About anti-SoftICE tricks

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. o3 z" {. J  b  Y( x& e<TD><PRE>Method 01
=========
" ^- B8 Z6 L9 n+ `3 E. g
This method of detection of SoftICE (as well as the following one) is
2 l0 o+ ?* J* y6 [3 }' X& Qused by the majority of packers/encryptors found on Internet.
It seeks the signature of BoundsChecker in SoftICE
* y3 r: {& ~7 U* H: @) F' ?+ H
4 ?$ D) L. S; H- p& T: y5 [    mov     ebp, 04243484Bh        ; 'BCHK'
    mov     ax, 04h
" Y" j$ H9 C# Y# X" L) g    int     3      
- t, z# A6 K( g. C    cmp     al,4
  |2 E( w: c- W/ U- Q( Z1 D    jnz     SoftICE_Detected

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Method 02
=========
& b6 W& ?" ?/ X( {; w1 G
Still a method very much used (perhaps the most frequent one).  It is used
to get SoftICE 'Back Door commands' which gives infos on Breakpoints,
or execute SoftICE commands...
8 N' U0 j& ~+ iIt is also used to crash SoftICE and to force it to execute any commands
(HBOOT...) :-((  
; R+ u3 m1 `* O" d/ p' Z3 A$ q
3 k1 A% T; R% t4 o8 L# jHere is a quick description:
-AX = 0910h   (Display string in SIce windows)
-AX = 0911h   (Execute SIce commands -command is displayed is ds:dx)
-AX = 0912h   (Get breakpoint infos)
9 g7 S9 X, n* M- b-AX = 0913h   (Set Sice breakpoints)
-AX = 0914h   (Remove SIce breakoints)
, B2 F/ D- s% |& H
Each time you'll meet this trick, you'll see:
2 `" a- R% n$ n. j' a/ z5 x$ n1 V-SI = 4647h
-DI = 4A4Dh
Which are the 'magic values' used by SoftIce.
( T* P; j: T: W: V" LFor more informations, see "Ralf Brown Interrupt list" chapter int 03h.
3 W$ B8 m* l* i4 s
" ^( c' V. u+ l. r; f) `7 i9 VHere is one example from the file "Haspinst.exe" which is the dongle HASP
Envelope utility use to protect DOS applications:
3 A* q2 e9 w5 ~# ~; @  O1 ~4 p- d

4C19:0095   MOV    AX,0911  ; execute command.
4C19:0098   MOV    DX,[BX]  ; ds:dx point to the command (see below).
3 {$ m+ |7 |" J5 ?# j3 U3 Q3 X9 B5 w4C19:009A   MOV    SI,4647  ; 1st magic value.
4C19:009D   MOV    DI,4A4D  ; 2nd magic value.
4C19:00A0   INT    3        ; Int call.(if SIce is not loaded, jmp to 00AD*)
; |& B& c  n  U4 D: P" y) Z* T4C19:00A1   ADD    BX,02    ; BX+2 to point to next command to execute
4C19:00A4   INC    CX
4C19:00A5   CMP    CX,06    ; Repeat 6 times  to execute
4C19:00A8   JB     0095     ; 6 different commands.
4C19:00AA   JMP    0002     ; Bad_Guy jmp back.
9 J: A# J. V- k9 H' b  L8 N4C19:00AD   MOV    BX,SP    ; Good_Guy go ahead :)

The program will execute 6 different SIce commands located at ds:dx, which
* @* z$ s8 ^( ^+ D1 X, _are: LDT, IDT, GDT, TSS, RS, and ...HBOOT.
+ z% u$ p- \( s+ p  |2 ^% _6 G( v
* the "jmp to 00ADh" is performed via an SEH if the debugger is not loaded.
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6 I2 e3 p1 ], GMethod 03
=========
6 z( O9 b  I+ {/ i) _* F
: L. B* k: ~- W/ L- w9 }Less used method.  It seeks the ID of SoftICE VxD via the int 2Fh/1684h
7 a" {) E" X/ `0 S3 v; x+ \; m(API Get entry point)
) |9 K0 F, }- t( ?$ _        
. _. @/ T. P- M0 x
    xor     di,di
    mov     es,di
    mov     ax, 1684h      
6 T; u! \6 s; \, c: p, a6 f    mov     bx, 0202h       ; VxD ID of winice
# _0 Z* Z$ }+ E1 S  a    int     2Fh
    mov     ax, es          ; ES:DI -&gt; VxD API entry point
    add     ax, di
: T, q/ o" i: a9 Y! u" E" t  S& X4 ~    test    ax,ax
    jnz     SoftICE_Detected

