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Posts Tagged ‘windows internals’

WoWMimic v50

June 11th, 2009

Another WoWMimic build was released recently. I’ve reversed it yet again to bring you the gory details.

They’ve beefed up (by their standards) the obfuscation on this one. I put “by their standards” because they’re morons, and by the standards of any real reverser ‘beefed up’ is hardly the right term. It seems they’ve learned two new ‘tricks’, one they use once, another they use constantly. Both are very lame and very obvious and easy to undo though.

The first is this:

15DEBE67 | 5B            | POP     EBX                         | ; Pop address of current line into EBX

15DEBE68 | 81EB 471A4000 | SUB     EBX, 401A47                 | ; Subtract 401A47 from EBX (15DEBE67) (Final: 159EA420)

15DEBE6E | 8B83 F1194000 | MOV     EAX, DWORD PTR [EBX+4019F1] | ; Move 7CCAE98C into EAX

15DEBE74 | 35 8CE9CA7C   | XOR     EAX, 7CCAE98C               | ; Xor EAX (7CCAE98C) with 7CCAE98C. (Final: 0)

15DEBE79 | 8D8B C81A4000 | LEA     ECX, DWORD PTR [EBX+401AC8] | ; Move EBX (159EA420) + 401AC8 into ECX (Final: 15DEBEE8)

15DEBE7F | 8D0401        | LEA     EAX, DWORD PTR [ECX+EAX]    | ; Move ECX (15DEBEE8) + EAX (0) into EAX (Final: 15DEBEE8)

15DEBE82 | FFE0          | JMP     NEAR EAX                    | ; Jump NEAR to EAX (15DEBEE8). Another obfuscation attempt.

They have attempted to hide the jump address with some VERY basic math. Sorry guys, but you’re gonna have to do better than that.

Second trick:

; MimicVectoredHandler

15DEBE06 | 55            | PUSH    EBP       | ; Standard stack frame setup

15DEBE07 | 8BEC          | MOV     EBP, ESP  | ; Standard stack frame setup

15DEBE09 | 81C4 00FFFFFF | ADD     ESP, -100 | ; Sub ESP 100. Room for local variables

15DEBE0F | EB 50         | JMP     15DEBE61  | ; Jump over garbage and into an instruction. Obfuscation attempt.

; Original - Nice try… Not!

15DEBE60 | 2A60 E8 | SUB     AH, BYTE PTR [EAX-18] | ; Jump lands one byte into this instruction.

15DEBE63 | 0000    | ADD     BYTE PTR [EAX], AL    | ; Just reassemble the bytes to fix it.

15DEBE65 | 0000    | ADD     BYTE PTR [EAX], AL    | ; See below for one I prepared earlier!

; Fixed - Wow.. that was hard…

15DEBE61 | 60          | PUSHAD           | ; Preserve registers

15DEBE62 | EB 00000000 | CALL    15DCBE67 | ; Call next line

They’re attempting to confuse disassemblers by jumping into what seems to be the middle of an instruction. What they don’t seem to realize is that there are two very easy ways to undo this. One is to realign your disassembler for that chunk if it has that functionality. The other is to just dump out the bytes, assemble them externally (in OllyDbg or another tool that can assemble bytes into mnemonics), and just read from there.  Thanks to Nessox and Apoc for doing that for me because Olly was being a whore on my PC.  To put it simply, its no barrier to any reverser with half a brain.

Both obfuscation ‘techniques’ (if you can call them that) just reek of the work of an amateur. I still think they’re waiting for “one of china’s best hackers” to turn up for work.

As for actual changes to the implementation, there isn’t much, they seem to have wasted the last week or so on obfuscation which took them 1000x longer to write than it took me to reverse. Nevertheless, there is one notable change, which is to their ZwQueryVirtualMemory hook.

They no longer null out pMemoryBasicInformation->BaseAddress, but they have started nulling out pMemoryBasicInformation->RegionSize. The reason for this is both obvious and hilarious.

