Abstract:
A system for automatic stability determination and deployment of discrete parts of a profile representing normal behavior to provide fast protection of web applications is disclosed. The system, in response to a sensor collecting from HTTP requests sent by the clients to the web application installed on the protected device, automatically creates for a web application a profile with discrete parts that will represent normal behavior so that deviations from the profile can be considered anomalous. The system automatically determines that a first of the discrete parts of the profile has become stable. The system then automatically deploys the first discrete part of the profile to the sensor that now will compare with the first discrete part of the profile subsequent HTTP requests sent by the clients to the web application to detect deviations from the normal behavior represented by the first discrete part.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/254,564, filed on Apr. 16, 2014, which is a continuation of U.S. patent application Ser. No. 12/814,753, filed on Jun. 14, 2010, which issued as U.S. Pat. No. 8,713,682 on Apr. 29, 2014, which is a continuation of U.S. patent application Ser. No. 10/991,467, filed on Nov. 19, 2004, which issued as U.S. Pat. No. 7,743,420 on Jun. 22, 2010, which further claims priority from U.S. Provisional Patent Application No. 60/526,098, filed on Dec. 2, 2003, the entire disclosures of which applications are incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Technical Field of the Invention 
         [0003]    The present invention relates generally to comprehensive security systems, and more particularly, to dynamic learning methods and adaptive normal behavior profile (NBP) architectures utilized by comprehensive security systems. 
         [0004]    Description of the Related Art 
         [0005]    Accessibility, ubiquity and convenience of the Internet rapidly changed the how people access information. The World Wide Web (“WWW”), usually referred to as “the web”, is the most popular means for retrieving information on the Internet. The web enables user access to practically an infinite number of resources, such as interlinked hypertext documents accessed by a hypertext transfer protocol (HTTP), or extensible markup language (XML) protocols from servers located around the world. 
         [0006]    Enterprises and organizations expose their business information and functionality on the web through software applications, usually referred to as “enterprise applications”. The enterprise applications use the Internet technologies and infrastructures. A typical enterprise application is structured as a three-layer system, comprising a presentation layer, a business logic layer and a data access layer. The multiple layers of the enterprise application are interconnected by application protocols, such as HTTP and structured query language (SQL). Enterprise applications provide great opportunities for an organization. However, at the same time, these applications are vulnerable to attack from malicious, irresponsible or criminally minded individual. An application level security system is required to protect enterprise applications from web hackers. 
         [0007]    In related art, application level security systems prevent attacks by restricting the network level access to the enterprises applications, based on the applications&#39; attributes. Specifically, the security systems constantly monitor requests received at interfaces and application components, gather application requests from these interfaces, correlate the application requests and match them against predetermined application profiles. These profiles comprise a plurality of application attributes, such as uniform resource locators (URLs), cookies, users&#39; information, Internet protocol (IP) addresses, query statements and others. These attributes determine the normal behavior of the protected application. Application requests that do not match the application profile are identified as potential attacks. 
         [0008]    An application profile is created during a learning period through which the security system monitors and learns the normal behavior of users and applications over time. The security system can apply a protection mechanism, only once the profile of a protected application is completed, i.e., when sufficient data is gathered for all attributes comprised in the profile. In addition, some security systems require that the application profile be manually defined. These requirements limit the ability of those security systems to provide a fast protection, since substantial time is required (usually days) in order to complete the application profile. Furthermore, this technique limits security systems from being adaptive to changes in application&#39;s behavior. 
         [0009]    Therefore, in the view of the limitations introduced in the related art, it would be advantageous to provide a solution that enables a fast protection of enterprise applications by an application level security system. 
       SUMMARY OF THE INVENTION 
       [0010]    The invention has been made in view of the above circumstances and to overcome the above problems and limitations of the prior art. 
         [0011]    Additional aspects and advantages of the invention will be set forth in part in the description that follows and in part will be obvious from the description, or may be learned by practice of the invention. The aspects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
         [0012]    A first aspect of the invention provides a method for dynamic learning the behavior of enterprise applications for providing the fast protection of the enterprise applications. The method comprises receiving enterprise application events processed by network sensors and analyzing the enterprise application events. The method further comprises generating an adaptive normal behavior profile (NBP), wherein the adaptive NBP comprises at least a plurality of profile items and each of the plurality profile items comprises a plurality of profile properties. The method further comprises performing statistical analysis to determine if the adaptive NBP is stable. The stable adaptive NBP is distributed to the network sensors connected to the protected devices, and the enterprise applications can reside in the protected device. The protected device can be a web server or a database server. Each of the network sensors can be one of a structured query language (SQL) sensor and a hypertext transfer protocol (HTTP) sensor. 