' A; @  }) C$ H5 F+ _" y___________________________________________________________________________

. }' c/ G/ i1 t) n# X7 ]Method 04
7 }5 L- {) F) W% F! t: L3 I/ P=========
! r: \8 x% X& @2 g3 @# Z5 R! P6 }! y
Method identical to the preceding one except that it seeks the ID of SoftICE
GFX VxD.

3 ?) n8 h1 q( b    xor     di,di
" D5 \2 R! e9 ^% \    mov     es,di
$ p! k( \" G4 M+ Z: C    mov     ax, 1684h      
/ C% J1 U+ ]" Y9 v    mov     bx, 7a5Fh       ; VxD ID of SIWVID
    int     2fh
/ n9 g. N. F: ~1 z& ~    mov     ax, es          ; ES:DI -&gt; VxD API entry point
    add     ax, di
# o) k) `/ M4 a( N( Z    test    ax,ax
# s" e5 T$ G+ L    jnz     SoftICE_Detected
8 s( c; s+ J  Y! Z2 N
) C0 {! h6 o) Y; ]2 H__________________________________________________________________________
2 H6 P7 W2 V& b* t+ ~5 y) ^' N, }+ Y
4 Y! d; y0 C% J/ O+ |
Method 05
3 z5 C8 x: v0 G1 l=========

Method seeking the 'magic number' 0F386h returned (in ax) by all system
: i# _4 z. Z- ^debugger. It calls the int 41h, function 4Fh.
; a. }# _9 w+ @There are several alternatives.  
+ C! \" r5 P  p  q+ U
6 \& n. Y/ Q9 M% e. y  F, Q* lThe following one is the simplest:
$ c  k5 P2 H) I0 b, R
    mov     ax,4fh
    int     41h
3 O( _5 n+ p/ V  o# Z    cmp     ax, 0F386
    jz      SoftICE_detected
7 v& U3 h! L9 |4 d7 R
# u3 Z- d# ~; g3 A  T4 r) M
Next method as well as the following one are 2 examples from Stone's
! N8 p( o! g5 n5 }5 f- L"stn-wid.zip" (www.cracking.net):
' g5 @( T' {6 w8 W, B% k& t8 S
" `' u/ [& y9 c* g* r    mov     bx, cs
) g  f& {/ i) h8 s    lea     dx, int41handler2
    xchg    dx, es:[41h*4]
    xchg    bx, es:[41h*4+2]
0 p( h/ ~6 [1 P& s, u/ }4 D    mov     ax,4fh
    int     41h
/ T! J- |; J8 E& p    xchg    dx, es:[41h*4]
    xchg    bx, es:[41h*4+2]
    cmp     ax, 0f386h
, E) |6 ^8 C0 w2 E* K/ @" ?% c1 ^  }    jz      SoftICE_detected

int41handler2 PROC
    iret
int41handler2 ENDP
$ Y- y4 i# \' r5 v6 A1 Y& I

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! X. ?* [8 G4 Z5 ]1 o: OMethod 06
=========
5 Z' ?4 Q8 _! y2 V: J& ~$ l+ P

9 K+ B& Y* T/ G+ f3 q2nd method similar to the preceding one but more difficult to detect:
& z% u& x( o2 V) H0 O; O

/ B9 U6 \3 `: z+ i. pint41handler PROC
/ x$ N+ ^6 ]# l4 [, ^% {    mov     cl,al
7 v1 g& n5 G! T7 \. i    iret
int41handler ENDP

) a# t3 D0 r7 X
    xor     ax,ax
    mov     es,ax
0 _' M6 g7 O3 B/ X& [    mov     bx, cs
: Q3 w6 ~" F4 c. ]3 ^    lea     dx, int41handler
    xchg    dx, es:[41h*4]
    xchg    bx, es:[41h*4+2]
! B4 A4 y; j$ K0 g5 \) {" v    in      al, 40h
    xor     cx,cx
5 Y4 D% J) L  U) x' G    int     41h
+ |% K# f% ]! z0 \3 t    xchg    dx, es:[41h*4]
    xchg    bx, es:[41h*4+2]
    cmp     cl,al
    jnz     SoftICE_detected

