Using a USB host controller security extension for controlling changes in and auditing USB topology

• US 7,761,618 B2
• Filed: 03/25/2005
• Issued: 07/20/2010
• Est. Priority Date: 03/25/2005
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Williams, Mark, Avraham, Idan, Wooten, David R., Ray, Kenneth D.
• Primary Examiner(s): Tsai; Henry W. H.
• Assistant Examiner(s): Nam; Hyun
• Application Number:
  US11/090,582
• Publication Number:
  US 20060218320A1
• Time in Patent Office: 1,943 Days
• Field of Search: 710/33, 710/36, 713/189
• US Class Current: 710/36
• CPC Class Codes: G06F 21/55 Detecting local intrusion or implementing counter-measures
• CPC Class Codes: G06F 21/554 involving event detection and direct action
• CPC Class Codes: G06F 2221/2101 Auditing as a secondary aspect

Abstract

Protecting computer systems from attacks that attempt to change USB topology and for ensuring that the system'"'"'s information regarding USB topology is accurate is disclosed. A software model is defined that, together with secure USB hardware, provides an ability to define policies using which USB traffic can be properly monitored and controlled. The implemented policy provides control over USB commands through a combination of software evaluation and hardware programming. Legitimate commands are evaluated and “allowed” to be sent to a USB device by a host controller. Illegitimate commands are evaluated and blocked. Additionally, the USB topology is audited to verify that the system'"'"'s topology map matches the actual USB topology.

Claims

1. A computer-readable storage medium having computer-executable instructions for performing steps, comprising:

receiving data for a USB device;

determining whether the data is permitted to be sent to the USB device; and

sending an instruction based on the determining to an entity, wherein the data is a result of program code corresponding to the USB device being executed outside of a trusted execution environment,

wherein the data is received in the trusted execution environment, and

wherein the entity is outside the trusted execution environment,

the computer-readable medium having computer-executable instructions for performing steps, comprising;

a USB host controller, prior to sending a command therefrom to the USB device, informing allow policy software in a hardware-based secure extension of the USB host controller of the command;

the allow policy software scrutinizing the command based on allow logic of the secure extension to decide whether to permit the command to be sent, and initially concluding based on the allow logic that the command cannot be sent to the USB device;

the allow policy software subsequently concluding that the command can be sent to the USB device based on predetermined security policy, and modifying the allow logic in accordance therewith;

the allow policy software instructing the USB host controller to send the command to the USB device; and

the secure extension only permitting the sent command from the USB host controller to be delivered to the USB device in accordance with the allow logic.

2. The computer-readable storage medium of claim 1, having further computer-executable instructions for performing the step of:

determining that a security extension of a host controller is programmed to permit the data to be sent to the USB device.

3. The computer-readable storage medium of claim 1, having further computer-executable instructions for performing the step of:

programming a security extension of a host controller to permit the data to be sent to the USB device.

4. The computer-readable storage medium of claim 1, having further computer-executable instructions for performing the step of:

programming a security extension of a host controller to block the data from being sent to the USB device.

5. The computer-readable storage medium of claim 1, wherein the instruction comprises directing that the data be sent to the USB device.

6. The computer-readable storage medium of claim 1, wherein the instruction comprises directing that the data not be sent to the USB device.

7. The computer-readable storage medium of claim 1, wherein receiving the data comprises receiving the data from a USB host controller driver.

8. The computer-readable storage medium of claim 1, wherein the entity is a USB host controller driver.

9. The computer-readable storage medium of claim 1, wherein the program code is part of a device driver corresponding to the USB device.

10. The computer-readable storage medium of claim 1, wherein the data comprises a USB command.

11. The computer-readable storage medium of claim 10, wherein the USB command is a setup command.

12. A computer system, comprising:

means for receiving data associated with a USB device;

means for determining whether the data is permitted to be sent to the USB device; and

means for sending an instruction based on the determining to an entity, wherein the data is a result of program code corresponding to the USB device being executed outside of a trusted execution environment,

wherein the data is received in the trusted execution environment, and

wherein the entity is outside the trusted execution environments,

the computer system comprising a USB host controller, prior to sending a command therefrom to the USB device, informing allow policy software in a hardware-based secure extension of the USB host controller of the command,

the allow policy software scrutinizing the command based on allow logic of the secure extension to decide whether to permit the command to be sent, and initially concluding based on the allow logic that the command cannot be sent to the USB device,

the allow policy software subsequently concluding that the command can be sent to the USB device based on predetermined security policy, and modifying the allow logic in accordance therewith,

the allow policy software instructing the USB host controller to send the command to the USB device, and

the secure extension only permitting the sent command from the USB host controller to be delivered to the USB device in accordance with the allow logic.

13. The computer system of claim 12, further comprising:

means for determining that a security extension of a host controller is programmed to permit the data to be sent to the USB device.

14. The computer system of claim 12, further comprising:

means for programming a security extension of a host controller to block the data from being sent to the USB device.

15. The computer system of claim 12, wherein the instruction comprises directing that the data be sent to the USB device.