         [0013]    The adaptive NBP has a hierarchic data structure, and can represents a HTTP profile or a SQL profile. The profile property comprises a descriptive value of its corresponding profile item, e.g., maintenance information. The maintenance information can comprise a current state of the profile property, a creation time of the profile property, a link to another profile item, a timestamp of last update, an update sequence number and a number of observations of the corresponded profile item. The current state can be a learn state, an enforceable state and a non-enforceable state, and the profile item comprises at least one of a current state of the profile item and a distinguishable name More particularly, the current state is at least one of a learn state, a protect state, a deleted state, a decayed state and a merged state. 
         [0014]    Analyzing the application events comprises performing a lexical analysis and performing a syntax analysis. The lexical analysis comprises breaking each of the plurality of application events into tokens, and creating a representation of the application event using the tokens&#39; properties. The syntax analysis comprises breaking each of the enterprises application events into functional units, and classifying the functional units as identification units and property units. The identification units are used for identifying the enterprise application event, and the property units describe the property of the enterprise application event. The property units having at least one similar identification unit are gathered to form the profile property, and attached to the profile property corresponding to the profile item. The adaptive NBP is considered stable if at least one of the plurality of profile items or at least one of the plurality of profile properties of the adaptive NBP is stable. 
         [0015]    In one embodiment, performing the statistical analysis comprises computing the Bayesian probability for a mistake. In another embodiment, the statistical analysis comprises computing a percentage of learning progress for each profile item and profile property out of the total number of the enterprise application events received over a predefined time, and determining the respective profile item or the profile property as stable if the percentage of learning progress exceeds a predefined threshold. 
         [0016]    A second aspect of the invention provides a computer program product, comprising computer-readable media with instructions to enable a computer to implement a method for dynamic learning the behavior of enterprise applications for providing fast the protection of the enterprise applications. The method embodied on the computer program product comprises receiving enterprise application events processed by network sensors and analyzing the enterprise application events. The method embodied on the computer program product further comprises generating an adaptive normal behavior profile (NBP), wherein the adaptive NBP comprises at least a plurality of profile items and each of the plurality profile items comprises a plurality of profile properties. The method embodied on the computer program product further comprises performing statistical analysis to determine if the adaptive NBP is stable. The stable adaptive NBP is distributed to the network sensors connected to the protected devices. 
         [0017]    The computer program product creates an adaptive NBP that has a hierarchic data structure, and can represents a HTTP profile or a SQL profile. The profile property comprises a descriptive value of its corresponding profile item, e.g., maintenance information. The maintenance information can comprise a current state of the profile property, a creation time of the profile property, a link to another profile item, a timestamp of last update, an update sequence number and a number of observations of the corresponded profile item. The current state can be a learn state, an enforceable state and a non-enforceable state, and the profile item comprises at least one of a current state of the profile item and a distinguishable name More particularly, the current state is at least one of a learn state, a protect state, a deleted state, a decayed state and a merged state. 
         [0018]    The computer program product analyzes the application events comprises performing a lexical analysis and performing a syntax analysis. The lexical analysis comprises breaking each of the plurality of application events into tokens, and creating a representation of the application event using the tokens&#39; properties. The syntax analysis comprises breaking each of the enterprises application events into functional units, and classifying the functional units as identification units and property units. The identification units are used for identifying the enterprise application event, and the property units describe the property of the enterprise application event. The property units having at least one similar identification unit are gathered to form the profile property, and attached to the profile property corresponding to the profile item. The adaptive NBP is considered stable if at least one of the plurality of profile items or at least one of the plurality of profile properties of the adaptive NBP is stable. 
         [0019]    In one embodiment, the computer program product performs the statistical analysis by computing the Bayesian probability for a mistake. In another embodiment, the statistical analysis comprises computing a percentage of learning progress for each profile item and profile property out of the total number of the enterprise application events received over a predefined time, and determining the respective profile item or the profile property as stable if the percentage of learning progress exceeds a predefined threshold. 
