Abstract:
Systems and methods for managing jobs to be scanned based on existence of processing nodes are described. One of the methods includes obtaining identification information regarding operation of a first set of the processing nodes from an inventory and creating a job for scanning the processing nodes of the first set for security vulnerability. The job includes the identification information. The method further includes verifying the inventory to determine the first identifying information of the first set of processing nodes for removal from the job and loading the job having second identifying information for a second set of processing nodes that remain after the verifying operation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority to and benefit of, under 35 U.S.C. §119(e), to provisional patent application having Application No. 61/543,795, filed on Oct. 5, 2011, and titled “Methods and Systems for Automated Network Scanning In Dynamic Virtualized Environments”, which is incorporated by reference herein in its entirety for all purposes. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to methods and systems for automated network scanning in dynamic virtualized environments. 
     BACKGROUND 
     A ‘cloud’ is a common word used to define computing systems and storage that have been networked to provide computing and storage resources to devices connected to the Internet. The reliability and security of a cloud is usually performed in a world where computer networks are a key element in intra-entity and inter-entity communications and transactions. Various tools have been used by network administrators, government, security consultants, and hackers to test the vulnerabilities of the cloud, such as, for example, whether any virtual machines (VMs) in the cloud can be accessed and controlled remotely without authorization. Through this intensive testing, the cloud can be “hardened” against common vulnerabilities and esoteric attacks. 
     A tool such as a vulnerability scanner can be used to test an individual VM in the cloud to determine which VMs are “open”, these “open” VMs may provide access for possible intrusion, and potentially represent a vulnerability that can be exploited by a malicious hacker. However, because of the vast number of hosts in a provider&#39;s multi-tenancy cloud, scanning takes a long time. 
     It is within this context that embodiments of the present invention arise. 
     SUMMARY 
     Embodiments of the present invention provide methods and systems for automated network scanning in dynamic virtualized environments 
     In one embodiment, a host information processing system (HIPRS) minimizes operational overhead when scanning rapidly-changing sets of hosts (also sometimes referred to as nodes) by automatically retrieving inventory records via an application programming interface (API), and synchronizing a job with the inventory records before each block within the job is dispatched for scanning. A job is a scan job performed by a vulnerability scanner. In some embodiments, HIPRS minimizes unintentional scanning of foreign hosts. In one embodiment, the foreign hosts are not owned or operated by an owner of the vulnerability scanner. 
     In various embodiments, HIPRS increases accuracy of scan data by preventing unintentionally scanned foreign hosts from being reported in result sets. In one embodiment, HIPRS load-balances blocks across multiple vulnerability scanners to increase overall performance and allow for horizontal scaling. 
     HIPRS uses cloud environments, with nearly all hosts indexed in a continuously-updated inventory database. Using this inventory database, HIPRS is able to construct a job that includes information, such as Internet Protocol (IP) addresses or nicknames, of a set of hosts and further includes associated state tracking information used to manage the job. 
     When the job is initialized, a snapshot of the current inventory including information about N hosts is taken and stored in a job bundle. The snapshot is then logically partitioned into X blocks of host information. 
     Before the job bundle is uploaded to a vulnerability scanner, HIPRS synchronizes a job host database with the current cloud inventory and removes information regarding terminated hosts from the blocks. The job host database is a part of a storage system that includes information regarding a job. In one embodiment, the synchronization is performed to subtract information regarding terminated hosts from blocks. 
     In one embodiment, the job initialization process also creates metadata entries for tracking the job, such as a job name and a runtime error log. Each block has a state value associated with it, which is used for tracking the state of the block and the overall progress of the job. If there are pending blocks to be scanned, HIPRS selects the next block available and queries a vulnerability scanner to determine a state of previously dispatched blocks and to determine whether there are scanning resources available to scan a new block. If the vulnerability scanner indicates that a previously dispatched scan task is finished, its associated work unit is marked complete in the job host database and no further processing is performed on the work unit. If scanning resources are available, HIPRS dispatches the next pending block for scanning and then records metadata to associate a task identification (ID) returned by the vulnerability scanner with the block for tracking. 
     In some embodiments, if an error is encountered when communicating with the vulnerability scanner or if the vulnerability scanner indicates that an exception occurred during a scan, the block is marked with an error flag and may be marked for rescan manually by a user. 
     In one embodiment, when all blocks within a job are marked complete or as having an error, the job is considered completed. 
