Insider - FAQ, Edition #7 UnComplete

½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½ »»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»» ▄▄▄▄▄ ▄▄▄ ▄▄▄ ▄▄▄▄▄▄▄ ▄▄▄▄▄ ▄▄▄▄▄▄ ▄▄▄▄▄▄▄ ▄▄▄▄▄▄▄ ▄▄▄▄▄▄▄ ▄▄▄▄▄▄▄ ▄▄▄▄▄▄▄ █▄ ▄█ █ ▀██ █ █ ▄▄▄▄█ █▄ ▄█ █ ▄▄▄▀█ █ ▄▄▄▄█ █ ▄▄▄ █ █ ▄▄▄▄█ █ ▄▄▄ █ █ ▄▄▄ █ ▄█ █▄ █ █▄▀ █ █▄▄▄▄ █ ▄█ █▄ █ ███ █ █ ▄▄▄█▄ █ ▄▄ ▄█ █ ▄▄█ █ ▄▄▄ █ █ ██▀ █ █▄▄▄█ █▄█▀█▄█ █▄▄▄▄▄█ █▄▄▄█ █▄▄▄▄█▀ █▄▄▄▄▄█ █▄██▄▄█ █▄█ █▄█ █▄█ █▄▄▄▄▄▀ INSIDER - FAQ Edition #7 UnComplete by Christoph Gabler Release Date : 06.02.99 ½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½ »»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»» ────── ────── ─── ─── ───────────────┐ │ Introduction │ └─────────────── The INSIDER - FAQ is meant for people who want to make their programs more secure against unpacking/viewing or modifying. You can input the code shown below into any of your ASM source codes or into other languages which got a ASM support like C++ or Pascal. Furthermore is the INSIDER - FAQ meant for those who are interested in AntiDebugging or AntiTraceCode tricks against realmode or protectedmode debuggers/unpackers. Last but not least might the INSIDER - FAQ also be helpful for protector writers or crackers which want to learn how AntiDebugging tricks look like or how to bypass them with debuggers. Please remember that the best tricks can be found in the uncovered version of the INSIDER - FAQ. To get such version contact me by writing an EMail with comments about TRAP and things I could add into the next version or AntiDebugging code which can't be found in the current INSIDER - FAQ. ──────────────────────────┐ │ Realmode Anti Debugging │ └────────────────────────── The following chapter describes ways how to crash/detect realmode debuggers or unpackers like TD or IUP. If we want to crash/detect a debugger we first have to know how they work. Most realmode tracers use INT1/3 to trace. If you point INT1 or INT3 to a corrupt area some stupid debuggers like TD get kicked. A better way is to insert code into INT1 and then afterwards restore it again. But CUP386 /1 and TR (with INT1) use there own interrupt table for these ints, so what to do against them? As ANY realmode debugger does not use its own stack, you can corrupt it and restore it after doing some instructions. Due to the fact that we need the keyboard to trace but not to execute code we can also pull the keyboard off to make realmode tracers mad. The keyboard has two important hardware ports : 60h and 64h. Nuking those two ports will kick most of the debuggers out. Interrupt 9 is also used by the keyboard, so play arround with that too. Realmode debugger use/need the following things : - INT1,INT3 and INT10 - Keyboard (INT9, Port 60h and 64h) - Stack (SS and SP) - Trap Flag to be on ╓══════════════════════════════╖ ║ Points INT1 to invalid area ║ ║ by Piotr Warezak (C) ║ ╚══════════════════════════════╝ »» INT1 can be either reset with INT21/AX=2501h or directly with MOV. INT1 is located at position 0000:0004. Old method to stop some realmode debuggers. »» push ds ;save DS register xor ax,ax ;zero DS register mov ds,ax not word ptr ds:[0004] ;cut off INT1 vector for a moment jmp short j1 db 09ah j1: not word ptr ds:[0004] ;restore INT1 vector pop ds ;restore DS register ╓═════════════════════════╖ ║ Nice stack-trick 1 ║ ║ by Christoph Gabler ║ ╚═════════════════════════╝ »» Here is a possibility how to detect any