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0 v: L8 n& [9 c- fMethod 07
3 Y2 ^  D0 p/ q* F9 z8 {& `- b=========

Method of detection of the WinICE handler in the int68h (V86)
4 c3 k2 D% _0 T0 C! i
    mov     ah,43h
+ x7 N1 P& E& s& L& f: ]    int     68h
    cmp     ax,0F386h
    jz      SoftICE_Detected
# c' j5 R7 R& a2 |% D% ]
+ F. u! {; h/ G( _7 i
=&gt; it is not possible to set a BPINT 68 with softice but you can hook a 32Bit
   app like this:
* v1 z+ Z3 P0 x: e) X
% }; ]; E9 l/ v+ B   BPX exec_int if ax==68
   (function called is located at byte ptr [ebp+1Dh] and client eip is
   located at [ebp+48h] for 32Bit apps)
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Method 08
=========
" F$ Y! u* x5 x
/ ^1 [2 e( |; rIt is not a method of detection of SoftICE but a possibility to crash the
  v+ }# Z: n, Bsystem by intercepting int 01h and int 03h and redirecting them to another
0 I  H" X- {. w3 jroutine.
It calls int 21h functions 25h and 35h (set/get int vector) and ds:dx points
to the new routine to execute (hangs computer...)
2 u% _& X: p$ ]9 a4 p
3 Y) O& r' J+ p: Y    mov     ah, 25h
    mov     al, Int_Number (01h or 03h)
    mov     dx, offset New_Int_Routine
1 B  f6 x3 X* ?    int     21h

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/ a) p7 i* D  m- X& b
Method 09
=========

' y4 I8 f% M5 \5 qThis method is closed to methods 03 and 04 (int 2Fh/1684h) but it is only
9 m+ D, c% T8 Z* G5 r( eperformed in ring0 (VxD or a ring3 app using the VxdCall).
The Get_DDB service is used to determine whether or not a VxD is installed
' Y2 p, W: p' @3 k- i: zfor the specified device and returns a Device Description Block (in ecx) for
! `) v1 e; L9 ^that device if it is installed.
0 F, Q' g# h; B* E" r
   mov     eax, Device_ID   ; 202h for SICE or 7a5Fh for SIWVID VxD ID
5 k6 X* S: F7 O9 {3 g/ f   mov     edi, Device_Name ; only used if no VxD ID (useless in our case ;-)
   VMMCall Get_DDB
% A" s9 e3 i3 P6 _+ w4 t2 A   mov     [DDB], ecx       ; ecx=DDB or 0 if the VxD is not installed
8 B3 ^, A4 H2 s  x
Note as well that you can easily detect this method with SoftICE:
/ [8 }3 d* k# L. Y$ l/ P   bpx Get_DDB if ax==0202 || ax==7a5fh
2 |+ R6 n! H& b& \" R$ {
+ o; \3 b0 \7 S7 q__________________________________________________________________________

Method 10
=========

4 I4 I+ [0 @  \2 ?! H=&gt;Disable or clear breakpoints before using this feature. DO NOT trace with
- O* s  a  H+ H) O0 i  SoftICE while the option is enable!!

This trick is very efficient:
4 P1 B* Z: s+ Z( q- rby checking the Debug Registers, you can detect if SoftICE is loaded
/ `" n, m/ E9 ?9 v  ?(dr7=0x700 if you loaded the soft with SoftICE loader, 0x400 otherwise) or if
there are some memory breakpoints set (dr0 to dr3) simply by reading their
' I0 T- s0 }9 ivalue (in ring0 only). Values can be manipulated and or changed as well
2 e9 @- F" x& }(clearing BPMs for instance)
- e1 w, r/ H2 \4 w9 P/ A1 B5 b
# {& f6 ]; F: x( M9 S__________________________________________________________________________

! ^( {) }- {7 ~) Z2 B  sMethod 11
* R* g+ {" [5 t=========
6 t3 N; F: ^% t9 |8 _- \
This method is most known as 'MeltICE' because it has been freely distributed
! [# V2 ]+ E: W: R; `9 W/ b8 Ivia www.winfiles.com. However it was first used by NuMega people to allow
Symbol Loader to check if SoftICE was active or not (the code is located
" D+ ?4 F/ b% M% \3 A4 ginside nmtrans.dll).

