Patent Publication Number: US-2016241583-A1

Title: Risk management in an air-gapped environment

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the filing date of United States Provisional Patent Application 62/116,245, filed Feb. 13, 2015, which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates generally to network security. More specifically, this disclosure relates to risk management in an air-gapped environment. 
     BACKGROUND 
     Processing facilities are often managed using industrial process control and automation systems. Conventional control and automation systems routinely include a variety of networked devices, such as servers, workstations, switches, routers, firewalls, safety systems, proprietary real-time controllers, and industrial field devices. Often times, this equipment comes from a number of different vendors. In industrial environments, cyber-security is of increasing concern, and unaddressed security vulnerabilities in any of these components could be exploited by attackers to disrupt operations or cause unsafe conditions in an industrial facility. 
     SUMMARY 
     This disclosure provides for risk management in an air-gapped environment. A method includes collecting data, by a risk manager system, from a plurality of computing devices in an air-gapped environment. The air-gapped environment includes a control system that is substantially or completely isolated from unsecured external networks. The method includes applying rules to analyze the collected data and identify cyber-security threats to the computing devices in the air-gapped environment. The method includes interacting with a user to display the results of the analysis and the identified cyber-security threats. 
     In some embodiments, the rules are applied by a rules engine. In some embodiments, the rules are applied using a risk management database that stores the rules and data identifying the cyber-security threats. In some embodiments, the risk manager system also transmits the results of the analysis and the identified cyber-security threats to a web-application user interface. In some embodiments, the risk manager system updates a risk management database to provide contemporaneous awareness of cyber-security threats to the computing devices in the air-gapped environment. In some embodiments, the risk manager system is deployed using physical media. In some embodiments, updates to a risk management database of the risk manager system are installed using physical media. 
     Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of this disclosure, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates an example industrial process control and automation system according to this disclosure; 
         FIG. 2  illustrates an example infrastructure for risk management in an air-gapped environment according to this disclosure; and 
         FIG. 3  illustrates a flowchart of a process in accordance with disclosed embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The figures, discussed below, and the various embodiments used to describe the principles of the present invention in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the invention may be implemented in any type of suitably arranged device or system. 
       FIG. 1  illustrates an example industrial process control and automation system  100  according to this disclosure. As shown in  FIG. 1 , the system  100  includes various components that facilitate production or processing of at least one product or other material. For instance, the system  100  is used here to facilitate control over components in one or multiple plants  101   a - 101   n . Each plant  101   a - 101   n  represents one or more processing facilities (or one or more portions thereof), such as one or more manufacturing facilities for producing at least one product or other material. In general, each plant  101   a - 101   n  may implement one or more processes and can individually or collectively be referred to as a process system. A process system generally represents any system or portion thereof configured to process one or more products or other materials in some manner. 
     In  FIG. 1 , the system  100  is implemented using the Purdue model of process control. In the Purdue model, “Level 0” may include one or more sensors  102   a  and one or more actuators  102   b . The sensors  102   a  and actuators  102   b  represent components in a process system that may perform any of a wide variety of functions. For example, the sensors  102   a  could measure a wide variety of characteristics in the process system, such as temperature, pressure, or flow rate. Also, the actuators  102   b  could alter a wide variety of characteristics in the process system. The sensors  102   a  and actuators  102   b  could represent any other or additional components in any suitable process system. Each of the sensors  102   a  includes any suitable structure for measuring one or more characteristics in a process system. Each of the actuators  102   b  includes any suitable structure for operating on or affecting one or more conditions in a process system. 
     At least one network  104  is coupled to the sensors  102   a  and actuators  102   b . The network  104  facilitates interaction with the sensors  102   a  and actuators  102   b . For example, the network  104  could transport measurement data from the sensors  102   a  and provide control signals to the actuators  102   b . The network  104  could represent any suitable network or combination of networks. As particular examples, the network  104  could represent an Ethernet network, an electrical signal network (such as a HART or FOUNDATION FIELDBUS network), a pneumatic control signal network, or any other or additional type(s) of network(s). 