realmode debuggers/unpacker. It is not very tight but to make it work everywhere I used some lines for compatibilty - they are actually not very important. It detects : CUP386 /1, TD, TD286, DEBUG and more... »» CLI MOV DX,SP ; Save SP to DX. MOV CL,CS:BYTE PTR [00] ; Save the original 00. For 100% compatibilty. =8] MOV BL,CS:BYTE PTR [01] ; Same as above with 01. MOV CS:BYTE PTR [00],0CDh ; Write the normal values - just to make sure. MOV CS:BYTE PTR [01],020h ; Same as above with 01. MOV AX,10h ; The value 3 would crash debuggers directly. MOV SP,AX ; Corrupt the stack, now lame debugs modify 01. MOV SP,DX ; Restore SP. XOR AX,AX MOV AL,CS:BYTE PTR [01] ; Write the value back. MOV CS:BYTE PTR [00],CL ; Write 00/01 back. MOV CS:BYTE PTR [01],BL CMP AX,20h ; If not 20h then a realmode debugger is there. JNE $ ; Jump at current position. STI ╓═════════════════════════╖ ║ Nice stack-trick 2 ║ ║ by Christoph Gabler ║ ╚═════════════════════════╝ »» Much tighter but much easier to find out how it works. Fills SS with my magic number (Most other numbers do not work). Of course only against realmode debuggers. »» CLI MOV BX,SS ; Save SS to BX MOV DX,52121d ; Preparing DX for the corruption MOV SS,DX ; Corrupt SS with the help of DX / Hlts DEBUG XOR DX,DX MOV SS,BX ; Restore SS MOV BX,DX STI ╓═════════════════════════╖ ║ Nice stack-trick 3 ║ ║ by Christoph Gabler ║ ╚═════════════════════════╝ »» The following code uses the stack to jump. Most realmode debugs get kicked at the SP-modify, to get every realmode tracer the JMP SP is included. This routine works best in addition with a decryption loop. »» MOV AX,OFFSET JUMP_TO ; Get the position to jump to. MOV BX,SP ; Save SP to BX. MOV SP,AX ; Fill SP with the jump value. JMP SP ; Jump to the position. JUMP_TO: MOV SP,BX ; Restore SP. »» Very common method to detect realmode tracers - often found in protectors. It stops: Debug,Turbo Debug,Realmode Debug... »» PUSH AX POP AX DEC SP DEC SP POP BX ; BX should point to the pushed AX. CMP AX,BX JNE $ ; Kill Debugger if found. »» Another wellknown and oftenseen stack trick. It stops: Debug,Turbo Debug,Realmode Debug... »» CLI MOV AX,SP ; Save SP. MOV SP,3 ; Kick realmode debugger. NOP ; Do a cmd between corruption and restore. MOV SP,AX ; Restore SP. STI ╓═════════════════════╖ ║ Fake entrypoint #1 ║ ║ by Christoph Gabler ║ ╚═════════════════════╝ »» Almost anyone has heard about fake entrypoints. They can be found in HS and RC to fool DECAY05 or in CS to fool CUP386. There are many other protectors in which such a entrypoint fake can be found. But how does it work? Pretty simple, the following code is such a routine. CUP386 and DECAY05 get fooled. Based on the unpackers Seek_For_IP=100h_If_So_Then_We_Are_Thru ;) »» MOV CX,9000h ; Fake the entrypoint 9000h times. XOR DX,DX ; We must clear DX first. MOV DL,CS:BYTE PTR [100h] ; Save the byte found at 100h. MOV CS:BYTE PTR [100h],0C3h ; Write a RET to 100h. MOV AX,100h FAKE_ENTRY: CALL AX ; Call 100h. LOOP FAKE_ENTRY MOV CS:BYTE PTR [100h],DL ; Restore the byte we overwrote before. ╓═════════════════════╖ ║ Fake entrypoint #2 ║ ║ by Christoph Gabler ║ ╚═════════════════════╝ »» Another possibility to fake some unpackers. This time it does not restore 100h and 101h - I think if you need to restore, you can do it yourself. »» MOV CX,9000h ; Fake the entrypoint 9000h times. XOR DX,DX ; We must clear DX first. MOV DL,OFFSET THERE - 100h ; This is