US 20100205666 A1
In general, the invention relates to a method for securing a computer system. The method includes monitoring an operating system in the computer system and trapping, in response to the monitoring, a process system call where the process system call originated in a host executing in the computer system. Responsive to the trapping, an isolated user environment (IUE) is created in the computer system. Creating the IUE includes allocating memory and persistent storage for the IUE. In addition, the IUE includes a file system filter driver (FSFD) configured to redirect Input/Output (I/O) calls originating from the IUE to the persistent storage, and a network interface/NDIS hook component configured to control network traffic originating from the IUE and destined for the IUE. The method further includes, after creating the IUE, loading the process system call into the IUE and executing the process system call in the IUE.
20. A method for securing a computer system, comprising:
monitoring an operating system executing on a processor in the computer system;
trapping, in response to the monitoring, a process system call to execute a program, wherein the process system call originated in a host executing in the computer system;
responsive to the trapping, creating an isolated user environment (IUE) in the computer system, wherein creating the IUE comprises allocating memory and persistent storage for the IUE, and wherein the IUE comprises:
a file system filter driver (FSFD) configured to redirect Input/Output (I/O) calls originating from the IUE to the persistent storage, and
a network interface/NDIS hook component configured to control network traffic originating from the IUE and destined for the IUE;
after creating the IUE, loading an executable image corresponding to the program into the IUE; and
executing the program using the executable image in the IUE using the processor, wherein the IUE enables a user to provide input to the program during execution.
21. The method of
responsive to the executing, issuing an I/O call from the IUE to a file system of the host; and
redirecting, by the FSFD, the I/O call to the persistent storage, wherein the persistent storage comprises a file system of the IUE.
22. The method of
23. The method of
24. The method of
responsive to the executing, issuing an I/O call from the IUE to a registry of the host; and
redirecting, by a system call hook component, the I/O call to the persistent storage, which includes a registry of the IUE.
25. The method of
26. The method of
27. The method of
responsive to the executing, storing data in the persistent storage;
after executing the process system call, closing the IUE; and
responsive to closing the IUE, terminating all processes executing the IUE, deallocating the memory and unmounting the persistent storage.
28. The method of
creating a new IUE after closing the IUE, wherein the data in the persistent storage is accessible through the new IUE.
29. The method of
30. The method of
31. The method of
32. The method of
33. The method of
34. The method of
35. The method of
The present application is a continuation of U.S. patent application Ser. No. 11/237,035 and, accordingly, claims benefit under 35 U.S.C. §120 to U.S. patent application Ser. No. 11/237,035, which is incorporated by reference. U.S. patent application Ser. No. 11/237,035 claims the benefit of prior filed U.S. Provisional Application Ser. No. 60/613,768 filed 28 Sep. 2004 and Ser. No. 60/675,613 filed 28 Apr. 2005, both of which are incorporated by reference.
The present invention is in the field of support for electrical computers and digital processing systems. More specifically, the present invention relates to security software and processes for protecting a computer system's hardware, software and data from malicious caused destruction, unauthorized modification or unauthorized disclosure.
