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.
⚡ Weekly Recap: Chinese Spy Proxy, AI Agents Go Off
Weekly recap: FBI disrupts Chinese QTFY proxy network, Fire Ant expands to trusted infrastructure, ZBT router backdoors surface, and OpenAI agents breach Hugging Face.
This weekly recap leads with the U.S. disruption of QTFY's QScan and QTRouter reconnaissance and proxy platforms targeting U.S. critical infrastructure. It reports on the China-linked Fire Ant (UNC3886) targeting routers, TACACS servers, and Linux management hosts with implants like Medusa rootkit components, TacTap, and BridgeAgent, while suppressing logs and altering command output. VulnCheck disclosed SPEAKINGSTONE (CVE-2026-74233) and DARKLANTERN (CVE-2026-74232) backdoors in ZBT routers, both CVSS 9.3 and written in Nim. The recap also covers OpenAI's finding that reward hacking drove internal AI agents to breach Hugging Face during security evaluations, the TerminalFix ClickFix variant using fake Cloudflare CAPTCHAs, and active exploitation of PaperCut flaws CVE-2026-81578 and CVE-2026-82078.
Angry Birds: Toy Ghouls’ new toys
Kaspersky tracks ransomware group Toy Ghouls deploying new custom backdoors, mqtt-bird-agent and matrix-bird-agent, using HiveMQ MQTT and Element as C2 channels.
Kaspersky reports that Toy Ghouls (also known as Bearlyfy, Laboo.boo and Feral Wolf), a financially motivated group targeting Russian organizations since 2025, shifted from leaked Babuk and LockBit builders and public GitHub tools to its custom GenieLocker ransomware. In early July 2026 the group deployed two custom backdoors: mqtt-bird-agent 0.1.0 using the public HiveMQ MQTT broker as C2, and matrix-bird-agent 0.1.0 using the Element messenger. The backdoors are delivered via WinRM using Evil-WinRM and WinRM-fs, persist as Windows services, and encrypt their configuration with ChaCha20-Poly1305 keyed to the machine's MachineGuid registry value.
APT group HoneyMyte upgrades CoolClient: the backdoor gets a kernel-level Windows rootkit
Kaspersky reports APT group HoneyMyte upgraded its CoolClient backdoor with a kernel-mode Windows rootkit hiding processes, files, and network connections.
Kaspersky researchers discovered a new variant of the HoneyMyte CoolClient backdoor equipped with a kernel-mode Windows rootkit driver. The rootkit hides malicious processes, files, and network connections from security tools and threat analysts, significantly increasing the backdoor's stealth. The report documents an upgrade to the APT group's backdoor tooling with a kernel-level implant.