WO2018194196A1

WO2018194196A1 - Method and system for detecting application of obfuscation to and evaluating security of elf file

Info

Publication number: WO2018194196A1
Application number: PCT/KR2017/004236
Authority: WO
Inventors: 안성범; 정명주; 김태우; 정상민; 임성열; 전상훈; 서동필; 류주현; 한광희
Original assignee: 라인 가부시키가이샤
Priority date: 2017-04-20
Filing date: 2017-04-20
Publication date: 2018-10-25

Abstract

Provided are a method and a system for detecting application of obfuscation to and evaluating the security of an executable and linking format (ELF) file. A method for evaluating security may comprise the steps of: registering a package file for installing and running an application; identifying an executable and linkable format (ELF) file included in the registered package file; determining whether obfuscation has been applied to at least one of an ELF header, a section header, a section, or a segment included in the ELF file; and determining a security level for the ELF file on the basis of whether the obfuscation has been applied.

Description

Method and system for detection and security evaluation of ELF file obfuscation

The following description relates to a method and system for detecting and evaluating the application of obfuscation of an ELF file and to a computer program stored in a computer readable recording medium in combination with a computer for executing the security evaluation method on a computer. .

The App store is an online content marketplace that sells various applications that can be mounted on a terminal such as a smartphone. For example, the developer of an application registers a file (for example, an Android Application Package (Apk)) for installing a developed application on a terminal in an app store, and users of the application are required through the app store. By downloading a file for the application it is possible to install and run the application on their terminal. In addition, there are cases where various game applications such as game publishers are distributed to users. As such, there are application publishers that register various applications that are not developed by themselves, and distribute the registered applications to users.

At this time, the risk of the application can be described from various viewpoints.

For example, the first risk of an application is that the application contains information developed by malicious intentions, such as malicious code, to perform malicious functions on the terminal of the application publisher or the user on which the application is installed and run. There is a risk in the case. Korean Patent Laid-Open No. 10-2014-0098025 relates to a system and method for security evaluation of an application uploaded to an app store, and when an application to be registered in an app store detects a malicious function, the application Disclosed is a technique for rejecting entry into an app store.

As another example, the second risk of an application is the risk to the security of the application itself. As the source code of the application is changed or modified through analysis of the deployed application, the application performs a function other than the function originally intended by the developer, thereby reducing the reliability of the service to be provided through the application. This exists. Therefore, there is a need for application publishers to provide a certain level of security for applications in distributing various applications (installation files of applications) that they did not develop directly.

However, with respect to the second risk of such applications, there is a difference in the level of security provided for each registered application. For example, each application may be equipped with security solutions of different security levels and may not include any security measures. In addition, there are differences in the security levels provided by the security solutions mounted in each application.

In the prior art, only a Java-level vulnerability check can be performed at the programming language level (for example, Android Application Package (Apk)), and from the application publisher's point of view, each of the numerous registered applications There is a problem that it is difficult to provide security that is maintained above a certain level.

From the point of view of the application publisher, the level of security applied to the registered application is analyzed and identified in an objective manner in terms of obfuscation, vulnerability, and / or security solution, and the analyzed information is provided to provide security for the application. It provides a method and system for evaluating security that can be used to improve gender.

Provides a security evaluation method and system that can detect whether obfuscation is applied to Executable and Linkable Format (ELF) files.

A method of evaluating security of an application, the method comprising: registering a package file for installing and running an application; Identifying an executable and linkable format (ELF) file included in the registered package file; Determining whether to apply obfuscation to at least one of an ELF header, a section header, a section, and a segment included in the ELF file; And determining a security grade of the ELF file based on whether the obfuscation is applied.

A computer program for recording a computer program for executing the security evaluation method is provided.

A computer program stored in a computer readable recording medium for executing the security evaluation method in a computer in combination with a computer is provided.

A system for evaluating the security of an application, comprising: at least one processor implemented to execute computer readable instructions, the at least one processor registering a package file for installation and running of the application, Identify an executable and linkable format (ELF) file included in a registered package file, determine whether to apply obfuscation to at least one of an ELF header, a section header, a section, and a segment included in the ELF file. It provides a security evaluation system, characterized in that for determining the security level for the ELF file based on whether obfuscation is applied.

From the point of view of the application publisher, the level of security applied to the registered application is analyzed and identified in an objective manner in terms of obfuscation, vulnerability, and / or security solution, and the analyzed information is provided to provide security for the application. Can be used to improve sex.

It can detect whether obfuscation is applied to Executable and Linkable Format (ELF) files.

1 is a diagram illustrating an example of a network environment according to an embodiment of the present invention.

2 is a block diagram illustrating an internal configuration of an electronic device and a server according to an embodiment of the present invention.

3 is a block diagram of a security evaluation system according to an embodiment of the present invention.

4 and 5 illustrate a first example of detecting obfuscation of a symbol in an ELF file included in a registered package file according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating a second example of detecting obfuscation of a symbol in an ELF file included in a registered package file according to one embodiment of the present invention.

FIG. 7 illustrates a third example of detecting obfuscation of a symbol in an ELF file included in a registered package file according to an embodiment of the present invention.

8 illustrates an example of detecting obfuscation of an ELF header of an ELF file according to an embodiment of the present invention.

9 is a diagram for one example of determining whether to apply obfuscation to a header of a section including executable code according to an embodiment of the present invention.

FIG. 10 illustrates an example of detecting obfuscation of a code according to an embodiment of the present invention.

FIG. 11 illustrates an example of code conformance according to an embodiment of the present invention. FIG.

12 is a diagram for one example of determining whether to apply obfuscation to a code based on information on a branch position according to an embodiment of the present invention.

FIG. 13 is a diagram for one example of adding a dummy code to source code according to one embodiment of the present invention.

14 is a block diagram illustrating an example of components that may be included in a processor of a server according to an embodiment of the present invention.

15 is a flowchart illustrating an example of a security evaluation method that can be performed by a server according to an embodiment of the present invention.

16 is a flowchart illustrating a method of determining whether obfuscation is applied to an ELF header according to an embodiment of the present invention.

17 is a flowchart illustrating a method of determining whether obfuscation is applied to a header of a dynamic linking symbol table section (.dynsym section) according to an embodiment of the present invention.

18 is a flowchart illustrating a method of determining whether obfuscation is applied to a header of a section including executable code according to an embodiment of the present invention.

19 is a flowchart illustrating a method of determining whether obfuscation is applied to a dynamic linking symbol table section according to an embodiment of the present invention.

20 is a flowchart illustrating a method of determining whether to apply obfuscation to a read-only section according to an embodiment of the present invention.

21 is a flowchart illustrating a first example of a method of determining whether obfuscation is applied to a code according to an embodiment of the present invention.