     In some embodiments, after the job completes, HIPRS provides a mechanism to retrieve an export of vulnerability scan data for additional post-processing. In various embodiments, the vulnerability scan data can be obtained in other forms and methods, such as by accessing a file, a database, a graphical user interface (GUI) that provides graphical results, tabulated data, lists, metrics, etc. In some embodiments, the vulnerability scan data can also be sent to interested administrators for review by email, notifications, text messages, links, etc. In one embodiment, hosts marked as terminated are not included in the job database to enhance reporting accuracy. 
     In one aspect, a method for managing jobs to be scanned based on existence of processing nodes is provided. The method includes obtaining identification information regarding operation of a first set of the processing nodes from an inventory and creating a job for scanning the processing nodes of the first set for security vulnerability. The job includes the identification information. The method further includes verifying the inventory to determine the first identifying information of the first set of processing nodes for removal from the job and loading the job having second identifying information for a second set of processing nodes that remain after the verifying operation. 
     In another aspect, the method includes receiving scanning results from the loaded job. The scanning results are processed to remove results associated with processing nodes that were removed during the scanning. 
     In yet another aspect, a method for managing jobs to be scanned based on existence of processing nodes is described. The method includes loading a job having identifying information for a first set of the processing nodes, receiving scanning results from the loaded job, and removing results associated with a second set of processing nodes that were removed during the scanning. 
     In another aspect, a system for managing jobs to be scanned based on existence of processing nodes is described. The system includes a memory device configured to store a job creator module and a job loader module. The system further includes a processor configured to execute the job creator module to obtain identification information regarding operation of a first set of the processing nodes from an inventory. The job loader module is executed to create a job for scanning the processing nodes of the first set for security vulnerability. The job includes the identification information. Moreover, the processor is configured to execute the job loader module to verify the inventory to determine first identifying information of a first one of the processing nodes of the first set for removal from the job. The job loader module is executed to load the job having second identifying information for a second set of processing nodes that remain after the verification. 
     In yet another aspect, a method for managing jobs to be scanned based on existence of processing nodes is described. The method includes obtaining identification information regarding operation of the processing nodes, creating a job having the identification information, determining identifying information of at least one of the processing nodes for removal from the job, and removing the at least one processing node based on the determined identifying information. The identification information is updated after the removing operation. The method further includes loading the job having the updated identification information for processing nodes that remain after the removing operation. The loading is performed for scanning the remaining processing nodes for vulnerability to security attacks. 
     Other aspects of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of various embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the present invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  illustrates a vulnerability scan architecture, in accordance with one embodiment of the present invention. 
         FIG. 2  illustrates a vulnerability scan architecture, in accordance with another embodiment of the present invention. 
         FIG. 3A  is a block diagram of a host information processing system (HIPRS) that can operated in the vulnerability scan architecture of  FIG. 1  and/or the vulnerability scan architecture of  FIG. 2 , in accordance with one embodiment of the present invention. 
         FIG. 3B  illustrates purging of Internet Protocol (IP) addresses of Virtual Machines (VMs) from blocks of a job bundle, in accordance with one embodiment of the present invention. 
         FIG. 4  is a flowchart of a method for creating one or more job bundles, in accordance with one embodiment of the present invention. 
         FIG. 5  is a flowchart of an embodiment of a method for executing a job, in accordance with one embodiment of the present invention. 
         FIG. 6  is a flowchart of an embodiment of a method for post processing a job bundle after scanning the job bundle and for reporting of vulnerability scan data related to the post-processed job bundle, in accordance with one embodiment of the present invention. 
         FIG. 7  is a block diagram of a computer, in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     It should be noted that various embodiments of the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure various embodiments of the present invention. 
     A host information processing system (HIPRS) and its functionality are described herein. A host is commonly referred to as a ‘node’, which has processing power and assigned an Internet Protocol (IP) address, or other identifier. A host may be a virtual machine (VM) or a physical machine, or a combination of the VM and the physical machine. Although specific mention may be made to virtual machines in various sections of the patent application, various embodiments can also work on physical machines. 
     In one embodiment, HIPRS includes a computer, which further includes a controller and may include a display device. In various embodiments, the controller may execute an interactive program to render a report on the display. A display device, as used herein, may be a monitor, which is capable of receiving and rendering video output from the controller. A monitor may be a cathode ray tube (CRT) monitor, a liquid crystal display (LCD) monitor, or a light emitting diode (LED) monitor. 
     In some embodiments, HIPRS communicates with a cloud to determine whether a host has been terminated. The determination is used to avoid a vulnerability scan of the host and/or to avoid generating a report that includes data from a vulnerability scan of the host. 