to generate the correct JMP back. ADD DX,100h ; Add 100h 'cause we jump there. MOV CS:BYTE PTR [100h],0FFh ; Write the jump command to 100h. MOV CS:BYTE PTR [101h],0E2h MOV AX,100h JMP AX ; Jump to 100h. THERE: CMP CX,0 ; If CX = 0 then we are done. JE OVER_FAKE DEC CX JMP AX ; Do it again. OVER_FAKE: ; Place the rest of your code here. ╓════════════════════════════╖ ║ Playing with the Trap Flag ║ ║ By Christoph Gabler ║ ╚════════════════════════════╝ »» INT1 tracer/unpacker have to set the Trap Flag which causes a INT1 to be executed after every instruction, which allows the single stepping procedure. By disabling this flag, we can disable the breakpoints from some INT1 tracers. But, most won't loose the control, because they turn the Trap Flag back on after every instruction and due to the fact that we need to do another instr. after the TF is fully turned off, the tracer gets the control back. »» Xor Ax, Ax ; Disable all flags. (Trap Flag too, of course) Push Ax PopF ; After one further instr., TF should be off. Mov Ax, 100h ; This will enable TF, by setting bit 8. Push Ax PopF »» Much better would be to turn the TF off, and then check if TF is *really* off. If it isn't a debugger is working in the background and we can crash it. »» Xor Ax, Ax ; Turn TF off. Push Ax PopF PushF ; Get the flag status Pop Ax ; and put it into AX. And Ah, 0Fh ; We only want the TF flag. Cmp Ah, 1 ; If AH=1 then TF is still on. Je $ ; Crash the CPU. ╓═════════════════════╖ ║ Nuke Interrupt 1/3 ║ ║ By Christoph Gabler ║ ╚═════════════════════╝ »» This routine kills INT1 and INT3 without using INT21. This method is very common and a similar version can be often found in protectors. CUP386 /1 does not loose the control - maybe it redirects INT1 and INT3. »» PUSH ES CLI xor ax,ax mov es,ax ; Clear ES. mov bx,4 ; Position of INT1. mov ax,es:[bx] ; Get and save INT1. mov es:[bx],0FFFFh ; Set INT1 to xxxx:FFFF add bx,2 ; Position of INT3. mov cx,es:[bx] ; Get and save INT3. mov es:[bx],0FFFFh ; Set INT3 to xxxx:FFFF sub bx,2 mov es:[bx],ax add bx,2 mov es:[bx],cx STI POP ES ╓═════════════════════╖ ║ Keyboard trick #1 ║ ║ by Christoph Gabler ║ ╚═════════════════════╝ »» This will lock and then unlock the keyboard using the keyboard port 64h. Nice against CUP, DG... »» ; Lock keyboard. MOV AL,0ADh OUT 64h,AL ; Unlock keyboard. MOV AL, 0AEh OUT 64h,AL ╓═════════════════════╖ ║ Keyboard trick #2 ║ ║ by Christoph Gabler ║ ╚═════════════════════╝ »» The following trick is a generic trick, one of the unstable ones. It is based on the fact that we have to press the ENTER key before we can execute a program. So, hardware port 60h will be set to 1Ch which means the ENTER key. If we debug the program, we have to press F7, F8 or F10 in order to trace step by step. Now, if we would check if the last key pressed is the ENTER key, we could make a generic detection routine. The problem is that if we press another key after pressing the ENTER key, the CPU will get detected also. ;) BTW, I think FSE uses this (or a similar one), because it crashs if I press another key in runtime. »» In Al, 60h ; Get the key which was pressed last. Cmp Al, 1Ch ; If not ENTER key then a debugger is tracing. Jne $ ; Hlt system. ╓═════════════════════╖ ║ Irritation code ║ ║ by Christoph Gabler ║ ╚═════════════════════╝ »» A stupid little routine to irritate the tracer. Of course only usefull if you place a decryptor with a C3 in it, jump