Late last week it was announced the security firm Swiss security firm ModZero had responsibly disclosed (defined) to HP back in early April 2017 their discovery of an audio driver (Conexant HD Audio) containing a keylogger. The driver is known to be present on 28 HP devices (listed here).
Conexant also creates drivers to Asus, Lenovo and Dell, at this time it is not clear if they use the same driver (security analysts have been unable to discover any other devices using the affected driver).
How can I tell if my HP (or other device) is affected by this vulnerability?
This BleepingComputer article explains how to check for this vulnerability.
Why should this vulnerability be considered important?
The affected audio driver (versions 126.96.36.199 up to and including 188.8.131.52) contained the issue with the issue first being created in December 2015. Thus it has the potential to have gathered a vast quantity of information since this time.
Not only does the driver record key presses (using a low-level keyboard input hook (defined)) but the driver exposes the OutputDebugString and MapViewOfFile APIs (API, defined). The OutputDebugString API enables any running application to capture keystrokes while MapViewOfFile enables any framework or application with access to MapViewOfFile API to do the same.
Since the unencrypted keystrokes are stored in a text file, forensic investigators with access to the log file (stored at C:\Users\Public\MicTray.log) could potentially recover previously saved sensitive data (a reboot or power of the device clears the file). When backups of the affected systems are performed previous versions of this file would contain further captured (and potentially sensitive) information.
Since our keyboards are used to enter all kinds of sensitive information, emails, chat/instant message conversations, social media posts, credit card numbers etc., this vulnerability could have serious consequences If the log contents were to be obtained by cyber criminals. The file might also contain credentials (usernames/passwords for the above mentioned activities.
From the information disclosed about this vulnerability, there is evidence to suggest the driver uploads/sends the information it gathers within that log to HP, Conexant or anyone else. However if you are creating unencrypted backups within a corporate, small business or consumer environment this file over time will contain more and more information gathered over time. If someone knew you create these backups and knew where to look within them (assuming they are not encrypted), they could gather significant volumes of sensitive information.
How can I protect myself from this vulnerability?
After ModZero disclosed this information to HP, HP made available a driver update (version 10.0.931.90) which removes the keylogging behavior. Moreover, the driver update will be made available via Windows Update for both 2016 and 2015 HP devices. HP Vice President Mike Nash clarified the logging feature of the driver was simply debugging code (defined) inadvertently left within the driver.
If you followed the steps above to check if your device was vulnerable but there is no driver update available, the same BleepingComputer article describes how to mitigate the vulnerability.