Abstract:
Described is a mechanism for collectively evaluating security risks associated with loading an application. A hosting environment associated with loading the application invokes a trust manager to evaluate the security risks. The trust manager invokes a plurality of trust evaluators, where each trust evaluator is responsible for analyzing and assessing a different security risk. Upon completion of each security risk evaluation, results of those individual security risk evaluations are returned to the trust manager. The trust manager aggregates the variety of security risk evaluation results and makes a security determination based on the aggregated evaluation results. That determination may be to move forward with loading the application, to block the load of the application, or perhaps to prompt the user for a decision about whether to move forward with the load.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to computer security systems. More particularly, the present invention relates to a mechanism for evaluating and aggregating security assessment information for computing systems.  
         BACKGROUND OF THE INVENTION  
         [0002]    Computer users today have access to a multitude of different applications and utilities. The typical computer user may install dozens of computer programs on a computer over the course of a year. Most times, computer users knowingly install programs on their computers. For instance, a user may purchase a software program and install it manually. Sometimes a user may install a program unknowingly, such as by visiting a particular Web site that is configured to install an applet or small program on the users computer. Installing programs on computers has become so commonplace today that some users are unaware of the security issues involved with installing new software. Other users are keenly aware of the security issues in general, but are typically uncertain about the particular issues that may surround installing a particular program.  
           [0003]    Most users understand that new programs can introduce viruses or other malicious code on their computers. Users also understand that some software developers make programs freely available that have an overt function or purpose, such as enhancing e-mail messages, and a covert function or purpose, such as recording information about the user that is later returned a marketing entity. This particular type of software is often referred to as “spyware.” So users often try to protect themselves from these security threats in various way. For instance, many users install anti-virus utilities to protect themselves against viruses. Fewer users also install anti-spyware utilities to address the spyware security issues.  
           [0004]    Unfortunately, each security utility operates separately from each other and without knowledge of each other&#39;s results, thus burdening the user with assimilating the information from each security utility. Security systems today operate in a vacuum with respect to each other, and each reports to the user only on its specific security risk. Most users do not want separate notifications of different security risks from several disparate systems. Rather, they want their security systems just to work. The patchwork nature of security utilities today typically leaves users in fear that they have left a hole in their defenses, and that malicious or undesirable programs will slip through. Because of that fear, many users are reluctant to try new programs, especially in online environments.  
           [0005]    Unfortunately, there are currently no mechanisms that can protect a user from multiple disparate security risks presented by a particular software program when it is being downloaded, installed, or executed. An adequate mechanism for evaluating security risks has eluded those skilled in the art.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is directed at a system and method for accumulating security assessment information about a program and operating on that information in a convenient and usable fashion. Briefly stated, a hosting environment is responsible for loading an application. In response to the initiation of the application load, the hosting environment invokes a trust manager to evaluate any security risks associated with that application. The trust manager invokes a plurality of trust evaluators, where each trust evaluator is responsible for analyzing and assessing a different security risk. Upon completion of each security risk evaluation, results of those individual security risk evaluations are returned to the trust manager. The trust manager aggregates the variety of security risk evaluation results and makes a security determination based on the aggregated evaluation results. That determination may be to move forward with loading the application, to block the load of the application, or perhaps to prompt the user for a decision about whether to move forward with the load. Advantageously, if prompted, the user can make a decision based on the collective security assessment of the application, which provides the user with a greater sense of protection about his computer system in general. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a functional block diagram that illustrates a computing device that may be used in implementations of the present invention.  
         [0008]    [0008]FIG. 2 is a functional block diagram generally illustrating components of a system for performing a security evaluation of an application and for presenting a user with a collective security assessment of that evaluation.  
         [0009]    [0009]FIG. 3 is a graphical representation of one illustrative grant set for an application that associates particular permissions with components of the application in the context of the application.  
         [0010]    [0010]FIG. 4 is a graphical representation of one illustrative user interface that may be used to present collective security assessment information to a user.  