22 is a flowchart illustrating a second example of a method of determining whether obfuscation is applied to a code according to an embodiment of the present invention.

23 is a flowchart illustrating a third example of a method of determining whether obfuscation is applied to a code according to an embodiment of the present invention.

24 is a flowchart illustrating a method of analyzing an instruction to determine whether obfuscation is applied to a code according to an embodiment of the present invention.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings.

The security evaluation system according to the embodiments of the present invention may be implemented through a server to be described later, and the security evaluation method according to the embodiments of the present invention may be performed through the server described above. For example, a computer program according to an embodiment of the present invention may be installed and run on a server, and the server may perform a security evaluation method according to an embodiment of the present invention under control of the driven computer program. have. The computer program described above may be stored in a computer-readable recording medium in combination with a computer-implemented server to execute a security evaluation method on a computer.

1 is a diagram illustrating an example of a network environment according to an embodiment of the present invention. The network environment of FIG. 1 illustrates an example including a plurality of

electronic devices

110, 120, 130, and 140, a plurality of

servers

150 and 160, and a network 170. 1 is an example for describing the present invention, and the number of electronic devices or the number of servers is not limited as shown in FIG. 1.

The plurality of

electronic devices

110, 120, 130, and 140 may be fixed terminals or mobile terminals implemented as computer devices. Examples of the plurality of

electronic devices

110, 120, 130, and 140 include a smart phone, a mobile phone, a navigation device, a computer, a notebook computer, a digital broadcasting terminal, a personal digital assistant (PDA), and a portable multimedia player (PMP). Tablet PC). For example, although FIG. 1 illustrates the shape of a smart phone as an example of the electronic device 1 110, in the embodiments of the present invention, the electronic device 1 110 may use a wireless or wired communication method to substantially connect the network 170. It may mean one of various physical devices that can communicate with other

electronic devices

120, 130, 140 and / or

servers

150, 160.

The communication method is not limited, and may include not only a communication method using a communication network (for example, a mobile communication network, a wired internet, a wireless internet, a broadcasting network) that the network 170 may include, but also a short range wireless communication between devices. For example, the network 170 may include a personal area network (PAN), a local area network (LAN), a campus area network (CAN), a metropolitan area network (MAN), a wide area network (WAN), and a broadband network (BBN). And one or more of networks such as the Internet. The network 170 may also include any one or more of network topologies, including bus networks, star networks, ring networks, mesh networks, star-bus networks, trees, or hierarchical networks, but It is not limited.

Each of the

servers

150 and 160 communicates with the plurality of

electronic devices

110, 120, 130, and 140 through the network 170 to provide a command, code, file, content, service, or the like. It may be implemented in devices. For example, the server 150 may be a system that provides a first service to a plurality of

electronic devices

110, 120, 130, and 140 connected through the network 170, and the server 160 may also have a network ( It may be a system that provides a second service to the plurality of

electronic devices

110, 120, 130, and 140 connected through the 170. As a more specific example, the server 150 may be at least some of the devices constituting the system of the application publisher, and receives a package file of an application installed and operated on the plurality of

electronic devices

110, 120, 130, and 140. The service to be distributed can be provided as the first service. As another example, the server 160 may provide a service associated with the application as the second service to a plurality of

electronic devices

110, 120, 130, and 140 that install and run the application through the distributed package file. . According to an embodiment, the server 150 may be implemented as a dedicated system for evaluating the security of a package file to be registered to provide information about the evaluated security for the package file to be registered.

2 is a block diagram illustrating an internal configuration of an electronic device and a server according to an embodiment of the present invention. 2 illustrates an internal configuration of the electronic device 1 110 and the server 150 as an example of the electronic device. In addition, the other

electronic devices

120, 130, 140, or the server 160 may also have the same or similar internal configuration as the aforementioned electronic device 1 110 or the server 150.

The electronic device 1 110 and the server 150 may include

memories

211 and 221,

processors

212 and 222,

communication modules

213 and 223, and input /

output interfaces

214 and 224. The

memories

211 and 221 may be computer-readable recording media, and may include a permanent mass storage device such as random access memory (RAM), read only memory (ROM), and a disk drive. In this case, the non-volatile mass storage device such as a ROM and a disk drive may be included in the electronic device 1 110 or the server 150 as a separate permanent storage device that is separated from the

memories

211 and 221. In addition, the

memory

211, 221 includes an operating system and at least one program code (for example, a browser installed and driven in the electronic device 1 110 or an application installed in the electronic device 1 110 to provide a specific service). Code) can be stored. These software components may be loaded from a computer readable recording medium separate from the

memories

211 and 221. Such a separate computer-readable recording medium may include a computer-readable recording medium such as a floppy drive, disk, tape, DVD / CD-ROM drive, memory card, and the like. In other embodiments, software components may be loaded into the

memory

211, 221 through a

communication module

213, 223 that is not a computer readable recording medium. For example, at least one program is a computer program that is installed by files provided by a file distribution system (for example, the server 160 described above) through the network 170 to distribute installation files of developers or applications. It may be loaded into the

memories

211 and 221 based on (for example, the above-described application).

Processors

212 and 222 may be configured to process instructions of a computer program by performing basic arithmetic, logic, and input / output operations. Instructions may be provided to the

processors

212, 222 by the

memory

211, 221 or the

communication modules

213, 223. For example, the

processors

212 and 222 may be configured to execute a command received according to a program code stored in a recording device such as the

memory

211 and 221.

The

communication modules

213 and 223 may provide a function for the electronic device 1 110 and the server 150 to communicate with each other through the network 170, and the electronic device 1 110 and / or the server 150 may communicate with each other. May provide a function for communicating with another electronic device (eg, electronic device 2 120) or another server (eg, server 160). For example, a request generated by the processor 212 of the electronic device 1 110 according to a program code stored in a recording device such as the memory 211 may be controlled by the server 170 through the network 170 under the control of the communication module 213. 150). Conversely, control signals, commands, contents, files, and the like provided according to the control of the processor 222 of the server 150 are transmitted to the communication module of the electronic device 1 110 via the communication module 223 and the network 170 ( It may be received by the electronic device 1110 through 213. For example, the control signal, command, content, file, etc. of the server 150 received through the communication module 213 may be transmitted to the processor 212 or the memory 211, and the content, file, etc. may be transferred to the electronic device 1. 110 may be stored as a storage medium (permanent storage described above) that may further include.

The input / output interface 214 may be a means for interfacing with the input / output device 215. For example, the input device may include a device such as a keyboard or a mouse, and the output device may include a device such as a display or a speaker. As another example, the input / output interface 214 may be a means for interfacing with a device in which functions for input and output are integrated into one, such as a touch screen. The input / output device 215 may be configured as one device with the electronic device 1110. In addition, the input / output interface 224 of the server 150 may be a means for interfacing with an apparatus (not shown) for input or output that may be connected to or included in the server 150. As a more specific example, the processor 212 of the electronic device 1110 uses data provided by the server 150 or the electronic device 2 120 in processing a command of a computer program loaded in the memory 211. The service screen or the content may be displayed on the display through the input / output interface 214.