; L! X/ B$ Z9 [2 OThe way it works is very simple:
It tries to open SoftICE drivers handles (SICE, SIWVID for Win9x, NTICE for
WinNT) with the CreateFileA API.

6 N7 ?& v+ U& ~Here is a sample (checking for 'SICE'):
& M8 F# t- l: v% N  H$ f
$ w1 E: \+ h3 S7 H! U. B8 c- \- p  lBOOL IsSoftIce95Loaded()
{
7 F1 s; l2 q! X8 o: S   HANDLE hFile;  
   hFile = CreateFile( "\\\\.\\SICE", GENERIC_READ | GENERIC_WRITE,
                      FILE_SHARE_READ | FILE_SHARE_WRITE,
4 V( _, ~2 Z4 a( Z6 H; p; W) i                      NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
   if( hFile != INVALID_HANDLE_VALUE )
% ?, E# d! i* z" y   {
      CloseHandle(hFile);
      return TRUE;
( ^1 G0 T) b* v) k   }
   return FALSE;
}
" V" [/ O6 y0 K
) a' i0 {& l& A2 XAlthough this trick calls the CreateFileA function, don't even expect to be
able to intercept it by installing a IFS hook: it will not work, no way!
, F# H6 J7 ?$ H) [4 K! yIn fact, after the call to CreateFileA it will get through VWIN32 0x001F
service _VWIN32_ReleaseWin32Mutex (via Kernel32!ORD_0001/VxDCall function)
and then browse the DDB list until it find the VxD and its DDB_Control_Proc
field.
In fact, its purpose is not to load/unload VxDs but only to send a
W32_DEVICEIOCONTROL (0x23) control message (DIOC_OPEN and DIOC_CLOSEHANDLE)
to the VxD Control_Dispatch proc (how the hell a shareware soft could try
to load/unload a non-dynamically loadable driver such as SoftICE ;-).
If the VxD is loaded, it will always clear eax and the Carry flag to allow
its handle to be opened and then, will be detected.
9 @; @% R: G, x- S8 Q: BYou can check that simply by hooking Winice.exe control proc entry point
* @" `1 W) I- O( |while running MeltICE.


' H2 R" U/ V$ y" b7 |" N  00401067:  push      00402025    ; \\.\SICE
  0040106C:  call      CreateFileA
. F' A. F) C" N  00401071:  cmp       eax,-001
8 x) e) I( I: C* N! Y  00401074:  je        00401091

  N5 _! @  o* i6 N  h
! T# ~9 k( ~+ w0 R$ y/ NThere could be hundreds of BPX you could use to detect this trick.
-The most classical one is:
  BPX CreateFileA if *(esp-&gt;4+4)=='SICE' || *(esp-&gt;4+4)=='SIWV' ||
! j: g) D1 z" J8 E3 z: X: h    *(esp-&gt;4+4)=='NTIC'
( h5 j5 v3 i7 @" {
9 g8 \7 f& w! b& I, B-The most exotic ones (could be very slooooow :-(
2 H' q$ O1 ?+ E3 @7 m   BPINT 30 if eax==002A001F &amp;&amp; (*edi=='SICE' || *edi=='SIWV')  
/ ~$ `. A0 V3 W7 F     ;will break 3 times :-(

-or (a bit) faster:
" f! I& P: p4 m; B   BPINT 30 if (*edi=='SICE' || *edi=='SIWV')