         [0011]    [0011]FIG. 5 is a logical flow diagram generally illustrating a process for evaluating the security risks associated with an application and for presenting to a user the collective security assessment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]    The invention will be described here first with reference to one example of an illustrative computing environment in which embodiments of the invention can be implemented. Next, a detailed example of one specific implementation of the invention will be described. Alternatives implementations may also be included with respect to certain details of the specific implementation. It will be appreciated that embodiments of the invention are not limited to those described here.  
         [0013]    Illustrative Computing Environment of the Invention  
         [0014]    [0014]FIG. 1 illustrates a computing device that may be used in illustrative implementations of the present invention. With reference to FIG. 1, one exemplary system for implementing the invention includes a computing device, such as computing device  100 . In a very basic configuration, computing device  100  typically includes at least one processing unit  102  and system memory  104 . Depending on the exact configuration and type of computing device, system memory  104  may be volatile (such as RAM), non-volatile (such as ROM, flash memory, etc.) or some combination of the two. System memory  104  typically includes an operating system  105 , one or more program modules  106 , and may include program data  107 . This basic configuration of computing device  100  is illustrated in FIG. 1 by those components within dashed line  108 .  
         [0015]    Computing device  100  may have additional features or functionality. For example, computing device  100  may also include additional data storage devices (removable and/or non-removable) such as, for example, magnetic disks, optical disks, or tape. Such additional storage is illustrated in FIG. 1 by removable storage  109  and non-removable storage  110 . Computer storage media may include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. System memory  104 , removable storage  109  and non-removable storage  110  are all examples of computer storage media. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (“DVD”) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computing device  100 . Any such computer storage media may be part of device  100 . Computing device  100  may also have input device(s)  112  such as keyboard  122 , mouse  123 , pen, voice input device, touch input device, scanner, etc. Output device(s)  114  such as a display, speakers, printer, etc. may also be included. These devices are well known in the art and need not be discussed at length here.  
         [0016]    Computing device  100  may also contain communication connections  116  that allow the device to communicate with other computing devices  118 , such as over a network. Communication connections  116  is one example of communication media. Communication media may typically be embodied by computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave or other transport mechanism, and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. The term computer readable media as used herein includes both storage media and communication media.  
         [0017]    Discussion of Specific Implementation  
         [0018]    [0018]FIG. 2 is a functional block diagram generally illustrating components of an environment implementing the present invention. As shown in FIG. 2, a trust evaluation system  200  is configured to evaluate an application  201  and identify any security risks associated with the application  201 . The application  201  may be any executable code that is available to the computing device  100 . There are inherently some security risks associated with executing the application  201  on the computing device  100 . For instance, the application  201  may contain a virus or it may constitute spyware. Accordingly, the system  200  is configured to analyze the application  201  to assess and quantify those risks in a meaningful way. The trust evaluation system  200  then makes a decision about loading the application  201 .  
         [0019]    The application  201  may be composed of several components operating in conjunction. For instance, the application  201  may include multiple modules or assemblies, such as assembly A  202  and assembly B  203 . The application  201  may include metadata that describes the application and each of its constituent components. That metadata may be contained in a manifest  205  or otherwise stored in association with the application  201 . The metadata may include information such as the name of the application, the version of the application, what rights and permissions the constituent components of the application desire, privacy policy information, digital signature information, and the like.  
         [0020]    The application  201  may be first loaded onto the computing device  100  in one of many ways. For instance, the application  201  may be downloaded during an Internet session, it may be obtained on an optical disk or other permanent storage, it may be received in an e-mail message, or through some other mechanism. In this implementation, the application  201  is loaded by and executed in a hosting environment  220 . For the purpose of this discussion, the hosting environment  220  includes any environment in which the application  201  will be executed. For instance, the hosting environment  220  may be a managed code runtime environment, a shell, another application, or the like. In this particular embodiment, the hosting environment  220  may include a priority rating based on the type of host it is. For instance, it may be determined that a hosting environment associated with an optical disk drive may pose a lower security risk than a hosting environment associated with a network session, such as the Internet. The priority rating may be used later when assigning a security score to the application  201 .  