     HIPRS communicates with one or more vulnerability scanner nodes to dispatch ‘pending’ blocks, which are described below, to perform a vulnerability scan. A vulnerability scan is used to determine whether a host possesses a vulnerability that can be exploited by a malicious hacker. 
       FIG. 1  illustrates an embodiment of a vulnerability scan architecture  10 . The vulnerability scan architecture  10  allows for automated network scanning in a dynamic network environment. In one embodiment, processing nodes N 1 , N 2 , and N 3  of a cloud  102  are scanned by a vulnerability scanner  120   a  automatically. The scanning may be periodic or random. Each processing node N 1 -N 4  may be a VM or a physical machine. A physical machine may be a computer, a server, or a processor. Each processing node N 1 -N 4  is associated with identifying information, such as an IP address, a media access control address (MAC address), or another other address that identifies the node. 
     Any processing node N 1 -N 4  may terminate at any time for a variety of reasons. In one embodiment, processing node N 1  terminates when it malfunctions or lacks operation. In some embodiments, processing node N 2  terminates when an application executing within the node changes. In other embodiments, the node N 3  terminates when an owner of the processing node N 3  releases ownership to another entity. For example, the processing node N 3  terminates when a company X takes control of the processing node N 3  to execute an application. In this example, the processing node N 3  was controlled by another company Y to execute an application before the termination. In one embodiment, an entity that executes an application on a node controls the node. In some embodiments, an entity that executes an operating system on a node controls the node. The termination of any processing node N 1 -N 4  from cloud  102  at any time provides a dynamic changing environment. The cloud  102  changes dynamically with termination of processing node. 
     An inventory  124  stores identifying information regarding operation of the nodes N 1 , N 2 , and N 3 , which are controlled by an entity. Inventory  124  is specific to an entity in that the inventory  124  includes identifying information regarding processing nodes controlled by the entity. In one embodiment, inventory  124  avoids storing identifying information regarding node N 4  that is controlled by an entity different from one controlling the nodes N 1 , N 2 , and N 3 . In one embodiment, identifying information regarding a node includes an IP address of the node, a MAC address of the node, a nickname of the node, a name of an application executing within the node, a name of an operating system executing within the node, or a combination thereof. 
     A job creator module  132  within HIPRS  118  accesses the identifying information regarding the nodes N 1 , N 2 , and N 3  from inventory  124  to create a job  12 . The job  12  has identifying information regarding the nodes N 1 , N 2 , and N 3 . The job  12  is created to provide to vulnerability scanner node  120  to determine whether any node N 1 , N 2 , or N 3  is vulnerable to security attacks by hackers. In one embodiment, the node N 1  is vulnerable to security attack when the node N 1  does not have the latest software security updates installed. In another embodiment, the node N 2  is vulnerable to security attack when the node is unprotected by a firewall. In one embodiment, a security attack includes installing or running unauthorized code or programs, such as viruses and malware, on node N 1 , N 2 , or N 3 . The unauthorized code or programs lack authorization from an owner of the node N 1 , N 2 , or N 3 . 
     Before uploading job  12  to vulnerability scanner node  120   a , a job loader module  138  accesses the inventory  124  to determine identifying information of any one of the plurality of processing nodes N 1 , N 2 , and N 3  for removal from the job  12 . In one embodiment, job loader module  138  compares identifying information stored in inventory  124  with identifying information in job  12  to determine whether processing node N 1 , N 2 , or N 3  is terminated. When processing node N 1 , N 2 , or N 3  is terminated, information identifying the node is deleted from inventory  124 . In one embodiment, processing node N 2  is terminated between a time of creation of job  12  and a time of the verification by job loader module  138 . 
     When job loader module  138  determines that identifying information regarding processing node N 1 , N 2 , or N 3  is missing from inventory  124 , the job loader module  138  determines to purge identifying information regarding the node from job  12  to create a job  14 . After the purge, the job loader module  138  submits job  14  to vulnerability scanner node  120   a . In one embodiment, the new job  14  includes identifying information regarding processing nodes N 1  and N 3 , and excludes identifying information regarding the processing node N 2 . 
     Upon receiving job  14 , the vulnerability scanner node  120   a  executes a vulnerability scan on the processing nodes, such as N 1  and N 3 , identified in the job  14 . The vulnerability scanner node  120   a  generates scanning results. In one embodiment, the vulnerability scanner node  120   a  generates scanning results indicating that node N 1  is a high risk node and N 3  is a low risk node. In another embodiment, vulnerability scanner  120  generates scanning results indicating that node N 1  has a risk score of 7 out of 10 and node N 3  has a risk score of 4 out of 10. 
