[VL] - Hunting CVE-2026-65400 Exploitation on macOS
CVE-2026-65400 affects the macOS Screen Sharing service and can allow an attacker on the network to authenticate without valid credentials. Huntress' research goes further, describing the pre-authentication path and opportunities to obtain root-level file access and ultimately code execution. First thing first: patch. Update affected devices to macOS Tahoe 26.6.1, Sequoia 15.7.9, or Sonoma 14.8.9. Apple released these versions on August 6 to address CVE-2026-65400. If patching is not immediately possible, disable Screen Sharing. After patching, we still need to answer the hunter's question: was any of this activity already happening before the update? The KQL below hunts across Microsoft Defender XDR telemetry for activity around the observed attack path: Screen Sharing file activity, SSH sessions, privileged file writes, LaunchDaemon persistence, process masquerading, Packet Filter changes, XMRig artefacts and related network activity. One process particularly worth reviewing is SSFileCopyReceiver / SSFileCopySender. Huntress notes that these are privileged Screen Sharing helpers, and their research highlights root-context activity and filesystem operations as useful hunting opportunities.
Microsoft Sentinel (KQL)