     In the Purdue model, “Level 1” may include one or more controllers  106 , which are coupled to the network  104 . Among other things, each controller  106  may use the measurements from one or more sensors  102   a  to control the operation of one or more actuators  102   b . For example, a controller  106  could receive measurement data from one or more sensors  102   a  and use the measurement data to generate control signals for one or more actuators  102   b . Each controller  106  includes any suitable structure for interacting with one or more sensors  102   a  and controlling one or more actuators  102   b . Each controller  106  could, for example, represent a proportional-integral-derivative (PID) controller or a multivariable controller, such as a Robust Multivariable Predictive Control Technology (RMPCT) controller or other type of controller implementing model predictive control (MPC) or other advanced predictive control (APC). As a particular example, each controller  106  could represent a computing device running a real-time operating system. 
     Two networks  108  are coupled to the controllers  106 . The networks  108  facilitate interaction with the controllers  106 , such as by transporting data to and from the controllers  106 . The networks  108  could represent any suitable networks or combination of networks. As a particular example, the networks  108  could represent a redundant pair of Ethernet networks, such as a FAULT TOLERANT ETHERNET (FTE) network from HONEYWELL INTERNATIONAL INC. 
     At least one switch/firewall  110  couples the networks  108  to two networks  112 . The switch/firewall  110  may transport traffic from one network to another. The switch/firewall  110  may also block traffic on one network from reaching another network. The switch/firewall  110  includes any suitable structure for providing communication between networks, such as a HONEYWELL CONTROL FIREWALL (CF9) device. The networks  112  could represent any suitable networks, such as an FTE network. 
     In the Purdue model, “Level 2” may include one or more machine-level controllers  114  coupled to the networks  112 . The machine-level controllers  114  perform various functions to support the operation and control of the controllers  106 , sensors  102   a , and actuators  102   b , which could be associated with a particular piece of industrial equipment (such as a boiler or other machine). For example, the machine-level controllers  114  could log information collected or generated by the controllers  106 , such as measurement data from the sensors  102   a  or control signals for the actuators  102   b . The machine-level controllers  114  could also execute applications that control the operation of the controllers  106 , thereby controlling the operation of the actuators  102   b . In addition, the machine-level controllers  114  could provide secure access to the controllers  106 . Each of the machine-level controllers  114  includes any suitable structure for providing access to, control of, or operations related to a machine or other individual piece of equipment. Each of the machine-level controllers  114  could, for example, represent a server computing device running a MICROSOFT WINDOWS operating system. Although not shown, different machine-level controllers  114  could be used to control different pieces of equipment in a process system (where each piece of equipment is associated with one or more controllers  106 , sensors  102   a , and actuators  102   b ). 
     One or more operator stations  116  are coupled to the networks  112 . The operator stations  116  represent computing or communication devices providing user access to the machine-level controllers  114 , which could then provide user access to the controllers  106  (and possibly the sensors  102   a  and actuators  102   b ). As particular examples, the operator stations  116  could allow users to review the operational history of the sensors  102   a  and actuators  102   b  using information collected by the controllers  106  and/or the machine-level controllers  114 . The operator stations  116  could also allow the users to adjust the operation of the sensors  102   a , actuators  102   b , controllers  106 , or machine-level controllers  114 . In addition, the operator stations  116  could receive and display warnings, alerts, or other messages or displays generated by the controllers  106  or the machine-level controllers  114 . Each of the operator stations  116  includes any suitable structure for supporting user access and control of one or more components in the system  100 . Each of the operator stations  116  could, for example, represent a computing device running a MICROSOFT WINDOWS operating system. 
     At least one router/firewall  118  couples the networks  112  to two networks  120 . The router/firewall  118  includes any suitable structure for providing communication between networks, such as a secure router or combination router/firewall. The networks  120  could represent any suitable networks, such as an FTE network. 
