WaitList.dat File on Your Windows Machine? Immediate Red Flag!

There is a nasty new finding applicable to Windows hosts (tablets, convertibles, and some laptops) with handwriting recognition enabled. According to Techspot and B2dfir, Windows contains a file called WaitList.dat which has been found to contain exposed text from email, contacts, and written documents when processed using handwriting recognition. The data is used by the Windows Search Indexer Service so that handwriting recognition can also be included within search requests. But this is a nasty side effect associated with indexing. It also creates a single point – although in a locked file – for a variety of sensitive information and history to reside with no mitigation for cleanup, encryption, or protection.

The file itself is located at the following path:

C:\Users\%User%\AppData\Local\Microsoft\InputPersonalization\TextHarvester\WaitList.dat

Testing the Problem

If you would like to see the potential risk for yourself, handwriting recognition and indexing must be enabled in order for the file to populate. To do so, make sure these pre-requisites are enabled and open Word, OneNote, or your favorite text editor. Using the handwriting recognition function on your touch-enabled screen, write a few sentences or something uniquely identifiable. Then save the file. After a few hours, Windows will index the text and populate the WaitList.dat file. Then, open the file and you will see the processed indexed text. Simply shocking.

What are the Risks? What are the Steps to Mitigation?

Currently, there is no known malware or threats that target this file but with the recent public disclosure, it will only be a few weeks before something will show up in the wild. For those in highly secure environments, there are a few mitigation procedures to take until Microsoft devises a method to encrypt or protect this file:

• Using Group Policy, disable handwriting recognition on all affected devices: HKEY_CURRENT_USER\SOFTWARE\Microsoft\InputPersonalization.
• Educate team members not to use handwriting recognition when documenting sensitive information until a remediation is available.
• Implement File Integrity Monitoring with PowerBroker for Windows to restrict access from individual users and only allow the System to access the file.

To implement the last recommendation, create a rule similar to this example (it may vary based on your implementation):

This will block all access (Everyone) and should allow the System to still process the file.

While this potential flaw appears all the way back to Windows 8 (and potentially earlier), the risks for data exposure should not be ignored. If you’d like to learn more about how PowerBroker for Windows can protect access to this file, or any other on your resources, contact us today.