The previous build of WardenMimic (new one coming once I get some free time) worked by enumerating all regions of memory to look for the one that has been hidden. It is identified by detecting the unique return values which would never be returned in normal circumstances. Whilst the change breaks WardenMimic, it does so for all the wrong reasons. Not only do they obviously have no idea how a NtQueryVirtualMemory hook is actually supposed to work, they’ve fucked up and left another gaping hole AGAIN. That’s right, the hook is STILL detectable by Warden because the morons obviously don’t understand the first thing about Windows internals and virtual memory.

The rest of the APIs (GetCursorPos, SetCursorPos, NtGetContextThread) remain unhooked for the time being. (GetCursorPos and SetCursorPos still have the bug that was left there from the previous build.)

So, in summary, the changes are as followed:

  • Had another crack at obfuscating their anti-detection code and failed hard.
  • Attempted to fix their NtQueryVirtualMemory hook. Whilst they broke WardenMimic they fucked up their hook AGAIN and so Mimic is STILL DETECTABLE.

It’s pretty funny it took them this long just to push out such a simple new build. Really says something about either the quality of the developers or the quality of the customer service department. (Regardless though, the fail obfuscation attempts definitely say something about the developers. — In case you’re slow, its says they’re incompetent.)

Full code (with documentation) is available again. Anything marked as “Fixed” has been realigned so most of the obfuscation will not be apparent unless you reverse it yourself.

WoWMimic v50 Anti-Detection Code.

WoWMimic v47 Changes

May 27th, 2009

Many of you will know by now that WoWMimic v47 is out. A few interesting changes, nothing really substantial though.

  1. GetCursorPos and SetCursorPos are now also hooked using VEH.
  2. ZwQueryVirtualMemory is now hooked at the return statement so values are modified AFTER the function is called. They have fixed one hole, but introduced another. Still hooked with VEH.
  3. ZeGetContextThread hook is still present but not longer activated. They have also updated their hook body, fixing one hole, but again, introducing another (see if you can spot it).
  4. They have implemented some VERY lame ‘obfuscation’ attempts. Really quite a poor job, 5 minutes tops to figure out the mess, or 30 or so seconds if you know what you’re looking at.

All in all quite disappointing. They broke the previous version of WardenMimic but only because they changed the offset at which they were hooking, and I was being nice and lowering the false positive rate by putting in lots of checks to detect only that exact build. Anyway, new WardenMimic incoming soon (when I don’t feel lazy).

Update:

Thanks to Harko for pointing out that GetCursorPos and SetCursorPos are still hooked with JMP hooks. It seems they implemented support for it in their VEH but didn’t actually hook it using VEH for some reason. Much like their unused changes to NtGetContextThread. Kinda retarded really….

Full code:

PrivatePaste Copy

; MimicVectoredHandler

169B379E | 55            | PUSH    EBP                         | ; Standard stack frame setup

169B379F | 8BEC          | MOV     EBP, ESP                    | ; Standard stack frame setup

169B37A1 | 81C4 00FFFFFF | ADD     ESP, -100                   | ; Sub ESP 100. Room for local variables.

169B37A7 | 60            | PUSHAD                              | ; Preserve all registers

169B37A8 | E8 00000000   | CALL    169B37AD                    | ; Obfuscation. ‘Calls’ next line and pushes the address of that line onto stack.

169B37AD | 5B            | POP     EBX                         | ; Pop address (of current line) back off and into EBX

169B37AE | 81EB 75164000 | SUB     EBX, 401675                 | ; Subtract 401675 from EBX (169B37AD) (Final: 165B2138)

169B37B4 | 8B75 08       | MOV     ESI, DWORD PTR [EBP+8]      | ; Get pExceptionInfo

169B37B7 | 8B7E 04       | MOV     EDI, DWORD PTR [ESI+4]      | ; Get pExceptionInfo->pContext

169B37BA | 8B36          | MOV     ESI, DWORD PTR [ESI]        | ; Get pExceptionInfo->pExceptionRecord

169B37BC | 8B87 B8000000 | MOV     EAX, DWORD PTR [EDI+B8]     | ; Get EIP

169B37C2 | 3B83 CD104000 | CMP     EAX, DWORD PTR [EBX+4010CD] | ; Compare EIP to address of GetCursorPos.