   BPX KERNEL32!ORD_0001 if *edi=='SICE' || *edi=='SIWV'  
     ;will break 3 times :-(
- v6 z% H9 t( S
-Much faster:
   BPX VMM_GetDDBList if eax-&gt;3=='SICE' || eax-&gt;3=='SIWV'
7 Z9 N* p3 q6 x4 W& V5 F( e% U
& D6 N; u7 V+ M% m! M6 uNote also that some programs (like AZPR3.00) use de old 16-bit _lopen
function to do the same job:
- m. ^/ b5 x" g& k: w
% ]3 I# i. t) q8 N   push    00                        ; OF_READ
   mov     eax,[00656634]            ; '\\.\SICE',0
# h- N. a- R7 n9 U- R   push    eax
) u+ @/ P2 h8 L2 @# B3 {# n; F   call    KERNEL32!_lopen
+ ]  x/ b% a$ ~  J; B5 f   inc     eax
3 `2 t3 G9 h7 Z% G) X, M# b. n   jnz     00650589                  ; detected
   push    00                        ; OF_READ
6 ]3 u3 a3 K  L- l; E   mov     eax,[00656638]            ; '\\.\SICE'
   push    eax
   call    KERNEL32!_lopen
. v2 T9 X! Z% d. g. @( ~0 ]) ?   inc     eax
7 }$ L# \' v3 y. N5 H   jz      006505ae                  ; not detected
+ X3 _" i; Z+ r; p! q) t5 i
) ?' l6 L1 I# Z6 D7 w- n) D) H
5 [$ a0 J- }6 d. C/ Y! _% i! g__________________________________________________________________________
4 S# H0 J& f5 A$ p( b5 O: d% p
" @  m6 u+ `6 t6 u/ F1 \7 UMethod 12
- r6 X" C: B/ o! q% `=========
9 V6 h# l8 W6 {, L4 r& K6 I5 T1 s
This trick is similar to int41h/4fh Debugger installation check (code 05
&amp; 06) but very limited because it's only available for Win95/98 (not NT)
# Y1 M# b, D% I* `+ _2 s3 G1 i" [9 Vas it uses the VxDCall backdoor. This detection was found in Bleem Demo.

- p% ?; L( p) X7 Z8 [   push  0000004fh         ; function 4fh
   push  002a002ah         ; high word specifies which VxD (VWIN32)
                           ; low word specifies which service
                             (VWIN32_Int41Dispatch)
   call  Kernel32!ORD_001  ; VxdCall
   cmp   ax, 0f386h        ; magic number returned by system debuggers
/ X$ h# o' ~6 J6 c3 D   jz    SoftICE_detected

7 V+ ~, L8 z! |Here again, several ways to detect it:

    BPINT 41 if ax==4f

- N, E$ Y+ ^" g) U9 w" \    BPINT 30 if ax==0xF386   ; SoftICE must be loaded for this one
) R0 t% e( V5 M7 {
) b" Y) `  H! P! x' o6 S! e    BPX Exec_PM_Int if eax==41 &amp;&amp; edx-&gt;1c==4f &amp;&amp; edx-&gt;10==002A002A
; p+ g) z' r, y% J7 c4 w6 A
; q- f0 h4 t% e# U  p* x    BPX Kernel32!ord_0001 if esp-&gt;4==002A002A &amp;&amp; esp-&gt;8==4f   ; slooooow!
- K" S+ H) b( C. X2 {
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/ }) U8 m% Q+ K) i/ y% ?, W! h
Method 13
=========

Not a real method of detection, but a good way to know if SoftICE is
4 t2 X3 ?% `  ?8 _! qinstalled on a computer and to locate its installation directory.
It is used by few softs which access the following registry keys (usually #2) :

-#1: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion
\Uninstall\SoftICE
9 |& V( x% k% F$ ~( g& M" b% c9 W4 J-#2: HKEY_LOCAL_MACHINE\Software\NuMega\SoftICE
3 k4 {$ F$ b' _; A0 D: O7 _2 k1 O6 e-#3: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion
* p$ W8 o" n7 q. X. w- u\App Paths\Loader32.Exe
2 N3 G0 E; T  x5 N, F

Note that some nasty apps could then erase all files from SoftICE directory
% U8 g' p* G% m' Z( B" e* Y(I faced that once :-(

Useful breakpoint to detect it:

& I+ a6 v& e. A- s* U/ }  ?     BPX _regopenkey if *(esp-&gt;8+0x13)=='tICE' || *(esp-&gt;8+0x37)=='tICE'

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Method 14
=========

A call to VMM 'Test_Debug_Installed' service. As the name says, its purpose
is to determines whether a debugger is running on your system (ring0 only).

0 D$ m: k4 O2 P" y0 m+ l   VMMCall Test_Debug_Installed
   je      not_installed

, }6 E# G( e0 E: q* T, KThis service just checks a flag.
# a% @& y8 _' p: _5 g. Y+ O</PRE></TD></TR></TBODY></TABLE>