there and do other irritating things. This is just an example. »» MOV DX,SP CALL POS JMP GO_ON POS: POP BX ; Get current position. CALL $+4 ; Call over the command, into C3. DB 04h,0C3h ; MOV AL,0C3h CALL $-1 ; Call back into C3. MOV [CS:00],AL ; Write a C3 into CS:00. ADD AL,03Dh ; Clear AL. MOV [CS:20C3h],0E3FFh ; Place a JMP BX to CS:20C3. JMP AX ; Jump to 00. GO_ON: MOV SP,DX ╓═════════════════════╖ ║ Irritation macro ║ ║ by Christoph Gabler ║ ╚═════════════════════╝ »» 98% of HackStop's "AntiDebugging code" consists of lame macros. Macro's were meant for making reading/debugging of code difficult, everyone of course knows that they are just joke (as HS itself ;). How do these marco's which were meant for irriatation work? The two instructions 'CALL FAR' and 'JUMP FAR' need 5 bytes of space for their working, that's why debuggers display the following 4 bytes as a 'CALL FAR' or 'JUMP FAR' instruction. So, what happens if we put a '0EAh' or a '09Ah' into our code? The following code will be displayed as the same instruction. If we now simply jump over the oppcode byte to avoid a crash we are done. »» MACRO_LOOP: ; Use a loop because this might be interesting for decryptors JMP OVER_1 ; First fake jump over oppcode '0EAh' DB 0EAh ; The oppcode itself. OVER_1: NOP ; Do a cmd, insert your code here. JMP OVER_2 ; Second fake jump. DB 09Ah ; The oppcode itself. OVER_2: CALL OVER_3 ; CALLing instead of JuMPing works better against TR. NOP ; Do another fucky cmd. CALL OVER_4 ; Do it again. ('cause lameness rules!) JMP OVER_6 ; And another time. DB 0EAh ; The oppcode itself. OVER_4: RET OVER_6: NOP JMP OVER_5 ; Jump a last time. DB 00,00,0EAh OVER_3: RET DB 00,00,00,09Ah OVER_5: LOOP MACRO_LOOP ╓═══════════════════════════════╖ ║ Screen AntiDebugging trick #1 ║ ║ by Christoph Gabler ║ ╚═══════════════════════════════╝ »» Often seen in protectors like Ciphator,FSE05,ExeLock666,PCrypt... Should irritate the tracer but I think it irritates the user. :) Here's the tightest way I know - directly over hardware port 3C6h. »» CLI MOV DX,3C6h ; Point to color area. IN AX,DX ; Get old settings. PUSH AX ; Save them. MOV AX,100h ; Value for black. OUT DX,AX ; Send to port. ; Place your Antidebugging Tricks here. POP AX ; Restore old settings. OUT DX,AX ; Send them to port. STI ╓═══════════════════════════════╖ ║ Screen AntiDebugging trick #2 ║ ║ ripped out of ExeLock666 ║ ╚═══════════════════════════════╝ »» 'Legandary' way to flicker the screen. Found in Ciphator and ExeLock666... Turns whole screen off for a while. »» ; Screen off. mov dx,03C4h mov al,1 out dx,al inc dx in al,dx or al,20h out dx,al ; Place your Antidebugging Tricks here. ; Screen on. mov dx,03C4h mov al,1 out dx,al inc dx in al,dx and al,dl out dx,al ──────────────────────────────┐ │ Protectedmode AntiDebugging │ └────────────────────────────── Everyone knows them, every protector author fears them : PM Debuggers. ;) Much more difficult to detect/crash then 'normal' realmode debuggers. Number one might be Iceunp or Winice, which keep their own stack, mostly their own interrupts and full 8086-486+ emulation. TR 2.52 does not trace the code, it interprets every single instructions. Unknown instructions must be traced. TR uses INT1 to trace these instructions. Deglucker acts similar to CUP386 - full interrupt reemulation, but bad DRx/CRx emulation. GTR uses asskicking keyboard routines which make keyboard-offs nearly