Patent Publication Number: US-11038844-B2

Title: System and method of analyzing the content of encrypted network traffic

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of priority under 35 U.S.C. § 119(a)-(d) to Russian Patent Application No. 2018123684, filed Jun. 29, 2018, the entire contents of which are incorporated herein by reference. 
     FIELD OF TECHNOLOGY 
     The present disclosure relates to systems and methods for analysis of protected network connections and more specifically to systems and methods of analyzing the content of encrypted network traffic to detect malicious objects. 
     BACKGROUND 
     In a reliable solution for antivirus protection of computer systems, several layers of protection should be provided. One such layer is the protection of the users against cyber threats when connected to the Internet by analyzing network traffic. In order to secure computer systems, antivirus protection performs analysis by routing network traffic through a proxy server. The proxy server extracts and analyzes the data of web site pages (HTML), files of various types (executable files, images, text documents, etc.), scripts, and the like to ensure user and computer security. Data in the context of a web browser&#39;s connections to remote web servers may be transmitted in open and in encrypted form. The Internet standard for protection of data transmissions at present is the transport layer cryptographic protection protocol (Transport Layer Security, TLS), which is used together with standard data transmission protocols forming, for example, the HTTPS (Hypertext Transfer Protocol Secure) protocol. In order to provide access to encrypted data of network traffic for the security systems, the proxy server substitutes the certificate of the web site in the course of the “handshake” procedure when establishing the protected connection. In the case of HTTPS connections, this results in the web browsers finding a non-original certificate for the web site and notifying the user about this. Alternatively, in the case of EV (Extended Validation) certificates, which are certificates of high reliability, the EV status is additionally lost at the web site, as indicated by the green bar alongside the address string of the web browser. The presence of the green bar tells the visitors that the web site is genuine. As a result, the intervention in the protected data transmission protocols in the context of a connection between a web browser and a web site leads to a negative impression for the users of antivirus solutions and a lower user experience (UX) criterion. Another example of applications (besides web browsers) needing an analysis of the network traffic for protecting a user against cyber threats on the Internet is messengers (Instant Messenger, or IM). 
     The claimed invention makes it possible to perform an analysis of the content of encrypted network traffic without intervening in the security protocols when establishing the protected connection. 
     Aspects of the disclosure propose methods and systems that analyze the content of encrypted network traffic without intervention in the security protocols during the establishing of a protected connection. 
     SUMMARY 
     Aspects of the present disclosure are directed to systems and methods of analyzing the content of encrypted network traffic to detect malicious objects. 
     The technical result of the present disclosure is to expand the arsenal of tools designed to accomplish the purpose of the proposed invention. 
     In some aspects, an exemplary method comprises rerouting traffic between a first process executing on a first computing device and a second process, to a server, to determine that there is a protected connection established between the first process and the second process, determining information related to an application pertaining to the first process, obtaining a session key for the protected connection by calling a function, wherein the information comprises an address of the function to call to obtain the session key, decrypting and analyzing the rerouted traffic on the server between the first process and the second process using the session key to determine whether the traffic contains malicious objects, and in response to determining the traffic contains malicious objects, counteracting the malicious objects by blocking or rerouting the traffic. 
     In one aspect, the method further comprises injecting a program module into an address space of the first process and obtaining the session key by instructing the program module to intercept a function called in establishing the protected connection. 
     In one aspect, the information related to the application is determined by querying the database containing a list of address of functions that return the session key for a plurality of applications. 
     In one aspect, the method further comprises finding the function in an import table of the application using the address retrieved from the database and placing a pointer to an intercepting function that copies the session key in place of the function called in establishing the protected connection. 
     In one aspect, the information is determined based at least on the version of the application. 
     In one aspect, the method further comprises verifying, prior to intercepting, compatibility of the version of the application with the method of analysis of content of the traffic between the first process and the second process. 
     In one aspect, the information is determined using program debugging files. 
     In one aspect, the server is a proxy server and the analysis is performed synchronously, wherein the traffic rerouted through the proxy server is delayed until analysis is complete and the malicious objects are removed from the traffic. 
