Method and apparatus for modifying a computer program in a trusted manner

Patent metadata

Field	Value
Publication number	US-2016203313-A1
Application number	US-201414913773-A
Country	US
Kind code	A1
Filing date	Aug 15, 2014
Priority date	Aug 23, 2013
Publication date	Jul 14, 2016
Grant date	—

Abstract

A computer system having a system memory and being arranged to permit a target program ( 90 ) installed on the system to be modified in a trusted manner. The system comprises a White-list Management Agent, WMA, module ( 10 ) for receiving, at a notification receiver ( 12 ), a notification that the target program ( 90 ) which is loaded into the system memory of the computer system has performed an update operation on the target program resulting in the generation and storage of a modified version of the target program on a storage device associated with the computer system. The WMA module is operable, upon receipt of a target program update notification, to determine if the program ( 90 ) as loaded into the system memory is in a trusted state by measuring the program ( 90 ) using a program measurer module ( 14 ) and comparing this, using a comparator ( 16 ), with a pre-stored value contained in a program whitelist ( 30 ), the pre-stored value being obtained from the program whitelist ( 30 ) using a whitelist reader/writer ( 18 ). If the determination is positive, the WMA module ( 10 ) generates a hash code of the modified version of the target computer program as stored on the storage device using the program measurer module ( 14 ) and stores this generated hash code as a new trusted hash code for the target program in the program whitelist ( 30 ), in order to permit subsequent verification of the modified version of the target program as being in a trusted state.

First claim

1 . A method of modifying a target computer program installed on a computer system and stored on a storage device associated with the computer system, the computer system having system memory, the method comprising:
establishing that a modifying application which is loaded into the system memory of the computer system has performed an update operation on the target computer program to generate and store a modified version of the target computer program on the storage device associated with the computer system; determining if the modifying application is in a trusted state; and, if the determination is positive, generating a hash code of the modified version of the target computer program as stored on the storage device, and storing this generated hash code as a new trusted hash code for the target program, in order to permit subsequent verification of the modified version as being in a trusted state.

2 . A method according to claim 1 wherein the modifying application is a copy of the target computer program having been loaded into the system memory.

3 . A method according to claim 1 wherein establishing that an update operation has been performed comprises generating a notification of the performance of the update and passing this to a whitelist management agent which is operable to determine if the modifying application is in a trusted state or not, and if it is, to generate and store the hash code of the modified version of the target program.

4 . A method according to claim 3 wherein the whitelist management agent executes in a separate execution environment to that in which the modifying application, which may be the target computer program, executes.

5 . A method according to claim 3 wherein the whitelist management agent executes within a trusted platform module.

6 . A method according to claim 5 wherein the trusted platform module is a virtual trusted platform module.

7 . A computer system having a system memory and being arranged to permit a target program installed on the system to be modified in a trusted manner, the system comprising:
a White-list Management Agent, WMA, module for receiving a notification that a modifying application which is loaded into the system memory of the computer system has performed an update operation on the target program resulting in the generation and storage of a modified version of the target program on a storage device associated with the computer system; wherein the WMA module is operable, upon receipt of a target program update notification, to determine if the modifying application as loaded into the system memory is in a trusted state and, if the determination is positive, to generate a hash code of the modified version of the target computer program as stored on the storage device and to store this generated hash code as a new trusted hash code for the target program, in order to permit subsequent verification of the modified version of the target program as being in a trusted state.

8 . A computer system according to claim 7 further comprising a parsing module for intercepting calls, to a main operating system executing on the computer system, requesting a write operation to be performed on the storage device associated with the computer system.

9 . A trusted platform module for use in a computer system arranged to permit a target program installed on the system to be modified, the trusted platform module comprising:
a White-list Management Agent, WMA, module for receiving a notification that a modifying application which is loaded into system memory of the computer system has performed an update operation on the target program to generate and store a modified version of the target program on a storage device associated with the computer system; the WMA module being operable, upon receipt of a target program update notification, to determine if the modifying application as loaded into the system memory is in a trusted state and, if the determination is positive, to generate a hash code of the modified version of the target computer program as stored on the storage device and to store this generated hash code as a new trusted hash code for the target program, in order to permit subsequent verification of the modified version of the target program as being in a trusted state.

10 . Processor implementable instructions for causing the method of claim 1 to be carried out during execution of the instructions.

11 . A non-transient carrier medium carrying the processor implementable instructions of claim 10 .

Assignees

• British Telecomm

Inventors

• El-Moussa Fadi Ali
• Paverd Andrew

Classifications

• G06F21/51 Primary

  at application loading time, e.g. accepting, rejecting, starting or inhibiting executable software based on integrity or source reliability · CPC title

• G06F21/57

  Certifying or maintaining trusted computer platforms, e.g. secure boots or power-downs, version controls, system software checks, secure updates or assessing vulnerabilities · CPC title

• G06F2221/033

  Test or assess software · CPC title

• G06F8/65 Primary

  Updates (security arrangements therefor G06F21/57) · CPC title

• G06F21/572

  Secure firmware programming, e.g. of basic input output system [BIOS] · CPC title