tsr技术给dos装上黑匣子

文章作者 100test 发表时间 2008:01:11 13:11:21
来源 100Test.Com百考试题网

seg_a segment byte public
assume cs:seg_a, ds:seg_a
org 100h
start:
jmp loc_9
c_1 db ’ SYZ ’
old_int21h_off dw 8888h
old_int21h_seg dw 8888h
count_1 dw 0h
FE_1 DB 20H
f_buff db 16 dup (0)
int_21h_entry:

pushf
cli
push ax
push bx
push cx
push dx
push si
push di
push ds
push es
push bp
cld
CMP Ax,4b00H
JZ HAND_1
JMP EXIT_21H_1
hand_1: push cs
pop es
mov si,dx
cld
con_1_1:lodsb
cmp al,2eh
jz f2e_1
cmp al,0
jz exit_21h_1
jmp con_1_1

f2e_1: dec si
sub si,dx
cmp si,16
ja a_16
mov cx,si
mov si,dx
push cx
mov di,offset f_buff
mov cx,16
mov al,20h
rep stosb
mov di,offset f_buff
pop cx
rep movsb
jmp rw_disk1
a_16: add si,dx
sub si,16
mov cx,16
mov di,offset f_buff
rep movsb
rw_disk1:
mov ax,201h
mov bx,offset disk_buff
mov cx,8h
mov dx,80h
int 13h
jb exit_21h_1
push cs