Method and system for secure running of untrusted content

• US 6,505,300 B2
• Filed: 06/12/1998
• Issued: 01/07/2003
• Est. Priority Date: 06/12/1998
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Ward, Richard B., Shah, Bharat, Swift, Michael M., Chan, Shannon, Jensenworth, Gregory, Goertzel, Mario C.
• Primary Examiner(s): Peeso, Thomas R.
• Application Number:
  US09/097,218
• Publication Number:
  US 20020019941A1
• Time in Patent Office: 1,670 Days
• Field of Search: 713/164-167, 713/200-201, 713/162, 710/240, 709/229
• US Class Current: 713/164
• CPC Class Codes: G06F 21/53 by executing in a restricted environment, e.g. sandbox or secure virtual machine
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database
• CPC Class Codes: G06F 2221/2101 Auditing as a secondary aspect
• CPC Class Codes: G06F 2221/2141 Access rights, e.g. capability lists, access control lists, access tables, access matrices
• CPC Class Codes: G06F 2221/2145 Inheriting rights or properties, e.g., propagation of permissions or restrictions within a hierarchy
• CPC Class Codes: G06F 2221/2149 Restricted operating environment

Abstract

Restricted execution contexts are provided for untrusted content, such as computer code or other data downloaded from websites, electronic mail messages and any attachments thereto, and scripts or client processes run on a server. A restricted process is set up for the untrusted content, and any actions attempted by the content are subject to the restrictions of the process, which may be based on various criteria. Whenever a process attempt to access a resource, a token associated with that process is compared against security information of that resource to determine if the type of access is allowed. The security information of each resource thus determines the extent to which the restricted process, and thus the untrusted content, has access. In general, the criteria used for setting up restrictions for each untrusted content'"'"'s process is information indicative of how trusted or untrusted the content is likely to be.

Claims

1. In a computer system having an operating system provided security mechanism that determines access of processes to resources based on information in an access token associated with each of the processes against security information associated with each of the resources, a method of restricting access of content to resources, comprising, setting up a process for the content, determining restriction information based on criteria available to the computer system, automatically creating a restricted access token based on the restriction information, the restricted access token having reduced access relative to a parent token, associating the restricted access token with the process, and in response to a request for access by the process to the resource, the security mechanism determining access by evaluating data in the restricted access token against separately maintained security information currently associated with the resource.

2. The method of claim 1 wherein the content comprises data obtained from an untrusted source.

3. The method of claim 2 wherein the untrusted source comprises a computer-readable medium.

4. The method of claim 2 wherein the content writes a file to the system, and further comprising generating a restricted security identifier based on a site identity, adding the security identifier to security information of the file, and storing the file in the system.

5. The method of claim 2 wherein the content writes a file to the system, and further comprising redirecting a path provided by the content to a path associated with a site.

6. The method of claim 2 wherein the data comprises network data and the untrusted source is a network site.

7. The method of claim 6 wherein the site is an Internet site, and determining restriction information includes generating a security identifier from unique information of the Internet site.

8. The method of claim 7 wherein the unique information comprises a binary certificate identifier of the Internet site.

9. The method of claim 7 wherein the unique information comprises a Uniform Resource Locator (URL) of the Internet site, and wherein generating a security identifier includes converting the URL to the restricted security identifier.

10. The method of claim 9 wherein converting the URL to the restricted security identifier includes hashing the URL with a cryptographic hash function.

11. The method of claim 1 wherein the content comprises an electronic mail message.

12. The method of claim 11 wherein determining restriction information includes determining the sender of the message.

13. The method of claim 12 wherein determining the sender of the message includes authenticating the sender.

14. The method of claim 1 wherein the content comprises a script.

15. The method of claim 14 wherein the system is a server, and wherein determining restriction information includes determining how a client was authenticated to the server.

16. The method of claim 1 wherein the content comprises data downloaded from a site, further comprising determining a zone corresponding to the site, and wherein creating the restricted access token includes adding a restricted security identifier corresponding to the zone to the restricted access token.

17. The method of claim 1 wherein the resource is unavailable for direct access by the restricted process, and further comprising, accessing the resource through a helper process associated with the restricted process.

18. The method of claim 17 wherein the helper process extracts information associated with the content from the restricted token.

19. The method of claim 17 further comprising detecting at an application programming interface an attempt to access a resource from the process having the restricted token as its access token, and in response, calling the helper process to access the resource, and returning information from the helper process to the process having the restricted token as its access token.