     In one embodiment, the scanning results are provided by the vulnerability scanner node  120   a  to job loader module  138 . During the scan, processing node N 1  or N 3  or both may have been terminated. If so, inventory  124  is updated to remove identifying information regarding the terminated processing node, such as N 3 . When inventory is updated, job creator  132  updates the job  14  to purge identifying information regarding the terminated node to create a job  16 . Job loader module  138  access the job  16  to determine that processing node, such as N 3 , was terminated. Job loader module  138  removes, such as deletes, from the scanning results, results of scanning the terminated processing node, such as node N 3 , to generate scanning results  18 . In some embodiments, the job loader module  138  deletes a risk score or a risk level provided to the node N 3  from scanning results received from vulnerability scanner node  120   a  to generate the scanning results  18 . In one embodiment, the scanning results  18  are displayed on a display device  150  to show to a user  133 . 
     In another embodiment, the job loader module  138  may avoid requesting scanning results for job  14  from vulnerability scanner node  120   a . Rather, the job loader module  138  accesses vulnerability scanning results to delete a portion of the scanning results to further generate the scanning results  18 . The portion corresponds to the terminated processing node that was terminated during execution of the job  14  by vulnerability scanning node  120   a . The scanning results  18  are displayed on display device  150  or on a display device  154  of vulnerability scanner node  120   a.    
     It should be noted that although four nodes are shown in cloud  102 , in one embodiment, a different number of nodes may be included within cloud  102 . 
       FIG. 2  illustrates an embodiment of a vulnerability scan architecture  100 . The vulnerability scan architecture  100  includes a cloud  102 . The cloud  102  has multiple servers  104   a - 104   c . The servers  104   a - 104   c  are used to process a large amount of data, which is generated by various lessee entities, such as Zynga Inc. of San Francisco, Calif. It is noted that an entity may be a corporation, a partnership, or an individual. The servers  104   a - 104   c  are owned by an owner entity. Processing power of the servers  104   a - 104   c  may be leased by an owner entity to lessees, such as an entity. 
     Each server  104   a - 104   c  includes a central processing unit (CPU). Servers  104   a ,  104   b , and  104   c  are coupled with networks  106   a ,  106   b , and  106   c . Each network  106   a ,  106   b , and  106   c  may be the Internet or an Intranet. 
     Servers  104   a - 104   c  are coupled with each other and to a storage system via one or more networks. In one embodiment, server  104   a  is coupled with a storage system  108   a  via network  106   a . Similarly, server  104   b  is coupled with a storage system  108   b  via network  106   b  and server  104   c  is coupled with a storage system  108   c  via network  106   c . Also, server  104   a  is coupled with server  104   b  via network  106   a  and server  104   b  is coupled with server  104   c  via network  106   b . The large amount of data is stored in one or more of storage systems  108  and accessed by one or more of servers  104  via one or more networks  106 . 
     As used herein, a storage system is a random access memory (RAM), a read-only memory (ROM), or a combination of RAM and ROM. In one embodiment, storage system  108   a  includes a database that allows one or more of servers  104   a - 104   c  to access data. In some embodiments, a storage system includes one or more memory devices, such as flash memory cards, a redundant array of independent disks (RAID), and hard disks. 
     Although a few components are shown in cloud  102 , in some embodiments, additional components, such as, a display device, an input device, a printer, speakers, an optical drive, a universal serial bus (USB) port, a graphics processing unit (GPU), a video card, are included. Examples of input device include a mouse, a keyboard, a stylus, and any other wired or wireless input device. Examples of a display device are provided above. 
     A VM, such as VM  112   a , VM  112   b , or VM  112   c , is executed by one or more servers  104   a - 104   c . In one embodiment, VM  112   a  is a software application executed by servers  104   a  and  104   b . A VM includes an operating system (OS). In one embodiment, VM  112   a  includes an OS  114   a , VM  112   b  includes an OS  114   b , and VM  112   c  includes an OS  114   c . It should be noted that a VM includes a virtual processor and a virtual storage system, which are not shown for convenience. A virtual processor is processing power of one or more servers  104 . Also, a virtual storage system is storage capability of one or more storage systems  108 . 
     An OS within a VM may be the same or different than an OS within another VM. In one embodiment, OS  114   a  may be a Linux operating system and OS  114   b  may be a Windows operating system. In another embodiment, OS  114   b  may be an OS X Lion operating system and OS  114   c  may be a Unix operating system. 
