CAL-20070730-1 BlueSkyCat ActiveX Remote Heap Overflow vulnerability Jul 31 2007 12:36AM
Code Audit Labs (vulnhunt gmail com)
CAL-20070730-1 BlueSkyCat ActiveX Remote Heap Overflow vulnerability


BlueSkychat is a professional voice and video chat software widely used
by large chat websites in china.


Code Audit Labs Code Audit for BlueSkyCat ActiveX Control and discovered
a vulnerability .

Remote exploitation of a buffer overflow in an ActiveX control
with Bluesky.cn could allow for the execution of arbitrary code.

When Blueskychat are installed, they register the following ActiveX
control on the system:

ProgId: V2.V2Ctrl.1
ClassId: 2EA6D939-4445-43F1-A12B-8CB3DDA8B855
File: v2.ocx

This control contains a buffer overflow in its ConnecttoServer() method.

This is a clent side vulnerability. So the clients of following chat
servers which install the affected BlueSkyCat software are affected.
bliao http://www.bliao.com
qqliao http://www.qqliao.com
7liao http://www.7liao.com
haoliao http://www.haoliao.net
51liao http://chat.51liao.net
heshang http://www.heshang.net
xicn http://vchat.xicn.net
CN104 http://www.cn104.com
liao-tian http://www.liao-tian.com
aliao http://www.aliao.net
kuailiao http://www.kuailiao.com
mtliao http://www.mtliao.com
pj0427 http://www.pj0427.com
uighur http://chat.uighur.cn
wmliao http://www.wmliao.com

We request a CVE number to assign to this vulnerability.

Affected version:
v2.ocx version and prior

BlueSky http://www.bluesky.cn/

<OBJECT ID="com" CLASSID="CLSID:{2EA6D939-4445-43F1-A12B-8CB3DDA8B855}">
<SCRIPT language="javascript">

function ClickForRunCalc()
var heapSprayToAddress = 0x0d0d0d0d;

var payLoadCode = "A" ;
while (payLoadCode.length <= 10000) payLoadCode+='A';
<button onclick="javascript:ClickForRunCalc();">ClickForRunCalc</button>

Code Audit Labs Suggestion
for vendor:
Do a full coverage Code Audit or Code Review

for client:
The following workarounds are available for this vulnerability:
* Disable Active Scripting
* Unregister the vulnerable control
* Set the killbit for the vulnerable control
* or update the software from http://www.bluesky.cn

1: 2007-07-29 notice vendor (mail to blueskychat (at) gmail (dot) com [email concealed])
2: 2007-07-29 the vendor reply "thank,had fixed it".
3: 2007-07-30 we check it out, in fact,the websites which install the
software did not almost all be updated,send mail to vendor again.
4: 2007-07-31 release this report

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