     In the Purdue model, “Level 3” may include one or more unit-level controllers  122  coupled to the networks  120 . Each unit-level controller  122  is typically associated with a unit in a process system, which represents a collection of different machines operating together to implement at least part of a process. The unit-level controllers  122  perform various functions to support the operation and control of components in the lower levels. For example, the unit-level controllers  122  could log information collected or generated by the components in the lower levels, execute applications that control the components in the lower levels, and provide secure access to the components in the lower levels. Each of the unit-level controllers  122  includes any suitable structure for providing access to, control of, or operations related to one or more machines or other pieces of equipment in a process unit. Each of the unit-level controllers  122  could, for example, represent a server computing device running a MICROSOFT WINDOWS operating system. Although not shown, different unit-level controllers  122  could be used to control different units in a process system (where each unit is associated with one or more machine-level controllers  114 , controllers  106 , sensors  102   a , and actuators  102   b ). 
     Access to the unit-level controllers  122  may be provided by one or more operator stations  124 . Each of the operator stations  124  includes any suitable structure for supporting user access and control of one or more components in the system  100 . Each of the operator stations  124  could, for example, represent a computing device running a MICROSOFT WINDOWS operating system. 
     At least one router/firewall  126  couples the networks  120  to two networks  128 . The router/firewall  126  includes any suitable structure for providing communication between networks, such as a secure router or combination router/firewall. The networks  128  could represent any suitable networks, such as an FTE network. 
     In the Purdue model, “Level 4” may include one or more plant-level controllers  130  coupled to the networks  128 . Each plant-level controller  130  is typically associated with one of the plants  101   a - 101   n , which may include one or more process units that implement the same, similar, or different processes. The plant-level controllers  130  perform various functions to support the operation and control of components in the lower levels. As particular examples, the plant-level controller  130  could execute one or more manufacturing execution system (MES) applications, scheduling applications, or other or additional plant or process control applications. Each of the plant-level controllers  130  includes any suitable structure for providing access to, control of, or operations related to one or more process units in a process plant. Each of the plant-level controllers  130  could, for example, represent a server computing device running a MICROSOFT WINDOWS operating system. 
     Access to the plant-level controllers  130  may be provided by one or more operator stations  132 . Each of the operator stations  132  includes any suitable structure for supporting user access and control of one or more components in the system  100 . Each of the operator stations  132  could, for example, represent a computing device running a MICROSOFT WINDOWS operating system. 
     At least one router/firewall  134  couples the networks  128  to one or more networks  136 . The router/firewall  134  includes any suitable structure for providing communication between networks, such as a secure router or combination router/firewall. The network  136  could represent any suitable network, such as an enterprise-wide Ethernet or other network or all or a portion of a larger network (such as the Internet). 
     In the Purdue model, “Level 5” may include one or more enterprise-level controllers  138  coupled to the network  136 . Each enterprise-level controller  138  is typically able to perform planning operations for multiple plants  101   a - 101   n  and to control various aspects of the plants  101   a - 101   n . The enterprise-level controllers  138  can also perform various functions to support the operation and control of components in the plants  101   a - 101   n . As particular examples, the enterprise-level controller  138  could execute one or more order processing applications, enterprise resource planning (ERP) applications, advanced planning and scheduling (APS) applications, or any other or additional enterprise control applications. Each of the enterprise-level controllers  138  includes any suitable structure for providing access to, control of, or operations related to the control of one or more plants. Each of the enterprise-level controllers  138  could, for example, represent a server computing device running a MICROSOFT WINDOWS operating system. In this document, the term “enterprise” refers to an organization having one or more plants or other processing facilities to be managed. Note that if a single plant  101   a  is to be managed, the functionality of the enterprise-level controller  138  could be incorporated into the plant-level controller  130 . 
     Access to the enterprise-level controllers  138  may be provided by one or more operator stations  140 . Each of the operator stations  140  includes any suitable structure for supporting user access and control of one or more components in the system  100 . Each of the operator stations  140  could, for example, represent a computing device running a MICROSOFT WINDOWS operating system. 
