Suspicious file downloads requiring additional backend processing to reach a determination will be locked by Microsoft Defender Antivirus on the first machine where the file is encountered, until it is finished uploading to the backend. In many cases this process can reduce the response time to new malware from hours to seconds. The cloud will perform additional analysis to reach a determination, blocking all future encounters of that file. Only after the cloud has received the file will Microsoft Defender Antivirus release the lock and let the file run.

If the cloud backend is unable to make a determination, the file will be locked by Microsoft Defender Antivirus while a copy is uploaded to the cloud. The cloud backend will apply heuristics, machine learning, and automated analysis of the file to determine the files as malicious or clean. When a Microsoft Defender Antivirus client encounters a suspicious but undetected file, it queries our cloud protection backend. See also: Use next-gen technologies in Windows Defender Antivirus through cloud-delivered protection | Microsoft Docs Block at First Sight requires a number of Group Policy settings to be configured correctly or it will not work. Some malware can also be programmed to run at unexpected times, not only when it's installed.īlock at First Sight is a feature of Microsoft Defender Antivirus cloud protection starting with Windows 10 Anniversary Update ( version 1607) that provides a way to detect and block new malware within seconds. Malware can infect your PC without your knowledge: it might install itself from an email message, when you connect to the Internet, or when you install certain apps using a USB flash drive, CD, DVD, or other removable media. Microsoft Defender Antivirus helps protect your PC against malware (malicious software) like viruses, spyware, and other potentially unwanted software.

How to Enable or Disable Microsoft Defender Antivirus Block at First Sight in Windows 10

Enable microsoft defender