Also, in other embodiments, the electronic device 1 110 and the server 150 may include more components than those of FIG. 2. However, it is not necessary to clearly show most of the prior art components. For example, the electronic device 1 110 may be implemented to include at least some of the above-described input / output devices 215 or other components such as a transceiver, a global positioning system (GPS) module, a camera, various sensors, a database, and the like. It may further include elements. More specifically, when the electronic device 1 110 is a smartphone, an acceleration sensor, a gyro sensor, a camera module, various physical buttons, a button using a touch panel, an input / output port, and vibration for a smartphone generally include Various components such as a vibrator may be implemented to be further included in the electronic device 1 110.

3 is a block diagram of a security evaluation system according to an embodiment of the present invention. The security evaluation system 300 of FIG. 3 may be implemented through the server 150 described above. In this case, the server 150 includes the package decomposition module 310, the file identification module 320, the parsing module 330, the analysis module 340, and the report module 350 included in the security evaluation system 300. May be representations of the different functions of the processor 222. For example, the package disassembly module 310 may be used as a function of the processor 222 in which the processor 222 of the server 150 disassembles a package file according to a control command included in a computer program. In this case, the vulnerability detection module 342 included in the analysis module 340 may be implemented as a core module for vulnerability detection.

As described above, the server 150 may provide a service for distributing package files of applications registered by developers to users.

In this case, the package disassembly module 310 may disassemble the registered package files. For example, an Android application package (Apk) is a file format of a package file used for distributing software and middleware of Android, which is a mobile operating system, and has a '.apk' extension. In the following embodiments, embodiments of the present invention will be described based on a package file such as an APK, but it will be readily understood by those skilled in the art that the same or similar features may be applied to other kinds of package files through this description. .

In addition, since the APK is already well known, the description of the APK file or the files themselves included in the APK file will be easily understood by those skilled in the art through the conventional arts, and thus, the APK file or the files included in the APK file itself. Detailed descriptions thereof will be omitted.

The file identification module 320 may identify files included in the disassembled package file. The extensions shown in Figure 3 ('dex', 'so', 'dll', 'json', 'ini', 'apk', 'xml', 'cert') as described previously, It will be readily understood by those skilled in the art.

The parsing module 330 may parse the identified files. To this end, the parser 331 may parse files of a specific extension (eg, 'dex', 'so', 'dll') among the identified files, and the collector 332 may parse a specific extension (eg, You can collect the necessary information from the files of 'json', 'ini', 'apk', 'xml', and 'cert').

For example, the parsing module 330 may identify each of the classes and methods included in the 'dex' file, and track a number of masses by instructing the instructions contained in the method. Can be identified by separating. The mass of instructions can be divided based on branch instructions such as the 'goto' statement, the 'switch' statement, or the 'if' statement. In addition, the parsing module 330 may generate and manage information on call relationships between these instruction masses. For example, the call relations between the instruction masses may be managed in a tree structure, and the information on the call relations may include information on a method called by a specific instruction mass. The generation and management of such information may be processed for each of files included in a package file such as an APK file, and the parsing method may vary according to the characteristics of the file.

The parsed information and the collected information may be passed to the analysis module 340.

The analysis module 340 obfuscates a corresponding package file (or an application installed and driven in a user terminal such as the electronic device 1 110 through the package file) based on the information transmitted from the parsing module 330. It can generate and provide analysis information from an obfuscation point of view, a vulnerability point of view, and a security solution point of view.

For example, the obfuscation detection module 341 may generate analysis information on the level of obfuscation applied to files of a specific extension (eg, 'dex', 'so', 'dll'). Can be. To this end, the obfuscation detection module 341 may determine whether obfuscation is applied for each preset item according to the type of file.

In addition, the vulnerability detection module 342 generates analysis information on whether there are any vulnerabilities in files of a specific extension (for example, 'dex', 'so', or 'config' which is a configuration file extension). can do. To this end, the security evaluation system 300 may manage information about known vulnerabilities, and the vulnerability detection module 342 uses information about these vulnerabilities to determine which vulnerabilities exist in which files. Analyze information can be generated.

In addition, the platform detection module 343 may extract information about the platform on which the corresponding application is developed and / or the platform on which the corresponding application operates. For example, the security evaluation system 300 may use different analysis methods depending on which platform the application is developed on, for example, a development tool such as Unity or Cocos.

Alternatively, the security evaluation system 300 may use a different analysis method for each platform because the file format included in the package file may vary for each platform on which the application operates.

To this end, the security evaluation system 300 may extract information about the platform for the package file, and may analyze the package file or provide information about the extracted platform to the outside based on such information.

The security tool detection module 344 can detect the security solution that the developer of the package file has inserted into the package file. For example, a first security tool provided in a library form by a third party may be added to a corresponding package file by a developer. As another example, a second security tool developed by the developer may be added to the package file by the developer. In other words, the security tool detection module 344 may generate analysis information about whether the security tool is applied to the package file.

The relationship analysis module 345 may generate analysis information about a reference relationship between files included in the package file. For example, when the first file includes code for calling the second file, the analysis information may be generated such that the information about the reference relationship between the first file and the second file is included in the analysis information.

The report module 350 collects the analysis information generated by the analysis module 340 and provides a report for the person of the security evaluation system 300 (for example, an administrator of the server 150 or a security inspection team of an application publisher). Can be generated. Such a report may be provided to terminals of related parties using Hypertext Markup Language (HTML) or eXtensible Markup Language (XML) as in the example of FIG. 3.

The Executable and Linkable Format (ELF), which will be described later, is a standard file format for executable files, object files, shared libraries, and core dumps.The ELF header, section header, and section that the ELF file contains Since header tables, sections, segments, and the like are already well known, those skilled in the art can easily understand them without further explanation. Obfuscation for such ELF files can be broadly classified into header obfuscation and code obfuscation.

4 illustrates a section header table 410 included in an ELF file and a header 411 of a dynamic linking symbol table section (.dynsym section) included in the section header table 410. 4 further shows a symbol entry table 420 of the dynamic linking symbol table section (.dynsym section) included in the ELF file, and the symbol entry table in the header 411 of the dynamic linking symbol table section. 420 is indicated. The symbol entry table 420 may be a table listing names and addresses of an import function and an export function.