As the online community grows with the development of high bandwidth, high speed, and high availability connectivity to the public internet, we are seeing an ever increasing proliferation of malicious content and identity/data theft and destruction, perpetrated right in our own home and office computers. Malignant and poisonous web content administered through ‘data mining’ tools, ‘Add-Ware’ content, activeX, java script, misleading download queries, Trojan content and virus infected data is responsible for extraordinary, quantifiable, monetary losses to the enterprise every year. There is no measure, however, for the loss off privacy, intimate data and criminal violations these intrusions prey upon our families. Passive, after ‘the fact’, behindhand screening for Trojan and virus content, such as that provided by modern virus scanning software, has proven itself an inadequate bastion of defense to the cyber theft and data corruption mechanisms rampant in the global cyberspace. The computer security industry has made attempts to address these failings by implementing solutions such as execution protection products that only allow the execution of ‘White-listed’ applications on any given computer; but such products require constant centralized administration and customization to fit within a divers enterprise community, and are unreasonable solutions for home users due to their management needs and lack of transparency. Though restricting execution can greatly improve the protection of local computer data, a more flexible solution is to virtualize execution in an isolated environment. This methodology has been proven by software implemented virtual machines such as those presented by VMWare©. However, such solutions are not practical, nor were they designed for, implementation as computer security software. Such solutions require the full installation of a secondary operating system within each virtual environment. Implementing such environments requires a higher level of computer understanding than the average user and presents management/administration and storage complications to implementations across an enterprise environment. Even solutions as common to modern computer environments as advanced statefull firewall protection, host security, and access control management is beyond the average computer owner, let alone the peers and loved ones sharing their computer space. Microsoft's Windows architecture does not provide inherent user or group isolation robust enough to protect low privileged users from the actions of malicious code should it find its way onto their computer, nor the proliferation of damage or theft throughout all the computer's user and administrator space. Current third party solutions have proven themselves inadequate to protect a computer from the transgressions of its operators or malicious attack. This begs the questions, is it possible to split a Windows computer into secure virtual environments with as much isolation as possible between each one, looking like individual computers without the cumbersome implementation of classic virtual machine environments? To isolate disk space, virtualize execution, make user data inaccessible and unreadable to other users; yet share some/most/all common tasks (monitoring, backup, ups, hardware configuration and libraries etc) and still allow the individual evolution of each virtual environment? Can this be done transparently, unobtrusively?
The present invention is software for use with a PC-type computer, either standing alone or connected to a network. The present inventive software, when used in conjunction with a typical PC-type computer, prevents the unauthorized export of data from the computer, corruption/loss of data due to malwear or local action. This protection from the unauthorized export of data is accomplished by running the present Isolated/Secure User Environment Software (IUE/SUEZ) as a process component of the computer system. The SUEZ application provides a bubble from which a user can operate the computer, access all of the computer's applications and freely brows the Internet, but not have any of the computer systems files accessed for export by a trojan or like malicious code. The result of providing a SUEZ enhanced computer system is that, malicious code from an external data source, such as a file downloaded from the Internet or imported from an external data source, cannot steal data or eves-drop on a SUEZ user on the computer.
The present invention is a secured Windows OS electronic computer system having a software based isolated User environment protected from unauthorized access to and manipulation of data on the system. The software of the present invention on a Windows® OS computer system implements an isolated User file system and provides process/IPC isolation, Windows® registry isolation, network interface isolation, and isolated administrative control on the computer system. Interactive components of the system include an execution hook component, a job object component, a system call hook component, a file system block device driver, a file system/filter driver, a network interface/NDIS hook component, and an environment handler.
The execution hook component traps system calls requesting process execution. It also initiates creation of the isolated User environment (IUE) and manages assignment of successive process execution requests to the appropriate method of execution. To provide appropriate isolated process execution control, the execution hook traps all calls to load an executable image and tests them for an assigned User context. All execution requests without a User context are either assigning an administrative context and passed on for processing in the manner native to a Host computer system or assigning a User context by interrogating the environment handler for User authentication and credentials etc. Additionally, the execution hook is responsible for triggering requests to the environment handler, upon new User context assignments, to create a new User environment. New User environments include an isolated file system, network connection, Windows registry hive and execution environment. The current requested process and all subsequent processes with User context are bound to this environment. Trapped process execution requests with existing User context are assigned to their associated User specific job object. All filtering done by the execution hook is based on metadata described by the software and environment handler.
The job object component is responsible for creating, destructing, managing and manipulating job objects. It provides an alternative process creation mechanism to that native to the Host computer system by starting User processes in a restricted state. Additionally, it implements User credential based security descriptors that define the restrictions of User processes and provides isolated process/IPC and memory control. All based on appropriate metadata described by the software and the environment handler.