         [0020]    A third aspect of the present invention is a non-intrusive network security system that utilizes a dynamic process for learning the behavior of enterprise applications to allow for the fast protection of the enterprise applications. The security system comprises a plurality of network sensors capable of collecting, reconstructing and processing enterprise application events and a secure server capable of building adaptive normal behavior profiles (NBPs). The security system further comprises connectivity means enabling the plurality of network sensors to monitor traffic directed to at least devices that require protection. In the security system, the enterprise applications reside in the protected devices, and the protected devices can be web servers and/or a database servers. Each of the network sensors can be a structured query language (SQL) sensor and/or a hypertext transfer protocol (HTTP) sensor. 
         [0021]    In the security system, the adaptive NBP is a hierarchic data structure that comprises a plurality of profile items and each of the plurality of the profile items comprises a plurality of profile properties. The adaptive NBP represents at least one of a HTTP profile and a SQL profile. The adaptive NBP is considered stable if at least one of the plurality of profile items or at least one of the plurality of profile properties of the adaptive NBP is stable. The secure sever is capable of distributing the stable adaptive NBP to the network sensors connected to the protected devices. 
         [0022]    In the security system, the dynamic learning process comprises receiving the enterprise application events processed by the network sensors, analyzing the enterprise application events and generating the adaptive NBP. The security system analyzes the application events by performing a lexical analysis and performing a syntax analysis. The lexical analysis comprises breaking each of the plurality of application events into tokens, and creating a representation of the application event using the tokens&#39; properties. The syntax analysis comprises breaking each of the enterprises application events into functional units, and classifying the functional units as identification units and property units. The identification units are used for identifying the enterprise application event, and the property units describe the property of the enterprise application event. The property units having at least one similar identification unit are gathered to form the profile property, and attached to the profile property corresponding to the profile item. The adaptive NBP is considered stable if at least one of the plurality of profile items or at least one of the plurality of profile properties of the adaptive NBP is stable. In addition, the security system performs a statistical analysis to determine if the adaptive NBP is stable. For example, in one embodiment, the security system performs the statistical analysis by computing the Bayesian probability for a mistake. In another embodiment, the statistical analysis comprises computing a percentage of learning progress for each profile item and profile property out of the total number of the enterprise application events received over a predefined time, and determining the respective profile item or the profile property as stable if the percentage of learning progress exceeds a predefined threshold. 
         [0023]    A fourth aspect of the present invention is an adaptive normal behavior profile (NBP) architecture that enables the fast protection of enterprise applications. The architecture comprises a plurality of profile items, wherein each of the plurality of profile items comprises a plurality of profile properties. The normal behavior profile (NBP) architecture is a hierarchic data structure, and can represent at least one of a HTTP profile and/or a SQL profile. Each of the plurality of profile properties comprises a descriptive value of its corresponding profile item. For example, each of the profile properties may comprise maintenance information. The maintenance information may comprise at least one of a current state of the profile property, a creation time of the profile property, a link to another profile item, a timestamp of last update, an update sequence number and a number of observations of the corresponding profile item. The current state is at least one of a learn state, an enforceable state and a non-enforceable state. Each of the plurality of profile items comprises at least a current state of the profile item and a distinguishable name The current state comprises at least one of a learn state, a protect state, a deleted state, a decayed state and a merged state. 
         [0024]    The profile items of the HTTP profile comprise at least a web server group, a web application, a virtual folder, a URL, a cookie and a parameter. The profile property corresponding to a web server group items comprises at least a list of acceptable web application aliases. The profile properties corresponding to the virtual folder item comprise at least a list of sub-folders of the virtual folder, an indication as whether the virtual folder is directly accessible and properties corresponding to a URL item. The profile properties corresponding to the URL item comprise at least a first indication as whether the URL maintained by the URL item generates a binding HTML form, a second indication as whether the URL maintained by the URL item is used as the first URL of a new session, broken links and broken references. The profile properties corresponding to the cookie item comprise at least one of a length restriction on a cookie value and an indication as whether the cookie item represents a set of actual cookies with the same prefix. The profile properties corresponding to the parameter item comprise at least one of a list of allowed aliases for the parameter name, a length restriction on the parameter&#39;s value, a parameter type, a first indication as whether the parameter is bounded to a HTTP response, a second indication as whether the parameter is required for a URL and a third indication as whether the parameter represents a set of actual parameters with a same prefix. 
