LyScript實現Hook隱藏偵錯程式的方法詳解

2022-09-18 22:00:58

LyScript 外掛整合的內建API函數可靈活的實現繞過各類反偵錯保護機制，前段時間釋出的那一篇文章並沒有詳細講解各類反偵錯機制的繞過措施，本次將補充這方面的知識點，運用LyScript實現繞過大多數通用偵錯機制，實現隱藏偵錯程式的目的。

我們以此實現Patches如下函數:

IsDebuggerPresent
ZwQueryInformationProcess
CheckRemoteDebuggerPresent
PEB.IsDebugged
PEB.ProcessHeap.Flag
PEB.NtGlobalFlag
PEB.Ldr 0xFEEEFEEE filling
GetTickCount
ZwQuerySystemInformation
FindWindowA
FindWindowW
FindWindowExA
FindWindowExW
EnumWindows

首先第一步我們需要自己封裝實現一個反組合轉機器碼的函數，其作用是當用戶傳入組合列表時，自動將其轉為機器碼並輸出為列表格式。

from LyScript32 import MyDebug

# 傳入組合程式碼,得到對應機器碼
def get_opcode_from_assemble(dbg_ptr,asm):
    byte_code = bytearray()

    addr = dbg_ptr.create_alloc(1024)
    if addr != 0:
        asm_size = dbg_ptr.assemble_code_size(asm)
        # print("組合程式碼佔用位元組: {}".format(asm_size))

        write = dbg_ptr.assemble_write_memory(addr,asm)
        if write == True:
            for index in range(0,asm_size):
                read = dbg_ptr.read_memory_byte(addr + index)
                # print("{:02x} ".format(read),end="")
                byte_code.append(read)
        dbg_ptr.delete_alloc(addr)
        return byte_code
    else:
        return bytearray(0)

# 傳入組合機器碼得到機器碼列表
def GetOpCode(dbg, Code):
    ShellCode = []

    for index in Code:
        ref = get_opcode_from_assemble(dbg,index)
        for opcode in ref:
            ShellCode.append(opcode)

    return ShellCode

if __name__ == "__main__":
    dbg = MyDebug()

    connect = dbg.connect()

    ShellCode = GetOpCode(dbg, ["DB 0x64","mov eax,dword ptr ds:[18]","sub eax,eax","ret"])

    print(ShellCode)

    dbg.close()

輸出效果如下：

Patch_PEB

PEB結構存在許多反偵錯變數，首先我們需要先將這些變數填充為空。

# ----------------------------------------------
# By: LyShark
# Email: me@lyshark.com
# Project: https://github.com/lyshark/LyScript
# ----------------------------------------------

from LyScript32 import MyDebug

# 傳入組合程式碼,得到對應機器碼
def get_opcode_from_assemble(dbg_ptr,asm):
    byte_code = bytearray()

    addr = dbg_ptr.create_alloc(1024)
    if addr != 0:
        asm_size = dbg_ptr.assemble_code_size(asm)
        # print("組合程式碼佔用位元組: {}".format(asm_size))

        write = dbg_ptr.assemble_write_memory(addr,asm)
        if write == True:
            for index in range(0,asm_size):
                read = dbg_ptr.read_memory_byte(addr + index)
                # print("{:02x} ".format(read),end="")
                byte_code.append(read)
        dbg_ptr.delete_alloc(addr)
        return byte_code
    else:
        return bytearray(0)

# 傳入組合機器碼得到機器碼列表
def GetOpCode(dbg, Code):
    ShellCode = []

    for index in Code:
        ref = get_opcode_from_assemble(dbg,index)
        for opcode in ref:
            ShellCode.append(opcode)

    return ShellCode

def Patch_PEB(dbg):
    PEB = dbg.get_peb_address(dbg.get_process_id())
    if PEB == 0:
        return 0

    # 寫出0 Patching PEB.IsDebugged
    dbg.write_memory_byte(PEB + 0x2,GetOpCode(dbg,["db 0"])[0])
    print("修補程式地址: {}".format(hex(PEB+0x2)))

    # 寫出0 Patching PEB.ProcessHeap.Flag
    temp = dbg.read_memory_dword(PEB + 0x18)
    temp += 0x10
    dbg.write_memory_dword(temp, GetOpCode(dbg,["db 0"])[0])
    print(("修補程式地址: {}".format(hex(temp))))

