Patent Publication Number: US-8533786-B2

Title: Method and apparatus for protecting against attacks from outside content

Description:
CLAIM OF PRIORITY 
     This application claims the benefit of U.S. Provisional Patent Application 61/418,990 entitled Method and System for Protecting Against Cross Site Scripting Attacks Originating from User Uploaded Content using a Child Sub-Session in a Separate Domain, by Harsimranjit Chabbewal et al., filed Dec. 2, 2010, the entire contents of which are incorporated herein by reference. 
     COPYRIGHT NOTICE 
     A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     FIELD OF THE INVENTION 
     One or more implementations relate generally to protecting against attacks that come in the form of outside content, such as uploaded content in a database network system. 
     BACKGROUND 
     The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions. 
     Domains that allow others to upload information can be subjected to many different forms of attack. One such attack is Cross Site Scripting (XSS) in which malicious code is introduced into a domain and from there can operate on a user&#39;s applications and an organization&#39;s data. Many web browsers reduce the impact and effectiveness of such attacks using a same-origin policy. The same-origin policy prevents attacks from a first domain from capturing valuable information from a second domain, such as a session cookie. With a session cookie, the XSS attack can gain access to the second domain and affect or obtain information in the second domain. 
     In some cases, network service providers use different domains for different services. However, authentication is not always maintained throughout all of the domains. For example, some network service providers serve user uploaded content, such as images and video, from a separate domain, but do so using the authentication from the primary domain. As a result, anyone with a link to content (for example, an image) on the content domain can access it without having to authenticate into the main domain or the content domain. 
     For example, in Facebook, as currently constituted, a friend&#39;s profile picture may be served from a separate domain, but to access the profile picture there is no authentication required. Authentication only protects the link. Anyone with a link to the picture URL can view it, even if they are not logged into Facebook and even if they do not have the right permissions. This type of structure allows an attack to harvest links in one domain and then use them in the other without any need to create a session or authenticate in either domain. 
     BRIEF SUMMARY 
     A method and apparatus for protecting against attacks from outside content is described. In one example, a request is received from a user to access content from a second domain. An active session for the user with the second domain is searched for. If no active session is found, then an active session with a related first domain is searched for. If an active session is found with the first domain, then a session is established with the second domain based on the active session with the first domain. The requested content is then provided to the user based on the established session with the second domain. 
     While one or more implementations and techniques are described with reference to an embodiment in which protecting against attacks from outside content is implemented in a system having an application server providing a front end for an on-demand database service capable of supporting multiple tenants, the one or more implementations and techniques are not limited to multi-tenant databases nor deployment on application servers. Embodiments may be practiced using other database architectures, i.e., ORACLE®, DB2® by IBM and the like without departing from the scope of the embodiments claimed. 
     Any of the above embodiments may be used alone or together with one another in any combination. The one or more implementations encompassed within this specification may also include embodiments that are only partially mentioned or alluded to or are not mentioned or alluded to at all in this brief summary or in the abstract. Although various embodiments may have been motivated by various deficiencies with the prior art, which may be discussed or alluded to in one or more places in the specification, the embodiments do not necessarily address any of these deficiencies. In other words, different embodiments may address different deficiencies that may be discussed in the specification. Some embodiments may only partially address some deficiencies or just one deficiency that may be discussed in the specification, and some embodiments may not address any of these deficiencies. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following drawings like reference numbers are used to refer to like elements. Although the following figures depict various examples, the one or more implementations are not limited to the examples depicted in the figures. 
         FIG. 1  is an operational flow diagram illustrating a high level overview of a technique for protecting against attacks from outside content in an embodiment; 
         FIG. 2  illustrates a representative system for protecting against attacks from outside content in an embodiment; 
         FIG. 3  illustrates a representative system for protecting against attacks from outside content in another embodiment; 
         FIG. 4  illustrates a block diagram of an example of an environment wherein an on-demand database service might be used; and 
         FIG. 5  illustrates a block diagram of an embodiment of elements of  FIG. 6  and various possible interconnections between these elements. 
     
    
    
     DETAILED DESCRIPTION 
     General Overview 
     Systems and methods are provided for protecting against attacks from outside content. 
     As used herein, the term multi-tenant database system refers to those systems in which various elements of hardware and software of the database system may be shared by one or more customers. For example, a given application server may simultaneously process requests for a great number of customers, and a given database table may store rows for a potentially much greater number of customers. As used herein, the term query plan refers to a set of steps used to access information in a database system. 
