Microsoft integrates ai.exe in Office 365; an explanation; and some trouble

[German]I am taking up an issue that has been brought to my attention several times now by blog readers and concerns users of Microsoft Office. Since "recently", attentive users have noticed that there is suddenly a program ai.exe on their system, which starts a process with Office applications, and can cause trouble. I'll take up the topic and summarize what I have found out in the meantime.


Microsoft 365 Copilot for Office Apps

Microsoft had unveiled its CoPilot feature for Microsoft 365 in March 2023 and announced that it would build this feature into its Office apps like Word, Excel, PowerPoint. Microsoft 365 Copilot uses machine learning (AI) models to extend the functionality of its Office apps like Word, Excel, PowerPoint. One combines the power of large language models (LLMs) with business data and the Microsoft 365 apps. Currently the feature isn't included in Office, but on it's way.

Readers report a new AI.exe prozess

I've received several references to "AI integration" in Microsoft Office from German blog readers over the past few days. Blog reader Fred writes in this comment (I've translated it):

Also worth mentioning: Microsoft is starting to integrate AI into MS Office. What you can do with it as a user or what Office does with it, I don't know yet either.

and has included the following screenshot (click to see the enlarged image).

Microsoft AI in Office 365
Microsoft AI in Office 365; Click to zoom

German blog reader Michael contacted me by email yesterday to alert me to the issue as well. He wrote the following about it (I've translated it):


Office 365: Artificial Intelligence (AI) Host start with e.g. Outlook

Hello Mr. Born,

I don't know with which build Microsoft delivers the AI Host. But it is a fact that the AI Host sometimes (not always) starts with one of the Office 365 programs additionally – see Task Manager.

Microsoft AI in Outlook

The AI stuff is called AI.exe and is stored here:

C:\Program Files\Microsoft Office\root\vfs\ProgramFilesCommonX64\Microsoft Shared\Office16

[…]Now the question, are you already aware of this and: aren't there already additional data protection concerns (GDPR)?

And in this comment German user Jo wrote "But with my processes now also an "ai.exe" (creation date March 07, 2023) runs".

Some mentions and some background about ai.exe

Blog reader Michael has referred in his mail to the post How do I disable the "Artificial Intelligence (AI) Host on April 9, 2023. Furthermore, Windows Latest published the post Microsoft 365 quietly adds Artificial Intelligence (AI) Host to Windows 11, Windows 10 about it on April 10, 2023.

The first "finds" of these components were reported in the Microsoft Answers forum back in November 2022. A Microsoft employee describes the approach there and lists the binaries involved.

Local Artificial Intelligence ( AI ) in Microsoft Office desktop apps on Windows was recently moved out-of-process. In other words, Office desktop apps ( like Word, Outlook, PowerPoint, etc. ) now communicate with another program ( ai.exe ) to perform most local AI.

For Microsoft Office desktop apps on Windows, the following are the main binaries associated with local AI:

  • aitrx.dll: The transceiver ( trx ) library loaded by Office desktop apps to transmit inputs to and receive outputs from ai.exe.
  • ai.exe: The executable used to host ai.dll. This executable receives inputs from aitrx.dll in an Office desktop app, runs those inputs through ai.dll to get the associated outputs, and transmits those outputs back to aitrx.dll in the Office desktop app.
  • ai.dll: The main library containing various AI functionality ( esp. from the onnxruntime and onnxruntime-extensions ).
  • mlg.dll: A natural language processing related library loaded as needed by ai.dll. This contains code created by Microsoft's Machine Learning Group ( MLG ).
  • aimgr.exe: The manager ( mgr ) executable used to manage various instances of ai.exe across Office desktop apps. Note: At the time of this reply, this executable is not yet enabled outside of Microsoft.

The post also gives the paths to these program files. The contributor gives some more hints on how the modules work. What will happen there in the future in terms of functionality (CoPilot) is open.

CPU load due to AI.exe

German blog reader Holger took up the topic of AI.exe in a completely different context in this comment. He suddenly got problems with the CPU load of the system and wrote (I've translated the comment):

I'm not sure if this fits in here, but AI.exe of the MS Office Suite has kept my system permanently busy since the last update.

It was installed without being asked and without any options, nor can it be deactivated or uninstalled anywhere.

It is also very popular with other users: How do I disable the "Artificial Intelligence (AI) Host [etc]" feature?

I only checked my mails in Outlook, so I didn't want an ai.exe to load the system all the time after closing the program. After the kill in Process Explorer, the CPU temp went directly from over 50°C down to 40°C.

The forum post in Microsoft Answers linked by Holger is already five pages long. On there is this thread on the topic and suspects "spyware" from Microsoft – but the explanation above says, it's a feature from office modules moved into a separate process.

Now the question remains how to disable this stuff. If you want to prevent the AI components that were silently installed on the systems via update from starting, you can rename them, as listed in the article How do I disable the "Artificial Intelligence (AI) Host [etc]" feature? But then the local AI component of Office will no longer work. And Joshua Burkholder points out in his answer in the Microsoft Answers forum that this renaming is undone with every Office update, because the binaries are recopied onto the system. I've received comments, that people created a script that kills the processes and renames the .exe via auto start.

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One Response to Microsoft integrates ai.exe in Office 365; an explanation; and some trouble

  1. AnnoyedMS User says:

    Just realised this process is running on our terminal server (6 users). Our Bandwidth in to the server has inceased by 10 times! This is ridiculous and should not have been dropped on us without options to install it.

    Very concerned and have now blocked the .exe from running. Has no impact on Office if stopped.

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