WO2020068182A1

WO2020068182A1 - Systems and methods for computer security

Info

Publication number: WO2020068182A1
Application number: PCT/US2019/034039
Authority: WO
Inventors: Daniel Chien
Original assignee: Daniel Chien
Priority date: 2018-09-28
Filing date: 2019-05-24
Publication date: 2020-04-02
Also published as: US11188622B2; EP3857416A4; JP7248219B2; JP2022501727A; US20200104468A1; EP3857416A1

Abstract

Computer security techniques are described. One example determines whether to allow a program (e.g., native executable, script, etc.) to execute. This decision is based at least in part on the source of the program, such as whether the program is provided by a privileged source. A privileged program source may be any module, mechanism, or process that can provide executable instructions, such as directory or folder (e.g., on a local disk or network-accessible store), a computing device (e.g., server computer), another program (e.g., a Web server), or the like.

Description

SYSTEMS AND METHODS FOR COMPUTER SECURITY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. Patent Application No. 16/393,930, filed

April 24, 2019; which claims priority from U.S. Provisional Patent Application No. 62/739,094, filed September 28, 2018, the contents of which applications is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to methods, techniques, and systems for computer security, and more particularly suppressing, controlling, or restricting execution of malicious software.

BACKGROUND

[0003] Hackers and other malicious parties are increasingly attempting to penetrate computing systems operated by home users, corporations, or governments. In many cases, hackers attempt to install and run malicious software on a target computing system. The malicious software (e.g., viruses, Trojan horses, worms, etc.) can be used by the hackerto damage, control, gain access, or otherwise compromise the computing system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figures 1 A-1 G are flow diagrams that illustrate processes performed by example embodiments.

[0005] Figure 2 is a block diagram of an example computing system or device for implementing a computer security module according to an example embodiment.

DETAILED DESCRIPTION

[0006] Embodiments described herein provide enhanced computer- and network-based methods, devices, and systems for computer security, and more particularly suppressing, controlling, or restricting execution of malicious software. Some embodiments provide a computer security module (“CSM”) that is configured to control (e.g., suppress, restrict, monitor) the execution of malicious software on a computing system.

[0007] The core function of the CSM is to determine whether or not to allow a program (e.g., native executable, script, etc.) to execute. This decision is based at least in part on the source of the program, specifically whether the program is provided by one of a set of privileged (or“safe”) source. A privileged program source may be any module, mechanism, or process that can provide executable instructions, such as directory or folder (e.g., on a local disk or network-accessible store), a computing device (e.g., server computer), another program (e.g. , a Web server), or the like.

[0008] In some cases, a privileged source is a privileged folder or directory. A privileged folder is a folder that has been identified as storing programs that are eligible to be executed on the computer system. The privileged set of folders may contain one or more of: operating system folders (e.g., /bin, /sbin, /system32, etc.); application folders (e.g., /Program Files, /usr/bin); startup or services folders; third-party app folders; folders for the organization (e.g., corporation) that owns or administers the computer to install their own authorized programs; or the like.

[0009] In some cases, a privileged source is a privileged computer or process. A privileged computer can be identified by one or more identifiers, such as a machine name, IP address, domain name, process name, process identifier, process/program signature (e.g., a hash of the program instructions), or the like.

[0010] Privileged sources can be managed by way of a“white list” or similar data structure. The white list includes multiple identifiers of privileged sources. The identifiers may be or include directory names (system32), directory paths (e.g., /usr/bin), I P addresses, domain names, machine names, or the like. In some cases, URLs may be used to identify privileged sources. A privileged source may be identified or determined based on other or additional properties. For example, some embodiments may consider a source privileged if communication with that source is occurring at a specified time of day (e.g. , within a time range), if the source is located in a specified geographic region, if the source address is associated with a particular organization (e.g., via a WHOIS lookup), or the like. Some embodiments may generally base the determination of whether a source is privileged on whether there are one or more allowed or allowable properties of the communication with the source. Additional information regarding determining the allowability of network communication can be found in U.S. Patent No. 10,084,791 , entitled“Evaluating a Questionable Network Communication,” issued September 25, 2018, the content of which is incorporated herein by reference.