     Cross Site Scripting (XSS) attacks can be frustrated by isolating user uploaded content to a separate content domain. This can prevent malicious code within the uploaded content from being introduced into applications and organization data in the primary domain. A web browser&#39;s same-origin policy can be used to prevent attacks from capturing the session cookie for a primary domain and applying it to a second domain without further authentication. At the same time, to present a seamless user experience between the domains, the primary domain session cookie can be used to authenticate the user to the content domain without requiring the user to log in separately into the content domain. 
     Additional measures can be used to prevent the separate content domain session from abuse. For example, permission checks can be performed to verify user access rights so that content is served only if the user has the requisite permissions and rights to view the content. For another example, a session cookie is preset on the separate content domain during the user&#39;s login. 
     These measures can prevent XSS attacks. Using authentication for the second domain, a user is prevented from viewing content on the second domain without permission. An authorized state in the primary domain can be securely propagated into the separate second domain using a sub-session. Finally, by performing the desired permission checks, content can be kept from a user or from an automated process even if the user is logged in to the main domain. 
     Process Description 
     In the described embodiment, a framework is used to facilitate serving user uploaded content from a separate content domain. However, the approaches described herein can be used to isolate any two or more domains from each other. Any one or more of these domains may allow for uploaded or other external content. Any one or more of these domains may have content that is to be kept secure from external attack. 
     In the described example, a first domain starts as a user landing domain. Login, access privileges, and secure data are all served from this domain. A second domain is used for a variety of other content including content that can be uploaded by users in a variety of formats. This content may contain hidden threats in the form of Cross Site Scripting (XSS) and other forms. 
     To allow this content in the secondary domain to be accessed while the user is logged into the primary domain, in one implementation, a special child sub-session is created for the secondary domain. The child sub-session is then used to authenticate the user&#39;s access to the secondary domain. In order to exploit the same origin policy of many web browsers, the sub session can be based on a sub-session cookie. The sub-session cookie can be preset when logging into the primary domain or it can be generated later when access to the secondary domain is requested. 
     In one example, a user logs in to a primary session on the primary domain. To enable access to the secondary domain, a session cookie is preset for a sub-session on the secondary domain during the user login using a special page. In this example, the secondary domain is a content domain and the special page may be called a “Content Door.” 
     To accomplish the functions described herein a framework is established. The framework, based on authentication on the primary domain, establishes a new sub-session cookie for the content domain. This cookie will store a sub-session valid only for the content domain. In one example, the sub-session is a child of the session in the primary domain. For security, the sub-session may also be configured as short lived with a lifetime no longer than the session in the primary domain. 
     Considered in more detail, first the framework looks for an existing fresh sub-session cookie. Such a check can be triggered by an initial login to the primary domain or by an attempt by the user to access the content domain. If there is no sub-session cookie, or if the cookie is stale, then the framework generates a sub-session generation servlet to get a fresh sub-session based on the primary domain session. The servlet can be generated within an application that the user is using to access or log in to the primary domain. In one example, the servlet is generated by a salesforce.com app. 
     In one example, when a user makes a request for any user uploaded content on the content domain, the framework looks for a sub-session cookie scoped to the content domain. If a sub-session cookie does not already exist, then the framework calls out to the session generation servlet on the primary salesforce.com domain. 
     The servlet first determines whether a valid parent salesforce.com domain session exists. If there is no valid session in the primary domain, then the user can be asked to log in or the request can be rejected. If the login credentials are provided for the primary domain or if there is already a valid session, then the servlet gives the framework a new sub-session for the content domain. The application can then make use of this sub-session to authenticate the user on the content domain. 
     In one example, the user or a user application generates a GET request, the framework redirects this request over to the servlet. The redirect passes the current request URL as a parameter; the servlet can then redirect back to the original URL with a new content domain sub-session as an added parameter. 
     In another example, the user or a user application generates a POST request, in order to not lose posted form data. The framework returns a postback form that posts to the servlet, which uses a second postback form to repeat the original request. 
     In some of the examples described above, if the parent primary domain session is invalid or cannot be found, then the framework goes to the primary domain login page, requests that the user login, and uses a return URL to get the user back to the requested content. Once the framework has opened a child sub-session for the content or other secondary domain, the framework can store the session in any of a variety of different ways. In one example, the framework stores the session in a content domain sub-session cookie for future use. Using a cookie allows the framework to benefit from a browser&#39;s same origin policy if one is available. 
