If your system disk is encrypted using
DiskCryptor, the system may stop loading after updating the Windows Defender database to version 118.1.0.0 of 10/24/2017.
Defender defines the bootloader as
Win32 / Tibbar.A and overwrites the MBR. DiskCryptor itself is defined as Trojan: Win32 / Rundas.B.
In the Windows Defender log, you can see the message:
Windows Defender has detected malware or other potentially unwanted software.
For more information please see the following:
http://go.microsoft.com/fwlink/?linkid=37020&name=Ransom:DOS/Tibbar.A&threatid=2147724200&enterprise=0
Name: Ransom:DOS/Tibbar.A
ID: 2147724200
Severity: Severe
Category: Trojan
Path: boot:_\Device\Harddisk0\DR0\(MBR)\(MBR)
Detection Origin: Local machine
Detection Type: Concrete
Detection Source: System
User: NT AUTHORITY\SYSTEM
Process Name: Unknown
Signature Version: AV: 1.255.60.0, AS: 1.255.60.0, NIS: 118.1.0.0
It is clear that this is done to protect against Ransomware, which uses DiskCryptor as an encryption tool, for example,
Mamba Ransomware , but in this case, ordinary users suffer from it as a means of protection.
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At the moment I do not see any alternatives to the DiskCryptor loader, since it allows you to set various actions if the boot password is not entered for a certain time or is entered incorrectly. He also allows you to hide the text of the password request at boot time. And the process of creating a decoy system is much easier than in the same VeraCrypt. If you know the alternative to DiskCryptor with the same functionality, please share in the comments.
Update: Most likely, the addition of DiskCryptor to the anti-virus database is caused by the appearance of the
Bad Rabbit trojan,
an article on Habré .