我一周前开始在 Windows10 上使用 NASM “学习”程序集，如果这个问题完全是“ wtf ，请原谅我“为了你。
我正在尝试使用kernel32.dll中的WinExec来运行程序，例如cmd.exe，calc.exe等...
Here我发现这段代码就像魅力一样，但只有当 lpCmdLine 等于4个字节时，我认为问题是与堆栈对齐有关的问题，但我不明白如何解决问题。 我已经搜索了3天的解决方案，阅读了我能找到的关于装配的所有内容，但我的大脑完全卡住了。
在这个示例代码中，我尝试启动cmd.exe（7个字节，8个带有最后的0x20 char ['']以避免空字节），但是没有用。
您可以在 62
行找到“问题” [BITS 64]
SECTION .text
%define B2W(b1,b2) (((b2) << 8) + (b1))
%define W2DW(w1,w2) (((w2) << 16) + (w1))
%define DW2QW(dw1,dw2) (((dw2) << 32) + (dw1))
%define B2DW(b1,b2,b3,b4) ((B2W(b3, b4) << 16) + B2W(b1, b2))
%define B2QW(b1,b2,b3,b4,b5,b6,b7,b8) ((B2DW(b5,b6,b7,b8) << 32) + B2DW(b1,b2,b3,b4))
%define W2QW(w1,w2,w3,w4) ((W2DW(w3,w4) << 32) + W2DW(w1,w2))
; x64 WinExec *requires* 16 byte stack alignment and four QWORDS of stack space, which may be overwritten.
; http://msdn.microsoft.com/en-us/library/ms235286.aspx
%ifndef PLATFORM_INDEPENDENT
global shellcode
shellcode:
%ifdef FUNC ; assumes stack ends with 8 on entry, use STACK_ALIGN if it might not be.
%ifdef CLEAN ; 64-bit calling convention considers RAX, RCX, RDX, R8, R9, R10 and R11
PUSH RAX ; volatile. Use CLEAN if you want to preserve those as well.
PUSH RCX
PUSH RDX
%endif
PUSH RBX
PUSH RSI
PUSH RDI
PUSH RBP ; Stack now ends with 8 (!CLEAN) or is 16 byte (CLEAN) aligned
%endif
%ifdef STACK_ALIGN
%ifdef FUNC
PUSH RSP
POP RAX
%endif
AND SP, -16 ; Align stack to 16 bytes
; (we can't force it to end with 8 without dummy push and then or)
PUSH RAX ; Force stack to end with 8 before next push, also saves RSP to restore stack
%elifdef CLEAN
PUSH RAX ; dummy push to make stack end with 8 before next push
%endif
; Note to SkyLined: instructions on 32-bit registers are automatically sign-extended to 64-bits.
; This means LODSD will set the high DWORD of RAX to 0 if top bit of EAX was 0, or 0xFFFFFFFF if it was 0x80000000.
PUSH BYTE 0x60 ; Stack
POP RDX ; RDX = 0x60
%else
%ifdef FUNC
%ifdef CLEAN
PUSH RAX ; exchanged RDX
PUSH RCX
%endif
PUSH RBX
PUSH RSI
PUSH RDI
PUSH RBP ; Stack now ends with 8 (!CLEAN) or is 16 byte (CLEAN) aligned
%endif
%ifdef CLEAN
%ifndef STACK_ALIGN
PUSH RAX ; dummy push to make stack end with 8 before next push
%endif
%endif
MOV DL, 0x60
%endif
%ifndef USE_COMMON
; > Here I don't understand why doesen't works <
PUSH 0x20657865 ; (space)exe
PUSH 0x2E646D63 ; .dmc
; I have already tried to use the macro B2DW, the same, crash at startup.
PUSH RSP
POP RCX ; RCX = &("calc")
%endif
SUB RSP, RDX ; Stack was 16 byte aligned already and there are >4 QWORDS on the stack.