     Process Flow 
     The framework above can be described in the context of a process flow as shown in  FIG. 1 . At  101 , a user logs in. This log in can be automated or manual. Instead of a login any other method of authentication can be used. After logging in, the framework can employ any of a variety of other processes to certify the authentication and to obtain privileges, rights, subscription status and any other information and validation that may be desired. In addition, a session is started based on the login. This may involve sending session cookies, establishing and applying security settings, configuring a VPN (Virtual Private Network) or any other operations that may be desired. 
     At  102 , the framework calls a servlet to generate a sub-session cookie for a related secondary domain. Before generating the sub-session cookie, the servlet first checks to make sure that the primary session from  101  is valid. The primary session may be invalid because of an error in the login process or because of time elapsing between blocks  101  and  102 . In that case, a valid session may have timed out. If there is no valid primary session then the user may be redirected to the log in screen or box. Alternatively, as with the original login, the login may be performed in another way. 
     If the session is valid, then at  103 , the servlet generates the sub-session cookie. This is a cookie for a session that is dependent upon the primary session for its existence and for its authentication. The sub-session cookie cannot be generated without the primary session being valid. 
     At  104 , the user finds a link to content on the second domain while on the primary domain. Accordingly, at  105 , the user requests the second domain content by selecting a link or in any other way. In one example, the content on the second domain is selected automatically when the user selects content on the primary domain. 
     At  106 , the framework checks for a sub-session cookie. This may be done each time the user requests content from the second domain. This ensures that the authentication is active and valid, improving security. Alternatively, some amount of content may be loaded or some timing may be allowed before the sub-session cookie is checked. A variety of different approaches may be applied depending on the particular implementation. 
     If a sub-session cookie is found, then at  107  user permissions are retrieved. If there is no valid sub-session cookie, then the framework calls the servlet to generate a new or fresh sub-session cookie based on the primary session. To do this the servlet returns to  102  to check the validity of the primary session. 
     If the user&#39;s permissions allow the user to access the content, then at  110 , the content is downloaded to the user. On the other hand if the user&#39;s permissions do not allow access to the content, then access is refused at  109 . 
     The above process provides several protections against latent attacks not only from uploaded user content but also from other sources. The separate domain used to serve the content, isolates the content in the separate domain from the primary domain. The separate domain serves its content seamlessly in the sense that the user does not need to re-authenticate when attempting to access the content domain. If the sub-session cookie is set when the user logs in for the primary domain session, then the user is already authenticated upon requesting content from the secondary domain. This provides a faster and easier user experience. 
     On the other hand, because the authentication for each domain is separate, requests for regular pages, data, or other content on the primary domain cannot be made from the content domain. Access to the primary domain is only possible after authentication specifically to the primary domain. 
     Accordingly, the process has protections to thwart the use of the content domain sub-session to request content from the primary domain. By using a separate domain for serving user uploaded content, any malicious scripts in the content can be prevented from accessing valuable information on the primary domain. In the same way, there are protections to thwart the use of a primary domain session to request content from the content domain. 
     The system may be equipped with additional features to enhance security and convenience. For example, the framework may include a domain redirect filter. The content on the secondary domain can be analyzed and classified as high and low risk. The low risk content can be whitelisted. A domain redirect filter may be used to intercept requests made to the content domain to ensure that only whitelisted content can be served from the content domain. Request for other data can be redirected to an access denied report. The domain redirect filter can also be used to prevent user requests from the primary domain without authorization on the primary domain. These requests can be redirected to a primary domain login page. 
     The framework can also be configured to provide session decoding checks. The framework can be provided with checks in the session decoding logic to detect the presence of active and valid sessions and sub sessions as necessary for each request. Checking for an active valid session whenever a request is made on a particular one of the domains, helps to prevent a session on one domain from being used to access the other domain. 
     The framework can also include a “ContentDoor” as a sub-session cookie pre-setting mechanism for the secondary domain. When a page is loaded for the first time after logging in to the primary domain through an application, the framework may be asked to serve a large number of user uploaded images from the content domain. This may occur, for example when an initial screen presents a variety of profiles to select from and many of the profiles include profile pictures from the content domain. Modern browsers parallelize the requests for images and other media that all come from the same secondary domain. The parallelized requests cause multiple redirections from the primary domain to the secondary domain in a short amount of time. If a session cookie for the content domain has not been set or has become stale, then there can be an extra database server load as the system tries to build a child sub-session for the content domain. 
     By presetting a session cookie for the content domain when the user logs in. The child sub-session cookie is already available. In the described examples, a “ContentDoor” is used. In one example, the “ContentDoor” is a page on the content domain whose primary purpose is just to receive a session meant for the content domain and to set a cookie for the same. After setting the cookie, the ContentDoor redirects the user back to the primary domain to resume the user&#39;s login flow. 