         [0021]    The hosting environment  220  is configured to create an Application Description Object (ADO)  221  based on the metadata about the application  201 . The hosting environment  220  includes in the ADO  221  sufficient information about the application  201  to effectively evaluate the security risks associated with the application  201 . Accordingly, the ADO  221  may include, in object form, the name of the application, the version of the application, what rights and permissions the constituent components of the application desire, privacy policy information, digital signature information, and the like. The hosting environment  220  is further configured to invoke a Trust Manager  210  to perform the evaluation.  
         [0022]    The Trust Manager  210  may be a trusted component of an operating system resident on the computing device  100 . In this particular embodiment, the Trust Manager  210  exposes an interface that is called by the hosting environment  220  to initiate the security evaluation of the application  201 . The Trust Manager  210  receives the ADO  221  from the hosting environment  220  via the interface. The Trust Manager  201  is further configured to invoke a series of trust evaluation engines to assess the security risk associated with the application  201 . Each evaluation engine is configured to evaluate a particular class of threat based on information in the ADO  221  or on the components of the application  201  itself For instance, evaluation engine  240  may be a scoring engine that evaluates evidence about the application, as may be contained in the ADO  221  or elsewhere, to determine the ability of the application to perform malicious acts on the computing device  100 . Evaluation engine  241  may be a virus checker and evaluation engine  242  may be configured to evaluate privacy concerns about the application  201 . Each of the evaluation engines may derive from a base class, or may be implemented as an interface.  
         [0023]    Each evaluation engine is configured to assess the application  201  against its particular rules or criteria to determine a score  245 . Examples of the score include a numerical value between a minimum and maximum, or a discrete value from a set of alternative security levels. These are only examples and not an exhaustive list. The score  245  may then be returned to the Trust Manager  210  by each evaluation engine at the conclusion of its assessment. The Trust Manager  210  is configured to aggregate the individual scores into a score collection  250 , which represents the collective security assessment of the application in each of the areas for which an evaluation engine exists. Any priorities that may exist, such as priorities associated with the particular type of hosting environment  220 , may be applied to the score collection  250  to further refine the collective security assessment. Based on the collective security assessment, the Trust Manager  210  may have sufficient information to make a loading decision without involving the user. For instance, pre-determined thresholds (either set by default or perhaps provided by the user) may govern what programs are loaded without seeking user acceptance, or what programs are blocked without prompting the user. If the collective security assessment for the particular application being loaded falls between those two thresholds, the user may be prompted for a loading decision.  
         [0024]    The Trust Manager  210  constructs a Trust Object  261  that describes the level of permissions with which the application will be loaded, if at all. The Trust Object  261  may include data that defines a permission grant set  262  for the application on a component-by-component basis. One example of an illustrative permission grant set  262  is illustrated in FIG. 3 and described below. If the collective security assessment for the application  201  falls between the two thresholds mentioned above, the Trust Manager  210  may pass the Trust Object  261  to a User Interface  260  so that the user may be prompted.  
         [0025]    The User Interface  260  is a mechanism for presenting the collective security assessment to the user in a meaningful way so that the user can make an informed decision about proceeding. The User Interface  260  may take many forms, such as a dialog box, an audible signal, an iconic indicator, or the like. One example of a potential User Interface  260  is illustrated in FIG. 4 and described below. In essence, the User Interface  260  represents a single point of presentation for various and disparate security information that, in conventional systems, does not exist.  
         [0026]    The User Interface  260  may prompt the user with the potential security ramifications of allowing the application load to proceed, and possibly presenting the user with various levels of permissions that may be assigned to the application. The user is asked to make a determination whether to proceed with loading the application or not. The User Interface  260  adds the user&#39;s response information to the Trust Object  261  and returns it to the Trust Manager  210 .  
