128 Seconds to disruption: Microsoft Defender stops ransomware at QNET

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What is device isolation?Case study: QNETAttack chain overviewMITRE ATT&CK techniques observedReferencesLearn more

Microsoft Defender’s attack disruption now includes device isolation, a new response action that extends autonomous protection directly to compromised endpoints.

At QNET, an attacker initiated a multi-stage attack using a legitimate Windows tool on a compromised endpoint to retrieve a malicious remote payload–a classic living-off-the-land (LOL) technique that often evades traditional containment. By automatically enforcing the new device isolation action on the compromised endpoint, Defender attack disruption stopped the attack dead in its tracks. From the first high-severity alert to completed isolation, after only 128 seconds, Defender cut off the attack chain before the second-stage payload could establish persistence or move beyond the host.

The growing threat: when the endpoint is the blast radius

Attack disruption has proven highly effective at stopping multistage, cross-domain attacks by disrupting the attacker’s ability to move across the environment. In many identity-driven attack scenarios, containing the compromised user is enough to shut down the attack chain, preventing lateral movement and limiting the attacker’s ability to access additional systems, identities, and resources.

However, we are increasingly seeing a different class of high-severity incidents that begin with initial access directly on the device. Once adversaries establish a foothold on an endpoint, they can plant multiple persistence …

Vollständiger Originalartikel ↗

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• Originalquelle / Hersteller-Advisory lesen: https://www.microsoft.com/en-us/security/blog/2026/08/04/129-seconds-disruption-microsoft-defender-stops-ransomware-qnet/
• Verfügbaren Patch oder Workaround einspielen und dokumentieren.