     System Description 
       FIG. 2  illustrates a simplified block diagram of a content delivery system. A customer, user, or client has a user terminal which may be fixed or mobile, that supports a client terminal interface  201 . In the illustrated example, the interface is a generic web browser, however, a specialized application may be used instead of a web browser depending on the particular implementation. Using the web browser or other interface, the user may upload and download content from a remote database and from many different locations. 
     The client browser  201  is connected through the cloud  203  or through a local area, metropolitan area, or wide area network to an application server  205 . The application server serves applications to the client browser through the cloud to provide access to a tenant database  207 . While in the present example, the tenant database is a multi-tenant database, the database may be for a single tenant or for one or more entities within a greater structural umbrella. 
     Within the client browser, in addition to a display  211 , and a user interface  213 , there is a cookie storage area  215  and a login and authentication module  217 . The cookie storage works with the authentication to track sessions and store authentication credentials for the user, as described above. 
     The application server includes applets and servlets  221  in addition to applications. As mentioned above, a sub-session authentication servlet includes cookie storage  223  or access to cookie storage. As explained above, these cookies are used for tracking authentication to the primary and any secondary sessions. The servlet can generate, request, and store cookies which are provided through the cloud  203  to the client browser. The application server also includes authentication and privileges  225  coupled to the servlet and cookie storage to track credentials and privileges for each of its users. The application server acts as an interface between the client browser and the tenant databases  207 . 
     The tenant databases include a database  231  for the primary domain, a database  233  for the secondary domain and additional databases  235  for other domains, other tenants, and other data shown as a single third database, however, there may be many databases to provide these additional components to the system. While the tenant database  207  is shown as being constructed from multiple databases, there may be a single database with all of the data separated into multiple domains. 
     In the illustrated example, the database  231  for the primary domain, or alternatively, the portion of the single database that corresponds to the primary domain contains client data  237  which the client can access through the client browser  201  and pointers  239  to content in one or more other domains. The database  233  for the secondary domain contain client data  241  indicated by the pointers in the primary domain. 
     As described above, the client begins by seeking information from the primary domain, but uploaded content and other content, depending on the particular implementation, is referenced only by pointers  239  to another domain. If the pointers point to content  241  in the secondary domain  233 , then the application will attempt to obtain the indicated content from the secondary domain. Because this data is in a different domain, the client must have a valid session with the secondary domain and the application refers to its authentication and cookie storage to provide this using, for example, the approach described in the context of  FIG. 1 . 
     An attacker  250  is also shown coupled to the application server  205  through the cloud  203 . The attacker seeks to gain access to either one of the domains of the tenant dB  207  using any credentials that the attacker can find or through a back door. After obtaining access, the attacker can then upload dangerous content into either of the domains. The dangerous content may be concealed within image files, embedded macros or in other ways. The attacker may be a user that intentionally seeks to compromise the system or other users, however, the attacker may also be an innocent user with a corrupted client system or an outsider that has accessed the system unintentionally. 
     In the system described above, the attacker is frustrated without having an authentication to access the primary domain. Since the secondary domain also requires a current authorization to access the primary domain, even the secondary domain cannot be accessed. 
       FIG. 3  illustrates a simplified block diagram of an alternative content delivery system. A first client terminal interface  301  has access to the cloud  303 . Additional client browsers  302 ,  304  also have access to the cloud. While three are shown, there may be many thousands or more. One or more of the client browsers may be that of an attacker. The cloud  303  represents any number of direct or indirect, wired or wireless connections. 
     The cloud provides access to an application server  305  which serves applications to the client browsers through the cloud to provide access to a tenant database  307 . In the present example, the tenant database is a single multi-tenant database which contains data stored for multiple users using multiple domains. 
     Within the client browsers, in addition to a display  311 , and a user interface  313 , there is a cookie storage area  315  and a login and authentication module  317 . The cookie storage works with the authentication to track sessions and store authentication credentials for the user, as described above. 
     The application server, as in the above examples, includes applications, applets and servlets  321 . A servlet may include cookie storage  323  or access to cookie storage to track authentication to the primary and secondary domains. Authentication and privileges  325  may be coupled to the servlet and cookie storage or may be located in another location, such as the tenant database  307 . 
     The tenant databases has a single database with multiple domains, a primary domain  331 , a secondary domain  333  and additional domains  335  for other data, other tenants. There may be many additional domains (not shown) for additional purposes not described herein. 