         [0025]    The profile items of the SQL profile comprise at least one of a database server group, a source group, a table access and a query. The profile properties corresponding to the source group items comprise at least a list of source IP addresses, a list of client applications, a list of database accounts, a list of tables and views for the source group, a first indication as whether an access profile should be enforced for the source group, a second indication as whether to allow database manipulation commands for the source group, a third indication as whether to allow access to a system administrator, a fourth indication as whether to allow access to tables in non-default schemas and a fifth indication as whether to allow access to tables in non-default schemas. The profile property corresponding to the table access item comprises at least an enforcement mode for each type of query, and the profile property corresponding to the query item comprises at least the SQL query. 
         [0026]    The above and other aspects and advantages of the invention will become apparent from the following detailed description and with reference to the accompanying drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The accompanying drawings, which are incorporated in and constitute a part of this specification illustrate embodiments of the invention and, together with the description, serve to explain the aspects, advantages and principles of the invention. In the drawings, 
           [0028]      FIG. 1  is an exemplary diagram of an application level security system for illustrating the principles of the disclosed invention. 
           [0029]      FIG. 2  is an exemplary diagram illustrating the operation of the application level security system in accordance with this invention. 
           [0030]      FIG. 3  is a non-limiting diagram of an adaptive NBP architecture. 
           [0031]      FIG. 4  is a non-limiting diagram of an adaptive NBP architecture characteristic to a HTTP profile. 
           [0032]      FIG. 5  is a non-limiting diagram of an adaptive NBP architecture characteristic to a SQL profile. 
           [0033]      FIG. 6  is an exemplary flowchart describing the dynamic learning process in accordance with an exemplary embodiment of this invention. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0034]    Referring to  FIG. 1 , an exemplary application level security system  100  for illustrating the principles of the present invention is shown. A security system  100  comprises a plurality of network sensors  130 - 1 ,  130 - 2 ,  130 - m  connected to a secure server  110 . The network sensors  130  may be connected to secure server  110  through a conventional network or through an out-of-band network (OOB)  120  for transferring traffic over a dedicated and secure network that is completely separated from the production traffic. A network sensor  130  is placed on each network segment that is coupled to the web servers  160 ,  160 - n  and the database servers  170 ,  170 - r  to be protected. In one embodiment, the network sensor  130  is a passive sniffing device that taps, gathers and reconstructs requests sent to the protected servers  160 ,  170  from an attacker machine  180 . Network device  150  may be, but is not limited to, a hub, a switch, a tap device, and so on. Network sensor  130  taps the traffic sent to and from Web servers  160  and database servers  170 . Network sensor  130  is not installed in the line of traffic between client  180  and Web servers  160  or database server  170 , thus traffic is copied to network sensors  130  and at the same time passing directly through. In another embodiment (not shown), the network sensors  130 - 1 ,  130 - 2 ,  130 -m are configured to operate in the line of traffic. Each network sensor  130  processes incoming application requests, which are sent as application events to the secure server  110 . 
         [0035]    The security system  100  operates in two different modes: a LEARN mode and a PROTECT mode. In one embodiment, in the LEARN mode, the security system  100  monitors and learns the normal behavior of users and applications over time, and builds an adaptive normal behavior profiles (NBP) for each protected entity. In the PROTECT mode, the security system  100  compares real time communications (i.e., application events) to the adaptive NBPs. Deviations from the adaptive NBP are defined as anomalies. Anomalies are further analyzed by advanced correlation and aggregation mechanisms to ensure that the anomalies are part of an attack. The analysis uses positive logic for intrusion detection. That is, if an event matches a profile, it is considered as a normal event, else if the event does not match any profile, it is considered as an irregular event. 
         [0036]    Application events may be collected either by analyzing network level protocol attributes of incoming network traffic, or by polling information about recent events from the web servers  160  or the database servers  170 . The network sensor  130  is capable of reconstructing application events from a plurality of network level protocols comprising, but not limited to, Oracle Net8™, Microsoft SQL server™ TDS, Sybase TDS, OpenGroup DRDA, HTTP, encrypted HTTP (HTTPS) and similar applications. In addition, the network sensor  130  is capable of gathering application events by polling information (e.g., SQL queries) from Oracle Database™, Microsoft SQL server and similar systems. Each of network sensors  130 - 1 ,  130 - 2 ,  130 -m operates autonomously, and thus the security system  100  is a scalable system. That is, to protect additional Web applications and databases, the user has just to add additional network sensors  130  to monitor the new protected entity. 