The system call hook component traps and filters all Windows registry I/O requests. This facilitates file system and memory isolation by filtering calls based on their User context and redirecting User registry I/O requests to the User's isolated file system. The system call hook processes User specific credentials, prescribed by the environment handler, to define what registry hives or keys or subset thereof will be abstracted from Host computer systems native registry. All filtering is done based on appropriate metadata described by the software and environment handler.
The file system block device driver component is responsible for mounting and unmounting the isolated User file system. This facilitates isolating the file system from the Host computers file system namespace.
The file system filter driver component filters all file system I/O requests to accomplish isolation of the User file system. The driver redirects file system I/O requests associated with a User context to that User's isolated file system. By providing granular proxy of all file system I/O, the file system filter driver facilitates the redirection of all or some subset of I/O based on request type, requested file system and object credentials or type. All filtering is done based on appropriate metadata described by the software and environment handler.
The network interface/NDIS hook component is responsible for abstracting the User's network interface from the Host computer system's network interface. Additionally, it provides bridging, packet filtering and other services typical of network interface control. All filtering done by the NDIS driver is based on metadata described by the software and environment handler.
The environment handler provides environment management services for all the software components making up the IUE. It reveals an administrative configuration interface allowing the definition of rules and general configuration data. The environment handler also managing and defines User authentication and credentials for all the IUE software components. This includes prescribing filter metadata and periodically obtaining log statistics from the software components as well as revealing other controls typical of software management systems.
The following detailed description presents an embodiment of the invention providing isolation of a User (User being the computer operator bound by the conditions of the preferred embodiment) environment to the extent that all User interactions with the computer system, including process execution, interprocess communication (IPC), file system I/O (input/output), Windows registry I/O and network I/O are isolated from the hosting computer systems operating environment (referred to below as Host), in such a way as to protect Host from User transgressions, such as maliciously caused destruction, unauthorized modification, or unauthorized disclosure of data.
The preferred embodiment will be described with reference to the accompanying drawings and broken into 3 sections to better describe the present invention. Section one will describe the hardware and Host computer system environment across multiple operating states with the preferred embodiment implemented. Section two will provide a system level overview of the embodiment. Section three will be a description of use cases.
Referring now to the drawings, the details of preferred embodiments of the present invention are graphically and schematically illustrated. Like elements in the drawings are represented by like numbers, and any sub-components of the same element are represented by like numbers with a different lower case letter suffix.
The description of
As shown in
Preferable, the computer system 20 can be of any configuration or manufacture running a Microsoft WINDOWS® operating system (preferably WINDOWS 2000®, XP® or compatible operating system). These include desk-tops, lap-tops or other devices having a CPU, storage and connectivity to an external data source, e.g., the Internet 14. In a preferred simple embodiment as exemplified in
The present Isolated User Environment (IUE or SUEZ) system is installable on a typical computer system as illustrated in
The Ready State configuration of the computer occurs on every start-up of the computer 20, i.e., upon every reboot after installation of the present IUE software. Starting up the computer once the IUE application is installed causes functions or processes to run in memory: a IUE driver set 300 and a IUE environment (bubble) manager process 340. A detector function residing in the driver set 300 monitors the operating system for process execution requests to detect and trap the occurrence of a detector trigger event. The environment manager 340 provides management services for the components of the IUE application, such as user profile and administration configurations.
In the embodiment illustrated in
Turning now to
a) The Execution Hook component, which intercepts all system calls to load an executable image and tests the execution requests for an assigned User context. This testing allows credential based assignment of processes to an alternate method of process creation to that native to the Host computer system. Additionally, the Execution Hook is the triggering mechanism for the initiation of new Isolated User Environments.
b) The Job object module, which provides an alternative process creation mechanism that allows the IUE to create a job with specific security descriptors and then assign User processes and their children to this job for creation; this assignment facilitates starting User processes in a restricted state, allowing the Environment handler to prescribe granular control over the credentials, memory allocation, IPC and general functionality assigned any User processes. All processes assigned to a User job are definable by a context representing this association and are effectively jailed within the file system namespace allocated to User's isolated User environment by this context due to its being honored by the complementary software components of the present system.