     In the illustrated example, the primary domain contains client data  337  which the client can access through the client browser  301 . It also contains pointers  339  to content in the secondary domain  333 , such as additional client data  341 . As described above, the client begins by seeking information from the primary domain, but uploaded content and other content, depending on the particular implementation, is referenced only by pointers  339  to the secondary domain. This data will be accessed using a valid session with the secondary domain, which in the examples above, is a sub-session of a valid session on the primary domain  331 . 
     System Overview 
       FIG. 4  illustrates a block diagram of an environment  610  wherein an on-demand database service might be used. Environment  10  may include user systems  612 , network  614 , system  616 , processor system  617 , application platform  18 , network interface  620 , tenant data storage  622 , system data storage  624 , program code  626 , and process space  628 . In other embodiments, environment  10  may not have all of the components listed and/or may have other elements instead of, or in addition to, those listed above. 
     Environment  610  is an environment in which an on-demand database service exists. User system  612  may be any machine or system that is used by a user to access a database user system. For example, any of user systems  612  can be a handheld computing device, a mobile phone, a laptop computer, a work station, and/or a network of computing devices. As illustrated in  FIG. 4  (and in more detail in  FIG. 5 ) user systems  612  might interact via a network  614  with an on-demand database service, which is system  616 . 
     An on-demand database service, such as system  616 , is a database system that is made available to outside users that do not need to necessarily be concerned with building and/or maintaining the database system, but instead may be available for their use when the users need the database system (e.g., on the demand of the users). Some on-demand database services may store information from one or more tenants stored into tables of a common database image to form a multi-tenant database system (MTS). Accordingly, “on-demand database service  616 ” and “system  616 ” will be used interchangeably herein. A database image may include one or more database objects. A relational database management system (RDMS) or the equivalent may execute storage and retrieval of information against the database object(s). Application platform  618  may be a framework that allows the applications of system  616  to run, such as the hardware and/or software, e.g., the operating system. In an embodiment, on-demand database service  16  may include an application platform  18  that enables creation, managing and executing one or more applications developed by the provider of the on-demand database service, users accessing the on-demand database service via user systems  612 , or third party application developers accessing the on-demand database service via user systems  612 . 
     The users of user systems  612  may differ in their respective capacities, and the capacity of a particular user system  612  might be entirely determined by permissions (permission levels) for the current user. For example, where a salesperson is using a particular user system  612  to interact with system  616 , that user system has the capacities allotted to that salesperson. However, while an administrator is using that user system to interact with system  616 , that user system has the capacities allotted to that administrator. In systems with a hierarchical role model, users at one permission level may have access to applications, data, and database information accessible by a lower permission level user, but may not have access to certain applications, database information, and data accessible by a user at a higher permission level. Thus, different users will have different capabilities with regard to accessing and modifying application and database information, depending on a user&#39;s security or permission level. 
     Network  614  is any network or combination of networks of devices that communicate with one another. For example, network  614  can be any one or any combination of a LAN (local area network), WAN (wide area network), telephone network, wireless network, point-to-point network, star network, token ring network, hub network, or other appropriate configuration. As the most common type of computer network in current use is a TCP/IP (Transfer Control Protocol and Internet Protocol) network, such as the global internetwork of networks often referred to as the “Internet” with a capital “I,” that network will be used in many of the examples herein. However, it should be understood that the networks that the one or more implementations might use are not so limited, although TCP/IP is a frequently implemented protocol. 
     User systems  612  might communicate with system  616  using TCP/IP and, at a higher network level, use other common Internet protocols to communicate, such as HTTP, FTP, AFS, WAP, etc. In an example where HTTP is used, user system  612  might include an HTTP client commonly referred to as a “browser” for sending and receiving HTTP messages to and from an HTTP server at system  616 . Such an HTTP server might be implemented as the sole network interface between system  616  and network  614 , but other techniques might be used as well or instead. In some implementations, the interface between system  616  and network  614  includes load sharing functionality, such as round-robin HTTP request distributors to balance loads and distribute incoming HTTP requests evenly over a plurality of servers. At least as for the users that are accessing that server, each of the plurality of servers has access to the MTS′ data; however, other alternative configurations may be used instead. 
     In one embodiment, system  616 , shown in  FIG. 4 , implements a web-based customer relationship management (CRM) system. For example, in one embodiment, system  616  includes application servers configured to implement and execute CRM software applications as well as provide related data, code, forms, webpages and other information to and from user systems  612  and to store to, and retrieve from, a database system related data, objects, and Webpage content. With a multi-tenant system, data for multiple tenants may be stored in the same physical database object, however, tenant data typically is arranged so that data of one tenant is kept logically separate from that of other tenants so that one tenant does not have access to another tenant&#39;s data, unless such data is expressly shared. In certain embodiments, system  616  implements applications other than, or in addition to, a CRM application. For example, system  16  may provide tenant access to multiple hosted (standard and custom) applications, including a CRM application. User (or third party developer) applications, which may or may not include CRM, may be supported by the application platform  618 , which manages creation, storage of the applications into one or more database objects and executing of the applications in a virtual machine in the process space of the system  616 . 