[001 1] The CSM may be implemented in various ways. The CSM may be implemented as code that exists in one or more locations within the operating system, including the loader, scheduler, memory manager, or the like. For example, the loader may check the location of every program as it is loaded into memory. If the location is not in the set of privileged folders, the loader terminates the execution. As another example, the scheduler may check, before switching to a next program on the ready queue, whether the program was loaded from one of the privileged folders. If not, the scheduler terminates the program. Similarly, the memory manager can check, when asked to create a new virtual address space (e.g., page tables, etc.), whether the requesting program was loaded from one of the privileged folders.

[0012] Script interpreters may also be employed to control the execution of potentially malicious programs. In some embodiments, script interpreters (e.g., for shell scripts, VBScript, Perl, Python, etc.) will refuse to execute/interpret a given script if it is not being loaded from one of the privileged folders.

[0013] The described techniques of course require that the privileged folders be“locked down.” In other words, the privileged folders are write protected for ordinary users, so that only users having the proper administrative privileges can install programs in those folders. In addition, other measures may be taken to restrict the ability of malicious parties from installing programs, such as secure boot, locked BIOS, and the like.

[0014] Figures 1A-1 G are flow diagrams of example security processes performed by example embodiments. The process may be implemented as computer instructions executing on a computing system. As noted above, these instructions may reside in one or more portions of the operating system, including the loader, scheduler, memory manager, and the like. The instructions may also or instead be present in programs that execute“outside” of the operating system, such as shell command interpreters, scripting language interpreters, virtual machines (e.g., Java Virtual Machine, C# VM), orthe like.

[0015] Figure 1 A is a flow diagram of example logicfor computer security. The illustrated logic in this and the following flow diagrams may be performed by, for example, the module 100 described with respect to Figure 2, below. Figure 1A illustrates a process 1A00 that includes the following block(s).

[0016] Block 1 A01 includes receiving and storing indications of one or more privileged sources that are each designated as providing programs that are allowed to be executed on a computing system. A source may be a directory or folder on a local or remote file system. A source may also or instead be a computer (e.g., a server) that is identified by an IP address, domain name, machine name, URL, or the like. In some embodiments, the process will read or access a“white list” of“safe” sources from a write protected document stored in the file system. In the white list, each source is designated as being a source of programs that are eligible for execution.

[0017] Block 1A02 includes receiving an indication of a program. The indication of the program may be received before or during the initiating of the program, such as prior to or during the loading process. The indication of the program will include or can be used to determine the location of the program, specifically the identity of the directory from which the program is being loaded. In the case of programs obtained from remote sources (e.g., JavaScript code received by a Web browser), the indication may be or include a URL, IP address, domain name, or other identifier of the remote source.

[0018] Block 1A03 includes determining whether or not the program is provided by one of the one or more privileged sources. The program is looked up in the white list of privileged sources. This may be accomplished via a dictionary lookup, hash table, orthe like. This operation can include looking up the program name, remote program source (e.g., domain name, IP address), or the like.

[0019] Block 1A04 includes disallowing execution of the program, when the program is not provided by any of the privileged sources. Disallowing execution of the program may accomplished in various ways, such as by terminating the loading process, raising an exception (so that the program will be terminated by the operating system), refusing to create a virtual memory space, the scheduler refusing to run or switch to the process, or the like.

[0020] Figure 1 B is a flow diagram of example logic illustrating an extension of process

1A00 of Figure 1A. Figure 1 B illustrates a process 1 B00 that includes the process 1A00, and which further includes the following block(s).

[0021] Block 1 B01 includes when the indicated program is provided by a network- accessible source, determining whether the network-accessible source is one of the one or more privileged sources. In typical embodiments, a Web browser or other module that fetches the program from a remote source will check whether the remote source is identified in the white list. This can include checking if the IP address, domain name, machine name, or other identifier of the remote source is present in the white list.

[0022] Block 1 B02 includes when the network-accessible source is not one of the one or more privileged sources, disallowing execution of the program. For example, if the source identifier is not present in the white list, then the Web browser or similar module will refuse to load or execute the program. Note that this approach may require the use of a Web browser that has been modified to perform these checks. Users are not able to execute arbitrary remote code because they cannot manually download and execute such code (because only code in designated directories can run), and because they are also not allowed to install an insecure Web browser in any of the designated privileged directories.