     In one aspect, the server is a proxy server and the analysis is performed asynchronously, wherein the analysis is performed continuously without delaying traffic rerouted through the proxy server. 
     In one aspect, the application is a web browser. 
     According to other exemplary aspects of the disclosure, a system is provided for analysis of content of encrypted traffic between processes. In some aspects, the system comprising: a processor configured to reroute traffic between a first process executing on a first computing device and a second process, to a server, to determine that there is a protected connection established between the first process and the second process, determine information related to an application pertaining to the first process, obtain a session key for the protected connection by calling a function, wherein the information comprises an address of the function to call to obtain the session key, decrypt and analyzing the rerouted traffic on the server between the first process and the second process using the session key to determine whether the traffic contains malicious objects and in response to determining the traffic contains malicious objects, counteract the malicious objects by blocking or rerouting the traffic. 
     The present disclosure further provides a computer readable medium storing instructions thereon for executing the methods described above. 
     The above simplified summary of example aspects of the disclosure serves to provide a basic understanding of the disclosure. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects of the disclosure. To the accomplishment of the foregoing, the one or more aspects of the disclosure include the features described and particularly pointed out in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more example aspects of the present disclosure and, together with the detailed description, serve to explain their principles and implementations. 
         FIG. 1  illustrates a block diagram of a system of analyzing the content of encrypted network traffic between a web browser and a web site, in accordance with exemplary aspects of the present disclosure. 
         FIG. 2  illustrates the architecture of the system of analyzing the content of encrypted traffic between processes, in accordance with exemplary aspects of the present disclosure. 
         FIG. 3  is a flow diagram of a method for analyzing the content of encrypted network traffic between a web browser and a web site, in accordance with exemplary aspects of the present disclosure. 
         FIG. 4  shows an example of a general-purpose computer system, in accordance with exemplary aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary aspects are described herein in the context of a system, method and computer program product for analyzing the content of encrypted network traffic for malicious objects. Those of ordinary skill in the art will realize that the following description is illustrative only and is not intended to be in any way limiting. Other aspects will readily suggest themselves to those skilled in the art having the benefit of this disclosure. Reference will now be made in detail to implementations of the example aspects as illustrated in the accompanying drawings. The same reference indicators will be used to the extent possible throughout the drawings and the following description to refer to the same or like items. 
     Encryption is an obvious method of concealing information from outside parties in the process of its transmittal. However, occasionally for purposes of ensuring the security, intercepted traffic is also decrypted in order to scan for the presence of signs of suspicious network activity, for example. One of the most widespread protocols at present, ensuring a protected transmission of data between nodes on the Internet, is the Transport Layer Security (TLS) protocol. This protocol is widely used in applications working with the Internet, such as web browsers, applications working with email, the exchanging of instant messages, and IP telephony (VoIP or Voice over Internet Protocol). Asymmetrical crypto-systems (with a public key) are not suited to a rapid transmittal of data streams. Therefore, symmetrical ciphers are used for encrypting data within a TLS session. These are usually block ciphers. In symmetrical ciphers, the identical key is used for the encrypting and decrypting. This key is called the session encryption key. The nodes agree on the symmetrical session encryption keys in the process of establishing the protected connection (handshake). Thus, after establishing the connection, the session encryption key is possessed by each side. It should be noted that the client (the web browser) initiates establishing the protected connection with the server (the web site). Upon such a request, in one of the variant aspects of the proposed invention, the proxy server may detect the establishing of a protected connection. In order to perform the analysis of the encrypted network traffic in the context of the proposed invention, the antivirus protection means must obtain the session encryption key. 
     An example of a system of analyzing the content of encrypted network traffic between a web browser and a web site is shown in  FIG. 1 . The figure shows a computer system  100  on which are running a web browser  101  and agent  106 . A web browser  101  and an agent  106  are processes that are executed on the computing device of the user of a computer system  100 . In one variant aspect, an antivirus protection means  103  and a proxy server  104  running under the control of the antivirus protection means  103  are executed on a remote server. In this variant, the agent  106  is a security application (such as an antivirus application) or a portion thereof and it is executed on the computer system  100 . In another variant aspect, the antivirus protection means  103  is a security application (such as an antivirus application) and it is executed on the computing device of the user of the computer system  100 . In this variant, the proxy server  104  and the agent  106  are means running on the computer system  100  under the control of the antivirus protection means  103 . 
