Microsoft Releases Mitigation for Yellowkey No Time Machine available
In TOP STORIES #167 I covered YellowKey with a blunt warning. If a Windows 11 notebook was protected only by standard TPM-based BitLocker and it disappeared, you could no longer simply assume the data was safe.
Microsoft has now published mitigation guidance for CVE-2026-45585, the BitLocker security feature bypass linked to YellowKey. Cybersecurity News reports that the issue affects Windows 11, Windows Server 2022 and Windows Server 2025, and works through the Windows Recovery Environment, WinRE.
The mitigation is important, but let’s not pretend it is magic.
It helps protect machines you still control.
It does not fix notebooks that have already been stolen, lost, donated, recycled, handed to an employee’s cousin, or left in that mysterious “old equipment” cupboard nobody wants to own.
If the device has already gone, the horse has bolted. And in this case, the horse may be holding a USB stick.
Microsoft’s mitigation involves modifying the WinRE image and removing the risky autofstx.exe entry from the BootExecute registry value, then re-establishing BitLocker trust. Microsoft is also recommending that organisations move away from TPM-only BitLocker and use TPM plus PIN for stronger protection.
The message is simple that you can no longer treat BitLocker as a checkbox.
Review high-risk Windows 11 notebooks first, especially executives, finance, HR, legal, developers, administrators, and anyone carrying customer data, pricing models, credentials, confidential mail, or sensitive documents.
Check the basics properly.
- Is BitLocker enabled?
- Is it TPM-only or TPM plus PIN?
- Is Secure Boot enabled?
- Is USB boot restricted where practical?
- Is BIOS or UEFI protected?
- Are recovery keys safely escrowed?
- Are Windows, firmware and BIOS updates current?
- Is Intune, Defender for Endpoint, or your endpoint platform reporting the real state of the device?
For devices already stolen or disposed of, assume you may have a data exposure problem until proven otherwise. Disable the device, revoke sessions, reset credentials, review MFA methods, block access through Conditional Access and check sign-in activity.
Remote wipe is useful only if the machine comes online and connects to the internet. If it stays offline, it will not wipe. That is not a security control, that is still just a wish with a Wi-Fi wand.
Please contact your First Technology Group account manager to connect with our security and endpoint specialists to review BitLocker, WinRE mitigation, Secure Boot, Intune compliance, and stolen-device response, and to assist in implementing the mitigation before the next notebook turns into someone else’s goldmine.
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