impossible. Protectedmode debugger use/need the following things : - INT10 - Keyboard (INT9,Port 60h and 64h or 21h) - Sometimes DRx (If hardware breakpoint tracing) ╓═════════════════════════╖ ║ Winice recognization ║ ║ by ? ║ ╚═════════════════════════╝ »» How to recognize Winice? The following routine shows how to do it. Stonehead told me that the routine hangs sometimes - I do not know, test it. Detects: Only Winice Win 3.1/Win95 NOT the Dos version. »» ; Anti SoftIce trick #1 mov ax,01684h mov bx,0202h ; VXD ID for Winice, check out Ralf Brown's INTLIST xor di,di mov es,di int 2fh mov ax,es add di,ax cmp di,0 jne $ »» The four following routines were send by somebody I met on IRC. I'm sorry but I forgot his name. Anyway, hope you enjoy the following Anti Winice tricks. »» ; Detect Winice #1 mov ebp, 'BCHK' ; use ice BoundsChecker interface mov ax, 04h int 3 cmp al,4 jz winicenotdetected ; Detect Winice #2 mov ah,43h int 68h ; winice has int 68h handler and returns following value cmp ax,0f386h jnz winicenotdetected ; Detect Winice #3 xor ax,ax mov es,ax mov bx, word ptr es:[68h*4] mov es, word ptr es:[68h*4+2] ; checking int 68h handler mov eax, 0f43fc80h cmp eax, dword ptr es:[ebx] jnz winicenotdetected ; Detect Winice #4 push cs pop es xor ax,ax mov es,ax mov bx, cs lea dx, int41handler xchg dx, es:[41h*4] xchg bx, es:[41h*4+2] in al, 40h xor cx,cx int 41h xchg dx, es:[41h*4] xchg bx, es:[41h*4+2] cmp cl,al jz winicenotpresent »» Here is another way to get Winice. Credits go to DarkStalker. Works while executing INT41 which is used by Winice itself. »» cli In Ax,40h Mov word ptr cs:[bp+keyval],Ax push 0 pop ds xor ebx,ebx mov bx,cs shl ebx,10h lea bx,[bp+newint2] xchg ebx,dword ptr ds:[41h*4] push ds cs pop ds Mov Ah,4Fh Int 41h pop ds XChg EBx,DWord Ptr Ds:[41h*4] Push Cs Pop Ds Cmp Ax,0000h keyval Equ $-2 Jne $ sti NewInt2: ╓══════════════════════════╖ ║ Anti Deglucker 0.04 code ║ ║ by Christoph Gabler ║ ╚══════════════════════════╝ »» The following routine shows a possibility of how to defeat DG with just 3 bytes. If you trace it with DG, a 'protection fault' will be displayed and you cannot continue. The problem is that you are still able to NOP the code out. »» DB 66h,0FAh,0FBh ; Opcode 66h, CLI, STI here another little instruction which causes DG to display 'protection fault' : CMPSD ; Compare string or doubleword 386+ ╓══════════════════════╖ ║ Mode Detections ║ ║ by different authors ║ ╚══════════════════════╝ »» Another nice section might be the detection of the different modes a CPU can be switched to. Here are ways of how to detect RealMode, ProtectedMode or Windows95. »» ; Realmode detection by Christoph Gabler. mov eax,cr0 cmp eax,10h ; Compare CR0 with 10h, if so, we must be in realmode. je Real_Mode_Found ; Realmode detection by ELiCZ. SMSW AX ; Get Machine Status Word and store in AX. TEST AL,1 JE Real_Mode_Found ; Jump if CPU in Real Mode. ; Protected Mode (QEMM, EMM386...) detection by Christoph Gabler. mov eax,cr0 cmp al,1 je Protected_Mode_Found ; V86 (Windows 3.x and Windows 95) detection by Christoph Gabler. mov eax,cr0 cmp ax,0000 ; CPU is in Virtual 8086 mode if CR0 is 0000. je V86_Mode_Found ; Windows Detection detection by tHE riDDLER mov ax, 01600h int 02fh ; Check for available BP. or al,al jne Windows_Found ╓═══════════════════════════════╖ ║ Generic Anti TR 1.97 trick ║ ║ by Torsten Becker ║ ╚═══════════════════════════════╝ »» Here is a nice