[0023] Figure 1 C is a flow diagram of example logic illustrating an extension of process

1A00 of Figure 1A. Figure 1 C illustrates a process 1 C00 that includes the process 1A00, and which further includes the following block(s).

[0024] Block 1 C01 includes disallowing modification one or more directories that are identified by the one or more sources as providers of programs that are allowed to be executed by the computing system. For safe sources that are directories, operating systems permissions can be employed to restrict modification of such directories (e.g., by adding or removing programs) by non-privileged users.

[0025] Figure 1 D is a flow diagram of example logic illustrating an extension of process

1A00 of Figure 1A. Figure 1 D illustrates a process 1 D00 that includes the process 1A00, wherein the disallowing execution of the program includes the following block(s). [0026] Block 1 D01 includes terminating the program, suspending the program, and/or raising an exception.

[0027] Figure 1 E is a flow diagram of example logic illustrating an extension of process

1A00 of Figure 1A. Figure 1 E illustrates a process 1 E00 that includes the process 1A00, wherein the disallowing execution of the program includes the following block(s).

[0028] Block 1 E01 includes executing the program in an alternative execution environment. In some embodiments, the program may instead be allowed to execute, but will be placed within an alternative execution environment, such as a sandbox or isolated virtual machine. In such embodiments, the program can be monitored to better understand the behavior and properties of potentially malicious code.

[0029] Figure 1 F is a flow diagram of example logic illustrating an extension of process

1A00 of Figure 1A. Figure 1 F illustrates a process 1 F00 that includes the process 1A00, and which further includes the following block(s).

[0030] Block 1 F01 includes receiving the indications of the one or more sources from a file. Some embodiments store the list of privileged sources in a file that is write protected from non-administrative users.

[0031] Block 1 F02 includes disallowing modification of the file by non-privileged users.

Only administrative users may modify the file that identifies the privileged execution sources.

[0032] Figure 1 G is a flow diagram of example logic for computer security. Figure 1 G illustrates a process 1 G00 that includes the following block(s).

[0033] Block 1 G01 includes receiving and storing indications of one or more directories that are each designated as containing programs that are allowed to be executed on a computing system. In some embodiments, the process will read a list of files from a write protected document stored in the file system.

[0034] Block 1 G02 includes receiving an indication of a program. The indication of the program may be received before or during the initiating of the program, such as prior to or during the loading process. The indication of the program will include or can be used to determine the location of the program, specifically the identity of the directory from which the program is being loaded. [0035] Block 1 G03 includes determining whether or not the program is located within one of the one or more directories. The location of the program is looked up in the list of privileged folders. This may be accomplished via a dictionary lookup, hash table, or the like.

[0036] Block 1 G04 includes disallowing execution of the program, when the program is not located within any of the one or more directories. Disallowing execution of the program may accomplished in various ways, such as by terminating the loading process, raising an exception (so that the program will be terminated by the operating system), refusing to create a virtual memory space, the scheduler refusing to run or switch to the process, or the like.

[0037]

[0038] Figure 2 is a block diagram of an example computing system or device for implementing a computer security module according to an example embodiment. In particular, Figure 2 shows a computing system 10 that executes a module 100 that implements at least some of the techniques described herein.

[0039] In the embodiment shown, computing system 10 comprises a computer memory

(“memory”) 1 1 , a display 12, one or more Central Processing Units (“CPU”) 13, Input/Output devices 14 (e.g., keyboard, mouse, CRT or LCD display, and the like), other computer-readable media 15, and a network connection 16. The module 100 is shown residing in memory 1 1 . In other embodiments, some portion of the contents, some or all of the components of the module 100 may be stored on and/or transmitted over the other computer-readable media 15. The module 100 preferably executes on one or more CPUs 13 and performs the techniques described herein. Other code or programs 30 (e.g., an administrative interface, a Web server, and the like) and potentially other data repositories, such as data repository 20, also reside in the memory 1 1 , and preferably execute on one or more CPUs 13. Of note, one or more of the components in Figure 7 may not be present in any specific implementation. For example, some embodiments may not provide other computer readable media 15 or a display 12.

[0040] The module 100 is shown executing in the memory 1 1 of the device 100. Also included in the memory 1 1 are a user interface manager41 and an application program interface (“API”) 42. The user interface manager 41 and the API 42 are drawn in dashed lines to indicate that in other embodiments, functions performed by one or more of these components may be performed externally to the module 100.

