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Dell Webcam Software Bundled ActiveX Control CrazyTalk4Native.dll sprintf Remote Buffer Overflow Vulnerability

Dell Webcam Software Bundled ActiveX Control CrazyTalk4Native.dll 
sprintf Remote Buffer Overflow Vulnerability

Tested against: Microsoft Windows Vista SP2
                Microsoft Windows XP SP3
                Microsoft Windows 2003 R2 SP2
                Internet Explorer 7/8/9

download url of a test version: 

file tested: Dell_SX2210-Monitor_Webcam SW RC1.1_ R230103.exe

This package contains the Dell Webcam Central software
developed by Creative Technologies for Dell.


I think this is a very common ActiveX, probably bundled with Dell Notebooks.

The mentioned software carries a third party ActiveX Control
with the following settings.

Binary path: C:\Program Files\Common Files\Reallusion\CT Player\crazytalk4.ocx
ProgID: CRAZYTALK4.CrazyTalk4Ctrl.1
CLSID: {13149882-F480-4F6B-8C6A-0764F75B99ED}
Safe for Scripting (Registry): True
Safe for Initialization (Registry): True

This control is marked safe for scripting and safe for initialization,
then Internet Explorer will allow scripting of this control from remote.


The 'BackImage' ,'ScriptName', 'ModelName' and 'SRC' properties
can be used to trigger a buffer overflow condition.
The crazytalk4.ocx ActiveX control will load the close CrazyTalk4Native.dll
library and, while constructing a local file path, will call sprintf()
with an insufficient size.

Call stack of main thread
Address    Stack      Procedure / arguments                                                                                             Called from                   Frame
0012EE24   023D4FAB   msvcrt.sprintf                                                                                                    CrazyTal.023D4FA5
0012EE28   0012F180     s = 0012F180
0012EE2C   023F431C     format = "%s%s%s"
0012EE30   042A2D6C     <%s> = "C:\DOCUME~1\Admin\LOCALS~1\Temp\RLTMP\~RW463\"
0012EE34   0012EF5C     <%s> = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
0012EE38   0012EE58     <%s> = ""
0012F164   023D601D   CrazyTal.023D4F20     

code, CrazyTalk4Native.dll :
023D4F80   85C0             test eax,eax
023D4F82   74 38            je short CrazyTal.023D4FBC
023D4F84   8B9C24 2C030000  mov ebx,dword ptr ss:[esp+32C]
023D4F8B   8D4424 1C        lea eax,dword ptr ss:[esp+1C]
023D4F8F   8D8C24 20010000  lea ecx,dword ptr ss:[esp+120]
023D4F96   50               push eax
023D4F97   81C6 443B0000    add esi,3B44
023D4F9D   51               push ecx
023D4F9E   56               push esi
023D4F9F   68 1C433F02      push CrazyTal.023F431C                   ; ASCII "%s%s%s"
023D4FA4   53               push ebx
023D4FA5   FF15 E4F33E02    call dword ptr ds:[<&MSVCRT.sprintf>]    ; msvcrt.sprintf

As attachment, proof of concept code which overwrites EIP and SEH.

0:008> lm -vm CrazyTalk4Native
start    end        module name
021c0000 0220b000   CrazyTalk4Native   (deferred)             
    Image path: C:\PROGRA~1\COMMON~1\REALLU~1\CTPLAY~1\CrazyTalk4Native.dll
    Image name: CrazyTalk4Native.dll
    Timestamp:        Thu May 17 12:13:42 2007 (464C2AD6)
    CheckSum:         00048AB2
    ImageSize:        0004B000
    File version:     4.5.815.1
    Product version:
    File flags:       0 (Mask 3F)
    File OS:          4 Unknown Win32
    File type:        2.0 Dll
    File date:        00000000.00000000
    Translations:     0409.04b0
    CompanyName:      C3D
    ProductName:      CrazyTalk4 ActiveX Control Module
    InternalName:     CrazyTalk4
    OriginalFilename: CrazyTalk4.OCX
    ProductVersion:   4, 0, 0, 1
    FileVersion:      4, 5, 815, 1
    PrivateBuild:     4, 5, 815, 1
    SpecialBuild:     4, 5, 815, 1
    FileDescription:  CrazyTalk4 Native Control Module
    LegalCopyright:   Copyright (C) 2005
    LegalTrademarks:  Copyright (C) 2005
    Comments:         Copyright (C) 2005

proof of concept: http://retrogod.altervista.org/9sg_dell_poc_nodep.html