In the ELF file, the section header table 410 defines information such as a name, a memory, a start address, a file offset, a size, a sorting method, and a presentation method for each section included in the ELF file. In addition to the .dynsym section described above, the sections include a dynamic linking information section (.dynamic section), a read-only data section (.rodata section or a .rdata section), and a section (.init section or .init_array section) containing code to be used at process initialization. It contains various sections such as) and is well known. For example, information about a .dynsym section may be defined via the header of the .dynsym section in the section header table 410, where the header of the .dynsym section may contain at least some of these defined values (e.g., the .dynsym section You can point to the .dynsym section by its starting address, file offset and size).

FIG. 5 illustrates an example of obfuscating values defined in the header 411 of the dynamic linking symbol table section of FIG. 4, and replacing the defined values with nulls 510. In this case, the header 411 of the dynamic linking symbol table section cannot point to the symbol entry table 420, so that the section header of the ELF file may be obfuscated.

As such, the values defined in the header 411 of the dynamic linking symbol table section may be obfuscated by changing to null 510 or other information to obfuscate the symbols used in the ELF file. In this case, the security evaluation system 300 may detect obfuscation of the section header by analyzing values defined in the header 411 of the dynamic linking symbol table section.

For example, the security assessment system 300 may include a first condition in which the header 411 of the dynamic linking symbol table section includes a null 510, and the header 411 of the dynamic linking symbol table section is parsed. If the condition of any one of the second condition that is impossible and the information contained in the header 411 of the dynamic linking symbol table section is not present in the dynamic linking information section (.dynamic section) among the sections is satisfied, It can be determined that obfuscation is applied to the header.

As described in FIG. 5, the first condition may refer to a condition in which a value defined in the header 411 of the dynamic linking symbol table section is replaced with a null 510.

Meanwhile, the header 411 of the dynamic linking symbol table section has a predefined structure, and there is an existing scheme for parsing the header 411 of the dynamic linking symbol table section according to the predefined structure. In this case, the second condition may mean a condition in which the header 411 of the dynamic linking symbol table section is attempted to be parsed through such a conventional parsing scheme, and the header 411 of the dynamic linking symbol table section is not normally parsed. . In other words, when the header 411 of the dynamic linking symbol table section is obfuscated, the security evaluation system 300 cannot parse the header 411 of the dynamic linking symbol table section, and thus the second condition is satisfied. can confirm.

In addition, at least some of the values defined according to the structure defined in the header 411 of the dynamic linking symbol table section are also included in the dynamic linking information section (.dynamic section), and the value of the dynamic linking information section (.dynamic section). Does not change. Therefore, the security evaluation system 300 checks whether the information included in the header 411 of the dynamic linking symbol table section exists in the dynamic linking information section (.dynamic section), and if it does not exist, It can be confirmed that the value included in the header 411 has been changed. In other words, the security evaluation system 300 may confirm that the third condition is satisfied.

If any one of the first condition, the second condition, and the third condition is satisfied, the security evaluation system 300 may determine that obfuscation is applied to the header 411 of the dynamic linking symbol table section.

FIG. 6 is a diagram illustrating a second example of detecting obfuscation of a symbol in an ELF file included in a registered package file according to one embodiment of the present invention. In the embodiment of FIG. 6, as an example of applying obfuscation to the value of the symbol entry table 420 instead of the header 411 of the dynamic linking symbol table section, the name of the import function 610 and the name of the export function 620 are nulled. null) shows an example.

For this case, the security assessment system 300 finds the symbol entry table 420 pointed to by the header 411 of the dynamic linking symbol table section and analyzes the values of the import and export functions to analyze the dynamic linking symbol table section. It can be determined whether or not obfuscation is applied. For example, the security assessment system 300 may determine a section (dynamic linking) if the values of the import and export functions contain nulls or are not represented in American Standard Code for Information Interchange (ASCII) code. It can be determined that obfuscation is applied to the symbol table section).

FIG. 7 illustrates a third example of detecting obfuscation of a symbol in an ELF file included in a registered package file according to an embodiment of the present invention. ELF files can contain read-only sections (.rdata section 710 or .rodata sections), and the section header table 410 contains headers for these read-only sections. (.rdata section header 720 or .rodata section header).

Obfuscation for such a read-only section may be achieved by encrypting or encoding the texts contained in the read-only section. Therefore, the security evaluation system 300 obfuscates the read-only section by checking the read-only section through the header for the read-only section and analyzing the read-only values included in the identified read-only section. Can be detected.

For example, in the embodiment of FIG. 7, the security assessment system 300 identifies the .rdata section header 720 in the section header table 410 of the ELF file, and the identified .rdata section header 720 is pointing. Find the .rdata section 730 to analyze the values contained in the .rdata section 730. In this case, the .rdata section 730 may be a section that obfuscates the texts included in the .rdata section 710, and the security evaluation system 300 determines that values included in the .rdata section 730 are null. ), Or not represented in ASCII code, it can be seen that obfuscation is applied to the .rdata section 730, unlike the .rdata section 710.

8 illustrates an example of detecting obfuscation of an ELF header of an ELF file according to an embodiment of the present invention. In FIG. 8, the first ELF header 810 is an unobfuscated header and shows an example including information such as the size of the section header 811, the number of section headers 812, and the size of the section 813. have. Meanwhile, the second ELF header 820 is a header to which obfuscation is applied, and shows an example in which original values are changed to manipulated values 821.

In order to detect such obfuscation, the security evaluation system 300 may determine whether to apply obfuscation to the ELF header by detecting an abnormal value of the ELF header. For example, normal values of the ELF header may have a range of values, but may be out of this range when obfuscation is applied.

To this end, the security assessment system 300 may set a range of normal values for at least one item of the size of the section header included in the ELF header, the number of section headers, and the size of the section, and in the ELF header, the at least A value of one item may be extracted, and if the extracted value is out of a set range of normal values, it may be determined that obfuscation is applied to the ELF header.

For example, in the embodiment of FIG. 7, values extracted from the first ELF header 810 will be included in the range of normal values, and values extracted from the second ELF header 820 will be out of the range of normal values. . As such, when the security evaluation system 300 detects an abnormal value of the extracted values, the security evaluation system 300 may detect that obfuscation is applied to the ELF header.

The section header table 410 described above may include a header of a section (.text section) including executable code. In this case, the header 910 of the normal .text section may include a size 911 of the executable code, and the size of the executable code 911 included in the header 910 of the normal .text section as one of the obfuscation schemes. There is a way to manipulate. FIG. 9 illustrates an example in which the obfuscation is applied to the header 910 of the normal .text section, and the header 920 of the obfuscated .text section including the manipulated value 921.

