Microsoft explains Windows 11 Recall in a revised version

[German]Microsoft is preparing to offer the Recall function again in Windows 11 24H2. After the disaster a few months ago, this function is optional and, according to Microsoft, has been significantly revised. In a post, Microsoft explains what has been changed. Will this be enough for safe use in private and enterprise environments?

Copilot+AI and Recall

Recall-Funktion enables Windows to constantly take screenshots of the user's screen and use a generative AI model to process the data and make it searchable. Microsoft's promise was that the user would then only have to type in a keyword to find out when they might have done something or where the documents with that keyword can be found on their computer. I first discussed Recall in the blog post Microsoft's AI PC with Copilot – some thoughts – Part 1 as part of the "Copilot+PC" concept presented by Microsoft.

The Recall fiasco some months ago

With Recall, "a surveillance feature" is implemented in Windows that precisely records everything the user does and then makes it searchable. The computer that once started as a "personal PC" then no longer shows anything personal – everyone becomes transparent – a nightmare for every user.

Security researchers tore the concept apart and Microsoft was forced to withdraw Recall and fundamentally revise it. I took up the topic in the article Copilot+AI: Recall, a security disaster – AI-assisted theft. At the beginning of September 2024, Recall was reintroduced via an update in Windows 11 24H2 (see Windows 11 24H2: Update KB5041865 ships Recall).

Microsoft explains the new features

David Weston, Vice President Enterprise and OS Security at Microsoft, has now explained the new Recall version in more detail in the article Update on Recall security and privacy architecture näher erläutert.

Recall is provided as an opt-in during setup – only for Copilot+ PCs, according to my reading. According to Microsoft, users will have the option to opt-in to the storage of snapshots with Recall.

If a user chooses not to use the feature, Recall will be turned off and no snapshots will be taken or saved. Users can also remove Recall completely by using the settings for optional functions in Windows.

The impression remains that the massive protests from users and the risk that the whole thing in its previous form violates the European GDPR and other laws has brought about an absolute paradigm shift at Microsoft.

Microsoft promises that the user is always in control. With regard to the point that secrets can be accessed without authorization via Recall, Microsoft writes that sensitive data in Recall is now always stored in encrypted form and the keys are protected.

Snapshots and all associated information should be stored in encrypted form in the vector database. The encryption keys are protected via the Trusted Platform Module (TPM). This binds them to a user's Windows Hello Enhanced Sign-in Security identity. Only processes within a secure environment (implemented as a virtualization-based security enclave, VBS) can be accessed. Other users should not have access to these keys and therefore not be able to decrypt this information.

Within Recall, the services that work with screenshots and associated data or carry out decryption processes are located in the aforementioned secure VBS enclave, according to Microsoft. The only information that leaves the VBS enclave should be the data requested by the user when actively using Recall.

Recall uses Windows Hello Enhanced Sign-in Security to authorize Recall-related operations. This includes actions such as changing Recall settings and authorizing access to the Recall user interface (UI) during runtime. According to Microsoft, Recall also protects against malware through rate-limiting and anti-hammering measures. However, once configured, Recall currently only supports PIN as a fallback method to prevent data loss if a secure sensor is corrupted.

Microsoft promises that snapshots will only be taken or saved locally if the user so wishes. Recall will not share snapshots or associated data with Microsoft or third parties, nor will they be shared between different Windows users on the same device. Windows asks for user consent before saving snapshots. They should always be in control and can delete, pause or turn off snapshots at any time. Future options for sharing data will require the explicit consent of the user.

My two cents

It was a disaster what Microsoft presented with the first recall draft. What they have put together in the meantime, and how secure the whole thing really is, remains an open question for me at the moment. Only people equipped with a Copilot+AI PC and Windows 11 24H2 will be able to test it.

Microsoft is currently making a lot of promises, but I don't see how much of them can be kept in the long term. The fundamental problem remains: A bug is installed on a "Personal Computer" (PC), which admittedly has to be activated by the user. But who is to say that the user cannot be forced or duped into giving access to the data? We'll see what other "collateral damage" Recall causes.

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