Microsoft Patch Tuesday for January 2023 fixed actively exploited zero
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The Defender’s Window
OpenAI details how AI is reshaping offensive and defensive cybersecurity and outlines steps security teams should take now.
OpenAI published 'The Defender's Window,' discussing how AI is changing cybersecurity for both attackers and defenders. The piece describes how OpenAI is strengthening its own defenses and offers guidance on what security teams can do now to adapt, functioning largely as corporate thought leadership rather than an incident or research disclosure.
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Microsoft Defender's Own Driver Can Be Weaponized to Delete Security Software at Boot
Check Point revealed BTR Reforged, a technique weaponizing Microsoft Defender's built-in BTR.sys driver to delete security software at boot without exploiting any vulnerability.
Check Point Research disclosed BTR Reforged, a technique that abuses BTR.sys, a legitimately signed Windows Defender boot-time remediation driver, to perform arbitrary kernel-level file and registry operations on Windows 7 through Windows 11 25H2 without exploiting a software flaw. The BTR_CLI proof-of-concept tool, presented at Black Hat USA 2026 and DEF CON 34, installs the driver via direct registry writes and executes deletions during the boot-time 'golden window' before Defender's user-mode services start, demonstrated by deleting the full Defender stack on a patched Windows 11 machine. Exploitation requires SeLoadDriverPrivilege; Microsoft confirmed it does not meet criteria for immediate servicing and no patch is planned. No evidence of real-world abuse was found, and related indicators of compromise via Sysmon events were published.
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Mustang Panda Upgrades CoolClient With a Kernel Rootkit
Mustang Panda's updated CoolClient backdoor deploys a signed kernel driver to hide processes, files and network activity in Asian intrusions.
Kaspersky analysis shows Mustang Panda (HoneyMyte) upgraded its CoolClient espionage backdoor with a signed kernel-mode driver installed as a Windows service, communicating via IOCTL requests to hide processes, files and registry entries. In a Myanmar campaign the actor deployed PlugX first, then CoolClient via a fake Windows Defender directory and Sangfor defender.exe DLL sideloading, with scheduled task and AutoRun persistence and UAC bypass. The updated variant was observed in intrusions across Pakistan, Mongolia and Myanmar, with victims also in Russia including confirmed government entities.
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Researcher Releases FalconFlank PoC Showing Privilege Escalation in CrowdStrike Falcon
Researcher Chaotic Eclipse released FalconFlank, a zero-day privilege escalation PoC abusing CrowdStrike Falcon's Office macro remediation; CrowdStrike is investigating and issued a tech alert.
Researcher Chaotic Eclipse published FalconFlank, a proof-of-concept zero-day local privilege escalation in CrowdStrike Falcon Sensor that abuses the Microsoft Office malicious macros remediation feature, tested on fully updated Windows 11 25H2 and Windows Server 2025. CrowdStrike said it is investigating, advised disabling the Microsoft Office File Suspicious Macro Removal policy, and pointed customers to a FalconFlank tech alert, noting cloud anti-malware protection remains active. The article also covers related PoCs from the same researcher: HardBreacher against Kaspersky (fixed via update), ShieldBreak (CVE-2026-69414) against Microsoft Defender, an unpatched patch bypass of CVE-2026-50656, GreenSection against NVIDIA, and PrettyPrague against Avast, which Gen Digital patched in versions 26.7.11086 and 26.8.11125.
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Microsoft February 2021 Patch Tuesday fixes 56 bugs, including an actively exploited Windows zero
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