     The network traffic between the web browser  101  and a website  102  flows through the proxy server  104 . The agent  106  has access to a database  105  containing the information needed for the agent  106  to obtain the session encryption key. The agent  106  transfers the session key so obtained to the antivirus protection means  103 . The database  105  is kept on a remote server or in a cloud service and in one variant aspect it has a local copy which is kept on the computer system  100  and synchronized with the remotely residing database  105 . The agent  106  also has access to a database of compatible program versions  108 , that, similar to the database  105 , is kept on a remote server or in a cloud service. In one variant aspect, there is a local copy of the database kept on the computer system  100  and synchronized with the remotely residing database of compatible program versions  108 . 
     The proxy server  104  within the claimed invention is a means allowing the antivirus protection means  103  to perform a search for and a deletion of all kinds of viruses, worms, Trojan horses and other malicious programs in the data stream between the web browser  101  and the website  102 . 
     In one variant aspect, the antivirus protection means  103  is able to perform any combination of functions related to the security of the computer system  100 , such as: counteracting malicious objects, detecting and deleting malicious objects, and neutralizing threats. These functions related to the security are described below only in general outline, as an illustration, and they do not constitute an exhaustive list of the functions relating to security under consideration. Various other functions relating to security may be used in addition to or in place of any of the functions relating to security and cited as an example in the present document. 
     Counteracting malicious objects involves blocking malicious objects, such as viruses, worms, and other malicious programs, advertising software, key logger programs, spam and so forth. Counteracting the malicious objects may also include blocking of unwanted traffic (by the proxy server  104 ), such as hacker attacks, before any of these objects is able to realize its malicious potential on the computer system  100 . Blocking the unwanted traffic may include blocking or rerouting the traffic content using the firewall, and also by the proxy server  104 . 
     The detection and removal of malicious objects is employed for objects which have gotten past the checks designed to prevent penetration and are now present in one form or another on the local device  100 , including when the analysis of the network traffic on the proxy server  104  is being done in an asynchronous mode. 
     The neutralization of threats is employed to detect unwanted content and to detect attacks or threats in real time and it involves taking steps to shut down any suspicious programs or processes, to block the network traffic by the antivirus protection module  103 , and to restore the system to its last known secure condition. The antivirus protection module  103  contains a set of components such as a firewall, a filter of email messages, an antivirus module/module for blocking of unwanted content/utility for removal of malicious software, a system for backup data copying and restoration, and also an intrusion prevention and detection system (IPS/IDS). These components may work in various combinations to realize the different functions of the antivirus protection module  103 . 
     In order to gain access to the session encryption key, the agent  106  running under the control of the antivirus protection means  103  introduces a program module  107  into the address space of the process of the web browser  101 . The program module  107 , using information from the database  105 , determines the address of the API function (or simply a function) which allows it to obtain the session encryption key. In one variant aspect, the calling of the given API function returns the generated session encryption key. In another variant aspect, the given API function is characterized in that a buffer containing the generated session encryption key is transferred to it as input parameters. 
     For obvious reasons, the information about such API functions is not documented, and as a result it is not publicly available. Moreover, each version of the web browser  101  may have different API functions residing at different addresses. The program code of the web browsers  101  ending up on the computer systems  100  of the users is a sequence of bytes in hex code, not containing data allowing an identification of functions. For example, the API function being sought is called GetTLSKey( ), but during the assembly of the application of the web browser  101 , all the names of the functions are removed by the compiler. Only the addresses remain at which the calls of the corresponding functions occur. For example, instead of the name of the API function GetTLSKey( ), an address of the kind 0x80555f1 is indicated. 