         [0037]    Referring to  FIG. 2 , an exemplary diagram  200  illustrating the operation of the application level security system  100  is shown. The security system  200  depicted in  FIG. 2  comprises two network sensors, a HTTP sensor  230  and a SQL sensor  240 . The HTTP sensor  230 , capable of gathering and reconstructing HTTP events, collects an HTTP request e 1  sent by a client  280 - 1  to the web server  260 . The SQL sensor  240  collects a SQL request e 2  by polling the database server  270 . The event e 2  may be a consequence of request e 1 . Requests e 1  and e 2  are processed by sensors  230  and  240 , respectively, and are sent as application events E 1  and E 2  to secure server  210 . Subsequently, the secure server  210  executes a profiling process for generating an adaptive NBP for each protected entity, i.e., for the web server  260  and for the database server  270 . 
         [0038]    To allow fast protection, the security system  200  implements a dynamic learning process for generating the adaptive NBP. Through this process, a decision whether to use an application event for protection or learning is based on a single profile item. Specifically, the generated adaptive NBP comprises a plurality of profile items, wherein each item comprises a plurality of profile properties. The adaptive NBP may be used for protecting the application if at least one profile item is considered stable. In one embodiment, a stable item comprises sufficient information regarding users&#39; or applications&#39; behavior, where sufficiency is based on statistical measures. The statistical measures may be, but not limited to, those described herein. 
         [0039]    The adaptive NBP generated by the present invention has a granular architecture allowing decisions to be made for discrete portions of the NPB. Furthermore, the NBP architecture allows the distribution of profile updates between the secure server  210  and the network sensors  230  and  240 . The architecture of the adaptive NBP is described in greater detail below. 
         [0040]    An approved NBP, i.e., an adaptive NBP that comprises at least one stable profile item, is distributed among the network sensors. A copy held by a network sensor may comprise only a subset of the information existing in the original NBP. The adaptive NBP is distributed from secure server to network sensors through a synchronous communication channel. The network sensors also use this channel to retrieve NBP updates 
         [0041]    In this example, the secure server  210  generates two adaptive NBPs, the first NBP characterizes the web server  260  and is uploaded to the HTTP sensor  230 , while the second NBP characterizes the database server  270  and is uploaded to the SQL sensor  240 . Once, the NBPs are uploaded to the sensors  230  and  240 , the security system  210  can protect the web server  260  and the database server  270  using the stable properties of the NBPs. It should be noted that the security system  210  always protects the web server  260  and the database server  270  using at least signatures detection, protocol analysis and other network means. 
         [0042]    In the PROTECT mode, the secure server  210  identifies deviations from at least one stable profile item in the adaptive NBP, analyzes the deviations, detects intrusions and block attacks according to a predefined security policy. Specifically, a HTTP request e 3  sent by a client  280 - 2  to the web server  260  is captured by HTTP the sensor  230  and classified. The request e 3  is compared with a copy of an adaptive NBP comprising at least one stable profile item maintained by the HTTP sensor  230 . If the request e 3  deviates from the adaptive NBP, then the HTTP sensor  230  classifies it as anomalous and sends an irregular event (IE 3 ) to the secure server  210 , which further processes the irregular event (IE 3 ) to determine whether or not an intrusion takes place. On the other hand, if the request e 3  matches the adaptive NBP, then the HTTP sensor  230  may discard this event, or alternatively, send the request to the secure server  210  for the purpose of amending or updating the adaptive NBP. Simultaneously, a SQL request e 4  generated by the web server  260 , possibly as a consequence of request e 3 , is captured by the SQL sensor  240 . If the request e 4  deviates from the adaptive NBP maintained by SQL sensor  240 , this event is declared as irregular event (IE 4 ) and sent to the secure server  210  for further analysis. Both events e 3  and e 4  may be compared against one stable profile item in each NBP maintained by the HTTP sensor  230  and the SQL sensor  240 . The secure server  210  declares an intrusion alert when an event or a series of events triggers a rule based mechanism. The rule-based mechanism includes a predefined set of correlation rules that allow to easily correlate different types of anomalies and set alerts for a combination of anomalies that increases the probability of an attack. The correlation rules are predefined by the user. The rule-based mechanism employs a state machine to define and evaluate correlations between anomalies in real-time. For example, the two irregular events IE 3  and IE 4  are correlated into a single intrusion alert. 