     Various levels of the Purdue model can include other components, such as one or more databases. The database(s) associated with each level could store any suitable information associated with that level or one or more other levels of the system  100 . For example, a historian  141  can be coupled to the network  136 . The historian  141  could represent a component that stores various information about the system  100 . The historian  141  could, for instance, store information used during production scheduling and optimization. The historian  141  represents any suitable structure for storing and facilitating retrieval of information. Although shown as a single centralized component coupled to the network  136 , the historian  141  could be located elsewhere in the system  100 , or multiple historians could be distributed in different locations in the system  100 . 
     In particular embodiments, the various controllers and operator stations in  FIG. 1  may represent computing devices. For example, each of the controllers  106 ,  114 ,  122 ,  130 ,  138  could include one or more processing devices  142  and one or more memories  144  for storing instructions and data used, generated, or collected by the processing device(s)  142 . Each of the controllers  106 ,  114 ,  122 ,  130 ,  138  could also include at least one network interface  146 , such as one or more Ethernet interfaces or wireless transceivers. Also, each of the operator stations  116 ,  124 ,  132 ,  140  could include one or more processing devices  148  and one or more memories  150  for storing instructions and data used, generated, or collected by the processing device(s)  148 . Each of the operator stations  116 ,  124 ,  132 ,  140  could also include at least one network interface  152 , such as one or more Ethernet interfaces or wireless transceivers. 
     As noted above, cyber-security is of increasing concern with respect to industrial process control and automation systems. Unaddressed security vulnerabilities in any of the components in the system  100  could be exploited by attackers to disrupt operations or cause unsafe conditions in an industrial facility. However, in many instances, operators do not have a complete understanding or inventory of all equipment running at a particular industrial site. As a result, it is often difficult to quickly determine potential sources of risk to a control and automation system. 
     In some installations, a control and automation system is “air gapped,” meaning the system is physically isolated from unsecured networks such as the Internet or other external networks. The isolation may be absolute or nearly absolute. While this approach does provide a way to mitigate some risk, it offers challenges to a risk management solution in that other vulnerabilities may still be exploited. Not only that, but the types and manners of vulnerabilities, exploitations, and associated risks change over time. 
     Disclosed embodiments address potential vulnerabilities in various systems, prioritize the vulnerabilities based on risk to an overall system, and automatically categorize and aggregate data for monitored control systems. This is accomplished (among other ways) by using a risk manager  154 . The risk manager  154  includes any suitable structure that supports risk management in an air-gapped environment. Here, the risk manager  154  includes one or more processing devices  156 ; one or more memories  158  for storing instructions and data used, generated, or collected by the processing device(s)  156 ; and at least one network interface  160 . Each processing device  156  could represent a microprocessor, microcontroller, digital signal process, field programmable gate array, application specific integrated circuit, or discrete logic. Each memory  158  could represent a volatile or non-volatile storage and retrieval device, such as a random access memory or Flash memory. Each network interface  160  could represent an Ethernet interface, wireless transceiver, or other device facilitating external communication (but not, in air-gapped implementations, with “external” systems that are not part of the system  100 ). The functionality of the risk manager  154  could be implemented using any suitable hardware or a combination of hardware and software/firmware instructions. 
       FIG. 2  illustrates an example infrastructure  200  for risk management in an air-gapped environment according to this disclosure. The infrastructure  200  could be supported or implemented using the risk manager  154 . The infrastructure  200  here supports operation in an air-gapped environment and allows for updates to a risk knowledge base in order to provide a contemporary representation of risks. Other solutions typically leverage external connections and external sources as enablers for operation and risk awareness. 
     In accordance with this disclosure, the risk manager  154  is specialized for air-gapped operation. In various embodiments, initial deployment of the risk management solution into the air-gapped environment can be performed in a secure and trusted manner. In some embodiments, the risk manager leverages modern computing mechanisms that allow for operation in an air-gapped environment. Various embodiments use secure and trusted mechanisms for functional and architectural updates into the air-gapped environment. Various embodiments support updates to the risk knowledge base to provide contemporaneous risk awareness. 