     An application within an OS runs on top of the OS. In one embodiment, application  116   a  runs on top of OS  114   a . Moreover, an application within a VM may be the same or different than an application within another VM. For example, application  116   a  may be FARMVILLE game software developed by ZYNGA Inc. and application  116   b  may be a word processing software developed by GOGGLE corporation of Mountain View, Calif. In another embodiment, application  116   b  may be MICROSOFT EXCEL software developed by MICROSOFT corporation of Seattle, Wash. and application  116   c  may be CITYVILLE game software developed by ZYNGA Inc. 
     In some embodiments, an application includes a gaming service application, a music service application, a video service application, a shopping service application, an image storage service application, a search service application, a document storage service application, a document creation service application, a social network service application, or any other service application that generates data that is distributed via a massive distributed server system. In one embodiment, the server system includes multiple servers  104 . 
     It should be noted that application  116   a ,  116   b , or  116   c  is developed by an entity. In one embodiment, if application  116   a ,  116   b , or  116   c  is not developed by an entity, it may be under control of the entity. In some embodiments, an application  116   a ,  116   b , or  116   c  is under control of an entity if the application is licensed by the entity from a developer of the application. In one embodiment, an application  116   a ,  116   b , or  116   c  is under control of an entity if the entity is authenticated with a passcode to allow the entity to control execution of the application. 
     A hypervisor  110  is a platform virtualization software that is executed by each server  104   a ,  104   b , and  104   c  to create, manage and monitor any number of VMs. The hypervisor  110  allocates components, such as servers  104 , networks  106 , storage systems  108 , and other components of cloud  102 , to VMs  112  for a time period based on availability of the components. In one embodiment, VM  112   a  is executed by server  104   a  for a time period and by server  104   b  for a time period. In another embodiment, OS  114   a  is stored within storage system  108   a  for a time period and is stored in storage system  108   b  for a time period. 
     In one embodiment, the hypervisor  110  is used to emulate virtual hardware, partition physical hardware, virtualize physical hardware, or execute VMs  112  to provide access to the components of cloud  102 . Hypervisor  110  may include a hypervisor manufactured by VMW are corporation of Palo Alto, Calif.; an open source product whose development is overseen by Xen.org community; HyperV, VirtualServer or virtual PC hypervisors provided by Microsoft corporation; or others. 
     Each VM  112   a ,  112   b , and  112   c  has an associated IP address. For example, VM  112   a  has an IP address IP A , VM  112   b  has another IP address IP B , and VM  112   c  has yet another IP address IP C . 
     One or more servers  104  collect and store one or more IP addresses of one or more VMs  112  in an inventory  124 . An inventory, as used herein, is a database. Inventory  124  includes one or more IP addresses of one or more VMs  112 , which is running one or more applications developed by or controlled by a single entity. In some embodiments, the single entity may own or control operation of the vulnerability scanner node  120   a  or  120   b.    
     When VM  112   a ,  112   b , or  112   c  terminates, one or more servers  114  delete an IP address of the VM from inventory  124 . A VM  112   a ,  112   b , or  112   c  terminates when an IP address of the VM changes, the VM stops executing, or an OS within the VM changes. In some embodiments, any change to a VM after storage of an IP address of the VM in inventory  124  is considered termination of the VM. 
     HIPRS  118 , which may be a computer or a processor, accesses the IP addresses within inventory  124  to create a job bundle. HIPRS  118  updates the job bundle before submitting the job bundle to a vulnerability scanner node  120   a  or  120   b . In one embodiment, HIPRS  118  updates the job bundle to delete an IP address of VM  112   a ,  112   b , or  112   c  that has been terminated. VM  112   a ,  112   b , or  112   c  is terminated between a time of storage of an IP address of the VM in inventory  124  and a time of access of the IP addressed by HIPRS  118  from the inventory  124 . The updated job bundle is provided by HIPRS  118  to vulnerability scanner node  120   a  or  120   b.    
     Upon receiving the updated job bundle, vulnerability scanner node  120   a  or  120   b  applies a set of security checks  122  to determine whether VM  112   a ,  112   b , or  112   c  is vulnerable to security attacks from hackers. In one embodiment, vulnerability scanner node  120   a  applies security checks  122  to determine whether VM  112   a  includes a Windows operating system and if so, determines that VM  112   a  may be subject to security attacks from hackers. In another embodiment, vulnerability scanner node  120   a  applies security checks  122  to determine whether VM  112   a  is executing a particular application, such as a computer virus or backdoor program, and if so, determines that VM  112   a  is vulnerable to security attacks from hackers. 
     Vulnerability scanner node  120   a  or  120   b  may be a computer or a processor connected to cloud  102 . In one embodiment, vulnerability scanner node  120   a  or  120   b  is a server. 
