mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-29 06:25:27 +00:00
307 lines
10 KiB
NASM
307 lines
10 KiB
NASM
|
||
; NOTE : This template is for .COM files only do not use for .EXE files!!
|
||
|
||
|
||
;
|
||
;
|
||
;
|
||
; Copyright 1986 by Dana Nowell - All rights reserved
|
||
;
|
||
; HISTORY:
|
||
; Version Date Name Description
|
||
; 1.0 11/10/86 dn first cut
|
||
; 1.01 11/21/86 dn Fixed memory allocation bug
|
||
; Added installation message
|
||
;
|
||
|
||
|
||
title TSR Template
|
||
|
||
|
||
|
||
NULL equ 00h
|
||
BELL equ 07h ; bell character
|
||
BACKSPACE equ 08h ; backspace character
|
||
TAB equ 09h ; tab character
|
||
LF equ 0ah ; line feed
|
||
F_FEED equ 0ch ; form feed
|
||
CR equ 0dh ; carriage return
|
||
EOF equ 1ah ; ctrl z ( end of file )
|
||
SPACE equ ' ' ; ascii space character
|
||
QUOTE equ '"'
|
||
|
||
SIGNATURE1 equ 6144h ; used for already
|
||
SIGNATURE2 equ 616eh ; resident check
|
||
|
||
DOS_INT equ 21h ; DOS function interrupt
|
||
DISP_CHAR equ 02h
|
||
GET_KEY equ 08h
|
||
DOS_SCR_MSG equ 09h
|
||
DOS_SET_INT equ 25h
|
||
DOS_RESIDENT equ 31h
|
||
DOS_GET_INT equ 35h
|
||
DOS_TERMINATE equ 4ch
|
||
DOS_STRING_TERM equ '$'
|
||
|
||
; Interrupt vectors used
|
||
|
||
HOOK_INT equ 1ch ; interrupt to be hooked ( timer tick now )
|
||
|
||
;------------------------------------------------------------------------------
|
||
;
|
||
; MACRO SECTION
|
||
;
|
||
;------------------------------------------------------------------------------
|
||
|
||
Version_msg macro
|
||
jmp short copyright_end
|
||
|
||
copyright_msg db CR, LF
|
||
db 'TSR Shell - Version 1.01', CR, LF
|
||
db 'Copyright 1986, Dana Nowell ', CR, LF, CR, LF
|
||
db 'May be distributed without license', CR, LF, '$'
|
||
copyright_end:
|
||
Msg copyright_msg
|
||
endm
|
||
|
||
|
||
Msg macro ptr
|
||
|
||
push dx
|
||
push ax
|
||
|
||
lea dx, ptr
|
||
mov ah, 09h
|
||
int 21h
|
||
|
||
pop ax
|
||
pop dx
|
||
|
||
endm
|
||
|
||
|
||
|
||
|
||
|
||
com segment para public 'code'
|
||
assume cs:com, ds:com, es:com
|
||
|
||
;------------------------------------------------------------------------------
|
||
;
|
||
; note: The PSP occurs at the beginning of the code segment
|
||
; for all programs. In COM files the code seg = data seg
|
||
;
|
||
;------------------------------------------------------------------------------
|
||
|
||
org 0
|
||
|
||
psp_start dw ? ; int 20h - possibly a block for unresolved
|
||
; externals during link ?
|
||
|
||
mem_size dw ? ; size of available memory in paragraphs
|
||
filler db ? ; reserved usually zero
|
||
|
||
dos_call db ? ; call
|
||
dd ? ; address of dos function handler
|
||
|
||
term_vector dd ? ; address of dos terminate routine
|
||
break_vector dd ? ; address of dos break routine
|
||
error_vector dd ? ; address of dos error routine
|
||
dos_reserved db 2 dup(?); reserved by dos
|
||
dos_handles db 20 dup(?) ; file handle array
|
||
environ_ptr dw ? ; seg of dos environment ( offset = 0 )
|
||
dos_work db 34 dup(?) ; dos work area
|
||
|
||
int_21h db ? ; int
|
||
db ? ; 21h
|
||
db ? ; retf ( return far )
|
||
|
||
reserved dw ? ; reserved by dos
|
||
fcb1_ext db 7 dup(?) ; fcb # 1 extension
|
||
fcb1 db 9 dup(?) ; fcb #1
|
||
fcb2_ext db 7 dup(?) ; fcb # 2 extension
|
||
fcb2 db 20 dup(?) ; fcb #2
|
||
|
||
;
|
||
; disk transfer area ( dta ) and parameter block occupy the same space
|
||
;
|
||
;
|
||
;dta db 128 dup(?) ; disk transfer area
|
||
|
||
|
||
|
||
param_len db ? ; length of parameter string ( excludes CR )
|
||
parameters db 127 dup(?) ; parameters
|
||
|
||
;------------------------------------------------------------------------------
|
||
;
|
||
; Note on standard fcb structure :
|
||
;
|
||
; The standard FCB is larger than the size reserved in the PSP if you
|
||
; intend to use to FCB data from the PSP move it to a different location.