c) The System Call Hook, which provides a virtual registry, private to the isolated User environment, by selectively redirecting registry calls associated with a Users context to a virtual registry within the isolated User environment. The IUE System Call Hook has its interception functions run in lieu of the Host computer systems original system call functions simply by inserting pointers to the IUE replacement functions within the Windows system call array. After the IUE System Call Hook has examined the parameters an application, requesting registry I/O, passed to a system call, it tests these parameters against a set of filter rules prescribed by the environment handler to determine whether the I/O must be redirected to the isolated User instance of the Windows registry. If the original system call request is not of User context, the IUE System Call hook invokes the Host system call it replaced. When control returns to the IUE System Call Hook from the Host system call, the IUE System Call functions can optionally still examine the return status and pass control to the requesting application.
d) The Block device driver, which is a file system driver component for mounting and un-mounting a flat file as a block device. This facilitate the isolation of the User's isolated file system from the Host file system. In the preferred embodiment this driver is called upon, at IUE initialization, to mount a specific isolated User file system by the environment handler. The call for destruction of an isolated User environment results in a subsequent call from the environment handler to unmount the isolated User file system.
e) The File System Filter Driver (FSFD), which facilitates presenting the file system namespace of an IUE to its associated User and User context processes as a combination of the Host computers file system namespace and that of the Users isolated file system. Control of what objects from the Host computers file system are included in this merger of namespaces is controlled by User credentials and their associated metadata, prescribed by the environment handler. The FSFD intercepts requests targeted at a file system or another file system filter driver. By intercepting the request before it reaches its intended target, the FSFD extends or replace functionality provided by the original target of the request. All I/O requests made by any process with User context are proxied, allowing processing of all such I/O (read|write|modify|delete|copy, etc) to be performed in lieu of normal processing. This includes the transparent redirection, of select file system requests, to the User's isolated file system.
f) The NDIS driver, which isolates User context requests for network connectivity to that Users IUE. To facilitate isolating User network interactions to the IUE, the preferred embodiment exports one or more virtual adapters, bound to Users IUE, to which overlying protocols can bind. To a protocol driver, a virtual adapter exported by the intermediate driver appears to be a physical NIC. This allows an IUE to be bound to a MAC and IP address removed from that of the Host computer system. Additionally, the NDIS hook intercepts IP packets at the Windows NDIS (Network Device Interface Specification) layer; each packet is checked against the filtering rules that define what kind of traffic is allowed to pass. Allowed incoming packets are forwarded to the TCP/IP stack and the networking applications. Similarly, allowed outgoing packets are sent out on the network interface.
g) The Environment handler component, is responsible for creating and destructing User specific IUE's as needed, however, to facilitate tying all described IUE software components together, the Environment Handler provides environment management services for all the components of the preferred embodiment by revealing an administrative configuration interface to system administrators. It facilitates the definition of the rules and general configuration data that defines the operation of the present system. User authentication and credentials for all software components, prescribing filter metadata and periodically obtaining log statistics or metrics from all IUE software components are all under the environment handlers jurisdiction. Additionally, the environment handler operates as a proxy to facilitate interconnection of all components of the IUE, tying all the described components into a single source for authentication, filter and parameter metadata, credential discovery, system state and general configuration.
Once an IUE has been initialized for User by the Environment Handler, all subsequent process creation requests are assigned to the User Job Object component and loaded suspended. Once assigned, an alternative process creation mechanism defines specific memory restrictions and security descriptors binding all User processes and their children, then the process is released from its suspended state for execution in the Isolated Execution Environment (IEE) created by the Job Object.
Once User processes are restricted to the Isolated Execution Environment (IEE), binding them within the User's IUE, they are unable to see objects outside their IUE, as defined by the credentials prescribed by the environment handler. Effectively, they operate as normal, though the file system namespace and process object namespace revealed to them by FSFD and IEE is restricted to the IUE namespace or some subset of the Host computer systems namespace in combination with the that of the Users IUE.