         [0043]    The disclosed security system creates, through the dynamic learning process, the adaptive NBPs without any prior knowledge of the enterprise application semantics. However, the NBPs may be automatically updated while the system is operating in the PROTECT mode. Specifically, adaptive NBPs are updated when the enterprise application undergoes major changes. During the dynamic learning process, the security system tracks certain characteristics in the user activity and stores the tracking data in an internal database. This raw tracking data is not considered as a profile until the data is compiled, analyzed and formed into an adaptive NBP structure. 
         [0044]    Referring to  FIG. 3 , an exemplary diagram illustrating the architecture of an adaptive NBP  300  in accordance with the present invention is shown. The adaptive NBP is hierarchic data structure (e.g., a directed tree) comprising a plurality of profile items  310 - 1 ,  310 - 2 ,  310 - 4 ,  310 - 5  holding a plurality of corresponding profile properties  320 - 1 ,  320 - 2 ,  320 - 3 ,  320 - 4 ,  320 - 5 ,  320 - 6 . The child of a profile item  310  may be at least a profile property  320  or another profile item  310 . The profile items  310  and properties  320  characterize one or more enterprises applications installed on a server, e.g., a web server or a database server. The profile items  310  are independent, and are the smallest profile entity that can be conveyed individually from the secure server  110  to the network sensors  130 . A profile property  320  is a descriptive value of a respective profile item  310 . Therefore, an observation of an event related to a profile item results in updating all profile properties of that item. The profile properties  320  contain the actual data of the items, the property type, their current state and an awareness flag. The current state may be either a LEARN state, an ENFORCEABLE state, or a NON-ENFORCEABLE state. In the LEARN state, events relating to the respective profile property are gathered. In the ENFORCEABLE state, the respective profile property contains sufficient amount of information so that this property can be uploaded to a network sensor and used for detecting attacks. The NON-ENFORCEABLE state means that the profile property cannot be uploaded to a network sensor. Each of the profile properties  320  have their own state, but they cannot be handled independently of their containing item (e.g., a specific property cannot be removed from a profile item). The current state may be automatically determined by the secure server  110  or manually by the user. The awareness flag indicates whether this property should be conveyed to a network sensor. A copy of the adaptive NBP transmitted from the secure server  110  to the network sensors  130  may comprise a subset of items affected by the system&#39;s configuration (e.g., entities protected by the network sensor  130 , policy regarding stable item, and so on) and a subset of properties for each profile item. 
         [0045]    Each profile item  310  is identified by a unique hierarchic key, thus the entire set of ancestors from an item&#39;s direct parent and up to the root of the profile tree can be determined by a single key. As a parent item may contain various child items, a parent item (e.g., item  310 - 2 ) must comprise at least one profile property that explicitly denominates the child profile items (e.g.,  310 - 4  and  310 - 5 ) of the parent item. Each profile item  310  is further identified by its implied type and preferably its distinguished name, which are used for classification purposes. Furthermore, each profile item  310  maintains information comprising, but not limited to, a creation time, a current state, a link to another profile item, a timestamp of last update, an update sequence number, a number of observations of item either at the network sensors  130  or the secure server  110  and a named collection of child items. The current state of a profile item may be a LEARN state, a PROTECT state, a DELETED state, a DECAYED state, or a MERGED state. In a LEARN state, events regarding to the respective profile item are gathered. In a PROTECT state, sufficient amount of information is gathered and the profile item is uploaded to a network sensor. A DELETED state indicates that the profile item was deleted. A DECAYED state indicates that a link to the profile item is broken. A MERGED state indicates that the respective profile item was merged with another profile item. The current state may be automatically determined by the secure server  110  or manually by the user. 
         [0046]      FIG. 4  shows a non-limiting architecture of an adaptive NBP  400  characteristic to HTTP. The profile items of NBP  400  comprise a web server group  410 -A, an application (or host)  410 -B, a virtual folder  410 -C, a URL  410 -D, a cookie  410 -E and a parameter  410 -F. The web server group item  410 -A is the root of the NBP structure  400  and its child is the web application item  410 -B. The web application item  410 -B describes a single web application in the web server group. The children of the application item  410 -B are the virtual folder item  410 -C, which defines a virtual folder within a web application and the cookie item  410 -E. The distinguished name of the virtual folder item  410 -C is the full path of the folder from the virtual root. The cookie item  410 -E comprises cookies for a single Web application of its parent item  410 -B. The distinguished name of the cookie item  410 -E is the name of the cookie. The URL item  410 -D is the child of virtual folder item  410 -C and describes a single URL within a web application. The distinguished name of the URL item  410 -D is the full path of the virtual folder (maintained by item  410 -C) together with the HTTP method (e.g., GET or POST). The parameter item  410 -F is the child of URL item  410 - 4  and describes a list of parameters of HTTP requests submitted to a web server. The distinguished name of the parameter item  410 -F is the parameter name within the URL. 