     In some embodiments, vulnerability scanner node  112   a  generates a report, such as one indicating the various classes of vulnerability, to display on a display device to a user. The display device on which the report is displayed may be a part of vulnerability scanner node  120   a  or a component of cloud  102 . 
     It should be noted that although a limited number of VMs  112 , servers  104 , networks  106 , and storage systems  108  are shown in  FIG. 1 , in some embodiments, a different number of servers  104 , networks  106 , and storage systems  108  may be used. Moreover, it should be noted that although a specific number of hypervisor  110  and HIPRS  118  are shown in  FIG. 1 , in other embodiments, a different number of hypervisors and HIPRSs may be used. Also, any number of vulnerability scanners  120  may be used. 
       FIG. 3A  is a block diagram of an embodiment of HIPRS  118 . A job creator module  132  accesses N IP addresses of N VMs  112  from inventory  124 , wherein N is an integer greater than zero. In one embodiment, the user  133  accesses a graphical user interface (GUI) or enters a script on display device  150  to execute job creator module  132 . In another embodiment, job creator module  132  is automatically executed without intervention from the user  133 . Job creator module  132  creates X blocks from the N IP addresses, where X is an integer greater than zero. Each block includes one or more IP addresses. One of the X blocks is shown as block  136 , which is stored in a storage system  135  by job creator module  132 . The X blocks are part of a job bundle  137 . An embodiment of block  136  and an embodiment of the job bundle  137  are shown in  FIG. 3B . Block  136  has IP addresses IP A , IP B , and IP C  of three VMs  112 . 
     Referring back to  FIG. 3A , a job loader module  138  accesses block  136  from storage system  135  and accesses updated IP addresses from inventory  124 . IP addresses within inventory  124  may have been updated by one or more servers  104  to drop IP address IP B . In one embodiment, the IP addresses IP A , IP B , and IP C  are updated within inventory  124  between a time of storage of the IP addresses IP A , IP B , and IP C  in inventory  124  and a time of access of one or more of the IP addresses IP A , IP B , and IP C  from the inventory  124  by job loader module  138 . 
     One or more servers  114  determines whether one of VMs  112  corresponding to IP address IP B  has been terminated and purges the IP address IP B  from inventory  124  upon determining that the VM has been terminated. After the purge, the job loader module  138  compares the inventory  124  with the block  136  to determine that the IP address IP B  has been purged from inventory  124  and to purge the IP address IP B  from block  136 . The IP address IP B  is purged from block  136  to generate a block  136   A  or to update block  136  to block  136   A . 
     When the block  136  is updated to block  136   A , another job bundle  137   A  is created and stored in storage system  135  by job loader module  138 . The job bundle  137   A  includes the block  136   A . An embodiment of block  136   A  and an embodiment of job bundle  137   A  are shown in  FIG. 3B . As shown, IP address IP B  is deleted from block  136  to create the block  136   A . 
     Referring back to  FIG. 3A , job loader module  138  provides the job bundle  137   A  including the block  136   A  to vulnerability scanner node  120   a . When block  136   A  is submitted to vulnerability scanner node  120   a , job loader module  138  may access a block report status  142  indicating a status, such as ‘pending’, of block  136   A  and may access a job report status  143  indicating a status, such as ‘pending’, of job bundle  137 . Unless all blocks within job bundle  137   A  are scanned by vulnerability scanner  120   a  or  120   b , job creator module  132  maintains the job report status  143  of ‘pending’. 
     In some embodiments, job loader module  138  submits a previously un-dispatched block to vulnerability scanner node  120   b . This distribution of blocks between different scanners  120   a  and  120   b  allows the job loader module  138  to distribute work load between vulnerability scanner nodes  120   a  and  120   b.    
     Vulnerability scanner node  120   a  receives the job bundle  137   A  including the block  136   A  and applies the security checks  122  via a portion of cloud  102  to VMs  112   a  and  112   c  having the IP addresses IP A  and IP C  to determine whether the VMs  112   a  and  112   c  are vulnerable to security attacks. Vulnerability scanner node  120   a  generates vulnerability scan report data indicating vulnerability of VMs  112   a  and  112   c  and provides the vulnerability scan report data to job loader module  138 . It should be noted that a large amount of time, which may have an order of hours, may have passed between submission of job bundle  137   A  to vulnerability scanner  120   a  for vulnerability scanning and reception of the vulnerability scan report data by job loader  138 . 