     The database  105  contains a list of the addresses of the sought API function, corresponding to the versions of the web browsers  101 . The database  105  is formed and constantly updated by specialists in computer security (such as the specialists of an antivirus company) by methods of reverse engineering. It is also possible to use PDB (program database) files to determine the address of the sought API function—these are program-debugging files, special files containing debugging symbols in which information is found as to which addresses correspond to which variables and functions. For example, by utilizing a certain PDB file one may learn that the variable at the address 0x80484e1 is called tlsKey, while the function at the address 0x80555f1 is called GetTLSKey( ). The PDB files containing the sought information are not made public and may only be obtained directly from the company developing the application in question (such as a web browser). For each version of a web browser  101  it is necessary to obtain the corresponding PDB, find out which API function is needed, and find its address in the PDB, in order to add a record to the database  105 . 
     In one variant aspect, the program module  107  to be introduced into the address space of the web browser  101  may intercept the mentioned sought API function which is called up in the process of establishing the protected connection. The technology of intercepting API function calls involves various approaches, which may be employed in the context of the present disclosure. One of the approaches is based on the fact that the calls of any given API functions in a process corresponding to a web browser  101  from the DLL libraries are carried out through a function import table. This table is filled in during the loading of the DLL into the process, and the addresses of all imported functions which might be needed by the process are written therein. The functions may include the API function that receives, as one of its arguments, the session encryption key generated in the process of establishing the protected connection. Accordingly, in order to intercept the API function call, the program module  107  will find the import table, and in it using the address from the database  105  it will find the API function whose call needs to be intercepted, and it places in the found import table a pointer to another function in place of the original API function. The other function whose pointer is placed in the import table in place of the original API function is a function allowing the copying of the session encryption key and a transfer of control back to the original API function. 
     The database  105  contains a list of the addresses of the API functions corresponding to the versions of the web browser  101 , where the API functions are characterized in that they receive, as one of their arguments, the session encryption key generated in the process of establishing the protected connection. 
     In another aspect of the disclosure, a method of analyzing the content of encrypted network traffic between the web browser  101  and the web site  102  is provided. According to this method, a list of addresses of API functions corresponding to the versions of the web browser  101  is stored in the database  105 . The API functions are characterized in that they receive, as one of their arguments, the session encryption key generated in the process of establishing the protected connection. The antivirus protection module  103  is used to route network traffic between the web browser  101  and the web site  102  through the proxy server  104 . The request to establish a protected connection between the web browser  101  and the website  102  may be discovered with the aid of the proxy server  104  (or with the aid of the antivirus protection means  103  under the control of which the proxy server  104  is running). With the aid of the agent  106 , the program module  107  is introduced into the address space of the web browser  101  and with its aid the call of the API function is intercepted at the address corresponding to the version of the web browser  101  in the database  105 , and a copy of the session encryption key is obtained. In another variant aspect, the program module  107  introduced into the address space of the web browser  101  is used to obtain the session encryption key by means of a call for the API function at an address corresponding to the version of the web browser  101  from the list in the database  105 . With the aid of the agent  106 , the obtained session encryption key is transferred to the antivirus protection means  103 . And with the aid of the antivirus protection means  103 , an analysis is made of the network traffic between the web browser  101  and the website  102 , decrypted by a copy of the session encryption key. 
     In the context of the proposed invention, the analysis of the network traffic between the web browser  101  and the web site  102  may be done either in synchronous or in asynchronous mode. In synchronous mode, the transmission of the data passing through the proxy server  104  is held up for the time needed to perform the analysis by the antivirus protection module  103 . Data found to be malicious according to the results of the analysis is removed from the network traffic. In asynchronous mode, the analysis of the data stream is done with no delay. 
     In the present disclosure, at least portions of the antivirus protection module  103 , the proxy server  104  and the database  105  may be implemented on the processor of a general-purpose computer (such as the one shown in  FIG. 4 ). 
       FIG. 2  shows a preferred variant aspect of the system of analysis of the content of encrypted traffic between processes. In one variant embodiment, the protected connection is established between two processes, the process  201  (the first process) and the process  202  (the second process). The process is an application that is being executed on the processor of the computer system. Furthermore, the application is characterized in that the application contains an internal realization of the cryptographical protocols designed to establish a protected connection to another application within which the network traffic being transferred between them is encrypted. In one variant embodiment, the processes execute on different computer systems: the process  201  executes on a first computer system, while the process  202  executes on a second computer system. In another variant embodiment, the process  201  and the process  202  execute on the same computer system. 