    # 寫出0 atching PEB.NtGlobalFlag
    dbg.write_memory_dword(PEB+0x68, 0)
    print(("修補程式地址: {}".format(hex(PEB+0x68))))

    # 迴圈替換 Patch PEB_LDR_DATA 0xFEEEFEEE fill bytes about 3000 of them
    addr = dbg.read_memory_dword(PEB + 0x0c)

    while addr != 0:
        addr += 1

        try:
            b = dbg.read_memory_dword(addr)
            c = dbg.read_memory_dword(addr + 4)

            # 僅修補填充執行
            print(b)
            if (b == 0xFEEEFEEE) and (c == 0xFEEEFEEE):
                dbg.write_memory_dword(addr,0)
                dbg.write_memory_dword(addr + 4, 0)
                print("patch")
        except Exception:
            break

if __name__ == "__main__":
    dbg = MyDebug()

    connect = dbg.connect()

    Patch_PEB(dbg)
    
    dbg.close()

Patch_IsDebuggerPresent

該函數用於檢測自身是否處於偵錯狀態，其C系列程式碼如下所示，繞過此種方式很簡單，只需要在函數頭部寫出ret指令即可。

#include <Windows.h>
#include <stdio.h>

int _tmain(int argc, _TCHAR* argv[])
{
	BOOL ref = IsDebuggerPresent();
	printf("是否被偵錯: %d n", ref);

	getchar();
	return 0;
}

注意：此Api檢查PEB中的值，因此如果修補PEB，則無需修補Api，這段繞過程式碼如下。

from LyScript32 import MyDebug

# 傳入組合程式碼,得到對應機器碼
def get_opcode_from_assemble(dbg_ptr,asm):
    byte_code = bytearray()

    addr = dbg_ptr.create_alloc(1024)
    if addr != 0:
        asm_size = dbg_ptr.assemble_code_size(asm)
        # print("組合程式碼佔用位元組: {}".format(asm_size))

        write = dbg_ptr.assemble_write_memory(addr,asm)
        if write == True:
            for index in range(0,asm_size):
                read = dbg_ptr.read_memory_byte(addr + index)
                # print("{:02x} ".format(read),end="")
                byte_code.append(read)
        dbg_ptr.delete_alloc(addr)
        return byte_code
    else:
        return bytearray(0)

# 傳入組合機器碼得到機器碼列表
def GetOpCode(dbg, Code):
    ShellCode = []

    for index in Code:
        ref = get_opcode_from_assemble(dbg,index)
        for opcode in ref:
            ShellCode.append(opcode)

    return ShellCode

def Patch_IsDebuggerPresent(dbg):
    # 得到模組控制程式碼
    ispresent = dbg.get_module_from_function("kernel32.dll","IsDebuggerPresent")
    print(hex(ispresent))

    if(ispresent <= 0):
        print("無法得到模組基地址,請以管理員方式執行偵錯程式.")
        return 0

    # 將反偵錯語句轉為機器碼
    ShellCode = GetOpCode(dbg, ["DB 0x64", "mov eax,dword ptr ds:[18]", "sub eax,eax", "ret"])
    print(ShellCode)

    flag = 0
    for index in range(0,len(ShellCode)):
        flag = dbg.write_memory_byte(ispresent + index,ShellCode[index])
        if flag:
            flag = 1
        else:
            flag = 0
    return flag

if __name__ == "__main__":
    dbg = MyDebug()

    connect = dbg.connect()

    ref = Patch_IsDebuggerPresent(dbg)
    print("修補程式狀態: {}".format(ref))

    dbg.close()

當程式執行後會向IsDebuggerPresent函數寫出返回，從而實現繞過偵錯的目的。

Patch_CheckRemoteDebuggerPresent

此Api呼叫ZwQueryInformationProcess因此通常不需要對兩者進行修補。

from LyScript32 import MyDebug

# 傳入組合程式碼,得到對應機器碼
def get_opcode_from_assemble(dbg_ptr,asm):
    byte_code = bytearray()

    addr = dbg_ptr.create_alloc(1024)
    if addr != 0:
        asm_size = dbg_ptr.assemble_code_size(asm)
        # print("組合程式碼佔用位元組: {}".format(asm_size))

        write = dbg_ptr.assemble_write_memory(addr,asm)
        if write == True:
            for index in range(0,asm_size):
                read = dbg_ptr.read_memory_byte(addr + index)
                # print("{:02x} ".format(read),end="")
                byte_code.append(read)
        dbg_ptr.delete_alloc(addr)
        return byte_code
    else:
        return bytearray(0)

