Tech Alert | Windows crashes related to Falcon Sensor | 2024-07-19

Published Date: Jul 19, 2024

Summary

• CrowdStrike is aware of reports of crashes on Windows hosts related to the Falcon Sensor.

Details

• Symptoms include hosts experiencing a bugcheck\blue screen error related to the Falcon Sensor.
• Windows hosts which have not been impacted do not require any action as the problematic channel file has been reverted.
• Windows hosts which are brought online after 0527 UTC will also not be impacted
• Hosts running Windows7/2008 R2 are not impacted.
• This issue is not impacting Mac- or Linux-based hosts
• Channel file “C-00000291*.sys” with timestamp of 0527 UTC or later is the reverted (good) version.
• Channel file “C-00000291*.sys” with timestamp of 0409 UTC is the problematic version.

Current Action

• CrowdStrike Engineering has identified a content deployment related to this issue and reverted those changes.

• If hosts are still crashing and unable to stay online to receive the Channel File Changes, the following steps can be used to workaround this issue:

Workaround Steps for individual hosts:

• Reboot the host to give it an opportunity to download the reverted channel file.  If the host crashes again, then:

  • Boot Windows into Safe Mode or the Windows Recovery Environment

    • Note:  Putting the host on a wired network (as opposed to WiFi) and using Safe Mode with Networking can help remediation.

  • Navigate to the %WINDIR%\System32\drivers\CrowdStrike directory

  • Locate the file matching “C-00000291*.sys”, and delete it.

  • Boot the host normally.

Note:  Bitlocker-encrypted hosts may require a recovery key.

Workaround Steps for public cloud or similar environment including virtual:

Option 1:

• Detach the operating system disk volume from the impacted virtual server

• Create a snapshot or backup of the disk volume before proceeding further as a precaution against unintended changes

• Attach/mount the volume to to a new virtual server

• Navigate to the %WINDIR%\\System32\drivers\CrowdStrike directory

• Locate the file matching “C-00000291*.sys”, and delete it.

• Detach the volume from the new virtual server

• Reattach the fixed volume to the impacted virtual server

Option 2:

• Roll back to a snapshot before 0409 UTC.

AWS-specific documentation:

• To attach an EBS volume to an instance
• Detach an Amazon EBS volume from an instance

Azure environments:

Please see this Microsoft article.

Bitlocker recovery-related KBs:

• BitLocker recovery in Microsoft Azure
• BitLocker recovery in Microsoft environments using SCCM
• BitLocker recovery in Microsoft environments using Active Directory and GPOs
• BitLocker recovery in Microsoft environments using Ivanti Endpoint Manager
• BitLocker recovery in Microsoft environments using ManageEngine Desktop Central

Latest Updates

• 2024-07-19 05:30 AM UTC | Tech Alert Published.
• 2024-07-19 06:30 AM UTC | Updated and added workaround details.
• 2024-07-19 08:08 AM UTC | Updated
• 2024-07-19 09:45 AM UTC | Updated
• 2024-07-19 11:49 AM UTC | Updated
• 2024-07-19 11:55 AM UTC | Updated

Support

• Find answers and contact Support with our Support Portal

Can someone explain why we’ve normalized companies like Crowdstrike shipping kernel-level spyware to millions of computers around the world?

It’s bad enough that they’re shipping code to customers like this without proper QA, but the fact that it’s bootlooping millions of computers kinda shines a light on how dumb this system is.