In order to detect such obfuscation, the security evaluation system 300 exports an export symbol entry (Export function of FIG. 9) from the symbol entry table 420 included in the dynamic linking symbol table section (.dynsym section). Function)) can be used to collect the address of functions. For example, the security evaluation system 300 may repeatedly collect the addresses of the functions through the addresses of these export functions, and calculate the size of the executable code using the collected addresses. In this case, the security evaluation system 300 may extract the size of the executable code 911 from the header 910 of the normal .text section, and extract the size of the extracted executable code 911 and the calculated size of the executable code. By comparing, it may be determined that obfuscation has not been applied to the header 910 of the normal .text section.

If the manipulated value 921 is extracted from the obfuscated .text section header 920, as in the embodiment of FIG. 9, the manipulated value 921 is the size of the original executable code 911. Since it is different from the calculated execution code size, the security evaluation system 300 may detect that the obfuscation is applied to the header 920 of the obfuscated .text section. .

FIG. 10 illustrates an example of detecting obfuscation of a code according to an embodiment of the present invention. The section header table 410 may include a header of a section (.init section and / or .init_array section) that contains code for process initialization. 10 shows a header 1010 of the .init section and a header 1020 of the .init_array section, respectively. 10 also shows a segment 1030. Segment 1030 is created as the linker merges the sections that the ELF file contains. The header 1010 of the .init section and / or the header 1020 of the .init_array section are executed first at run time so that the segment 1030 ) May be implemented to execute codes of a code segment 1031. Here, the code segment 1031 may have a read-write-execute (RWE) right, and the data segment 1032 may have a read-write (RW) right.

This code segment 1031 contains actual executable code for driving an application. However, when obfuscation is performed on executable codes (for example, when at least some of the executable code is encrypted), and when the codes of the code segment 1031 are executed in a normal manner, the executable code is executed normally due to the encrypted code. Can't.

Therefore, in the case of such code obfuscation, a new segment having read-write-execute (RWE) rights is added to restore the obfuscated code. 10 illustrates an example in which an instruction for restoring obfuscated code is added to an added segment 1033. In this case, the header 1010 of the .init section and / or the header 1020 of the .init_array section that are executed first at runtime may be changed to point to the added segment 1033 instead of the code segment 1031.

In one embodiment for detecting such obfuscation, security assessment system 300 may detect the presence of added segment 1033. In this case, the security evaluation system 300 may determine that obfuscation is applied to the code segment 1031 when an added segment 1033 having a read-write-execute (RWE) right exists. have.

In another embodiment, the security assessment system 300 may detect whether there is a pointing to the segment 1033 added to the header 1010 of the .init section and / or the header 1020 of the .init_array section. . At this time, the security evaluation system 300 obfuscates the code segment 1031 when there is a pointing to the segment 1033 added to the header 1010 of the .init section and / or the header 1020 of the .init_array section. You can decide that the paint is applied.

In another embodiment, security assessment system 300 analyzes (eg, disassembles) the added segment 1032 to restore obfuscated code contained in code segment 1031 (eg, encrypted). When the code for decoding the code is present in the added segment 1033, it may be determined that obfuscation is applied to the code segment 1031.

In addition, the security evaluation system 300 may detect whether the code is obfuscated by analyzing the code itself.

FIG. 11 illustrates an example of code conformance according to an embodiment of the present invention. FIG. As described with reference to FIG. 9, the security evaluation system 300 may export an export symbol entry (the export function of FIG. 9) from a symbol entry table 420 included in a dynamic linking symbol table section (.dynsym section). Function)) can be used to collect the address of functions. At this time, the security evaluation system 300 may analyze the instructions included in each function through the collected address.

For example, as shown in FIG. 11, the instructions Push and Pop are the most commonly used instructions in assembly language, and push a and b 1110 are instructions for storing the values of operands a and b in a stack (register). Pop a, b (1120) is an instruction for the operation of taking out the value of the top of the stack and storing it in the operands a, b. Accordingly, as shown in FIG. 11, the security evaluation system 300 may analyze whether the code is pushed by searching whether the value of the pushed register is Pop. If the value of the pushed register is not Pop, it may be determined that obfuscation is applied to at least some code.

In addition to Push and Pop described with reference to FIG. 11, such matching is required between a pair of instructions stmfd and ldmfd and a pair of instructions stmdb and pop.w. The security evaluation system 300 may further analyze the consistency of such pairs of instructions stmfd and ldmfd and pairs of instructions stmdb and pop.w, and if there is no consistency between the instructions, at least some of the code may be obfuscated. You can judge.

In addition, the security evaluation system 300 may determine whether to apply obfuscation to at least some of the codes depending on the existence of an operation code (opcode) combination that does not exist (not predefined). In other words, in the case where an obfuscation code is formed according to obfuscation, the security evaluation system 300 may detect obfuscation of the code.

In addition, the security evaluation system 300 may determine whether to apply obfuscation to the code based on the information on the branch position of the branch (branch) code. For example, as described above, the security evaluation system 300 has information about all functions through information about addresses of functions. At this time, if the position of the instruction to be performed next through the branch code is not the position to these functions, the security evaluation system 300 may detect obfuscation of the code.

12 is a diagram for one example of determining whether to apply obfuscation to a code based on information on a branch position according to an embodiment of the present invention. FIG. 12 illustrates an example of branching to an added segment 1033 through the branch code 1210 included in the function A 1200, rather than the code segment 1031 of the segment 1030 described with reference to FIG. 10. have. In this case, the security evaluation system 300 may detect that obfuscation is applied to at least some code.

In addition, the security evaluation system 300 may determine whether to apply obfuscation to the binary code based on the presence of a dummy code of a predefined pattern. Dummy code is code that is added to make code analysis difficult without affecting registers. Therefore, the security evaluation system 300 may predefine and manage information on patterns of these dummy codes, and if there are codes of a managed pattern, it may be determined as dummy codes, and code obfuscation may be performed. To detect that a dummy code has been added.

Table 1 below shows an example of a dummy code.

SUBGE SP, SP, # 0x84EORVS R2, R2, # 0x9EMOVMI R2, R2EORVS R2, R2, # 0x9EBX PCDCD

In addition, the security evaluation system 300 may be obfuscated by adding dummy code to the source code. Such dummy code may be converted into junk code through compilation.

FIG. 13 is a diagram for one example of adding a dummy code to source code according to one embodiment of the present invention. FIG. 13 illustrates that the dummy code 1321 is added to the source code 1310 including the operation code 1311 to generate the obfuscated source code 1320, and the obfuscated source code 1320 is compiled to the junk code. An example of generating a binary code 1330 including a 1133 and a compiled operation code 1332 is shown.