         [0027]    Each time the application  201  is launched or executed, it&#39;s hosting environment  220  could invoke the Trust Manager  210  to retrieve the security assessment of the application  201 . In the case where the grant set  262  has already been created, the Trust Manager  210  may return that grant set  262  to the hosting environment  220 . Alternatively, the hosting environment  220  could cache the security assessment information for subsequent use without involving the Trust Manager  210 . The hosting environment  220  will then apply any access permissions identified in the grant set  262  to the application  201 . More specifically, the hosting environment  220  may apply the access permissions to each individual component, such as assembly A  202 , of the application  201 . It is equally feasible that the hosting environment  220  or some other application may present a component to the Trust Manager  210  for a security assessment without the specific intent of then executing the component.  
         [0028]    [0028]FIG. 3 is a graphical representation of one illustrative grant set  301  that may be generated by implementations of the present invention. It should be noted that the term “grant set,” as used in this document, means any collection of information that is used to define the security environment in which an application may execute. The term “grant set” used in this document is not limited to a particular security environment, such as a Common Language Runtime environment, but rather is intended to cover information used to define the security environment within which an application executes regardless of the particular operating environment.  
         [0029]    In this particular example, the grant set  301  may be data within an object, such as a Trust Object or the like. In this example, the grant set  301  includes information that identifies each component of the application. In addition, the grant set  301  includes information that defines the permissions for each component of the application. In this case, a components table  310  identifies the components Assembly A, Assembly B, and Assembly C and associates each of those components with a permission set. For instance, in the grant set  301 , Assembly A is identified as having permission set PSI.  
         [0030]    A permissions table  320  is also included in the grant set  301  to define specifically those permissions are security rights that are associated with each permission set. In this example, permission set PS1 includes those permissions and rights identified in the example as Permissions 1. It will be appreciated that, as described above, when the hosting environment  220  begins to load the components of the application, by referring to the grant set  301  the appropriate permissions may be applied to each component of the application in the context of the application. In other words, some other application may also include Assembly B, but in the context of that other application, Assembly B may have a different permission set. In that case, when the other application was executed, and Assembly B was loaded, it would have the permission set defined by a grant set associated with the other application.  
         [0031]    [0031]FIG. 4 is an illustrative User Interface dialogue that may be presented to a user based on a security assessment of an application. In this particular example, the dialog  401  is presented based on an evaluation of an application that has requested access to the file system and the network. In addition, a virus evaluator has determined that the application does not contain a virus. In iconic indication of the risk level  405  may also be included. The user is presented with the option of allowing the load to proceed, such as by clicking an OK button  410 , or to abort the load. The User Interface shown in FIG. 4 is for the purpose of illustration only, and is not to be viewed as limiting or the exclusive mechanism for presenting security information to the user. Indeed, it is envisioned that very many different forms of collective security assessment presentation will become apparent from the teachings of this document.  
         [0032]    [0032]FIG. 5 is a logical flow diagram generally illustrating a process for identifying and collectively presenting, in meaningful way, information about security risks posed by an application. The process begins at starting block  501 , where an application is being loaded for execution on a computing system. As discussed above, an application may be loaded in many ways through various types of hosts. Accordingly, at starting block  501 , a particular application is being loaded through use of a particular host. The process continues at block  503 .  
         [0033]    At block  503 , the host constructs an Application Description Object (ADO) based on information about the application. As described above, the information may be obtained from a manifest included with the application, or through any other metadata associated with the application. The ADO contains descriptive information about the application, such as the name and version of the application, any rights being requested by the application, any code access permissions being requested by the application, digital signature information related to the application, privacy policy information, and the like. The process continues at block  505 .  
         [0034]    At block  505 , the host invokes a Trust Manager with an instruction to evaluate the security risks associated with the application. The host passes the ADO to the Trust Manager for use in the evaluation.  