|
||
;
|
||
;
|
||
; STANDARD STRUCTURE OF A FILE CONTROL BLOCK
|
||
;
|
||
;
|
||
; extension :
|
||
; offset length description
|
||
; -7 1 extension active flag ( 0ffh = active )
|
||
; -6 5 normally unused should be zeros
|
||
; -1 1 file attribute when extension is active
|
||
; 1 . . . . . . . 1 read-only
|
||
; 2 . . . . . . 1 . hidden
|
||
; 4 . . . . . 1 . . system
|
||
; 8 . . . . 1 . . . volume label
|
||
; 16 . . . 1 . . . . subdirectory
|
||
; 32 . . 1 . . . . . archive
|
||
; 64 . 1 . . . . . . unused
|
||
; 128 1 . . . . . . . unused
|
||
;
|
||
; fcb :
|
||
; offset length description
|
||
; 0 1 special drive number ( 1 byte )
|
||
; 0 = default
|
||
; 1 = a:
|
||
; 2 = b: etc
|
||
; 1 8 filename or device name
|
||
; 9 3 filename extension
|
||
; 12 2 current block number
|
||
; 14 2 record size
|
||
; 16 4 file size in bytes ( dos dir entry at open )
|
||
; 20 2 file date ( bit coded as in dir )
|
||
; 22 10 dos work area
|
||
; 32 1 current record number ( 0 - 127 )
|
||
; 33 4 random record number
|
||
;
|
||
;------------------------------------------------------------------------------
|
||
|
||
|
||
|
||
org 100h ; required for COM file ( skips PSP )
|
||
|
||
|
||
start:
|
||
jmp install ; install the demon
|
||
|
||
;-------------------------------------------------------------------
|
||
;
|
||
; resident data structures go here
|
||
;
|
||
;-------------------------------------------------------------------
|
||
|
||
old_int dd 0 ; original value of hooked interrupt
|
||
resident1 dw SIGNATURE1
|
||
resident2 dw SIGNATURE2
|
||
|
||
|
||
;-------------------------------------------------------------------
|
||
;
|
||
; new interrupt starts here
|
||
;
|
||
;-------------------------------------------------------------------
|
||
|
||
new_int:
|
||
pushf
|
||
|
||
sti ; must turn INT on if we're going to use them
|
||
|
||
;-------------------------------------------------------------------
|
||
;
|
||
; be well behaved and pass control to original int
|
||
;
|
||
;-------------------------------------------------------------------
|
||
|
||
popf
|
||
pushf
|
||
call dword ptr cs:old_int ; do old interrupt
|
||
|
||
iret ; bye bye
|
||
|
||
;------------------------------------------------------------------------------
|
||
;
|
||
; INSTALLATION DATA STRUCTURES AND CODE GO HERE
|
||
;
|
||
; WARNING WARNING WARNING - this area does not exist after installation
|
||
;
|
||
;------------------------------------------------------------------------------
|
||
|
||
last_resident_byte db 0 ; last resident byte
|
||
resident_flag dw 0 ; am I already resident ? ( 0 = NO )
|
||
|
||
install_msg db CR, LF, 'Installation Complete', CR, LF, '$'
|
||
|
||
already_installed_msg db CR, LF
|
||
db 'Already Installed - Installation Aborted'
|
||
db CR, LF, '$'
|
||
|
||
install proc near
|
||
|
||
Version_msg
|
||
|
||
|
||
mov al, HOOK_INT ; int to hook
|
||
mov ah, DOS_GET_INT ; get int(AL) vector ==> ES+BX
|
||
int DOS_INT ; do the int
|
||
lea si, old_int ; where to put old timer interrupt vector
|
||
mov [si], bx ; save the offset and segment
|
||
mov 2[si], es ; ( es also used in check resident )
|
||
|
||
call check_resident ; am I already resident ?
|
||
|
||
cmp resident_flag, 0
|
||
je not_resident
|
||
|
||
Msg already_installed_msg
|
||
|
||
mov ah, DOS_TERMINATE ; terminate & stay resident
|
||
mov al, 1 ; return value is 1 (already installed)
|
||
int DOS_INT ; bye-bye
|
||
|
||
not_resident:
|
||
mov dx, offset new_int ; offset of new timer interrupt
|
||
mov al, HOOK_INT ; timer tick
|
||
mov ah, DOS_SET_INT ; set int(AL) vector from DS+DX
|
||
int DOS_INT ; do the int
|
||
|
||
; program terminate and stay resident
|
||
|
||
Msg install_msg ; Display the installation message
|
||
|
||
mov dx, offset last_resident_byte
|
||
|
||
mov cl, 4 ; convert to paragraphs required to
|
||
shr dx, cl ; remain resident ( divide by 16 )
|
||
inc dx ; allow for any remainder of division
|
||
|
||
mov ah, DOS_RESIDENT ; terminate & stay resident
|
||
mov al, 0 ; return value is 0 (good return)
|
||
int DOS_INT ; bye-bye
|
||
|
||
install endp
|
||
|
||
|
||
;
|
||
; Check resident procedure
|
||
; requires es register to contain the segment address of
|
||
; the current location for the interrupt being hooked.
|
||
; use the DOS function 35h to obtain this information.
|
||
;
|
||
|
||
check_resident proc near
|
||
|
||
cmp es:resident1, SIGNATURE1
|
||
jne not_res
|
||
cmp es:resident2, SIGNATURE2
|
||
jne not_res
|
||
|
||
mov resident_flag, 1
|
||
|
||
not_res:
|
||
ret
|
||
|
||
check_resident endp
|
||
|
||
com ends
|
||
end start
|
||
|