[0041] The Ul manager41 provides a view and a controller that facilitate user interaction with the module 100 and its various components. For example, the Ul manager41 may provide interactive access to the module 100, such that users or administrators can interact with the module 100. In some embodiments, access to the functionality of the Ul manager 41 may be provided via a Web server, possibly executing as one of the other programs 30. In such embodiments, a user operating a Web browser executing on the user computing system 60 can interact with the module 100 via the Ul manager 41.

[0042] The API 42 provides programmatic access to one or more functions of the module 100. For example, the API 42 may provide a programmatic interface to one or more functions of the module 100 that may be invoked by one of the other programs 30 or some other module. In this manner, the API 42 facilitates the development of third- party software, such as user interfaces, plug-ins, adapters (e.g., for integrating functions of the module 100 into Web applications), and the like.

[0043] The module 100 may interact using network connection 16 via a network 99 with other devices/systems including computing systems 60, 62, and 64. The network 99 may be any combination of media (e.g., twisted pair, coaxial, fiber optic, radio frequency), hardware (e.g., routers, switches, repeaters, transceivers), and protocols (e.g., TCP/IP, UDP, Ethernet, Wi-Fi, WiMAX) that facilitate communication between remotely situated humans and/or devices.

[0044] Note that one or more general purpose or special purpose computing systems/devices may be used to implement and/or execute the module 100. However, just because it is possible to implement the module 100 on a general purpose computing system does not mean that the techniques themselves or the operations (taken alone or in combination) required to implement the techniques are conventional or well known. The techniques are not conventional at least because they address and improve an existing technology, such as by improving the operation, integration, or efficiency of one or more computing systems. [0045] In an example embodiment, components/modules of the module 100 are implemented using software programming techniques. For example, the module 100 may be implemented as a“native” executable running on the CPU 13, along with one or more static or dynamic libraries. In other embodiments, the module 100 may be implemented as instructions processed by a virtual machine that executes as one of the other programs 30.

[0046] The various components may be implemented using more monolithic programming techniques, for example, as an executable running on a single CPU computer system, or alternatively decomposed using a variety of structuring techniques, including but not limited to, multiprogramming, multithreading, client-server, or peer-to- peer, running on one or more computer systems each having one or more CPUs. Some embodiments may execute concurrently and asynchronously, and communicate using message passing, remote procedure call, or other distributed computing paradigms. Equivalent synchronous embodiments are also supported. Also, other functions could be implemented and/or performed by each component/module, and in different orders, and by different components/modules, yet still achieve the described functions.

[0047] In addition, programming interfaces to the data stored as part of the module 100, such as in the data store 20, can be available by language-specific APIs; libraries for accessing files, databases, or other data repositories; through representational languages such as XML; or through Web servers, FTP servers, or other types of servers providing access to stored data. The data store 20 may be implemented as one or more database systems, file systems, or any other technique for storing such information, or any combination of the above, including implementations using distributed computing techniques.

[0048] Furthermore, in some embodiments, some or all of the components of the module 100 may be implemented or provided in other manners, such as at least partially in firmware and/or hardware, including, but not limited to one or more application-specific integrated circuits (“ASICs”), standard integrated circuits, controllers executing appropriate instructions, and including microcontrollers and/or embedded controllers, field-programmable gate arrays (“FPGAs”), complex programmable logic devices (“CPLDs”), and the like. Some or all of the system components and/or data structures may also be stored as contents (e.g., as executable or other machine- readable software instructions or structured data) on a computer-readable medium (e.g., as a hard disk; a memory; a computer network or cellular wireless network or other data transmission medium; or a portable media article to be read by an appropriate drive or via an appropriate connection, such as a DVD orflash memory device) so as to enable or configure the computer-readable medium and/or one or more associated computing systems or devices to execute or otherwise use or provide the contents to perform at least some of the described techniques. Some or all of the components and/or data structures may be stored on tangible, non-transitory storage mediums. Some or all of the system components and data structures may also be stored as data signals (e.g., by being encoded as part of a carrier wave or included as part of an analog or digital propagated signal) on a variety of computer-readable transmission mediums, which are then transmitted, including across wireless-based and wired/cable-based mediums, and may take a variety of forms (e.g., as part of a single or multiplexed analog signal, or as multiple discrete digital packets orframes). Such computer program products may also take other forms in other embodiments. Accordingly, embodiments of this disclosure may be practiced with other computer system configurations.