way to stop TR. You can put the following two bytes before any other instruction like a NOP or a XOR... The problem is that TR is able to bypass when in INT1-mode. You are asking yourself how to hinder tracing it with INT1? Ask me for the uncovered INSIDER.FAQ. :) »» DB 66h,67h ; Kicks TR 1.97 NOP ; Or any other command. ╓══════════════════════════════════╖ ║ TR - unknown instruction listing ║ ║ by Christoph Gabler ║ ╚══════════════════════════════════╝ »» The following source shows a few commands which cannot be traced with TR 1.97 without using INT1. Most instruction are unknown to TR and some simply hang TR when trying to trace them. Of course they are more or less useless if you can bypass them with INT1 but there are so MANY ways to get TR's INT1 - trace method : Cut INT1 before placing these instructions or play with the stack... »» Instructions which are unknown to TR 1.97 : CLTS ; Clear Task Switched Flag 286+ privileged mode JECXZ LABEL ; Jump to LABEL if ECX zero 386+ BSR EAX,EBX ; Bit Scan Reverse 386+ BSF EAX,EBX ; Bit Scan Forward 386+ CMPXCHG EAX,EBX ; Compare and Exchange 486+ BSWAP EAX ; Byteswap 486+ ╓═════════════════════════╖ ║ Cheap IceUnp detection ║ ║ by Christoph Gabler ║ ╚═════════════════════════╝ »» IceUnp uses good trace modes but the coder forgot one really dumb thing : His program does always use the same temporary file that is created before the Iceunp traced the file - a very stupid mistake because Iceunp can be detected while just searching the temp file called '1ICEUNP' Here is a method how to do it. > This one is cheap too. Get a REAL IceUnp detection in the UNcovered version of INSIDER.FAQ ! »» mov ah,4Eh ; Find the first match mov dx,offset ICETEMP ; Load the offset filemask dx int 21h ; Call DOS jnc $ ; Jump at current pos. if 1ICEUNP found. ; Rest of your code ICETEMP db '1ICEUNP',0 ; This must be placed out of range. ╓═════════════════════════╖ ║ Startup register tricks ║ ║ By Christoph Gabler ║ ╚═════════════════════════╝ »» These kind of tricks are the funny part of the antidebugging section. Why can TR not unpack Glue'd nor ATEU'd files? Pretty simple, the decryptor uses LODSB/STOSB for decryption which means: LODSB = Mov Ax, DS:word ptr [SI] INC/DEC SI STOSB = Mov ES:word ptr [DI], Ax INC/DEC DI The obvious part is, that SI and DI don't get set before the decryptor: e.g. Mov Di, xxxxh Which means, that the values loaded at the execution of the file will be used. Of course, every single register has its own allocation. The following table will show to which values the registers are set by load time. »» Normal CPU: ─────────── AX Contains DS:[80h] (Number of characters entered in cmd tail) BX:CX The load module memory size in 32 bit DX Set to DS SI Set to IP at entrypoint (in COM always 100h) DI Set to SP at entrypoint SP In COM set to FFFEh, in EXE set to the SP header value SS In COM set to CS, in EXE set to the SS header value DS In COM set to CS, in EXE set to the DS header value ES In COM set to CS, in EXE set to DS CS In COM to current memory adress, in EXE to the CS header value IP In COM to 100h, in EXE to the IP header value TR and Deglucker: ────────── AX Zero [Wrong] BX:CX Zero [Wrong] DX Set to DS SI Always set to 100h [In EXE wrong] DI Zero [Wrong] SP In COM set to FFFEh, in EXE set to the SP header value SS In COM set to CS, in EXE set to the SS header value DS In COM set to CS, in EXE set to the DS header value ES In