     One arrangement for elements of system  616  is shown in  FIG. 4 , including a network interface  620 , application platform  618 , tenant data storage  622  for tenant data  623 , system data storage  624  for system data  625  accessible to system  616  and possibly multiple tenants, program code  626  for implementing various functions of system  616 , and a process space  628  for executing MTS system processes and tenant-specific processes, such as running applications as part of an application hosting service. Additional processes that may execute on system  616  include database indexing processes. 
     Several elements in the system shown in  FIG. 4  include conventional, well-known elements that are explained only briefly here. For example, each user system  612  could include a desktop personal computer, workstation, laptop, PDA, cell phone, or any wireless access protocol (WAP) enabled device or any other computing device capable of interfacing directly or indirectly to the Internet or other network connection. User system  612  typically runs an HTTP client, e.g., a browsing program, such as Microsoft&#39;s Internet Explorer browser, Netscape&#39;s Navigator browser, Opera&#39;s browser, or a WAP-enabled browser in the case of a cell phone, PDA or other wireless device, or the like, allowing a user (e.g., subscriber of the multi-tenant database system) of user system  612  to access, process and view information, pages and applications available to it from system  616  over network  614 . Each user system  612  also typically includes one or more user interface devices, such as a keyboard, a mouse, trackball, touch pad, touch screen, pen or the like, for interacting with a graphical user interface (GUI) provided by the browser on a display (e.g., a monitor screen, LCD display, etc.) in conjunction with pages, forms, applications and other information provided by system  616  or other systems or servers. For example, the user interface device can be used to access data and applications hosted by system  616 , and to perform searches on stored data, and otherwise allow a user to interact with various GUI pages that may be presented to a user. As discussed above, embodiments are suitable for use with the Internet, which refers to a specific global internetwork of networks. However, it should be understood that other networks can be used instead of the Internet, such as an intranet, an extranet, a virtual private network (VPN), a non-TCP/IP based network, any LAN or WAN or the like. 
     According to one embodiment, each user system  612  and all of its components are operator configurable using applications, such as a browser, including computer code run using a central processing unit such as an Intel Pentium® processor or the like. Similarly, system  616  (and additional instances of an MTS, where more than one is present) and all of their components might be operator configurable using application(s) including computer code to run using a central processing unit such as processor system  617 , which may include an Intel Pentium® processor or the like, and/or multiple processor units. A computer program product embodiment includes a machine-readable storage medium (media) having instructions stored thereon/in which can be used to program a computer to perform any of the processes of the embodiments described herein. Computer code for operating and configuring system  16  to intercommunicate and to process webpages, applications and other data and media content as described herein are preferably downloaded and stored on a hard disk, but the entire program code, or portions thereof, may also be stored in any other volatile or non-volatile memory medium or device as is well known, such as a ROM or RAM, or provided on any media capable of storing program code, such as any type of rotating media including floppy disks, optical discs, digital versatile disk (DVD), compact disk (CD), microdrive, and magneto-optical disks, and magnetic or optical cards, nanosystems (including molecular memory ICs), or any type of media or device suitable for storing instructions and/or data. Additionally, the entire program code, or portions thereof, may be transmitted and downloaded from a software source over a transmission medium, e.g., over the Internet, or from another server, as is well known, or transmitted over any other conventional network connection as is well known (e.g., extranet, VPN, LAN, etc.) using any communication medium and protocols (e.g., TCP/IP, HTTP, HTTPS, Ethernet, etc.) as are well known. It will also be appreciated that computer code for implementing embodiments can be implemented in any programming language that can be executed on a client system and/or server or server system such as, for example, C, C++, HTML, any other markup language, Java™, JavaScript, ActiveX, any other scripting language, such as VBScript, and many other programming languages as are well known may be used. (Java™ is a trademark of Sun Microsystems, Inc.). 