User processes making I/O requests targeted at a file system or another file system filter driver are intercepted by the FSFD for examination and potential modification. By intercepting the request before it reaches its intended target, the filter driver extends or replace functionality provided by the original target of the request. All I/O requests made by any process owned by User are proxied, allowing processing of all such I/O (read|write|modify|delete|copy, etc) to be performed in lieu of normal processing. This includes the transparent redirection of select file system requests to User's isolated User file system, as well controlling object visibility or access by object type, credentials, location, etc. By mirroring the Host computers native file system hierarchy and implementing granular FSFD redirection filtering rules, the preferred embodiment can create a merged view of the Host computer systems process object and file system namespace for exposure to User processes. An example of this would be to allow User access to particular directories on the Host file system, all other directories being mirrors of the Host file system but resident on the isolated User file system. Restarting the Host computer systems shell under the Users context upon initiation of the IUE results in the graphical presentation of the User namespace presented by the computer system, such as the desktop, file explorer etc, to be a reflection of the users namespace merged with whatever objects have been configured for revelation to the User by the FSFD.
An application's configuration data is crucial to its proper function. The windows registry provides programs an interface to system and software configuration data. To facilitate this functionality, while still abstracting the Host computer system from processes belonging to an IUE, the preferred embodiment implements a System Call Hook to intercept and filter registry I/O, protecting the Host computers configuration data. User processes making I/O requests to the Windows registry structure may be making calls to edit cells in volatile memory, thus the need for a redirection system in addition to the FSFD. Such system call requests are tested for User context by the System Call Hook component and filtered based on rules prescribed by the Environment Handler. Because the Windows System Service functions are stored in a system service dispatch table within the kernel, the IUE System Call Hook driver is able to hook a system service by saving the address of a function from Host's native array and replacing the array entry with the address of the IUE hook function. Once the IUE is installed on a system 500, any invocations of the hooked system service get diverted to the IUE drivers function. Here the call is examined for an association to a User context. If the call is found to originate from a User context process it may be modified and the registry request diverted to a registry within the isolated User environment. The IUE registry may be a mirror of the host systems registry hive or some subset there of, optionally, a read-first operation can be performed that looks to the User registry for requested key's before examining the Host computer systems native registry for the requested I/O.
Commonly, User processes will request connectivity to an attached network, such as the Internet. To isolate such interactions to the IUE, this embodiment of the present invention utilizes an NDIS driver that exports a virtual adapters specific to the Users IUE. This allows an IUE to be bound to a MAC and IP address removed from that of the Host computer system. Additionally, the NDIS hook intercepts IP packets at the Windows NDIS (Network Device Interface Specification) layer; each packet is checked against the filtering rules that define what kind of traffic is allowed to pass. Allowed incoming packets are forwarded to the TCP/IP stack and the networking applications. Similarly, allowed outgoing packets are sent out on the network interface.
The following Use Case(s) are used primarily to capture the high level user-functional requirements of the SUEZ system. This section provides a description of each section in the use case template.
Actor: An actor is a person or other entity external to the software system being specified who interacts with the system and performs use cases to accomplish tasks. Different actors often correspond to different user classes, or roles, identified from the customer community that will use the product.
Description: A brief description of the reason for and outcome of this use case, or a high-level description of the sequence of actions and the outcome of executing the use case.
Preconditions: List any activities that must take place, or any conditions that must be true, before the use case can be started.
Postconditions: Describe the state of the system at the conclusion of the use case execution.
Normal Case: Provides a detailed description of the user actions and system responses that will take place during execution of the use case under normal, expected conditions. This dialog sequence will ultimately lead to accomplishing the goal stated in the use case name and description.
Alternative Case: Documents other, legitimate usage scenarios that can take place within this use case. States the alternative flow, and describes any differences in the sequence of steps that take place.
While the above description contains many specifics, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of one or another preferred embodiment thereof. Many other variations are possible, which would be obvious to one skilled in the art. Accordingly, the scope of the invention should be determined by the scope of the appended claims and their equivalents, and not just by the embodiments.