MOV RSI, [GS:RDX] ; RSI = [TEB + 0x60] = &PEB
MOV RSI, [RSI + 0x18] ; RSI = [PEB + 0x18] = PEB_LDR_DATA
MOV RSI, [RSI + 0x10] ; RSI = [PEB_LDR_DATA + 0x10] = LDR_MODULE InLoadOrder[0] (process)
LODSQ ; RAX = InLoadOrder[1] (ntdll)
MOV RSI, [RAX] ; RSI = InLoadOrder[2] (kernel32)
MOV RDI, [RSI + 0x30] ; RDI = [InLoadOrder[2] + 0x30] = kernel32 DllBase
; Found kernel32 base address (RDI)
shellcode_common:
ADD EDX, DWORD [RDI + 0x3C] ; RBX = 0x60 + [kernel32 + 0x3C] = offset(PE header) + 0x60
; PE header (RDI+RDX-0x60) = @0x00 0x04 byte signature
; @0x04 0x18 byte COFF header
; @0x18 PE32 optional header (= RDI + RDX - 0x60 + 0x18)
MOV EBX, DWORD [RDI + RDX - 0x60 + 0x18 + 0x70] ; RBX = [PE32+ optional header + offset(PE32+ export table offset)] = offset(export table)
; Export table (RDI+EBX) = @0x20 Name Pointer RVA
MOV ESI, DWORD [RDI + RBX + 0x20] ; RSI = [kernel32 + offset(export table) + 0x20] = offset(names table)
ADD RSI, RDI ; RSI = kernel32 + offset(names table) = &(names table)
; Found export names table (RSI)
MOV EDX, DWORD [RDI + RBX + 0x24] ; EDX = [kernel32 + offset(export table) + 0x24] = offset(ordinals table)
; Found export ordinals table (RDX)
find_winexec_x64:
; speculatively load ordinal (RBP)
MOVZX EBP, WORD [RDI + RDX] ; RBP = [kernel32 + offset(ordinals table) + offset] = function ordinal
LEA EDX, [RDX + 2] ; RDX = offset += 2 (will wrap if > 4Gb, but this should never happen)
LODSD ; RAX = &(names table[function number]) = offset(function name)
CMP DWORD [RDI + RAX], B2DW('W', 'i', 'n', 'E') ; *(DWORD*)(function name) == "WinE" ?
JNE find_winexec_x64 ;
MOV ESI, DWORD [RDI + RBX + 0x1C] ; RSI = [kernel32 + offset(export table) + 0x1C] = offset(address table)
ADD RSI, RDI ; RSI = kernel32 + offset(address table) = &(address table)
MOV ESI, [RSI + RBP * 4] ; RSI = &(address table)[WinExec ordinal] = offset(WinExec)
ADD RDI, RSI ; RDI = kernel32 + offset(WinExec) = WinExec
; Found WinExec (RDI)
CDQ ; RDX = 0 (assuming EAX < 0x80000000, which should always be true)
CALL RDI ; WinExec(&("calc"), 0);
%ifdef FUNC
%ifdef CLEAN
%ifdef STACK_ALIGN
ADD RSP, 0x68 ; reset stack to where it was after pushing registers
%else
ADD RSP, 0x70 ; reset stack to where it was after pushing registers
%endif
%else
ADD RSP, 0x68 ; reset stack to where it was after pushing registers
%endif
%ifndef PLATFORM_INDEPENDENT
%ifdef STACK_ALIGN
POP RSP
%endif
%endif
POP RBP ; POP registers
POP RDI
POP RSI
POP RBX
%ifndef PLATFORM_INDEPENDENT
%ifdef CLEAN
POP RDX ; POP additional registers
POP RCX
POP RAX
%endif
RET ; Return
%else
%ifdef CLEAN
POP RCX ; POP additional registers
POP RDX
%endif
%ifdef STACK_ALIGN
POP RSP
%endif
%ifdef CLEAN
POP RAX
%endif
RET ; Return
%endif
%endif
为了测试一切是否正常，我得到 null 字节shellcode并从C ++启动
void *exec = VirtualAlloc(0, sizeof(shellcode), MEM_COMMIT, PAGE_EXECUTE_READWRITE);
memcpy(exec, shellcode, sizeof(shellcode));
((void(*)())exec)();
如果我使用推送0x636C6163 （计算），一切正常。
再次，如果这是一个总noob 问题，我很抱歉，但我无法弄清楚如何解决它。
感谢您的时间！