     In one variant embodiment, an agent  206  is also a process which is executed on a first computer system, while an antivirus protection means  203  and a proxy server  104  under the control of which the antivirus protection means  203  is running are executed on a remote server. In this variant, the agent  206  is a security application (such as an antivirus application). In another variant embodiment, the antivirus protection means  203  is a security application (such as an antivirus application) and it is executed on the first computer system. In this variant, the proxy server  104  and the agent  206  are means running on the first computer system under the control of the antivirus protection means  203 . The encrypted network traffic between the process  201  and the process  202  flows through the proxy server  104 . 
     The agent  206  has access to a database  205  containing a list of function addresses, characterized in that it returns the session encryption key generated when establishing the protected connection between the process  201  and the process  202 . In addition, the addresses of the mentioned function correspond to different applications and their versions. The agent  206  transfers the session key so obtained to the antivirus protection means  203 . In another variant embodiment, the agent  206  transfers the session key so obtained to the proxy server  104 , which is under the control of the antivirus protection means  203 . The database  205  is kept on a remote server or in a cloud service and in one variant embodiment it has a local copy which is kept on the first computer system and synchronized with the remotely residing database  205 . 
     The agent  206  also has access to a database of compatible program versions  208 , that, similar to the database  205 , is kept on a remote server or in a cloud service. In one variant aspect, the database is kept locally on the first computer system and is synchronized with the remotely residing database of compatible program versions  208 . In one variant aspect, the agent  206  before introducing a program module  207  into the address space of the process  201  verifies the compatibility of the introducing technology and/or of the program module  207  with the version of the application pertaining to the process  201 . If the version and the name of the application corresponding to the process  201  are contained in the database of compatible program versions  208 , the agent  206  carries out the introduction of the program module  207  in the address space of the process  201 . Absence of the version and name of the application corresponding to the process  201  means that the method provided in the claimed invention cannot be applied to the process  201 . 
     In a general variant aspect of the claimed invention, a method is carried out for analysis of the content of encrypted traffic between the process  201  and the process  202 . According to this method, a list of function addresses is kept in the database  205 . The database  205  returns the session encryption key that was generated while establishing a protected connection between the process  201  and the process  202 . The program module  207  is introduced with the aid of the agent  206  into the address space of the process  201 . In one variant aspect, the mentioned list from the database  205  is contained inside the program module  207  being introduced into the address space of the process  201 . The traffic between the process  201  and the process  202  is rerouted through the proxy server  104  with the aid of the agent  206  (or with the aid of the antivirus protection means  203  under the control of which the agent  206  is running). 
     The proxy server  104  discovers the protected connection between the process  201  and the process  202 . With the aid of the program module  207  introduced into the address space of the process  201 , the session encryption key is obtained by a function call at the address corresponding to the version of the application from the mentioned list from the database  205 . With the aid of the antivirus protection means  203 , the traffic between the process  201  and the process  202  is analyzed after the traffic is decrypted with the aid of the session encryption key. Furthermore, in one variant embodiment, before introducing the program module  207  into the address space of the process  201 , a verification is made of the compatibility of the current version of the application corresponding to the process  201  with mentioned method for analysis of the content of the encrypted traffic between the process  201  and the process  202  according to the database of compatible program versions  208 . 
     The proxy server  204  discovers the protected connection between the process  201  and the process  202 . With the aid of the program module  207  introduced into the address space of the process  201 , the session encryption key is obtained by a function call at the address corresponding to the version of the application from the mentioned list from the database  205 . With the aid of the antivirus protection means  203 , the traffic between the process  201  and the process  202  is analyzed after the traffic is decrypted with the aid of the session encryption key. Furthermore, in one variant embodiment, before introducing the program module  207  into the address space of the process  201 , a verification is made of the compatibility of the current version of the application corresponding to the process  201  with mentioned method for analysis of the content of the encrypted traffic between the process  201  and the process  202  according to the database of compatible program versions  208 . 