# 傳入組合機器碼得到機器碼列表
def GetOpCode(dbg, Code):
    ShellCode = []

    for index in Code:
        ref = get_opcode_from_assemble(dbg,index)
        for opcode in ref:
            ShellCode.append(opcode)

    return ShellCode

def Patch_CheckRemoteDebuggerPresent(dbg):
    # 得到模組控制程式碼
    ispresent = dbg.get_module_from_function("kernel32.dll","CheckRemoteDebuggerPresent")
    print(hex(ispresent))

    # 將反偵錯語句轉為機器碼
    ShellCode = GetOpCode(dbg,
                          [
                              "mov edi,edi",
                              "push ebp",
                              "mov ebp,esp",
                              "mov eax,[ebp+0xc]",
                              "push 0",
                              "pop dword ptr ds:[eax]",
                              "xor eax,eax",
                              "pop ebp",
                              "ret 8"
                          ]
                          )

    print(ShellCode)

    flag = 0
    for index in range(0,len(ShellCode)):
        flag = dbg.write_memory_byte(ispresent + index,ShellCode[index])
        if flag:
            flag = 1
        else:
            flag = 0
    return flag

if __name__ == "__main__":
    dbg = MyDebug()

    connect = dbg.connect()

    ref = Patch_CheckRemoteDebuggerPresent(dbg)
    print("寫出狀態: {}".format(ref))

    dbg.close()

寫出效果如下：

Patch_GetTickCount

GetTickCount返回（retrieve）從作業系統啟動所經過（elapsed）的毫秒數，常用於定時計數，繞過方式只需初始化即可。

from LyScript32 import MyDebug

# 傳入組合程式碼,得到對應機器碼
def get_opcode_from_assemble(dbg_ptr,asm):
    byte_code = bytearray()

    addr = dbg_ptr.create_alloc(1024)
    if addr != 0:
        asm_size = dbg_ptr.assemble_code_size(asm)
        # print("組合程式碼佔用位元組: {}".format(asm_size))

        write = dbg_ptr.assemble_write_memory(addr,asm)
        if write == True:
            for index in range(0,asm_size):
                read = dbg_ptr.read_memory_byte(addr + index)
                # print("{:02x} ".format(read),end="")
                byte_code.append(read)
        dbg_ptr.delete_alloc(addr)
        return byte_code
    else:
        return bytearray(0)

# 傳入組合機器碼得到機器碼列表
def GetOpCode(dbg, Code):
    ShellCode = []

    for index in Code:
        ref = get_opcode_from_assemble(dbg,index)
        for opcode in ref:
            ShellCode.append(opcode)

    return ShellCode

def Patch_GetTickCount(dbg):
    # 得到模組控制程式碼
    ispresent = dbg.get_module_from_function("kernel32.dll","GetTickCount")
    print(hex(ispresent))

    # 將反偵錯語句轉為機器碼
    ShellCode = GetOpCode(dbg,
                          [
                              "mov edx,0x7ffe0000",
                              "sub eax,eax",
                              "add eax,0xB0B1560D",
                              "ret"
                          ]
                          )

    print(ShellCode)

    flag = 0
    for index in range(0,len(ShellCode)):
        flag = dbg.write_memory_byte(ispresent + index,ShellCode[index])
        if flag:
            flag = 1
        else:
            flag = 0
    return flag

if __name__ == "__main__":
    dbg = MyDebug()

    connect = dbg.connect()

    ref = Patch_GetTickCount(dbg)
    print("寫出狀態: {}".format(ref))

    dbg.close()

寫出效果如下：

Patch_ZwQueryInformationProcess

此函數打修補程式需要跳轉兩次，原因是因為函數開頭部分無法填充更多指令，需要我們自己來申請空間，並實現跳轉。

# ----------------------------------------------
# By: LyShark
# Email: me@lyshark.com
# Project: https://github.com/lyshark/LyScript
# ----------------------------------------------

from LyScript32 import MyDebug

# 傳入組合程式碼,得到對應機器碼
def get_opcode_from_assemble(dbg_ptr,asm):
    byte_code = bytearray()

    addr = dbg_ptr.create_alloc(1024)
    if addr != 0:
        asm_size = dbg_ptr.assemble_code_size(asm)
        # print("組合程式碼佔用位元組: {}".format(asm_size))

        write = dbg_ptr.assemble_write_memory(addr,asm)
        if write == True:
            for index in range(0,asm_size):
                read = dbg_ptr.read_memory_byte(addr + index)
                # print("{:02x} ".format(read),end="")
                byte_code.append(read)
        dbg_ptr.delete_alloc(addr)
        return byte_code
    else:
        return bytearray(0)