169B37C8 | 75 0E         | JNZ     169B37D8                    | ; If not equal go to ContinueSearchRet

169B37CA | 8D83 F8164000 | LEA     EAX, DWORD PTR [EBX+4016F8] | ; Get address of GetCursorPos_Hook

169B37D0 | 8987 B8000000 | MOV     DWORD PTR [EDI+B8], EAX     | ; Move address into EIP

169B37D6 | EB 4C         | JMP     169B3824                    | ; Go to ContinueExecRet

169B37D8 | 3B83 D1104000 | CMP     EAX, DWORD PTR [EBX+4010D1] | ; Compare EIP to address of SetCursorPos

169B37DE | 75 0E         | JNZ     169B37EE                    | ; If not equal go to ContinueSearchRet

169B37E0 | 8D83 2D174000 | LEA     EAX, DWORD PTR [EBX+40172D] | ; Get address of SetCursorPos_Hook

169B37E6 | 8987 B8000000 | MOV     DWORD PTR [EDI+B8], EAX     | ; Move address into EIP

169B37EC | EB 36         | JMP     169B3824                    | ; Go to ContinueExecRet

169B37EE | 3B83 84134000 | CMP     EAX, DWORD PTR [EBX+401384] | ; Compare EIP to address of ZwQueryVirtualMemory_Retn

169B37F4 | 75 0E         | JNZ     169B3804                    | ; If not equal go to ContinueSearchRet

169B37F6 | 8D83 50174000 | LEA     EAX, DWORD PTR [EBX+401750] | ; Get address of ZwQueryVirtualMemory_Hook

169B37FC | 8987 B8000000 | MOV     DWORD PTR [EDI+B8], EAX     | ; Move address into EIP

169B3802 | EB 20         | JMP     169B3824                    | ; Go to ContinueExecRet

169B3804 | 3B83 8C134000 | CMP     EAX, DWORD PTR [EBX+40138C] | ; Compare EIP to address of ZwGetContextThread_Hook. Currently not used/enabled.

169B380A | 75 0E         | JNZ     169B381A                    | ; If not equal go to ContinueSearchRet

169B380C | 8D83 88174000 | LEA     EAX, DWORD PTR [EBX+401788] | ; Get address of ZwGetContextThread_Hook.

169B3812 | 8987 B8000000 | MOV     DWORD PTR [EDI+B8], EAX     | ; Move address into EIP

169B3818 | EB 0A         | JMP     169B3824                    | ; Go to ContinueExecRet

169B381A | 61            | POPAD                               | ; Restore registers

169B381B | B8 00000000   | MOV     EAX, 0                      | ; Move EXCEPTION_CONTINUE_SEARCH into return value

169B3820 | C9            | LEAVE                               | ; Standard function prologue

169B3821 | C2 0400       | RETN    4                           | ; Return

169B3824 | 61            | POPAD                               | ; Restore registers

169B3825 | B8 FFFFFFFF   | MOV     EAX, -1                     | ; Move EXCEPTION_CONTINUE_EXECUTION into return value

169B382A | C9            | LEAVE                               | ; Standard function prolugue

169B382B | C2 0400       | RETN    4                           | ; Return

; GetCursorPos_Hook

169B3830 | E8 00000000      | CALL    169B3835                    | ; Obfuscation. ‘Calls’ next line and pushes the address of that line onto stack.

169B3835 | 5A               | POP     EDX                         | ; Pop address (of current line) back off and into EDX

169B3836 | 81EA FD164000    | SUB     EDX, 4016FD                 | ; Subtract 4016FD from EDX (169B3835) (Final: 165B2138)

169B383C | 83BA 09104000 01 | CMP     DWORD PTR [EDX+401009], 1   | ; Compare some internal flag to 1

169B3843 | 75 15            | JNZ     169B385A                    | ;

169B3845 | 8B4C24 04        | MOV     ECX, DWORD PTR [ESP+4]      | ; Get lpPoint

169B3849 | 8B82 0D104000    | MOV     EAX, DWORD PTR [EDX+40100D] | ; Get custom mouse x

169B384F | 8901             | MOV     DWORD PTR [ECX], EAX        | ; Set lpPoint->x to custom mouse x

169B3851 | 8B82 11104000    | MOV     EAX, DWORD PTR [EDX+401011] | ; Get custom mouse y