20. The method of claim 17 further comprising setting the security information of the resource to allow access to the helper process and deny access to the process having the restricted token as its access token.

21. The method of claim 17 wherein accessing the resource unavailable to the restricted process through a helper process includes communicating with the resource through the helper process.

22. The method of claim 17 wherein accessing the resource unavailable to the restricted process through a helper process includes requesting the helper process to make the resource available.

23. The method of claim 1 further comprising putting the process into a job object.

24. The method of claim 1 wherein the content attempts to access a system registry, and further comprising redirecting a registry location provided by the content to a registry location associated with the content.

25. A computer-readable medium having computer-executable instructions for performing the method of claim 1.

26. In a computer system, a system for restricting access of content to resources, comprising, a process set up for the content, a discrimination mechanism configured with executable code to determine restriction data based on information corresponding to the content, a mechanism configured with executable code to automatically create a restricted access token for the process based on the restriction data, the restricted access token having reduced access relative to a parent token, and a security mechanism configured with executable code to determine access of the content'"'"'s process to a resource by comparing information in the restricted access token to separately maintained security information currently associated with the resource.

27. The system of claim 26 wherein the content comprises data downloaded from a site.

28. The system of claim 27 wherein the site is an Internet site, and wherein the discrimination mechanism generates a restricted security identifier from information of the Internet site.

29. The system of claim 28 wherein the information of the Internet site comprises a binary certificate identifier of the Internet site.

30. The system of claim 28 wherein the information of the Internet site comprises a Uniform Resource Locator (URL), and further comprising a converter for converting the URL to the restricted security identifier.

31. The system of claim 30 wherein the converter includes a one-way cryptographic hash function.

32. The system of claim 26 wherein the content comprises an electronic mail message.

33. The system of claim 32 wherein the discrimination mechanism determines a restricted security identifier based on the sender of the message.

34. The system of claim 26 wherein the content comprises a script.

35. The system of claim 26 wherein the computer system comprises a server, and wherein a restricted security identifier is generated for a client connected to the server according to how the client was authenticated to connect to the server.

36. The system of claim 26 further comprising a helper process for extracting information associated with the content from the restricted access token and for accessing the resource on behalf of the process.

37. The system of claim 26 further comprising a job object, wherein the process runs in the job object.

38. The method of claim 26 wherein the restriction data corresponds to at least one restricted security identifier to add to the restricted access token relative to a parent access token.

39. The method of claim 26 wherein the restriction data corresponds to at least one privilege to remove from the restricted access token relative to a parent access token.

40. The method of claim 26 wherein the restriction data corresponds to at least one security identifier to modify in the restricted access token relative to a parent access token.

41. In a computer server, a system for restricting access of content to resources, comprising, content arranged in a web site, the content having a process set up therefor, a discrimination mechanism configured with executable code to determine at least one restricted security identifier based on information corresponding to the site, a mechanism configured with executable code to automatically derive from a parent token a restricted access token for the process by adding relative to the parent token the at least one restricted security identifier corresponding to the site to the restricted access token, and a security mechanism that determines access of the content'"'"'s process to a resource by comparing information in the restricted access token to separately maintained security information currently associated with the resource.

42. A method comprising,

automatically creating authorization data based on security information in a parent access token and restriction information available to a computer system;

associating the authorization data with a process;

receiving a request for access by the process to a selected resource; and

in response to the request, comparing in a security environment the authorization data associated with the process against security information currently associated with the selected resource to determine whether to grant access of the process to the selected resource, the security information currently associated with the selected resource being maintained separately from the authorization data associated with the process.

43. The method of claim 42 wherein the process restriction data is based on an application program.

44. The method of claim 42 wherein the process restriction data is based on a parent process.

45. The method of claim 42 wherein the process restriction data is based on a job.

46. The method of claim 42 wherein the process restriction data is based on a site.

47. The method of claim 42 wherein the authorization data further comprises user or group identity data.

48. The method of claim 42 wherein the authorization data includes certificate information.

49. The method of claim 42 wherein the authorization data is associated with the process via a restricted token, wherein the set of security information associated with the selected resource comprises an access control list, and wherein at least part of the security environment is incorporated into an operating system.

50. A computer-readable medium having computer-executable instructions for performing the method of claim 42.