# 傳入組合機器碼得到機器碼列表
def GetOpCode(dbg, Code):
    ShellCode = []

    for index in Code:
        ref = get_opcode_from_assemble(dbg,index)
        for opcode in ref:
            ShellCode.append(opcode)

    return ShellCode

# 獲取指定位置前index條指令的長度
def GetOpCodeSize(dbg,address,index):
    ref_size = 0

    dasm = dbg.get_disasm_code(address,index)
    for index in dasm:
        count = dbg.assemble_code_size(index.get("opcode"))
        ref_size += count
    return ref_size

def Patch_ZwQueryInformationProcess(dbg):
    # 得到模組控制程式碼
    ispresent = dbg.get_module_from_function("ntdll.dll","ZwQueryInformationProcess")
    print(hex(ispresent))

    create_address = dbg.create_alloc(1024)
    print("分配空間: {}".format(hex(create_address)))


    # 將反偵錯語句轉為機器碼
    ShellCode = GetOpCode(dbg,
                          [
                              "cmp dword [esp + 8],7",
                              "DB 0x74",
                              "DB 0x06",
                              f"push {hex(ispresent)}",
                              "ret",
                              "mov eax,dword [esp +0x0c]",
                              "push 0",
                              "pop dword [eax]",
                              "xor eax,eax",
                              "ret 14"
                          ]
                          )

    print(ShellCode)

    # 把shellcode寫出到自己分配的堆中
    flag = 0
    for index in range(0,len(ShellCode)):
        flag = dbg.write_memory_byte(create_address + index,ShellCode[index])
        if flag:
            flag = 1
        else:
            flag = 0

    # 填充跳轉位置
    jmp_shellcode = GetOpCode(dbg,
                              [
                                  f"push {hex(create_address)}",
                                  "ret"
                              ]
                              )
    for index in range(0,len(jmp_shellcode)):
        flag = dbg.write_memory_byte(ispresent + index,jmp_shellcode[index])
        if flag:
            flag = 1
        else:
            flag = 0

    return flag

if __name__ == "__main__":
    dbg = MyDebug()

    connect = dbg.connect()

    ref = Patch_ZwQueryInformationProcess(dbg)

    print("修補程式狀態: {}".format(ref))

    dbg.close()

這段程式碼執行後，首先會申請記憶體，然後將特定的一段機器碼寫出到此記憶體中。

記憶體寫出以後，再將函數頭部替換為跳轉，這樣一來當函數被呼叫，也就自動轉向了。

Patch_FindWindow

FindWindow函數功能是取表單控制程式碼，有AW與Ex系列，使用同上方法替代即可。

# ----------------------------------------------
# By: LyShark
# Email: me@lyshark.com
# Project: https://github.com/lyshark/LyScript
# ----------------------------------------------

from LyScript32 import MyDebug
import ctypes

# 傳入組合程式碼,得到對應機器碼
def get_opcode_from_assemble(dbg_ptr,asm):
    byte_code = bytearray()

    addr = dbg_ptr.create_alloc(1024)
    if addr != 0:
        asm_size = dbg_ptr.assemble_code_size(asm)
        # print("組合程式碼佔用位元組: {}".format(asm_size))

        write = dbg_ptr.assemble_write_memory(addr,asm)
        if write == True:
            for index in range(0,asm_size):
                read = dbg_ptr.read_memory_byte(addr + index)
                # print("{:02x} ".format(read),end="")
                byte_code.append(read)
        dbg_ptr.delete_alloc(addr)
        return byte_code
    else:
        return bytearray(0)

# 傳入組合機器碼得到機器碼列表
def GetOpCode(dbg, Code):
    ShellCode = []

    for index in Code:
        ref = get_opcode_from_assemble(dbg,index)
        for opcode in ref:
            ShellCode.append(opcode)

    return ShellCode

def Patch_FindWindow(dbg):
    # 得到模組控制程式碼
    FindWindowA = dbg.get_module_from_function("user32.dll","FindWindowA")
    FindWindowW = dbg.get_module_from_function("user32.dll","FindWindowW")
    FindWindowExA = dbg.get_module_from_function("user32.dll","FindWindowExA")
    FindWindowExW = dbg.get_module_from_function("user32.dll","FindWindowExW")
    print("A = {} w = {} exA = {} exW = {}".format(hex(FindWindowA),hex(FindWindowW),hex(FindWindowExA),hex(FindWindowExW)))

    # 將反偵錯語句轉為機器碼
    ShellCode = GetOpCode(dbg,
                          [
                              "xor eax,eax",
                              "ret 0x8",
                          ]
                          )