     While vulnerability scanning is in progress, job loader  138  accesses a job bundle  137   B  to determine whether one or more of the VMs  112   a  and  112   c  having IP addresses IP A  and IP C  have been terminated. The job bundle  137   B  is generated by updating the job bundle  137   A . The update is performed by job loader module  138  to match IP addresses of job bundle  137   A  with IP addresses of inventory  124 . The IP addresses within inventory  124  may have been updated by one or more servers  104  to purge the IP address IP C . In response to determining that IP address IP C  is purged from inventory  124 , the job loader module  138  updates the block  136   A  to purge the IP address IP C  of VM  112   c  from block  136   A . The purge is performed to generate another block  136   B , an embodiment of which is shown in  FIG. 3B . The block  136   B  excludes the IP address IP C  of VM  112   c . When the block  136   A  is updated to block  136   B , another job bundle  137   B  is created and stored in storage system  135  by job loader module  138 . The job bundle  137   B  includes the block  136   B . An embodiment of the job bundle  137   B  is also shown in  FIG. 3B . As shown in  FIG. 3B , block  136   B  indicates to job loader module  138  that VM  112   c  has been terminated. 
     Job loader module  138  requests to receive the vulnerability scan report data for VMs  112   a  and  112   c  identified by block  136   A  from vulnerability scanner node  120   a . Upon reception of the vulnerability scan report data for block  136   A , job loader module  138  deletes a portion of the vulnerability scan report data corresponding to scan of the VM  112   c  that was terminated while a vulnerability scan of the VMs  112   a  and  112   c  was in progress. The deletion of the portion is performed to generate vulnerability scan report data  148 , which is provided by job loader  138  to display device  150 . In one embodiment, display device  150  receives the vulnerability scan report data  148  to render a vulnerability scan report to show to user  133 . 
     In another embodiment, instead of requesting the vulnerability scan report for the block  136   A  from vulnerability scanner node  120   a , the job loader module  138  deletes the portion of the vulnerability scan report data from the vulnerability scanner  120   a  to generate the vulnerability scan report data  148 . A processor  153  of the vulnerability scanner  120   a  stores the vulnerability scan report data  148  in a storage system  152 . In one embodiment, display device  154  of the vulnerability scanner  120   a  receives the vulnerability scan report data  148  from the processor  153  to render a vulnerability scan report. 
     In some embodiments, display device  150  receives the block report status  142  to render a block report to show to user  133 . In one embodiment, display device  150  accesses the job report status  143  from storage system  135  to render a job report on display device  150  to show to user  133 . The job report is an aggregation of block report status  142  of all blocks within job bundle  137   B . 
       FIG. 4  is a flowchart of an embodiment of a method  176  for creating one or more job bundles, in accordance with one embodiment of the present invention. The method  176  is a part of job creator module  132 . In operation  178 , a job container, which is a memory space within storage system  135 , is created for a job bundle. Moreover, metadata, such as the block report status  142  and the job report status  143 , is initiated. In operation  180 , host records, such as the IP addresses IP A , IP B  and IP C , are accessed from inventory  124 . The host records are stored in a host list. In operation  182 , the host list is split into the X blocks to create the job bundle  137  and all the X blocks are marked ‘pending’. 
       FIG. 5  is a flowchart of an embodiment of a method  202  for running a job. The method  202  is a part of job loader module  138 . In operation  204 , job loader module  138  determines whether job bundle  137  is specified. Job bundle  137  is specified if the job bundle  137  is stored in storage system  135 . In response to determining that the job bundle  137  is not specified, the job loader module  138  searches, in operation  206 , for a job bundle in storage system  135  for which a job is to be executed. In response to determining that the job bundle  137  is specified or to determining that a job bundle exists in storage system  135  for which a job is to be executed, job loader module  138  accesses inventory  124  to determine whether any VMs  112  have been terminated since the job bundle  137  was stored in storage system  135 . 
     In operation  210 , in response to determining that one or more of VMs  112  have been terminated, IP addresses of the VMs are subtracted from job bundle  137 . In operation  212 , it is determined whether any unprocessed blocks within the job bundle  137  remain. For example, job loader module  138  determines whether all blocks within job bundle  137  have been scanned for vulnerability scan. If all blocks have been scanned, the job bundle  137  is marked ‘complete’ in block report status  142  in operation  218 . On the other hand, in response to determining that a ‘pending’ block remains in job bundle  137  to be scanned, in operation  214 , the ‘pending’ block is selected. In operation  232 , the ‘pending’ block is uploaded to vulnerability scanner node  120   a  or  120   b  for vulnerability scanning. 