     According to one embodiment, each system  616  is configured to provide webpages, forms, applications, data and media content to user (client) systems  612  to support the access by user systems  612  as tenants of system  616 . As such, system  616  provides security mechanisms to keep each tenant&#39;s data separate unless the data is shared. If more than one MTS is used, they may be located in close proximity to one another (e.g., in a server farm located in a single building or campus), or they may be distributed at locations remote from one another (e.g., one or more servers located in city A and one or more servers located in city B). As used herein, each MTS could include one or more logically and/or physically connected servers distributed locally or across one or more geographic locations. Additionally, the term “server” is meant to include a computer system, including processing hardware and process space(s), and an associated storage system and database application (e.g., OODBMS or RDBMS) as is well known in the art. It should also be understood that “server system” and “server” are often used interchangeably herein. Similarly, the database object described herein can be implemented as single databases, a distributed database, a collection of distributed databases, a database with redundant online or offline backups or other redundancies, etc., and might include a distributed database or storage network and associated processing intelligence. 
       FIG. 5  also illustrates environment  610 . However, in  FIG. 5  elements of system  616  and various interconnections in an embodiment are further illustrated.  FIG. 5  shows that user system  612  may include processor system  612 A, memory system  612 B, input system  612 C, and output system  612 D.  FIG. 5  shows network  614  and system  616 .  FIG. 5  also shows that system  616  may include tenant data storage  622 , tenant data  623 , system data storage  624 , system data  625 , User Interface (UI)  730 , Application Program Interface (API)  732 , PL/SOQL  734 , save routines  736 , application setup mechanism  738 , applications servers  1000   1 - 1000   N , system process space  702 , tenant process spaces  704 , tenant management process space  710 , tenant storage area  712 , user storage  714 , and application metadata  716 . In other embodiments, environment  610  may not have the same elements as those listed above and/or may have other elements instead of, or in addition to, those listed above. 
     User system  612 , network  614 , system  616 , tenant data storage  622 , and system data storage  624  were discussed above in  FIG. 4 . Regarding user system  612 , processor system  612 A may be any combination of one or more processors. Memory system  612 B may be any combination of one or more memory devices, short term, and/or long term memory. Input system  612 C may be any combination of input devices, such as one or more keyboards, mice, trackballs, scanners, cameras, and/or interfaces to networks. Output system  612 D may be any combination of output devices, such as one or more monitors, printers, and/or interfaces to networks. As shown by  FIG. 5 , system  616  may include a network interface  620  (of  FIG. 4 ) implemented as a set of HTTP application servers  700 , an application platform  618 , tenant data storage  622 , and system data storage  624 . Also shown is system process space  702 , including individual tenant process spaces  704  and a tenant management process space  710 . Each application server  1000  may be configured to tenant data storage  622  and the tenant data  623  therein, and system data storage  624  and the system data  625  therein to serve requests of user systems  612 . The tenant data  623  might be divided into individual tenant storage areas  712 , which can be either a physical arrangement and/or a logical arrangement of data. Within each tenant storage area  712 , user storage  714  and application metadata  716  might be similarly allocated for each user. For example, a copy of a user&#39;s most recently used (MRU) items might be stored to user storage  714 . Similarly, a copy of MRU items for an entire organization that is a tenant might be stored to tenant storage area  712 . A UI  730  provides a user interface and an API  732  provides an application programmer interface to system  616  resident processes to users and/or developers at user systems  612 . The tenant data and the system data may be stored in various databases, such as one or more Oracle™ databases. 
     Application platform  618  includes an application setup mechanism  738  that supports application developers&#39; creation and management of applications, which may be saved as metadata into tenant data storage  622  by save routines  736  for execution by subscribers as one or more tenant process spaces  704  managed by tenant management process  710  for example. Invocations to such applications may be coded using PL/SOQL  34  that provides a programming language style interface extension to API  732 . A detailed description of some PL/SOQL language embodiments is discussed in commonly owned co-pending U.S. Provisional Patent Application 60/828,192 entitled, PROGRAMMING LANGUAGE METHOD AND SYSTEM FOR EXTENDING APIS TO EXECUTE IN CONJUNCTION WITH DATABASE APIS, by Craig Weissman, filed Oct. 4, 2006, which is incorporated in its entirety herein for all purposes. Invocations to applications may be detected by one or more system processes, which manages retrieving application metadata  716  for the subscriber making the invocation and executing the metadata as an application in a virtual machine. 
     Each application server  700  may be communicably coupled to database systems, e.g., having access to system data  625  and tenant data  623 , via a different network connection. For example, one application server  700   1  might be coupled via the network  614  (e.g., the Internet), another application server  700   N-1  might be coupled via a direct network link, and another application server  700   N  might be coupled by yet a different network connection. Transfer Control Protocol and Internet Protocol (TCP/IP) are typical protocols for communicating between application servers  700  and the database system. However, it will be apparent to one skilled in the art that other transport protocols may be used to optimize the system depending on the network interconnect used. 
