On September 30th, Microsoft Defender began deleting instances of Tor Browser from users’ PCs. The antivirus tool falsely identified Tor Browser as a “Win32/Malgent!MTB” trojan. Microsoft confirms that this was a false-positive and has removed Tor Browser from the latest Defender signature database (version 1.397.1910.0). You may now update Microsoft Defender and reinstall Tor Browser (or restore it from quarantine).
Source : Windows Defender Accidentally Flags Tor Browser as a Trojan