    ShellCodeEx = GetOpCode(dbg,
                            [
                                "xor eax,eax",
                                "ret 0x10",
                            ]
                            )
    # 寫出
    flag = 0
    for index in range(0,len(ShellCode)):
        flag = dbg.write_memory_byte(FindWindowA + index,ShellCode[index])
        flag = dbg.write_memory_byte(FindWindowW + index,ShellCode[index])
        if flag:
            flag = 1
        else:
            flag = 0

    for index in range(0,len(ShellCodeEx)):
        flag = dbg.write_memory_byte(FindWindowExA + index,ShellCodeEx[index])
        flag = dbg.write_memory_byte(FindWindowExW + index,ShellCodeEx[index])
        if flag:
            flag = 1
        else:
            flag = 0

    return flag

if __name__ == "__main__":
    dbg = MyDebug()

    connect = dbg.connect()

    ref = Patch_FindWindow(dbg)
    print("修補程式狀態: {}".format(ref))

    dbg.close()

修補程式應用會分別替換四個函數。

Patch_EnumWindows

列舉表單的修補程式與上方程式碼一致，此處就不再分析了。

如下案例，實現了在列舉表單過程中實現彈窗，並不影響表單的列舉。

from LyScript32 import MyDebug

# 傳入組合程式碼,得到對應機器碼
def get_opcode_from_assemble(dbg_ptr,asm):
    byte_code = bytearray()

    addr = dbg_ptr.create_alloc(1024)
    if addr != 0:
        asm_size = dbg_ptr.assemble_code_size(asm)
        # print("組合程式碼佔用位元組: {}".format(asm_size))

        write = dbg_ptr.assemble_write_memory(addr,asm)
        if write == True:
            for index in range(0,asm_size):
                read = dbg_ptr.read_memory_byte(addr + index)
                # print("{:02x} ".format(read),end="")
                byte_code.append(read)
        dbg_ptr.delete_alloc(addr)
        return byte_code
    else:
        return bytearray(0)

# 傳入組合機器碼得到機器碼列表
def GetOpCode(dbg, Code):
    ShellCode = []

    for index in Code:
        ref = get_opcode_from_assemble(dbg,index)
        for opcode in ref:
            ShellCode.append(opcode)

    return ShellCode

# 獲取指定位置前index條指令的長度
def GetOpCodeSize(dbg,address,index):
    ref_size = 0

    dasm = dbg.get_disasm_code(address,index)
    for index in dasm:
        count = dbg.assemble_code_size(index.get("opcode"))
        ref_size += count
    return ref_size

def Patch_EnumWindows(dbg):
    # 得到模組控制程式碼
    address = dbg.get_module_from_function("user32.dll","EnumWindows")
    print(hex(address))

    msg_box = dbg.get_module_from_function("user32.dll","MessageBoxA")
    print(hex(msg_box))

    create_address = dbg.create_alloc(1024)
    print("分配空間: {}".format(hex(create_address)))

    # 找call地址，找到後取出他的記憶體地址
    dasm_list = dbg.get_disasm_code(address,20)
    call_addr = 0
    call_next_addr = 0
    for index in range(0,len(dasm_list)):

        # 如果找到了call，取出call地址以及下一條地址
        if dasm_list[index].get("opcode").split(" ")[0] == "call":
            call_addr = dasm_list[index].get("addr")
            call_next_addr = dasm_list[index+1].get("addr")
            print("call = {} call_next = {}".format(hex(call_addr),hex(call_next_addr)))

    # 將反偵錯語句轉為機器碼
    ShellCode = GetOpCode(dbg,
                          [
                              "push 0",
                              "push 0",
                              "push 0",
                              "push 0",
                              f"call {hex(msg_box)}",
                              "mov eax,1",
                              "pop ebp",
                              "ret 10",

                              f"call {hex(call_addr)}",
                              "pop ebp",
                              "ret 8"
                          ]
                          )

    print(ShellCode)

    # 把shellcode寫出到自己分配的堆中
    flag = 0
    for index in range(0,len(ShellCode)):
        flag = dbg.write_memory_byte(create_address + index,ShellCode[index])
        if flag:
            flag = 1
        else:
            flag = 0


    # 填充跳轉位置
    jmp_shellcode = GetOpCode(dbg,
                              [
                                  f"push {hex(create_address)}",
                                  "ret"
                              ]
                              )
    for index in range(0,len(jmp_shellcode)):
        flag = dbg.write_memory_byte(call_addr + index,jmp_shellcode[index])
        if flag:
            flag = 1
        else:
            flag = 0

    return flag

if __name__ == "__main__":
    dbg = MyDebug()
    connect = dbg.connect()

    ref = Patch_EnumWindows(dbg)

    dbg.close()