System and method for identity decisions and invalidation

• US 7,756,841 B2
• Filed: 03/22/2005
• Issued: 07/13/2010
• Est. Priority Date: 03/22/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Rector, John, Fernandes, Genevieve, Li, Eric, Probert, David B.
• Primary Examiner(s): Breene; John E
• Assistant Examiner(s): LE, THU NGUYET T
• Application Number:
  US11/087,222
• Publication Number:
  US 20060218389A1
• Time in Patent Office: 1,939 Days
• Field of Search: None
• US Class Current: 707/690
• CPC Class Codes: G06F 21/52 during program execution, e.g. stack integrity ; Preventing unwanted data erasure; Buffer overflow

Abstract

A system and method for identity decisions and invalidation. Modified objects (e.g., files, executables, etc.) are flagged for reevaluation. Privileges associated with the object are only persisted if the modifications are determined to be authorized (e.g., updates and patches). In one embodiment, a tagging system registers to be notified of all writes, renames, truncations, moves, deletions, or any other relevant modifications to objects. If the tagging system detects a modification operation targeting the object, it invalidates all identity decisions cached with the object. The next time the object runs, the system does not recognize the object and it is forced to reevaluate its identity. Thus, patching and other write operations are still permitted, but the system detects the changed object and reevaluates the identity.

Claims

1. A method for identity decisions, comprising:

registering to automatically receive at least one change notification on at least one modification to an executable object resulting in a modified executable object, wherein, prior to the at least one modification, identity privileges and decisions regarding an identity of the executable object are cached for the executable object;

flagging the modified executable object for reevaluation;

upon automatically receiving the at least one change notification, invalidating all of the identity privileges and decisions cached for the executable object;

when the modified executable object is flagged for the reevaluation, recomputing an identity of the modified executable object;

recomputing the identity privileges and decisions of the modified executable object only when the modified executable object is needed to be executed; and

the executable object is associated with a removable media, and wherein, if media-removed change notifications are not supported, the executable object is copied locally into a local copy and all of the identity privileges and decisions associated with the executable object prior to modifying the executable object are computed on the local copy.

2. The method of claim 1, wherein the at least one modification to the executable object comprises at least one of one or more writes, renames, truncations, moves, and deletions.

3. The method of claim 1, wherein after all of the cached identity privileges and decisions are invalidated, new identity privileges and decisions are recomputed prior to executing the modified executable object.

4. The method of claim 1, wherein if the at least one modification to the executable object is determined to be authorized, all of the identity privileges and decisions associated with the executable object prior to modifying the executable object are persisted.

5. The method of claim 1, wherein the executable object is associated with a network volume, and wherein, if the network volume is not trusted, the executable object is copied locally into a local copy and all of the identity privileges and decisions associated with the executable object prior to modifying the executable object are computed on the local copy.

6. The method of claim 1, wherein the executable object is associated with a multi-boot system, and wherein operating system identifications are stored and when the multi-boot system accesses a stored data for the modified executable object, a currently executing operating system identification is checked against the stored operating system identifications, and if there is a mismatch of the currently executing operating system identification and its stored identification from the stored operating system identifications, invalidating all of the identity privileges and decisions cached for the executable object prior to modifying the executable object.

7. A computer system for identity decisions, comprising:

a detection module for automatically receiving change notifications on at least one modification to executable objects resulting in modified executable objects, wherein, prior to the at least one modification, identity metadata regarding an identity of the executable objects are cached for the executable objects;

a protection module for flagging the modified executable objects for reevaluation;

a cache for caching the identity metadata for the executable objects prior to modifying the executable objects;

an invalidation engine for invalidating the identity metadata cached for the executable objects prior to modifying the executable objects;

a computer for recomputing the identity privileges and decisions of the modified executable object only when the modified executable object is needed to be executed; and

the executable object is associated with a removable media, and wherein, if media-removed change notifications are not supported, the executable object is copied locally into a local copy and all of the identity privileges and decisions associated with the executable object prior to modifying the executable object are computed on the local copy.

8. The computer system of claim 7, wherein the cache receives the identity metadata from a plurality of metadata providers.

9. The computer system of claim 8, wherein the computer system further comprises an identity engine which generates identity metadata for the modified executable objects.

10. The computer system of claim 9, wherein the computer system further comprises a plurality of decision makers which exchange information regarding the modified executable objects and the identity metadata for the modified executable objects with the identity engine and which provide information regarding the identity metadata for the modified executable objects to the cache and which retrieve the cached identity metadata for the executable objects from the cache prior to modifying the executable objects.

11. The computer system of claim 10, wherein the computer system maintains a per-identity table which associates each of the plurality of metadata providers with a corresponding sequence number and decision metadata for the executable objects.

12. The computer system of claim 11, wherein the computer system maintains a global current sequence number table which associates each of the plurality of metadata providers with a corresponding current sequence number.

13. The computer system of claim 12, wherein in order to obtain a valid decision metadata for an executable object, a metadata provider'"'"'s sequence number is obtained from the per-identity table and is compared with the current sequence number for the metadata provider from the global current sequence number table, and if there is a mismatch of the metadata provider'"'"'s sequence number and its current sequence number, the metadata provider is invoked to generate current metadata for the executable object prior to executing the decision metadata for the executable object.

14. One or more computer-readable storage media having stored thereon a computer program segment that when executed by a computer performs identity decisions, said computer-readable storage media comprising:

a set of computer-executable instructions that when executed by the computer;

register change notifications automatically received on at least one modification to an executable object resulting in a modified executable object, wherein, prior to the at least one modification, identity privileges and decisions regarding an identity of the executable object are cached for the executable object;

flag the modified executable object for reevaluation;

invalidate all of the identity privileges and decisions cached for the executable object;

when the modified executable object is flagged for the reevaluation, computing an identity of the modified executable object; and

recompute the identity privileges and decisions of the modified executable object only when the modified executable object is needed to be executed; and

the executable object is associated with a removable media, and wherein, if media-removed change notifications are not supported, the executable object is copied locally into a local copy and all of the identity privileges and decisions associated with the executable object prior to modifying the executable object are computed on the local copy.

15. The storage media of claim 14, wherein the at least one modification to the executable object comprises at least one of one or more writes, renames, truncations, moves, and deletions.

16. The storage media of claim 14, wherein after all of the cached identity privileges and decisions are invalidated, new identity privileges and decisions are recomputed prior to executing the modified executable object.

17. The storage media of claim 14, wherein the executable object is associated with a network volume, and wherein, if the network volume is not trusted, the executable object is copied locally into a local copy and all identity privileges and decisions associated with the executable object prior to modifying the executable object are computed on the local copy.

18. The storage media of claim 14, wherein the executable object is associated with a multi-boot system, and wherein operating system identifications are stored, and when the multi-boot system accesses a stored data for the modified object, a currently executing operating system identification is checked against the stored operating system identifications, and if there is a mismatch of the currently executing operating system identification and its stored identification from the stored operating system identifications, invalidating all of the identity privileges and decisions cached for the executable object prior modifying the executable object.