[0049] While embodiments of the invention have been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the above disclosure.

Claims

1. A method for computer security, the method comprising:

receiving and storing indications of one or more privileged sources that are each designated as providing programs that are allowed to be executed on a computing system;

receiving an indication of a program;

determining whether or not the program is provided by one of the one or more privileged sources; and

disallowing execution of the program, when the program is not provided by any of the privileged sources.

2. The method of claim 1 , further comprising:

when the indicated program is provided by a network-accessible source, determining whether the network-accessible source is one of the one or more privileged sources; and

when the network-accessible source is not one of the one or more privileged sources, disallowing execution of the program.

3. The method of claim 1 , further comprising: disallowing modification one or more directories that are identified by the one or more sources as providers of programs that are allowed to be executed by the computing system.

4. The method of claim 1 , wherein the disallowing execution of the program includes: terminating the program, suspending the program, and/or raising an exception.

5. The method of claim 1 , wherein the disallowing execution of the program includes: executing the program in an alternative execution environment.

6. The method of claim 1 , further comprising:

receiving the indications of the one or more sources from a file; and

disallowing modification of the file by non-privileged users.

7. The method of claim 1 , further comprising:

receiving the indication of the program in a Web browser, wherein the program is JavaScript code; and

determining whether the program is provided by a server that is one or more of the privileged sources.

8. The method of claim 1 , wherein the determining whether or not the program is provided by one of the one or more privileged sources includes looking up an identifier of the source in a white list.

9. The method of claim 1 , further comprising: disallowing installation of programs on the computing system.

10. The method of claim 1 , further comprising:

when the indicated program is provided by a network-accessible source, determining whether the network-accessible source is one of the one or more privileged sources;

when the network-accessible source is not one of the one or more privileged sources, disallowing execution of the program;

disallowing modification one or more directories that are identified by the one or more sources as providers of programs that are allowed to be executed by the computing system;

receiving the indications of the one or more sources from a file;

disallowing modification of the file by non-privileged users; and

executing the program in an alternative execution environment that is a virtual machine executed by the computing system

1 1. A non-transitory computer-readable medium including contents that are configured, when executed, to cause a computing system to perform a method for computer security, the method comprising: receiving and storing indications of one or more privileged sources that are each designated as providing programs that are allowed to be executed on a computing system;

receiving an indication of a program;

12. The computer-readable medium of claim 1 1 , wherein the method further comprises:

receiving the indications of the one or more sources from a file; and

disallowing modification of the file by non-privileged users.

13. The computer-readable medium of claim 1 1 , wherein the disallowing execution of the program includes: terminating the program, suspending the program, and/or raising an exception.

14. The computer-readable medium of claim 1 1 , wherein the disallowing execution of the program includes: executing the program in an alternative execution environment that is a virtual machine executed by the computing system.

15. A computing system for computer security, the computing system comprising: a processor; a memory;

a module that is stored in the memory and that is configured, when executed by the processor, to perform a method comprising:

receiving an indication of a program;

16. The computing system of claim 15, further comprising a virtual machine executing on the computing system, and wherein the method further comprises: when the indicated program is provided by a network-accessible source, determining whether the network-accessible source is one of the one or more privileged sources;

when the network-accessible source is not one of the one or more privileged sources, disallowing execution of the program; and

disallowing execution of the program includes by executing the program in an alternative execution environment that is the virtual machine.

17. The computing system of claim 15, further comprising a Web browser that is configured to:

receive the indication of the program in a Web browser, wherein the program is JavaScript code; and

determine whether the program is provided by a server that is one or more of the privileged sources.

18. The computing system of claim 17, wherein the Web browser is configured to determine whether or not the program is provided by one of the one or more privileged sources by looking up an identifier of the source in a white list.

19. The computing system of claim 18, wherein the Web browser is further configured to determine whether or not the program is provided by one of the one or more privileged sources based on one or more properties associated with a communication with the source, including one or more of a geographic location of the source, a time of communication, and an organization associated with the source.