     Although  FIG. 1  illustrates one example of an industrial process control and automation system  100 , various changes may be made to  FIG. 1 . For example, a control and automation system could include any number of sensors, actuators, controllers, servers, operator stations, networks, risk managers, and other components. Also, the makeup and arrangement of the system  100  in  FIG. 1  is for illustration only. Components could be added, omitted, combined, or placed in any other suitable configuration according to particular needs. Further, particular functions have been described as being performed by particular components of the system  100 . This is for illustration only. In general, control and automation systems are highly configurable and can be configured in any suitable manner according to particular needs. In addition,  FIG. 1  illustrates an example environment in which the functions of the risk manager  154  can be used. This functionality can be used in any other suitable device or system. 
     In  FIG. 2 , the risk manager  154  is implemented as an air-gapped control system  200 . Control system  200  includes at least one data collection function  210 , a rules engine  220 , a risk management (RM) database  230 , and user interface (UI) web application  240 . The devices  250  include any other devices or components of the air-gapped control system  200 , such as any of the components in system  100 . Air-gapped environment  260  illustrates the physical disconnection or “gap” between air-gapped control system  200  an external systems. 
     The data collection function  210  collects data from various computing devices  250  in an air-gapped environment. The rules engine  220  applies rules to analyze the collected data and identify cyber-security threats to the computing devices  250  in the air-gapped environment. The RM database  230  stores rules and data identifying the cyber-security threats. The UI web application  240  allows interaction with the risk manager  154  via a web-based interface. These components function in a closed (air-gapped) environment  260 , meaning there is no or virtually no mechanism to access outside capabilities (such as the Internet or cloud-based applications). Thus, information cannot be conveyed via these mechanisms to the risk manager  154  or any other part of control system  200 . 
     Conventional computers and smartphones typically have access to the Internet and thus external capabilities that provide updates for operating systems, applications, anti-virus components, etc. In contrast, the control system  200  in  FIG. 2  is deployed, operated, and updated in an effectively closed environment. Air-gapped systems are not immune to all external threats in that there is always a risk of someone locally injecting malware or some other malicious agent into a system via a USB stick, installing software that is thought to be legitimate but is itself infected, etc. 
     In accordance with this disclosure, the RM architecture supports the initial deployment of a risk management solution into an air-gapped environment in a secure and trusted manner. This can be accomplished, for example, using physical media for solution deployment, signed executables, or security certificates. 
     The RM architecture also leverages only those modern computing mechanisms that allow for operation in an air-gapped environment. This can be accomplished, for example, using external port blocking, locally deployed applications, or secure user account access to RMS capabilities. 
     The RM architecture further supports secure and trusted mechanisms for functional and architectural updates into the air-gapped environment. This can be accomplished, for example, using physical media for update deployment, signed executables, or security certificates. 
     In addition, the RM architecture supports updates to the risk knowledge base to provide contemporaneous risk awareness. This can be accomplished, for example, using physical media for update deployment, signed executables, or security certificates. 
     Although  FIG. 2  illustrates one example of a control system  200  for risk management in an air-gapped environment, various changes may be made to  FIG. 2 . For example, the functional division of the components in  FIG. 2  is for illustration only. Various components could be combined, further subdivided, rearranged, or omitted and additional components could be added according to particular needs. 
       FIG. 3  illustrates a flowchart of a process  300  in accordance with disclosed embodiments, that can be performed, for example, by risk manager  154 , control system  200 , or other device configured to perform as described, referred to generically as the “risk manager system” below. 
     The risk manager system collects data from a plurality of computing devices in an air-gapped environment ( 305 ). The air-gapped environment includes a control system that is substantially or completely isolated from unsecured external networks. The data collection can be performed by a data collection function. 
     The risk manager system applies rules to analyze the collected data and identify cyber-security threats to the computing devices in the air-gapped environment ( 310 ). This can be performed by a rules engine. This can be performed using a risk management database that stores rules and data identifying the cyber-security threats. The risk manager system can also update the risk management database to provide contemporaneous awareness of cyber-security threats to the computing devices in the air-gapped environment. 
     The risk manager system stores the results of the analysis and the identified cyber-security threats, and interacts with a user to display the results of the analysis and the identified cyber-security threats ( 315 ). This can include transmitting the results to a web-application user interface. 