         [0047]    Each of items  410  may comprise at least one profile property  420  containing the descriptive value of the item. Specifically, the profile property  421 -B of application item  410 -B is a list of acceptable web application (or host) aliases. The virtual folder item  410 -C comprises two profile properties  421 -C,  422 -C holding, respectively, a list of sub-folders of a virtual folder and indication whether the virtual folder is directly accessible. The profile properties  421 -D,  422 -D of URL item  410 -D comprise two indications, respectively, with one indicating whether the URL maintained by the item generates HTML form used for binding parameter values, and the other indicating whether the URL can be used as the first URL of a new session. In addition, the profile property  423 -D comprises a list of identified broken links and broken references. The cookie property  421 -E is the length restriction on the cookie values and the property  422 -E is an indication whether the cookie represents a set of actual cookies with the same prefix. The parameter properties  421 -F,  422 -F,  423 -F,  424 -F,  425 -F and  426 -F, respectively, comprise a list of allowed aliases for the parameter name, length restriction on the parameter&#39;s value, a parameter type, an indication whether the parameter is bounded to a HTTP response, an indication whether the parameter is required for a URL, and an indication whether the parameter represents a set of actual parameters with the same prefix. As can be noted, the web server group item  410 -A does not comprise any additional profile properties. 
         [0048]    A profile property may further comprise maintenance information comprising, but not limited to, a current state of the profile property, a creation time of the profile property, a link to another profile item, a timestamp of last update, an update sequence number and a number of observations of a corresponding profile item. 
         [0049]    Referring to  FIG. 5 , a non-limiting architecture of an adaptive NBP architecture  500  that characterizes a SQL profile is shown. The items of NBP  500  comprise a database server group  510 -A, a source group  510 -B, a table access  510 -C and a query  510 -D. The database server group item  510 -A is the root of the NBP  500  and its children are the source group item  510 -B and the query item  510 -D. The source group item defines a homogeneous group of database clients having access to database servers. The child of source group item  510 -B is the table access item  510 -C, which defines the access profile of database clients to a database table. The distinguished name of table access item  510 -C is the name of the table. The query item  510 -D defines a specific SQL query and its distinguished name is the normalized text of the query. The distinguished names of database server group item  510 -A and source group item  510 -B comprise default values and are not used for classification. 
         [0050]    Each of items  510  may comprise at least one profile property  520  containing the descriptive value of the item. Specifically, the profile properties  521 -B,  522 -B and  523 -B of source group item  510 -B comprise a list of source IP address, a list of client applications, and a list of database accounts, each of these lists defines the source group, i.e., the clients that can access database servers. Furthermore, profile properties  524 -B,  525 -B,  526 -B,  527 -B,  528 -B and  529 -B comprise an indication whether the access profile should be enforced for this source group, an indication whether to allow database manipulation commands for this source group, an indication whether to allow access to a system administrator, an indication whether to allow access to tables in non-default schemas, tables and views for this source group, and limitations on the operations of the source group. The profile property  521 -C of the table access item  510 -C defines the enforcement mode for each type of query, e.g., SELECT, UPDATE, DELETE, INSERT, and so on. The profile property  521 -D holds the SQL query. As can be noted, database server group item  510 -A does not comprise additional profile properties. It should be noted by a person skilled in the art that these examples are intended for purposes of demonstration only and are not intended to limit the scope of the disclosed invention. As described above for a HTTP profile item, a SQL profile item can have a LEARN state, a PROTECT state, a DELETED state, a DECAYED state and a MERGED state. 