     In certain embodiments, each application server  700  is configured to handle requests for any user associated with any organization that is a tenant. Because it is desirable to be able to add and remove application servers from the server pool at any time for any reason, there is preferably no server affinity for a user and/or organization to a specific application server  700 . In one embodiment, therefore, an interface system implementing a load balancing function (e.g., an F5 Big-IP load balancer) is communicably coupled between the application servers  700  and the user systems  612  to distribute requests to the application servers  700 . In one embodiment, the load balancer uses a least connections algorithm to route user requests to the application servers  700 . Other examples of load balancing algorithms, such as round robin and observed response time, also can be used. For example, in certain embodiments, three consecutive requests from the same user could hit three different application servers  700 , and three requests from different users could hit the same application server  700 . In this manner, system  616  is multi-tenant, wherein system  616  handles storage of, and access to, different objects, data and applications across disparate users and organizations. 
     As an example of storage, one tenant might be a company that employs a sales force where each salesperson uses system  616  to manage their sales process. Thus, a user might maintain contact data, leads data, customer follow-up data, performance data, goals and progress data, etc., all applicable to that user&#39;s personal sales process (e.g., in tenant data storage  622 ). In an example of a MTS arrangement, since all of the data and the applications to access, view, modify, report, transmit, calculate, etc., can be maintained and accessed by a user system having nothing more than network access, the user can manage his or her sales efforts and cycles from any of many different user systems. For example, if a salesperson is visiting a customer and the customer has Internet access in their lobby, the salesperson can obtain critical updates as to that customer while waiting for the customer to arrive in the lobby. 
     While each user&#39;s data might be separate from other users&#39; data regardless of the employers of each user, some data might be organization-wide data shared or accessible by a plurality of users or all of the users for a given organization that is a tenant. Thus, there might be some data structures managed by system  616  that are allocated at the tenant level while other data structures might be managed at the user level. Because an MTS might support multiple tenants including possible competitors, the MTS should have security protocols that keep data, applications, and application use separate. Also, because many tenants may opt for access to an MTS rather than maintain their own system, redundancy, up-time, and backup are additional functions that may be implemented in the MTS. In addition to user-specific data and tenant specific data, system  616  might also maintain system level data usable by multiple tenants or other data. Such system level data might include industry reports, news, postings, and the like that are sharable among tenants. 
     In certain embodiments, user systems  612  (which may be client systems) communicate with application servers  700  to request and update system-level and tenant-level data from system  616  that may require sending one or more queries to tenant data storage  622  and/or system data storage  624 . System  616  (e.g., an application server  700  in system  616 ) automatically generates one or more SQL statements (e.g., one or more SQL queries) that are designed to access the desired information. System data storage  624  may generate query plans to access the requested data from the database. 
     Each database can generally be viewed as a collection of objects, such as a set of logical tables, containing data fitted into predefined categories. A “table” is one representation of a data object, and may be used herein to simplify the conceptual description of objects and custom objects. It should be understood that “table” and “object” may be used interchangeably herein. Each table generally contains one or more data categories logically arranged as columns or fields in a viewable schema. Each row or record of a table contains an instance of data for each category defined by the fields. For example, a CRM database may include a table that describes a customer with fields for basic contact information such as name, address, phone number, fax number, etc. Another table might describe a purchase order, including fields for information such as customer, product, sale price, date, etc. In some multi-tenant database systems, standard entity tables might be provided for use by all tenants. For CRM database applications, such standard entities might include tables for Account, Contact, Lead, and Opportunity data, each containing pre-defined fields. It should be understood that the word “entity” may also be used interchangeably herein with “object” and “table”. 
     In some multi-tenant database systems, tenants may be allowed to create and store custom objects, or they may be allowed to customize standard entities or objects, for example by creating custom fields for standard objects, including custom index fields. U.S. patent application Ser. No. 10/817,161, filed Apr. 2, 2004, entitled “Custom Entities and Fields in a Multi-Tenant Database System”, and which is hereby incorporated herein by reference, teaches systems and methods for creating custom objects as well as customizing standard objects in a multi-tenant database system. In certain embodiments, for example, all custom entity data rows are stored in a single multi-tenant physical table, which may contain multiple logical tables per organization. It is transparent to customers that their multiple “tables” are in fact stored in one large table or that their data may be stored in the same table as the data of other customers. 
     While one or more implementations have been described by way of example and in terms of the specific embodiments, it is to be understood that one or more implementations are not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.