Trick, treat, repeat

Welcome to this week's edition of the Threat Source newsletter. This one is pretty much an updated, Halloween-themed version of my newsletter from July, including data up through Q3. October 14th has passed, so free support for Windows 10 has come to an end, leaving you with no more fixes unless...

Patch Tuesday, October 2025 ‘End of 10’ Edition

Microsoft today released software updates to plug a whopping 172 security holes in its Windows operating systems, including at least two vulnerabilities that are already being actively exploited. October's Patch Tuesday also marks the final month that Microsoft will ship security updates for...

The king is dead, long live the king! Windows 10 EOL and Windows 11 forensic artifacts

Introduction Windows 11 was released a few years ago, yet it has seen relatively weak enterprise adoption. According to statistics from our Global Emergency Response Team GERT investigations, as recently as early 2025, we found that Windows 7, which reached end of support in 2020, was encountered...

September 25, 2025—KB5066198 (OS Build 19045.6396) Preview

September 25, 2025—KB5066198 OS Build 19045.6396 Preview Windows Secure Boot certificate expirationImportant: Secure Boot certificates used by most Windows devices are set to expire starting in June 2026. Microsoft has been updating these certificates on consumer and non-managed business devices...

August 26, 2025—KB5063842 (OS Build 19045.6282) Preview

August 26, 2025—KB5063842 OS Build 19045.6282 Preview Windows Secure Boot certificate expirationImportant: Secure Boot certificates used by most Windows devices are set to expire starting in June 2026. Microsoft has been updating these certificates on consumer and non-managed business devices for...

August 12, 2025—KB5063889 (OS Build 10240.21100)

August 12, 2025—KB5063889 OS Build 10240.21100 Windows Secure Boot certificate expirationImportant: Secure Boot certificates used by most Windows devices are set to expire starting in June 2026. Microsoft has been updating these certificates on consumer and non-managed business devices for the pa...

May 28, 2025—KB5058481 (OS Build 19045.5917) Preview

May 28, 2025—KB5058481 OS Build 19045.5917 Preview Support for Windows 10 has ended on October 14, 2025 After October 14, 2025, Microsoft will no longer provide free software updates from Windows Update, technical assistance, or security fixes for Windows 10. Your PC will still work, but we...

May 27, 2025—KB5061978 (OS Build 17763.7322) Out-of-band

May 27, 2025—KB5061978 OS Build 17763.7322 Out-of-band Support for Windows 10 has ended on October 14, 2025 After October 14, 2025, Microsoft will no longer provide free software updates from Windows Update, technical assistance, or security fixes for Windows 10. Your PC will still work, but we...

April 16, 2025—KB5059091 (OS Build 17763.7249) Out-of-band

April 16, 2025—KB5059091 OS Build 17763.7249 Out-of-band Support for Windows 10 has ended on October 14, 2025 After October 14, 2025, Microsoft will no longer provide free software updates from Windows Update, technical assistance, or security fixes for Windows 10. Your PC will still work, but we...

March 25, 2025—KB5053643 (OS Build 19045.5679) Preview

March 25, 2025—KB5053643 OS Build 19045.5679 Preview Support for Windows 10 has ended on October 14, 2025 After October 14, 2025, Microsoft will no longer provide free software updates from Windows Update, technical assistance, or security fixes for Windows 10. Your PC will still work, but we...

February 25, 2025—KB5052077 (OS Build 19045.5555) Preview

February 25, 2025—KB5052077 OS Build 19045.5555 Preview Support for Windows 10 has ended on October 14, 2025 After October 14, 2025, Microsoft will no longer provide free software updates from Windows Update, technical assistance, or security fixes for Windows 10. Your PC will still work, but we...

February 15, 2022—KB5010415 (OS Builds 19042.1566, 19043.1566, and 19044.1566) Preview

February 15, 2022—KB5010415 OS Builds 19042.1566, 19043.1566, and 19044.1566 Preview 3/15/22 IMPORTANT Windows 10, version 20H2 will reach end of service on May 10, 2022 for devices running the Home, Pro, Pro Education, and Pro for Workstations editions. After May 10, 2022, these devices will no...

September 16, 2020—KB4577069 (OS Build 17763.1490) Preview

September 16, 2020—KB4577069 OS Build 17763.1490 Preview IMPORTANT Starting in July 2020, we will resume non-security releases for Windows 10 and Windows Server, version 1809 and later. There is no change to the cumulative monthly security updates also referred to as the "B" release or Update...

January 23, 2020—KB4534308 (OS Build 17134.1276)

January 23, 2020—KB4534308 OS Build 17134.1276 Windows 10, version 1803 the April 2018 Update Home and Pro editions have reached end of service. For Windows 10 devices that are at, or within several months of reaching end of service, Windows Update will automatically initiate a feature update wit...

January 23, 2020—KB4534318 (OS Build 16299.1654)

January 23, 2020—KB4534318 OS Build 16299.1654 Reminder March 12 and April 9 were the last two Delta updates for Windows 10, version 1709. Security and quality updates will continue to be available via the express and full cumulative update packages. For more information on this change please vis...

December 3, 2018—KB4478877 (OS Build 14393.2641)

December 3, 2018—KB4478877 OS Build 14393.2641 Windows 10, version 1607, reached end of service on April 10, 2018. Devices running Windows 10 Home or Pro editions will no longer receive monthly security and quality updates that contain protection from the latest security threats.To continue...

November 27, 2018—KB4467684 (OS Build 14393.2639)

November 27, 2018—KB4467684 OS Build 14393.2639 Windows 10, version 1607, reached end of service on April 10, 2018. Devices running Windows 10 Home or Pro editions will no longer receive monthly security and quality updates that contain protection from the latest security threats.To continue...

June 26, 2019—KB4509476 (OS Build 15063.1898)

June 26, 2019—KB4509476 OS Build 15063.1898 Reminder: March 12 and April 9 will be the last two Delta updates for Windows 10, version 1703. Security and quality updates will continue to be available via the express and full cumulative update packages. For more information on this change please...

May 28, 2019—KB4499162 (OS Build 15063.1839)

May 28, 2019—KB4499162 OS Build 15063.1839 Reminder: March 12th and April 9th will be the last two Delta updates for Windows 10, version 1703. Security and quality updates will continue to be available via the express and full cumulative update packages. For more information on this change please...

January 15, 2019—KB4480959 (OS Build 15063.1596)

January 15, 2019—KB4480959 OS Build 15063.1596 Windows 10, version 1703, reached end of service on October 8, 2018 . Devices running Windows 10 Home, Pro, Pro for Workstation, and IoT Core editions will no longer receive monthly security and quality updates that contain protection from the latest...