         [0051]    Referring to  FIG. 6 , an exemplary flowchart  600  describing the dynamic learning process, in accordance with an exemplary embodiment of the present invention is shown. The dynamic learning process generates the adaptive NBPs described in greater detailed above. At S 610 , application events processed by a network sensor  130  are received at the secure server  110 . At  5620 , the application events are analyzed to create the adaptive NBP. Specifically, in one embodiment, the secure server  110  performs a lexical analysis and a syntax analysis to create the NBP. When performing a lexical analysis, the event is broken into tokens and a representation of the event based on token properties is created. SQL queries are modeled using a lexical analysis by replacing any literals with standard placeholders. When performing a syntax analysis of application events are broken into functional units. Some of the units are used for the purpose of identification of the event (the “identification units”) and others are considered to be properties (the “property units”). At  5630 , the property units having similar identification units are classified, gathered and attached to their respective profile item. For example, URLs having the same path are unified and added to the URL item  410 -D. At S 640 , a statistical analysis is performed to determine if the profile item or profile property is stable. In one embodiment, the statistical analysis computes the percentage of learning progress out of the total number of application events collected over time. If the percentage of learning progress exceeds a predefined threshold, the item is considered stable. The percentage of learning progress is computed for both a profile property and its respective item. In another embodiment, the statistical analysis may be the probability for mistakes computed using Bayesian methods. At S 650 , a check is made to determine if the item or property is stable, and if so, at S 660 , the current state of the profile item and property are respectively changed to a PROTECT state and an ENFORCEMENT state; otherwise, execution continues with S 610 . At S 670 , the adaptive NBP that comprises at least one stable item is distributed to the network sensors  130  and then the security system  100  can protect the protected servers using the stable items properties of the NBP. 
         [0052]    It should be noted that in the protect mode of the security system  100  protection is achieved based on at least one stable item or one stable property comprised in the adaptive NBP. For example, if the length for a first parameter item in a URL is stable and the length a second parameter is not, then the enforcement is made only for the first parameter but not for the second. The processes for determining the stability of a parameter item are discussed above. 
         [0053]    In accordance with an embodiment, adaptive NBPs are distributed to the network sensors through a proprietary protocol. The protocol provides at least the following operations: a) add a profile item together with its descendants to an adaptive NBP residing in a network sensor; b) update the NBP if an existing profile item is altered; and c) remove an item and its descendants from the NBP. Any changes made by the secure server  110  are immediately imposed onto the network sensors  130 . 
         [0054]    The present invention can be implemented in software, hardware, firmware or various combinations thereof. In an embodiment of the present invention, the elements are implemented in software that is stored in a memory and that configures and drives a digital processor situated in the respective wireless device. The software can be stored on any computer-readable media for use by or in connection with any suitable computer-related system or method. It will be appreciated that the term “predetermined operations” and the term “computer system software” mean substantially the same thing for the purposes of this description. It is not necessary to the practice of the present invention that the memory and the processor be physically located in the same place. That is to say, it is foreseen that the processor and the memory might be in different physical pieces of equipment or even in geographically distinct locations. 
         [0055]    As used herein, one of skill in the art will appreciate that “media” or “computer-readable media” may comprise a diskette, a tape, a compact disc, an integrated circuit, a cartridge, or any other similar tangible media useable by computers. For example, to distribute computer system software, the supplier might provide a diskette or might transmit the instructions for performing predetermined operations in some form via satellite transmission, via a direct telephone link, or via the Internet. More specific examples of computer-readable media would comprise an electrical connection (electronic) having one or more wires, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM or Flash memory) (magnetic), an optical fiber (optical), and a portable compact disc read-only memory (CD-ROM) (optical). 
         [0056]    Although computer system software might be “written on” a diskette, “stored in” an integrated circuit, or “carried over” a communications circuit, it will be appreciated that, for the purposes of this discussion, the computer usable media will be referred to as “bearing” the instructions for performing the predetermined operations. Thus, the term “bearing” is intended to encompass the above and all equivalent ways in which instructions for performing predetermined operations are associated with a computer usable media. 
         [0057]    Therefore, for the sake of simplicity, the term “program product” is hereafter used to refer to a computer useable media, as defined above, which bears instructions for performing predetermined operations in any form. 
         [0058]    The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. 
         [0059]    Thus, while only certain embodiments of the invention have been specifically described herein, it will be apparent that numerous modifications may be made thereto without departing from the spirit and scope of the invention. Further, acronyms are used merely to enhance the readability of the specification and claims. It should be noted that these acronyms are not intended to lessen the generality of the terms used and they should not be construed to restrict the scope of the claims to the embodiments described therein.