COM set to CS, in EXE set to DS CS In COM to current memory adress, in EXE to the CS header value IP In COM to 100h, in EXE to the IP header value ╓══════════════════════════════════════╖ ║ 32 Bit Control- & Debug Register FAQ ║ ║ By Christoph Gabler ║ ╚══════════════════════════════════════╝ »» The following section should complain the working and function of the 32 Bit Control and Debug registers which can used to detect nearly ANY 80386 Debugger/GenericUnpacker. This short FAQ should describe what the CPU and Debugger does when it executes modification on DRx/CRx. If you know anything more about these registers please write it down and I'll add it here! »» (1) - The following 'enhanced' 32 Bit registers exist : [CRx] Control Registers (Modifications are QEMM incompatible) CR0,CR2,CR3 [DRx] Debug Registers DR0,DR1,DR2,DR3,DR4,DR5,DR6,DR7 [TRx] Test Registers TR4,TR5,TR6,TR7 (2) - Description/function of the single register : CR0 = Main Control Register Used to switch into Protected Mode and back to Real Mode. If already in PM mode under the OS, a crash will follow (EMM,QEMM...) CR2-3 = Should not be modified. DR0-4 = Breakpoint location registers Must contain the linear adress of the adress of where to break. DR6 = Debug status register Sets/Disables flags to show the status of the DRx status. DR7 = Debug Control Register GD Avaible on 486i+ - setting it enables a breakpoint on access to debug registers the GD bit is cleared by the processor on entry to the exception handler. (3) - Which values they are able to hold : CR0 = Handles values till ca. 2000h, adds 10h to itself if modified CR2-CR3 = Should not be accessed, values are same as they were set to DR0-DR5 = Handles 32 bit values, the fourth position is always a zero DR6 = Handles 32 bit values, behaves different from OS to OS DR7 = Handles 32 bit values, adds either 400h or 00 to itself if modified, the fourth position is always a zero (4) - Generic Unpacker Description : CUP386 /1 = Tracing with INT1 using the TF. CUP386 /3 = V86 mode tracer using hw brkpoints. CUP386 /7 = 386+ interpreter, bad debug register emulation. GTR 1.C0 = Very unhandy in usage, but nice tracing engine. Clever HW breakpoint tracing method. IceUnp = Very strong IUP rip, using the TF, yes the TF! Own stack, INT1/3 emulation, DRx tracing. TR 2.25 = Very nice DRx,CRx emulations now! Uses interpreting mode. INT1 tracing also available. Best DOS debugger! AUP386 = Seems like an unstable HW breakpoint method. DECAY05 = Uses hardware breakpoints in order to trace. Breakpoint set to IP=100h. EDump 1.0 = Uses the Win95 PM mode for ring tracing. Full control over RL/SelfTracing. LTR 1.0 = Mighty interpreter, full DRx hardware breakpoint possibility. Only a few bugs left and no PM instr. interpreting. ┌────────────────────── │ Anti-AntiVirus Code │ ──────────────────────┘ ╓═════════════════════════╖ ║ Anti F-Prot Heuristic ║ ║ By someone at Crypt ?? ║ ╚═════════════════════════╝ »» A very popular routine to avoid F-Prot's Heuristic Analysis. I think it's a dumb waste of space using it - I have something better - watch at TOP SECRETS!. Poor F-Prot, if it can be avoided by just jumping forwards a few times. =8] »» call screw_fprot ; confusing f-protect's call screw_fprot ; heuristic scanning call screw_fprot ; Still effective as of call screw_fprot ; version 2.10 call screw_fprot ; call screw_fprot ; [cf] Crypt Newsletter 18 call screw_fprot ; for explanation & call screw_fprot ; rationale call screw_fprot ; call screw_fprot ; screw_fprot: jmp $ + 2 ; Pseudo-nested calls to confuse call screw2 ; f-protect's heuristic call screw2 ; analysis call screw2 ; call screw2 ; call screw2 ; These are straight from ret ; YB-X. screw2: jmp $ + 2 call screw3 call screw3 call screw3 call screw3 call screw3 ret screw3: jmp $ + 2 call screw4 call screw4 call screw4 call screw4 call screw4 ret screw4: jmp $ + 2 ret ╓═════════════════════════╖ ║ Anti TBClean routine ║ ║ By someone at Crypt ??? ║ ╚═════════════════════════╝ »» Here is THE popularest routine to stop TBClean. It is very big in size and it sucks 'cause TBClean can be stopped with 'CLI and STI'. »» look_4_tbclean: mov ax, word ptr ds:[si] xor ax, 0A5F3h je check_it ; Jump If It's TBClean look_again: inc si ; Continue Search loop look_4_tbclean jmp not_found ; TBClean Not Found check_it: mov ax, word ptr ds:[si+4] xor ax, 0006h jne look_again mov ax, word ptr ds:[si+10] xor ax, 020Eh jne look_again mov ax, word ptr ds:[si+12] xor ax, 0C700h jne look_again mov ax, word ptr ds:[si+14] xor ax, 406h jne look_again mov bx, word ptr ds:[si+17] ; Steal REAL Int 1 Offset mov byte ptr ds:[bx+16], 0CFh ; Replace With IRET mov bx, word ptr ds:[si+27] ; Steal REAL Int 3 Offset mov byte ptr ds:[bx+16], 0CFh ; Replece With IRET mov byte ptr cs:[tb_here][bp], 1 ; Set The TB Flag On mov bx, word ptr ds:[si+51h] ; Get 2nd Segment of mov word ptr cs:[tb_int2][bp], bx ; Vector Table mov bx, word ptr ds:[si-5] ; Get Offset of 1st Copy mov word ptr cs:[tb_ints][bp], bx ; of Vector Table not_found: mov ax, 0CA00h ; Exit It TBSCANX In Mem mov bx, 'TB' int 2Fh cmp al, 0 je tbcleanok ret tbcleanok: ────────────────────────┐ │ How to fool unpackers │ └──────────────────────── ╓═════════════════════╖ ║ Intruder FakeCode ║ ║ By Christoph Gabler ║ ╚═════════════════════╝ »» This funny little piece of code will show the lameness of a startup code unpacker called Intruder. Everything behind this is that Intruder hooks INT21, than executes your program and tries to find (via INT21) if a Pascal, C or C++ compile program was found, then reconstruct the header and dump the code. The following few bytes will make Intruder think our program was compiled with Pascal and then write a lot of shit to disk. »» Mov Ah,30h Int 21h ; Now Intruder will get back control and will mov bp,ds:[0002h] ; find the following few bytes so that a mov bx,ds:[002Ch] ; wrong dump will appear. »» If you want to find out more such fakecode to fool TEU, UPC and similar try the following : (1) - Run the unpacker and specify C:\COMMAND.COM for unpacking. (2) - Trace INT21 using a debugger like CUP386 or TR. (3) - Try to find JE, JNE and other 7xh opcodes which might lead to the unpacking procedure. (4) - Rebuild the neccassary bytes which will get checked if the INT21 function xxh will be executed and try to unpack it with your unpacker Good luck. ;) »» ──────────────── │ TOP SECRETS! │ ──────────────── Ehm, 'cause this is the uncomplete version of the INSIDER.FAQ this section has been cutten - send a email in order to get a complete version. -> If you have coded your own anti-trace/debug routine please send it to me and it will be added here! (C)opright by Christoph Gabler between 1998 and 1999 Routines are licensed for free usage »»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»» »»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»