         [0035]    At block  507 , the Trust Manager begins evaluating the security risks of the application by invoking a series of Trust Evaluators that each evaluate a specific area of security risk. For instance a virus evaluator may be configured to examine each component of an application for the possibility that the application contains a virus. A privacy evaluator may evaluate the permissions requested by the application to determine what level of threat to privacy the application presents. Many other Trust Evaluators may also be used, as will be apparent to those skilled in the art.  
         [0036]    Loop  508  is performed for each Trust Evaluator in the system. The Loop  508  begins at block  509 , where the current Trust Evaluator examines the information in the ADO and/or the components of the application to assess the security risk. The information in the ADO may be compared against a set of rules or other criteria to build a score that quantifies the security risk of the application. In one example, a score may be a value from zero (maximum risk) to one (minimum risk). The score may also include a priority and a string descriptor.  
         [0037]    It will be appreciated that the evaluations being performed by each Trust Evaluator are analogous to similar security risk evaluations that may be performed by conventional mechanisms. However, in accordance with the invention, each Trust Evaluator assesses its respective security risk and returns the score collection to the Trust Manager (block  511 ). When each Trust Evaluator has returned its score collection to the Trust Manager, the loop  508  terminates and the process continues to block  513 .  
         [0038]    At block  513 , the Trust Manager analyzes the score collections from the Trust Evaluators. The Trust Manager may prioritize the score collections based on some pre-determined criteria, such as a priority associated with a particular Trust Evaluator, or some other prioritization scheme. For instance, a high risk that a virus is present may outweigh a low risk that a privacy violation may occur. The Trust Manager determines, from the prioritized score collections, an aggregate security impact on the computing system. If the aggregate security impact on the system exceeds some pre-determined threshold, the Trust Manager may simply block the load of the application. If the aggregate security impact is below some other threshold, the Trust Manager may simply build a Trust Object that includes sufficient permissions for the application to execute. If however, neither of these cases exists, the Trust Manager may invoke a User Interface to prompt the user to make the determination.  
         [0039]    At block  515 , the Trust Manager passes the prioritized score collection and aggregate impact information to the User Interface for final evaluation if required from the user. If so, the aggregate security impact is presented to the user. The presentation may be in the form of a dialog box that summarizes or details specifically the security risks associated with loading the application. For instance, a scoring engine may have determined that the application has requested sufficient permissions to read and modify files on the computer, and to transmit data over a network connection. Based on that information, together with perhaps other evidence, a privacy evaluator may have determined that the application is likely to share the user&#39;s information over the network. Accordingly, that information may be combined to inform the user that loading the application is likely to result in the user being targeting by telemarketing campaigns or other inappropriate uses of the user&#39;s personal information. Advantageously, the user is presented with disparate security information collected into a common notification, such as a dialog box or the like.  
         [0040]    At block  517 , with any input from the User Interface, the Trust Manager modifies the Trust Object to describe the security environment in which the application may be executed. In one embodiment, the Trust Object includes data that associates the application, or components of the application, with a permission grant set. The permission grant set describes the level of security that will be applied to the application when executed. In one specific environment, a permission grant set is associated with each component of the application. In that way, a component that is shared among different applications may be executed with different permissions depending on the application context in which it is executing. The process may idle at block  517  until the application is actually executed, thereby causing the host to begin loading components of the evocation. At that point, the process continues to block  519 .  
         [0041]    At block  519 , the application is being loaded by the host. As part of a security policy that applies to applications being loaded, the host queries the Trust Manager for the Trust Object associated with the application. As each component of the application is loaded, the permission grant set associated with that component is applied. In this way, applications that have been loaded in accordance with the invention are only allowed those permissions which the user has, in an informed way, directly and comprehensively established. If sufficient privileges to execute have not been granted to the application, the Trust Manager may block the execution of the application.  
         [0042]    The above specification, examples and data provide a complete description of the concepts and illustrative implementations of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.