     Note that the risk manager  154  and/or the infrastructure  200  shown here could use or operate in conjunction with various features described in the following previously-filed patent applications (all of which are hereby incorporated by reference):
         U.S. patent application Ser. No. 14/482,888 entitled “DYNAMIC QUANTIFICATION OF CYBER-SECURITY RISKS IN A CONTROL SYSTEM”;   U.S. Provisional Patent Application No. 62/036,920 entitled “ANALYZING CYBER-SECURITY RISKS IN AN INDUSTRIAL CONTROL ENVIRONMENT”;   U.S. Provisional Patent Application No. 62/113,075 entitled “RULES ENGINE FOR CONVERTING SYSTEM-RELATED CHARACTERISTICS AND EVENTS INTO CYBER-SECURITY RISK ASSESSMENT VALUES” and corresponding non-provisional U.S. patent application ______ of like title (Docket No. H0048932-0115) filed concurrently herewith;   U.S. Provisional Patent Application No. 62/113,221 entitled “NOTIFICATION SUBSYSTEM FOR GENERATING CONSOLIDATED, FILTERED, AND RELEVANT SECURITY RISK-BASED NOTIFICATIONS” and corresponding non-provisional U.S. patent application ______ of like title (Docket No. H0048937-0115) filed concurrently herewith;   U.S. Provisional Patent Application No. 62/113,100 entitled “TECHNIQUE FOR USING INFRASTRUCTURE MONITORING SOFTWARE TO COLLECT CYBER-SECURITY RISK DATA” and corresponding non-provisional U.S. patent application ______ of like title (Docket No. H0048943-0115) filed concurrently herewith;   U.S. Provisional Patent Application No. 62/113,186 entitled “INFRASTRUCTURE MONITORING TOOL FOR COLLECTING INDUSTRIAL PROCESS CONTROL AND AUTOMATION SYSTEM RISK DATA” and corresponding non-provisional U.S. patent application ______ of like title (Docket No. H0048945-0115) filed concurrently herewith;   U.S. Provisional Patent Application No. 62/113,165 entitled “PATCH MONITORING AND ANALYSIS” and corresponding non-provisional U.S. patent application ______ of like title (Docket No. H0048973-0115) filed concurrently herewith;   U.S. Provisional Patent Application No. 62/113,152 entitled “APPARATUS AND METHOD FOR AUTOMATIC HANDLING OF CYBER-SECURITY RISK EVENTS” and corresponding non-provisional U.S. patent application ______ of like title (Docket No. H0049067-0115) filed concurrently herewith;   U.S. Provisional Patent Application No. 62/114,928 entitled “APPARATUS AND METHOD FOR DYNAMIC CUSTOMIZATION OF CYBER-SECURITY RISK ITEM RULES” and corresponding non-provisional U.S. patent application ______ of like title (Docket No. H0049099-0115) filed concurrently herewith;   U.S. Provisional Patent Application No. 62/114,865 entitled “APPARATUS AND METHOD FOR PROVIDING POSSIBLE CAUSES, RECOMMENDED ACTIONS, AND POTENTIAL IMPACTS RELATED TO IDENTIFIED CYBER-SECURITY RISK ITEMS” and corresponding non-provisional U.S. patent application ______ of like title (Docket No. H0049103-0115) filed concurrently herewith; and   U.S. Provisional Patent Application No. 62/114,937 entitled “APPARATUS AND METHOD FOR TYING CYBER-SECURITY RISK ANALYSIS TO COMMON RISK METHODOLOGIES AND RISK LEVELS” and corresponding non-provisional U.S. patent application ______ of like title (Docket No. H0049104-0115) filed concurrently herewith.       

     In some embodiments, various functions described in this patent document are implemented or supported by a computer program that is formed from computer readable program code and that is embodied in a computer readable medium. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable memory device. 
     It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “application” and “program” refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer code (including source code, object code, or executable code). The term “communicate,” as well as derivatives thereof, encompasses both direct and indirect communication. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C. 
     While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.