At this time, the dummy code 1321 and the junk code 1331 have a predetermined pattern. This is because the dummy code 1321 must have a certain format that can be compiled, and must not affect the original operation code 1311 or the compiled operation code 1332. Therefore, the security evaluation system 300 may pre-set and manage the patterns for the dummy code 1321 and / or the junk code 1331, and if a predefined pattern is found in the source code or the binary code. For example, it can detect the application of obfuscation to the code. For example, successive use of instruction ldr and / or instruction lsls in binary code may be set as a pattern for junk code 1331. In this case, the security evaluation system 300 may detect the application of obfuscation to the code by analyzing a binary code and detecting a pattern in which the instruction ldr and / or the instruction lsls are repeatedly used.

14 is a block diagram illustrating an example of a component that may be included in a processor of a server according to an embodiment of the present invention, and FIG. 15 is a security evaluation that may be performed by a server according to an embodiment of the present invention. A flowchart illustrating an example of the method.

The security evaluation system 300 according to the embodiments of the present invention may be implemented in the form of a computer device such as the server 150 described above. In addition, as shown in FIG. 14, the processor 222 of the server 150 is a package file register 1410, an ELF file identifier 1420, and obfuscation as components for implementing the security evaluation system 300. The determiner 1430, the security grade determiner 1440, and the reporter 1450 may be included. The processor 222 and the components of the processor 222 may perform steps 1510 to 1550 included in the security evaluation method of FIG. 15. In this case, the processor 222 and the components of the processor 222 may be implemented to execute a control instruction according to a code of an operating system included in the memory 221 or a code of at least one program. Here, the components of the processor 222 may be representations of different functions of the processor 222 performed by the processor 222 according to a control command provided by a code stored in the server 150. . For example, the package file register 1410 may be used as a functional representation of the processor 222 in which the processor 222 registers a package file according to the above-described control command.

In operation 1510, the package file registration unit 1410 may register a package file for installing and driving the application. The package file can be registered with the application publisher for distribution to users of the application. As described above, the security evaluation system 300 may be implemented in a device that provides a service for distributing package files of applications for which an application publisher is registered, or as a separate system that communicates with the aforementioned device through the network 170. Can be implemented. For example, the security evaluation system 300 may receive and register a package file registered with an application publisher through the network 170. Such a package file may include an Android application package (Apk) as described above.

In operation 1520, the ELF file identification unit 1420 may identify an executable and linkable format (ELF) file included in the registered package file. For example, if the package file is an Android application package, the PE file may be a so file. As described with reference to FIG. 3, the ELF file to be identified may be identified through an extension of the file among the files identified through the package decomposition module 310 and the file identification module 320.

In operation 1530, the obfuscation determiner 1430 may determine whether to apply obfuscation to at least one of an ELF header, a section header, a section, and a segment included in the ELF file. Various embodiments for determining whether to apply obfuscation have already been described in detail, and more detailed operations of the obfuscation determiner 1430 according to these embodiments will be described in more detail with reference to the following drawings.

In operation 1540, the security rating determiner 1440 may determine a security rating for the ELF file based on whether obfuscation is applied. For example, the security level of the ELF file may be determined according to whether obfuscation is applied to the ELF file, the type or degree of obfuscation applied to the ELF file, and the like. The type of obfuscation has been described in detail through various embodiments described above, and the degree of obfuscation may be determined based on, for example, the number of types of obfuscation applied, the degree of conformity of codes, and the like.

In operation 1550, the reporting unit 1450 may report information on whether obfuscation is applied and information on a security level determined for the ELF file. For example, for an identified ELF file, whether the section header is obfuscated, whether obfuscation is applied to strings and / or string tables, whether obfuscation is applied to symbol tables, whether obfuscation is applied to code, and so on. Information may be provided to an administrator or user of the security evaluation system 300.

16 is a flowchart illustrating a method of determining whether obfuscation is applied to an ELF header according to an embodiment of the present invention. Steps 1610 through 1630 of FIG. 16 may be included in step 1530 of FIG. 15. In this case, step 1610 may be included in step 1530 but may be performed before step 1530.

In operation 1610, the obfuscation determiner 1430 may set a range of normal values for at least one item of the size of the section header included in the ELF header, the number of section headers, and the size of the section.

In operation 1620, the obfuscation determiner 1430 may extract a value of at least one item from the ELF header. If the ELF header is not obfuscated, a value included in the range of normal values will be extracted, and if the ELF header is obfuscated, a value outside the range of normal values will be extracted.

In operation 1630, the obfuscation determination unit 1430 may determine that the obfuscation is applied to the ELF header when the extracted value is out of the set range of the normal value. In other words, the obfuscation determiner 1430 sets a range of normal values for at least one of the size of the section header, the number of section headers, and the size of the section in advance, and then obfuscates the ELF header of the ELF file. This can be used to determine whether or not the application is applied. Obfuscation detection for such an ELF header has already been described in detail with reference to FIG. 8.

Steps

1710 and 1720 of FIG. 16 may be included in step 1530 of FIG. 15.

In operation 1710, the obfuscation determiner 1430 may extract a header of the dynamic linking symbol table section (.dynsym section) from the section header table included in the ELF file.

In operation 1720, the obfuscation determiner 1430 may determine whether to apply obfuscation to the section header by analyzing the header of the extracted dynamic linking symbol table section. To this end, the obfuscation determination unit 1430 may include a first condition in which the header of the extracted dynamic linking symbol table section includes null, and a header in which the header of the extracted dynamic linking symbol table section cannot be parsed. If the condition included in the condition 2 and the third condition in which the information included in the header of the extracted dynamic linking symbol table section does not exist in the dynamic linking information section (.dynamic section) of the sections is satisfied, the section It can be determined that obfuscation is applied to the header. Obfuscation detection for the header of this dynamic linking symbol table section (.dynsym section) has already been described in detail with reference to FIGS. 4 and 5.

18 is a flowchart illustrating a method of determining whether obfuscation is applied to a header of a section including executable code according to an embodiment of the present invention. Steps 1810 through 1830 of FIG. 18 may be included in step 1530 of FIG. 15.

In operation 1810, the obfuscation determiner 1430 may collect addresses of functions through an export symbol entry included in a dynamic linking symbol table section (.dynsym section) among sections included in the ELF file. . For example, the obfuscation determiner 1430 may disassemble the address of an export symbol entry to track the entire functions and collect the address.

In operation 1820, the obfuscation determination unit 1430 may extract a value for the size of the executable code from the header of the section (.text section) including the executable code in the section header table included in the ELF file. If the header of the section containing the executable code (.text section) has been manipulated (obfuscated), the value extracted will be different from the value computed through the collected addresses.

In operation 1830, the obfuscation determination unit 1430 may determine whether to apply obfuscation to the header of the section including the execution code by comparing the extracted value with the size of the execution code calculated through the collected addresses. In other words, if the calculated value and the extracted value are different, the obfuscation of the header of the section including the executable code is detected. Obfuscation detection for the header of the section containing such executable code has already been described in detail with reference to FIG. 9.