       FIG. 3  is a flow diagram of a method for analysis of content of encrypted traffic between processes. 
     The method begins at step  302  and proceeds to step  304 . At step  304 , the traffic between a first process executing on a first computing device and a second process is rerouted to a server. In some aspects, the server may be a proxy server (e.g. proxy server  104 ) or the like. In some aspects, the second process may be a remote process, or a process that also executes on the same computing device executing the first process. The traffic is rerouted in order to determine whether there is a protected connection being established between the two processes. In some aspects, this protected connection encrypts all information/traffic transmitted over the connection. In some aspects, an agent (e.g., agent  206  of  FIG. 2 ) performs the rerouting. 
     At step  306 , information related to an application pertaining to the first process is determined. In some aspects, determining the information related to an application comprises querying a database for the information related to the application based on application data, such as version number of the application, name of the application or the like, and receiving the information related to the application. In some aspects, the information related to the application includes addresses of functions that are intercepted to obtain a session key. The session key is used to decrypt the traffic between the two processes. In some aspects, the functions are intercepted by introducing a program module (e.g., program module  207 ) into the address space of the first process. 
     At step  308 , using the information related to the application, the session key is obtained. For example, the agent  206 , in some aspects, introduces the program module  207  into the first process. The program module  207  may place the address of a new function call at the address of the old function that receives a session key indicated in the information related to the application. Instead of the first process sending the session key to the originally intended function, the session key is sent to the new function whose address was placed in the address space of the process. The session key is then obtained by the new function. 
     At step  310 , the obtained session key is used to decrypt the traffic that was rerouted to the server. The traffic is then analyzed to search for malicious objects in the traffic. In some aspects, the analysis is performed synchronously, where analyzing further traffic is delayed until malicious objects found in the traffic currently being analyzed is removed or counteracted. In other aspects, the analysis is performed asynchronously and continues without delay or regard to whether other malicious objects have been removed or counteracted. 
     At step  312 , the malicious objects found in the rerouted traffic are counteracted. In some aspects, counteracting the malicious objects includes removing the malicious objects from the traffic, replacing the malicious objects in the traffic, or disabling the malicious objects. 
     The method terminates at  314 . 
       FIG. 4  is a block diagram illustrating a general-purpose computer system  20  on which aspects of the present disclosure may be implemented in accordance with an exemplary aspect. It should be noted that the computer system  20  can correspond to the system  100 , and/or individual components thereof. 
     As shown, the computer system  20  (which may be a personal computer or a server) includes a central processing unit  21 , a system memory  22 , and a system bus  23  connecting the various system components, including the memory associated with the central processing unit  21 . As will be appreciated by those of ordinary skill in the art, the system bus  23  may comprise a bus memory or bus memory controller, a peripheral bus, and a local bus that is able to interact with any other bus architecture. The system memory may include permanent memory (ROM)  24  and random-access memory (RAM)  25 . The basic input/output system (BIOS)  26  may store the basic procedures for transfer of information between elements of the computer system  20 , such as those at the time of loading the operating system with the use of the ROM  24 . 
     The computer system  20 , may also comprise a hard disk  27  for reading and writing data, a magnetic disk drive  28  for reading and writing on removable magnetic disks  29 , and an optical drive  30  for reading and writing removable optical disks  31 , such as CD-ROM, DVD-ROM and other optical media. The hard disk  27 , the magnetic disk drive  28 , and the optical drive  30  are connected to the system bus  23  across the hard disk interface  32 , the magnetic disk interface  33  and the optical drive interface  34 , respectively. The drives and the corresponding computer information media are power-independent modules for storage of computer instructions, data structures, program modules and other data of the computer system  20 . 
     In one aspect, the hard disk  27 , the removable magnetic disk  29  and the removable optical disk  31  may be connected to the system bus  23  via the controller  55 . It will be understood by those of ordinary skill in the art that any type of media  56  that is able to store data in a form readable by a computer (solid state drives, flash memory cards, digital disks, random-access memory (RAM) and so on) may also be utilized. 