       FIG. 6  is a flowchart of an embodiment of a method  276  for post processing of job bundle  137   A  after completion of scan of the job bundle  137   A  and reporting of vulnerability scan data related to the post processed job bundle. The method  276  is executed by job loader module  138 . In operation  278 , it is determined whether the job bundle  137   A  is specified. The job bundle  137   A  is specified if the job bundle  137   A  is stored in storage system  135 . In response to determining that the job bundle  137   A  is not specified, the job loader module  138  searches, in operation  280 , for a job bundle, whose scan has been performed, in storage system  135 . In response to determining that the job bundle  137   A  is specified or to determining that a job bundle exists in storage system  135  for which a job is to be executed, job loader module  138  accesses the job bundle  137   A  to determine whether any VMs  112  have been terminated since the job bundle  137   A  was stored in storage system  135 . 
     In operation  282 , in response to determining that one or more of VMs  112  have died, IP addresses of the VMs are subtracted from job bundle  137   A  to create the job bundle  137   B . The job bundle  137   A  is updated, in operation  284 , to create the job bundle  137   B . 
     It is noted that various embodiments are described using information, such as IP addresses, of VMs  112 . In other embodiments, these various embodiments can be described using other information, such as VM nicknames instead or a combination of the nicknames and IP addresses. In one embodiment, VM nicknames include nicknames of applications  116 . For example, a VM nickname is ‘FarmVille’. Another VM nickname may be ‘Mafia’. 
       FIG. 7  is a block diagram of an embodiment of a computer  300 . Computer  300  includes a CPU  302  and a memory device  304 . Computer  300  further includes a network interface  306 , an I/O interface  308 , a display device  310 , and an input device  312 . Input device  312  may be a keyboard, a mouse, or a stylus. The memory device  304  may include an operating system and one or more applications. 
     The CPU  302  is a logic circuit that responds to and processes instructions fetched from memory device  304 . In many embodiments, CPU  302  is provided by a microprocessor unit, such as: that manufactured by Intel Corporation of Mountain View, Calif.; that manufactured by Motorola Corporation of Schaumburg, Ill.; that manufactured by Transmeta Corporation of Santa Clara, Calif.; that manufactured by International Business Machines of White Plains, N.Y.; or that manufactured by Advanced Micro Devices of Sunnyvale, Calif. Computer  300  may be based on any of these processors, or any other processor capable of operating as described herein. 
     In one embodiment, network interface  306  is a network interface card (NIC) that enables CPU  302  to communicate with a network, such as the Internet. 
     In one embodiment, memory device  304  is one or more memory chips capable of storing data and allowing any storage location to be directly accessed by the CPU  302 . In some embodiments, memory device  304  is a Static random access memory (SRAM), Dynamic random access memory (DRAM), or Ferroelectric RAM (FRAM). The memory device  304  may be based on any of the above described memory chips, or any other available memory chips capable of operating as described herein. The CPU  302  communicates with memory device  304 , I/O interface  308 , and network interface  306  via a system bus  312 . 
     It should be noted that in one embodiment, one or more modules  132  and  138  may be stored in memory device  304  and executed by CPU  302 . 
     Embodiments of the present invention may be practiced with various computer system configurations including hand-held devices, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers and the like. The embodiments can also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a wire-based or wireless network. 
     With the above embodiments in mind, it should be understood that the embodiments can employ various computer-implemented operations involving data stored in computer systems. These operations are those requiring physical manipulation of physical quantities. Any of the operations described herein that form part of the invention are useful machine operations. The invention also relates to a device or an apparatus for performing these operations. The apparatus can be specially constructed for a specific purpose. The apparatus is selectively activated or configured by a computer program stored in the computer. 
     In one embodiment, a module, as used herein, is embodied as computer readable code on a computer readable medium. The computer readable medium is any data storage device that can store data, which can be thereafter be read by a computer. Examples of the computer readable medium include hard drives, network attached storage (NAS), read-only memory (ROM), random-access memory, compact disc-ROMs (CD-ROMs), CD-recordables (CD-Rs), CD-rewritables (RWs), magnetic tapes and other optical and non-optical data storage devices. The computer readable medium can include computer readable tangible medium distributed over a network-coupled computer system so that the computer readable code is stored and executed in a distributed fashion. 
     Although the method operations were described in a specific order, it should be understood that other housekeeping operations may be performed in between operations, or operations may be adjusted so that they occur at slightly different times, or may be distributed in a system which allows the occurrence of the processing operations at various intervals associated with the processing, as long as the processing of the overlay operations are performed in the desired way. 
     Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.