19 is a flowchart illustrating a method of determining whether obfuscation is applied to a dynamic linking symbol table section according to an embodiment of the present invention. Step 1910 of FIG. 19 may be included in step 1530 of FIG. 15.

In operation 1910, the obfuscation determiner 1430 analyzes the symbol entry included in the dynamic linking symbol table section (.dynsym section) among the sections included in the ELF file, and includes at least one of a name and an address included in the symbol entry. If one contains null or is not represented in American Standard Code for Information Interchange (ASCII) code, it can be determined that obfuscation has been applied to the dynamic linking symbol table section. This obfuscation detection process has already been described in detail with reference to FIG. 6.

20 is a flowchart illustrating a method of determining whether to apply obfuscation to a read-only section according to an embodiment of the present invention. Step 2010 of FIG. 20 may be included in step 1530 of FIG. 15.

In operation 2010, the obfuscation determination unit 1430 analyzes the information included in the read-only section among the sections included in the ELF file, so that the included information includes null or If not expressed in ASCII code, you can determine that obfuscation is applied to the read-only section. This read-only section may include a .rdata section or a .rodata section, and the obfuscation detection for these sections has already been described in detail with reference to FIG. 7.

21 is a flowchart illustrating a first example of a method of determining whether obfuscation is applied to a code according to an embodiment of the present invention. Step 2110 of FIG. 21 may be included in step 1530 of FIG. 15.

In operation 2110, the obfuscation determiner 1430 may have other read-write-execute privileges in addition to the segments in which sections included in the ELF file are integrated and created through the linker. Depending on whether the segment is added, it is possible to determine whether or not to obfuscate the code included in the predefined segment. In FIG. 10, the added segment 1033 has been described, and the addition of the segment itself may mean that obfuscation is applied to the code. Accordingly, the obfuscation determiner 1430 may interpret that obfuscation is applied to the code that another segment having a read-write-execute right is added.

22 is a flowchart illustrating a second example of a method of determining whether obfuscation is applied to a code according to an embodiment of the present invention. Steps 2210 through 2230 of FIG. 22 may be included in step 1530 of FIG. 15.

In operation 2210, the obfuscation determiner 1430 may read-write-execute (RWE) permission in addition to the segment in which sections included in the ELF file are integrated and created by the linker. You can check the addition of other segments with

In operation 2220, the obfuscation determiner 1430 may identify a header of a section (.init section or .init_array section) including code for process initialization in the section header table included in the ELF file.

In operation 2230, the obfuscation determiner 1430 may determine that obfuscation is applied to a code included in a predefined segment when a pointer to another segment identified in the header of the identified section exists.

As described in FIG. 10, when the code is obfuscated, a code for restoring the obfuscated code is required and a segment for adding such code may be added. In addition, the header of the section (.init section or .init_array section) containing the code for process initialization that is executed first at runtime will point to the segment added to restore the obfuscated code. Accordingly, the obfuscation determiner 1430 detects that the .init section or the .init_array section points to the segment to which it is added, and includes the code included in the predefined segment (for example, the code segment 1031 of FIG. 10). Can be detected as obfuscation for.

Steps

2310 and 2320 of FIG. 23 may be included in step 1530 of FIG. 15.

In operation 2310, the obfuscation determiner 1430 may read-write-execute (RWE) permission in addition to the segment in which sections included in the ELF file are integrated and created by the linker. You can check the addition of other segments with

In operation 2320, the obfuscation determination unit 1430 analyzes another identified segment, and when there is a code for restoring the encrypted code at runtime of the application, the obfuscation is included in the code included in the predefined segment. It can be determined that it has been applied.

As already explained, if the code is obfuscated, code is required to restore the obfuscated code and segments for adding such code may be added. Accordingly, the obfuscation determination unit 1430 analyzes the added segment to determine whether there is a code for restoring the encrypted code, and determines the existence of the code (eg, the code segment of FIG. 10). 1031) can be detected as obfuscation of the code included in).

Steps

2410 and 2420 of FIG. 24 may be included in step 1530 of FIG. 15.

In operation 2410, the obfuscation determiner 1430 may collect addresses of functions through an export symbol entry included in a dynamic linking symbol table section (.dynsym section) among sections included in the ELF file. .

In operation 2420, the obfuscation determination unit 1430 may determine whether to apply obfuscation to the code by analyzing the instructions included in the functions by using the collected address.

In this case, the obfuscation determiner 1430 may determine the consistency between the instructions included in the functions, whether there is an undefined operation code (opcode) combination, information on the branch position of the branch code, and the predefined location. It may be determined whether obfuscation is applied to the code based on at least one of whether a dummy code of the pattern exists.

For example, in operation 2420, the obfuscation determiner 1430 may read-write-execute, in addition to the segment in which the sections included in the ELF file are integrated and generated through the linker. RWE) confirm the addition of another segment with authority, and if the instructions included by the functions branch to code included in the other segment, it may be determined that obfuscation is applied to the code.

16 to 24 may be performed in parallel with each other in step 1530. In addition, since these steps are performed in parallel with each other, the steps of performing the same operation may not be performed in duplicate, but may be performed only once. For example, collecting the addresses of the

functions

1810 and 2410 may be performed only one of the two.

As described above, according to embodiments of the present invention, in the objective of the application publisher, the security level applied to the registered application is determined in an objective manner in accordance with obfuscation, vulnerability, and / or security solution. It can be used to improve the security of the application by analyzing and understanding and providing the analyzed information. In addition, it is possible to detect whether obfuscation is applied to an Executable and Linkable Format (ELF) file.

The system or apparatus described above may be implemented as a hardware component, a software component or a combination of hardware components and software components. For example, the devices and components described in the embodiments are, for example, processors, controllers, arithmetic logic units (ALUs), digital signal processors, microcomputers, field programmable gate arrays (FPGAs). Can be implemented using one or more general purpose or special purpose computers, such as a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to the execution of the software. For convenience of explanation, one processing device may be described as being used, but one of ordinary skill in the art will appreciate that the processing device includes a plurality of processing elements and / or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as parallel processors.

The software may include a computer program, code, instructions, or a combination of one or more of the above, and configure the processing device to operate as desired, or process it independently or collectively. You can command the device. Software and / or data may be any type of machine, component, physical device, virtual equipment, computer storage medium or device in order to be interpreted by or to provide instructions or data to the processing device. It can be embodied in. The software may be distributed over networked computer systems so that they may be stored or executed in a distributed manner. Software and data may be stored on one or more computer readable media.

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Such a recording medium may be various recording means or storage means in the form of a single or several hardware combined, and is not limited to a medium directly connected to any computer system, but may be distributed on a network. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

Although the embodiments have been described by the limited embodiments and the drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the claims that follow.