     The computer system  20  has a file system  36 , in which the operating system  35 , may be stored, as well as additional program applications  37 , other program modules  38 , and program data  39 . A user of the computer system  20  may enter commands and information using keyboard  40 , mouse  42 , or any other input device known to those of ordinary skill in the art, such as, but not limited to, a microphone, joystick, game controller, scanner, etc. . . . . Such input devices typically plug into the computer system  20  through a serial port  46 , which in turn is connected to the system bus, but those of ordinary skill in the art will appreciate that input devices may be also be connected in other ways, such as, without limitation, via a parallel port, a game port, or a universal serial bus (USB). A monitor  47  or other type of display device may also be connected to the system bus  23  across an interface, such as a video adapter  48 . In addition to the monitor  47 , the personal computer may be equipped with other peripheral output devices (not shown), such as loudspeakers, a printer, etc. 
     Computer system  20  may operate in a network environment, using a network connection to one or more remote computers  49 . The remote computer (or computers)  49  may be local computer workstations or servers comprising most or all of the aforementioned elements in describing the nature of a computer system  20 . Other devices may also be present in the computer network, such as, but not limited to, routers, network stations, peer devices or other network nodes. 
     Network connections can form a local-area computer network (LAN)  50  and a wide-area computer network (WAN). Such networks are used in corporate computer networks and internal company networks, and the networks generally have access to the Internet. In LAN or WAN networks, the personal computer  20  is connected to the local-area network  50  across a network adapter or network interface  51 . When networks are used, the computer system  20  may employ a modem  54  or other modules well known to those of ordinary skill in the art that enable communications with a wide-area computer network such as the Internet. The modem  54 , which may be an internal or external device, may be connected to the system bus  23  by a serial port  46 . It will be appreciated by those of ordinary skill in the art that said network connections are non-limiting examples of numerous well-understood ways of establishing a connection by one computer to another using communication modules. 
     In various aspects, the systems and methods described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the methods may be stored as one or more instructions or code on a non-transitory computer-readable medium. Computer-readable medium includes data storage. By way of example, and not limitation, such computer-readable medium can comprise RAM, ROM, EEPROM, CD-ROM, Flash memory or other types of electric, magnetic, or optical storage medium, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a processor of a general purpose computer. 
     In various aspects, the systems and methods described in the present disclosure can be addressed in terms of modules. The term “module” as used herein refers to a real-world device, component, or arrangement of components implemented using hardware, such as by an application specific integrated circuit (ASIC) or field-programmable gate array (FPGA), for example, or as a combination of hardware and software, such as by a microprocessor system and a set of instructions to implement the module&#39;s functionality, which (while being executed) transform the microprocessor system into a special-purpose device. A module may also be implemented as a combination of the two, with certain functions facilitated by hardware alone, and other functions facilitated by a combination of hardware and software. In certain implementations, at least a portion, and in some cases, all, of a module may be executed on the processor of a general purpose computer (such as the one described in greater detail in  FIG. 4 , above). Accordingly, each module may be realized in a variety of suitable configurations, and should not be limited to any particular implementation exemplified herein. 
     In the interest of clarity, not all of the routine features of the aspects are disclosed herein. It would be appreciated that in the development of any actual implementation of the present disclosure, numerous implementation-specific decisions must be made in order to achieve the developer&#39;s specific goals, and these specific goals will vary for different implementations and different developers. It is understood that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art, having the benefit of this disclosure. 
     Furthermore, it is to be understood that the phraseology or terminology used herein is for the purpose of description and not of restriction, such that the terminology or phraseology of the present specification is to be interpreted by the skilled in the art in light of the teachings and guidance presented herein, in combination with the knowledge of the skilled in the relevant art(s). Moreover, it is not intended for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. 
     The various aspects disclosed herein encompass present and future known equivalents to the known modules referred to herein by way of illustration. Moreover, while aspects and applications have been shown and described, it would be apparent to those skilled in the art having the benefit of this disclosure that many more modifications than mentioned above are possible without departing from the inventive concepts disclosed herein.