Method and system for persisting untrusted files

A method performed in a computer having a processor and a memory containing instructions executable by the processor to provide a host operating system and a container operating system isolated from the host operating system by a secure boundary, comprising:

• receiving, at the container operating system, a request for performing a file operation on a file stored in the host operating system;
• and
• upon receiving the request,
• determining, at the host operating system, a trust level assigned to the file, the trust level representing a level of security threat to the host operating system from performing the requested file operation on the file;
• in response to determining that the trust level assigned to the file meets or exceeds a predetermined trust threshold, performing the requested file operation on the file in the host operating system and denying access to performing the file operation in the container operating system;
• and
• in response to determining that the trust level assigned to the file does not meet or exceed the predetermined trust threshold, performing the requested file operation on the file in the container while preventing the file operation from being performed in the host operating system.

A method performed in a computer having a processor and a memory containing instructions executable by the processor to provide a host operating system and a container operating system isolated from the host operating system by a secure boundary, comprising:

• detecting a file operation request directed to a file stored in the computer is received in the container operating system;
• and
• upon receiving the request,
• determining, at the host operating system, a trust level assigned to the file by accessing metadata of the file, the trust level representing a level of security threat to the host operating system from performing the requested file operation on the file;
• in response to determining that the trust level assigned to the file meets or exceeds a predetermined trust threshold, denying access to the container operating system for performing the file operation;
• and
• in response to determining that the trust level assigned to the file does not meet the predetermined trust threshold,
• preventing the file operation from being performed in the host operating system;
• and
• performing the file operation in the container operating system by exchanging data with the host operating system without exposing a file system of the host operating system to the container operating system.