (a ^ b ^ key2[0] ^ 0x100) >> 1
else:
dec_byte = (a ^ b) >> 1
chksum ^= dec_byte
dec_bytes[i] = dec_byte
if chksum != (val2 >> 16) & 0xFF:
raise Exception("CHECKSUM FAILED!")
print(dec_bytes)
first = 0
last = num_relocs - 1
while last >= first:
index = (first + last) // 2
addr = private_relocs[index] & 0xFFFFFFF
if ecstart_offset >= addr:
if ecstart_offset == addr:
first = (first + last) // 2
break
first = index + 1
else:
last = index - 1
index = first
while index < num_relocs:
addr = private_relocs[index] & 0xFFFFFFF
if addr >= (ecstart_offset + data_size):
break
offset = 0
ofmode = (private_relocs[index] >> 28) & 3
if ofmode == 1:
offset = -ecstart % (1 << 32)
elif ofmode == 2:
offset = ecstart
if ((private_relocs[index] >> 30) & 3) == 2 and offset != 0:
print(f"RELOC @ OFFSET {hex(addr - ecstart_offset)} +{hex(offset)}")
val = array_read_int(dec_bytes, addr - ecstart_offset)
val = (val + offset - start_offset) % (1 << 32)
dec_bytes = array_write_int(dec_bytes, addr - ecstart_offset, val)
print(dec_bytes)
index += 1
dec_bytes = bytes(dec_bytes)
for instr in md.disasm(dec_bytes, start_offset):
print(instr)
return dec_bytes
def nearest_block(caddr):
return list(filter(lambda a: a <= caddr, obfu_code_table))[-1]
def deobfu_func(ecstart):
print("DEOBFUSCATING CODE @ " + hex(ecstart))
ecstart_offset = ecstart - image_start
code_chunks = []
index, val1, val2, val3, unk3 = obfu_code_table[ecstart]
min_index = index
addr = 0
max_addr = ecstart
while addr < max_addr:
addr, addr0, addr1 = obfu_ctrlflow[index]
max_addr = max(max_addr, addr, addr0, addr1)
if max_addr not in obfu_code_table:
max_addr = nearest_block(max_addr)
print(hex(addr), hex(max_addr))
code_chunks.append(decrypt_code(addr))
index += 1
max_index = index
ctrlflow = obfu_ctrlflow[min_index:max_index]
code_out = b""
for i in range(max_index - min_index):
addr, addr0, addr1 = ctrlflow[i]
code_out += decrypt_code(addr, len(code_out))
unk3 = obfu_code_table[addr][4]
cont_mode = (unk3 >> 12) & 0x7F
if cont_mode in [0x0B, 0x10, 0x13, 0x16, 0x33, 0x38, 0x45, 0x74]:
print("INDIRECT JUMP?")
param1 = (unk3 >> 18) & 0x3F00 | (unk3 >> 12) & 0x80 | cont_mode & 0xFFF0007F | ((unk3 & 0x100000 | ((unk3 & 0x1E00000 | (unk3 >> 5) & 0x100000) >> 5)) >> 1)
param2 = val3
# return b""
elif cont_mode in [0x19, 0x2F, 0x58, 0x63]:
ret_size = (unk3 >> 21) & 0xF
print(f"RETURN {ret_size}")
print(hex(addr))
ret_code_bin = assemble(f"ret {ret_size * 4}")
ret_code_bin += b"\x90" * (16 - len(ret_code_bin))
code_out += ret_code_bin
else:
print("DIRECT JUMP")
jmp_code = ""
# 0x01 CF
# 0x04 PF
# 0x10 AF
# 0x40 ZF
# 0x80 SF
# 0x100 TF
# 0x200 IF
# 0x400 DF
# 0x800 OF
if cont_mode in [0x00, 0x34, 0x5A, 0x6C]:
pass
# SF == 0 -> Addr1 else Addr0
# js addr0
# jmp addr1
jmp_code = "js {addr0}; jmp {addr1}"