169B3857 | 8941 04          | MOV     DWORD PTR [ECX+4], EAX      | ; Set lpPoint->y to custom mouse y

169B385A | 8B82 CD104000    | MOV     EAX, DWORD PTR [EDX+4010CD] | ; Get address of GetCursorPos

169B3860 | 83C0 02          | ADD     EAX, 2                      | ; Jump over invalid instruction

169B3863 | FFE0             | JMP     NEAR EAX                    | ; Jump to GetCursorPos (+2)

; SetCursorPos_Hook

169B3865 | E8 00000000      | CALL    169B386A                    | ; Obfuscation. ‘Calls’ next line and pushes the address of that line onto stack.

169B386A | 5A               | POP     EDX                         | ; Pop address (of current line) back off and into EDX

169B386B | 81EA 32174000    | SUB     EDX, 401732                 | ; Subtract 401732 from EDX (169B386A) (Final: 165B2138)

169B3871 | 83BA 09104000 01 | CMP     DWORD PTR [EDX+401009], 1   | ; Compare some internal flag to 1

169B3878 | 75 03            | JNZ     169B387D                    | ; Jump if not equal to RetnCallOrig

169B387A | C2 0800          | RETN    8                           | ; Return without calling original

169B387D | 8B82 D1104000    | MOV     EAX, DWORD PTR [EDX+4010D1] | ; Get address of SetCursorPos

169B3883 | 83C0 02          | ADD     EAX, 2                      | ; Jump over invalid instruction

169B3886 | FFE0             | JMP     NEAR EAX                    | ; Jump to SetCursorPos (+2)

; ZwQueryVirtualMemory_Hook

169B3888 | E8 00000000      | CALL    169B388D                    | ; Obfuscation. ‘Calls’ next line and pushes the address of that line onto stack.

169B388D | 5A               | POP     EDX                         | ; Pop address (of current line) back off and into EDX

169B388E | 81EA 55174000    | SUB     EDX, 401755                 | ; Subtract 401755 from EDX (169B388D) (Final: 165B2138)

169B3894 | 50               | PUSH    EAX                         | ; Preserve EAX

169B3895 | 8B4424 14        | MOV     EAX, DWORD PTR [ESP+14]     | ; Get pMemoryBasicInformation

169B3899 | 8B48 04          | MOV     ECX, DWORD PTR [EAX+4]      | ; Get pMemoryBasicInformation->Allocationbase

169B389C | 3B8A 21104000    | CMP     ECX, DWORD PTR [EDX+401021] | ; Compare to MimicModuleBase

169B38A2 | 75 18            | JNZ     169B38BC                    | ; If not equal jump to LocRetn

169B38A4 | C700 00000000    | MOV     DWORD PTR [EAX], 0          | ; Zero out pMemoryBasicInformation->BaseAddress

169B38AA | C740 04 00000000 | MOV     DWORD PTR [EAX+4], 0        | ; Zero out pMemoryBasicInformation->AllocationBase

169B38B1 | C740 10 00000100 | MOV     DWORD PTR [EAX+10], 10000   | ; Set pMemoryBasicInformation->State to MEM_FREE

169B38B8 | 58               | POP     EAX                         | ; Restore EAX

169B38B9 | C2 1800          | RETN    18                          | ; Return

169B38BC | 58               | POP     EAX                         | ; Restore EAX

169B38BD | C2 1800          | RETN    18                          | ; Return

; ZwGetContextThread_Hook

169B38C0 | 8B4C24 08        | MOV     ECX, DWORD PTR [ESP+8] | ; Get pContext

169B38C4 | C741 04 00000000 | MOV     DWORD PTR [ECX+4], 0   | ; Zero out DR0

169B38CB | C741 08 00000000 | MOV     DWORD PTR [ECX+8], 0   | ; Zero out DR1

169B38D2 | C741 0C 00000000 | MOV     DWORD PTR [ECX+C], 0   | ; Zero out DR2

169B38D9 | C741 10 00000000 | MOV     DWORD PTR [ECX+10], 0  | ; Zero out DR3

169B38E0 | C2 0800          | RETN    8                      | ; Return