Claims

In the method of evaluating the security of an application,

Registering a package file for installing and running the application;

Identifying an executable and linkable format (ELF) file included in the registered package file;

Determining whether to apply obfuscation to at least one of an ELF header, a section header, a section, and a segment included in the ELF file; And

Determining a security level for the ELF file based on whether obfuscation is applied or not

Security evaluation method comprising the.
The method of claim 1,

Reporting information on whether obfuscation is applied and information on a security level determined for the ELF file;

Security evaluation method characterized in that it further comprises.
The method of claim 1,

Setting a range of normal values for at least one item of a size of a section header included in the ELF header, a number of section headers, and a size of a section;

More,

Determining whether or not the obfuscation is applied,

Extracting a value of the at least one item from the ELF header; And

And when the extracted value is out of a range of the set normal value, determining that obfuscation is applied to the ELF header.
The method of claim 1,

Determining whether or not the obfuscation is applied,

Extracting a dynamic linking symbol table (.dynsym) section header from a section header table included in the ELF file; And

Analyzing the extracted dynamic linking symbol table section header to determine whether to apply obfuscation to the section header;

Security evaluation method comprising the.
The method of claim 4, wherein

Determining whether to apply obfuscation to the section header by analyzing the extracted dynamic linking symbol table section header,

A first condition in which the extracted dynamic linking symbol table section header contains null, a second condition in which the extracted dynamic linking symbol table section header is not parseable, and the extracted dynamic linking symbol table section header Is determined that obfuscation is applied to the section header when any one of the third conditions not present in the dynamic linking information (.dynamic) section of the sections is satisfied.
The method of claim 1,

Determining whether or not the obfuscation is applied,

Collecting addresses of functions through an export symbol entry included in a dynamic linking symbol table (.dynsym) section among sections included in the ELF file;

Extracting a value of an executable code size from a header of a section (.text) including executable code in a section header table included in the ELF file; And

Determining whether to apply obfuscation to a header of a section (.text) including the executable code by comparing the size of the executable code calculated through the collected addresses with the extracted value.

Security evaluation method comprising the.
The method of claim 1,

Determining whether or not the obfuscation is applied,

Analyzing a symbol entry included in a dynamic linking symbol table (.dynsym) section among the sections included in the ELF file, at least one of a name and an address included in the symbol entry includes null or an ASCII ( And if it is not represented by an American Standard Code for Information Interchange (ASCII) code, determining that obfuscation is applied to the dynamic linking symbol table section.
The method of claim 1,

Determining whether or not the obfuscation is applied,

Analyzing the information contained in the read-only section of the sections included in the ELF file, if the included information is null or not represented in ASCII code, the read- Security evaluation method characterized in that it is determined that obfuscation for the dedicated section has been applied.
The method of claim 1,

Determining whether or not the obfuscation is applied,

In addition to the segments in which the sections included in the ELF file are integrated and created by the linker, the predefined segments are added depending on whether another segment having read-write-execute permission is added. Security evaluation method characterized in that it determines whether or not to apply obfuscation for the code included in the segment.
The method of claim 1,

Determining whether or not the obfuscation is applied,

Confirming addition of another segment having Read-Write-Execute (RWE) rights, in addition to a segment in which sections included in the ELF file are integrated and created through a linker;

Identifying a header of a section (.init section or .init_array section) including code for process initialization in a section header table included in the ELF file; And

Determining that obfuscation has been applied to the code included in the predefined segment if a pointing from the header of the identified section to the identified other segment exists

Security evaluation method comprising the.
The method of claim 1,

Determining whether or not the obfuscation is applied,

Confirming addition of another segment having Read-Write-Execute (RWE) rights, in addition to a segment in which sections included in the ELF file are integrated and created through a linker; And

Analyzing the identified other segment and determining that obfuscation is applied to the code included in the predefined segment when there is code for restoring the encrypted code at runtime of the application;

Security evaluation method comprising the.
The method of claim 1,

Determining whether or not the obfuscation is applied,

Collecting addresses of functions through an export symbol entry included in a dynamic linking symbol table (.dynsym) section among sections included in the ELF file; And

Determining whether or not obfuscation is applied to the code by analyzing the instructions included in the functions using the collected address

Security evaluation method comprising the.
The method of claim 12,

Determining whether to apply obfuscation to the code by analyzing the instructions,

The consistency between the instructions contained in the functions, the presence of undefined operation codes (opcodes), information on the branch location of branch codes, and the presence of dummy patterns of predefined patterns. And determining whether to apply obfuscation to the code based on at least one of whether or not.
The method of claim 12,

Determining whether to apply obfuscation to the code by analyzing the instructions,

Confirming addition of another segment having Read-Write-Execute (RWE) rights, in addition to a segment in which sections included in the ELF file are integrated and created through a linker; And

Determining that the obfuscation is applied to the code when the instructions included by the functions branch to code included by the other segment.

Security evaluation method comprising the.
A computer-readable recording medium having recorded thereon a computer program for causing a computer to execute the method of any one of claims 1 to 14.
In the system for evaluating the security of the application,

At least one processor implemented to execute computer-readable instructions

Including,

The at least one processor,

Register the package file for installing and running the application,

Identify an executable and linkable format (ELF) file included in the registered package file,

Determine whether to apply obfuscation to at least one of an ELF header, a section header, a section, and a segment included in the ELF file;

Determining a security level for the ELF file based on whether obfuscation is applied or not

Security evaluation system characterized in that.
The method of claim 16,

The at least one processor,

Reporting information on whether obfuscation is applied and information on a security level determined for the ELF file.

Security evaluation system characterized in that.
The method of claim 16,

The at least one processor,

Setting a range of normal values for at least one item of a size of a section header, a number of section headers, and a size of a section included in the ELF header,

In order to determine whether to apply the obfuscation,

Extract a value of the at least one item from the ELF header,

Determining that the obfuscation is applied to the ELF header when the extracted value is out of a range of the set normal value.

Security evaluation system characterized in that.
The method of claim 16,

The at least one processor,

In order to determine whether to apply the obfuscation,

Extracting a dynamic linking symbol table (.dynsym) section header from the section header table included in the ELF file,

Analyzing the extracted dynamic linking symbol table section headers to determine whether obfuscation is applied to the section headers;

Security evaluation system characterized in that.
The method of claim 16,

The at least one processor,

In order to determine whether to apply the obfuscation,

Collecting the addresses of functions through an export symbol entry included in a dynamic linking symbol table (.dynsym) section among the sections included in the ELF file,

Extracting a value for the size of the executable code from the header of the section (.text) including the executable code in the section header table included in the ELF file,

Determining whether to apply obfuscation to a header of a section (.text) including the executable code by comparing the size of the executable code calculated through the collected addresses with the extracted value.

Security evaluation system characterized in that.