elif cont_mode in [0x01, 0x20, 0x2D, 0x42]:
pass
# ZF != 0 || SF != OF -> Addr0 else Addr1
# jz addr0
# jl addr0
# jmp addr1
jmp_code = "jz {addr0}; jl {addr0}; jmp {addr1}"
elif cont_mode in [0x02, 0x21, 0x2E, 0x35]:
pass
# jmp addr1
jmp_code = "jmp {addr1}"
elif cont_mode in [0x03, 0x0F, 0x4A, 0x67]:
pass
# SF != 0 -> Addr0
# SF == 0 && OF == 0 -> Addr0
# SF == 0 && OF != 0 -> Addr1
# js addr0
# jno addr0
# jmp addr1
jmp_code = "js {addr0}; jno {addr0}; jmp {addr1}"
elif cont_mode in [0x05, 0x11, 0x5D, 0x78]:
pass
# PF == 0 -> Addr1 else Addr0
# jp addr0
# jmp addr1
jmp_code = "jp {addr0}; jmp {addr1}"
elif cont_mode in [0x06, 0x4D, 0x54, 0x6D]:
pass
# ZF != 0 || SF == OF -> Addr0 else Addr1
# jz addr0
# jnl addr0
# jmp addr1
jmp_code = "jz {addr0}; jnl {addr0}; jmp {addr1}"
elif cont_mode in [0x07, 0x0E, 0x3C, 0x53]:
pass
# OF == 0 -> Addr1 else Addr0
# jo addr0
# jmp addr1
jmp_code = "jo {addr0}; jmp {addr1}"
elif cont_mode in [0x08, 0x0D, 0x1F, 0x5B]:
pass
# ZF != 0 -> Addr1
# ZF == 0 && SF == OF -> Addr0
# ZF == 0 && SF != OF -> Addr1
# jz addr1
# jl addr1
# jmp addr0
jmp_code = "jz {addr1}; jl {addr1}; jmp {addr0}"
elif cont_mode in [0x09, 0x22, 0x25, 0x31]:
pass
# PF != 0 -> Addr1 else Addr0
# jnp addr0
# jmp addr1
jmp_code = "jnp {addr0}; jmp {addr1}"
elif cont_mode in [0x0A, 0x17, 0x24, 0x32]:
pass
# ZF != 0 -> Addr0
# ZF == 0 && OF == 0 -> Addr0
# ZF == 0 && OF != 0 -> Addr1
# jz addr0
# jno addr0
# jmp addr1
jmp_code = "jz {addr0}; jno {addr0}; jmp {addr1}"
elif cont_mode in [0x0C, 0x4B, 0x56, 0x65]:
pass
# PF && CF -> Addr1 else Addr0
# jnp addr0
# jnc addr0
# jmp addr1
jmp_code = "jnp {addr0}; jnc {addr0}; jmp {addr1}"
elif cont_mode in [0x12, 0x18, 0x1D, 0x51]:
pass
# SF != OF -> Addr1 else Addr0
# jnl addr0
# jmp addr1
jmp_code = "jnl {addr0}; jmp {addr1}"
elif cont_mode in [0x14, 0x3B, 0x4F, 0x5F]:
pass
# OF != 0 -> Addr1 else Addr0
# jno addr0
# jmp addr1
jmp_code = "jno {addr0}; jmp {addr1}"
elif cont_mode in [0x15, 0x1E, 0x41, 0x55]:
pass
# PF == 0 -> Addr1
# PF != 0 && ZF == OF -> Addr0
# PF != 0 && ZF != OF -> Addr1
# jnp addr1
# push eax
# push ecx
# pushfd
# pop eax
# mov ecx, eax
# shr eax, 5
# xor eax, ecx
# test al, 40h
# pop eax
# pop ecx
# jz addr0
# jmp addr1
elif cont_mode in [0x1A, 0x3E, 0x60, 0x72]:
pass
# PF != 0 -> Addr1 else Addr0
# jnp addr0
# jmp addr1
jmp_code = "jnp {addr0}; jmp {addr1}"
elif cont_mode in [0x1B, 0x44, 0x48, 0x7E]:
pass
# ZF == 0 -> Addr1 else Addr0
# jz addr0
# jmp addr1
jmp_code = "jz {addr0}; jmp {addr1}"
elif cont_mode in [0x1C, 0x26, 0x2B, 0x75]:
pass
# ZF == 0 || PF != 0 -> Addr0 else Addr1
# jnz addr0
# jp addr0
# jmp addr1
jmp_code = "jnz {addr0}; jp {addr0}; jmp {addr1}"
elif cont_mode in [0x27, 0x43, 0x64, 0x6B]:
pass
# SF != 0 -> Addr1 else Addr0
# jns addr0
# jmp addr1
jmp_code = "jns {addr0}; jmp {addr1}"
elif cont_mode in [0x28, 0x40, 0x68, 0x7B]:
pass
# CF != 0 -> Addr1
# CF == 0 && ZF == 0 -> Addr0
# CF == 0 && ZF != 0 -> Addr1
# ja addr0
# jmp addr1
jmp_code = "ja {addr0}; jmp {addr1}"
elif cont_mode in [0x29, 0x3A, 0x71, 0x76]:
pass
# ZF != 0 || CF != PF -> Addr0 else Addr1
# jz addr0
# push eax
# push ecx
# pushfd
# pop eax
# mov ecx, eax
# shr eax, 2
# xor eax, ecx
# test al, 01h
# pop eax
# pop ecx
# jnz addr0
# jmp addr1
elif cont_mode in [0x2C, 0x30, 0x3F, 0x7C]:
pass
# DF == 0 -> Addr1 else Addr0
# push eax
# push ecx
# pushfd
# pop eax
# mov ecx, eax
# shr eax, 4
# xor eax, ecx
# test al, 40h
# pop eax
# pop ecx
# jz addr0
# jmp addr1
elif cont_mode in [0x36, 0x59, 0x61, 0x7D]:
pass
# CF == 0 -> Addr1 else Addr0
# jc addr0
# jmp addr1
jmp_code = "jc {addr0}; jmp {addr1}"
elif cont_mode in [0x37, 0x52, 0x5E, 0x79]:
pass
# CF != 0 || ZF != 0 -> Addr0 else Addr1
# jna addr0
# jmp addr1
jmp_code = "jna {addr0}; jmp {addr1}"
elif cont_mode in [0x39, 0x4E, 0x6F, 0x7A]:
pass
# SF == OF -> Addr0 else Addr1
# jge addr0
# jmp addr1
jmp_code = "jge {addr0}; jmp {addr1}"
elif cont_mode in [0x46, 0x6A, 0x70, 0x77]:
pass
# CF != 0 -> Addr1
# CF == 0 && OF == 0 -> Addr0
# CF == 0 && OF != 0 -> Addr1
# jc addr1
# jo addr1
# jmp addr0
jmp_code = "jc {addr1}; jo {addr1}; jmp {addr0}"
elif cont_mode in [0x47, 0x49, 0x62, 0x73]:
pass
# ZF != 0 -> Addr1 else Addr0
# jnz addr0
# jmp addr1
jmp_code = "jnz {addr0}; jmp {addr1}"
elif cont_mode in [0x4C, 0x66, 0x69, 0x7F]:
pass
# CF != 0 -> Addr1
# CF == 0 && PF != 0 -> Addr0
# CF == 0 && PF == 0 -> Addr1
# jc addr1
# jnp addr1
# jmp addr0
jmp_code = "jc {addr1}; jnp {addr1}; jmp {addr0}"
elif cont_mode in [0x50, 0x57, 0x5C, 0x6E]:
pass
# CF != 0 -> Addr1 else Addr0
# jnc addr0
# jmp addr1
jmp_code = "jnc {addr0}; jmp {addr1}"
else:
pass
# jmp addr0
jmp_code = "jmp {addr0}"
print(hex(addr), hex(addr0), hex(addr1))
block_offset0 = addr0 - nearest_block(addr0)
block_offset1 = addr1 - nearest_block(addr1)
addr0_index = obfu_code_table[addr0 - block_offset0][0] - min_index
addr1_index = obfu_code_table[addr1 - block_offset1][0] - min_index
print(addr0_index, addr1_index)
jmp_code = jmp_code.format(addr0=block_offset0 + sum(map(len, code_chunks[:addr0_index])) + 16 * addr0_index - len(code_out), addr1=block_offset1 + sum(map(len, code_chunks[:addr1_index])) + 16 * addr1_index - len(code_out))
jmp_code_bin = assemble(jmp_code)
jmp_code_bin += b"\x90" * (16 - len(jmp_code_bin))
code_out += jmp_code_bin
for instr in md.disasm(code_out, 0):
print(instr)
with open(hex(ecstart) + ".bin", "wb") as f:
f.write(code_out)
return code_out
# obfu_code(0x12016af)