CN104657639B - A kind of method of testing and system of operating system identity authentication scheme - Google Patents

Abstract

The invention discloses a testing method and system for an operating system identity authentication mechanism. The method is: 1) create a client virtual machine on the host computer, run a test program on the virtual machine monitor VMM of the host computer; the test program includes a keyboard/mouse message sending module, a client virtual machine image acquisition module, an image Comparing module and test case configuration module; Test case configuration module sets up a standard image storehouse to be tested operating system; 2) run this operating system on client virtual machine; For each test item of setting, keyboard/mouse message sends module to The client virtual machine sends the simulated keyboard/mouse message; 3) the client virtual machine executes the received keyboard/mouse message and caches the screen shot after execution; 4) the client virtual machine image acquisition module compares each screen shot with the standard image library The standard image is matched to determine whether the test item is successfully tested. The invention greatly improves the testing efficiency and accuracy.

Description

A testing method and system for operating system identity authentication mechanism

technical field

The invention relates to the field of computer security, in particular to a testing method and system for an operating system identity authentication mechanism.

Background technique

As the first line of defense for operating system security, identity authentication is the portal to ensure the security of the operating system. At present, identity authentication is mainly realized through one of the following three basic ways or a combination thereof: ①Knowledge: knowledge known or mastered by individuals, such as passwords. ②Own: things owned by individuals, such as ID cards, passports, credit cards, keys or certificates, etc. ③Personal characteristics: The biological characteristics of individuals, such as fingerprints, palmprints, voiceprints, face shapes, DNA, retina, etc. Password-based identity authentication technology is widely used because of its simplicity and ease of use, and almost all operating systems support password authentication. The basic principle is: the user generates a username and an initial password during the registration phase, and the system stores the user's information list (username ID+password PW) in its database. When the authenticated object requests access to the system that provides the service, the authenticating party that provides the service requires the authenticated object to submit the password of the object. After receiving the password, the authenticating party compares it with the user password stored in the system to confirm the authenticated object Whether the object is a legitimate visitor.

Since the implementation of password-based identity authentication is very simple, its security is worth considering. At present, the single-factor authentication system using password authentication mainly has the following problems:

1. Guessing attack (social engineering attack): Some attackers use the characteristics of meaningful words or numbers such as birthdays and personal names in user passwords to try the user's password by guessing. Therefore, adding various special characters to the password can increase the security of the password.

2. Exhaustive attack: If the user password is short, the attacker will use the complete set of character strings as a dictionary to guess the user password. It is a special form of dictionary attack. Therefore, using longer passwords can significantly reduce the risk of brute force attacks.

In addition, if the password replacement period is long or not changed at all, the password will be easily stolen. If the system can check the password modified by the user to ensure that it is different from the previous password, the security of the password can also be improved.

To deal with these problems, some operating systems implement password security policies. Password security policies mainly include the following types:

1. The password must comply with the complexity rules, specifically, it includes the rules that cannot use pure numbers or characters as the password, the password cannot be the same as the user name, and the password length must meet certain requirements.

2. Password history records, which record the passwords used by users in the past, and require users not to use the same password repeatedly.

3. Account lock policy, that is, when a user exceeds the specified number of failed logins, the operating system will automatically lock the account and cannot log in for a certain period of time.

After the password security policy of the operating system is implemented, it is necessary to test whether the declared functions are completed correctly. Currently, these tests are often done manually. If the password test can be automated, the efficiency can be greatly improved.

Virtualization refers to computing elements operating on a virtual basis rather than a real one. Virtualization technology can expand the capacity of hardware and simplify the process of reconfiguring software. CPU virtualization technology can simulate multiple CPUs in parallel with a single CPU, allowing a physical computer to run multiple virtual machines (logical computers) at the same time, each virtual machine can run a different operating system, and applications can run in independent spaces It runs within the computer without affecting each other, thereby significantly improving the work efficiency of the computer.

As AMD and Intel successively launched products supporting hardware virtualization, virtualization technology has been widely used. Enterprises use virtualization to reduce capital costs, reduce space requirements, improve availability, improve business flexibility and adaptability, and improve security.

An important part of the virtualization platform is the virtual machine monitor (Virtual Machine Monitor, VMM). Virtual machines can share the resources of the same physical computer. The VMM can access various resources of the guest virtual machine and provide various interfaces for the virtual machine. In this way, the operating system running on the guest virtual machine is consistent with the operating environment of the operating system running on the physical machine.

The invention proposes a method for simulating a manual password test in a virtual machine environment, the method can automatically realize the password test and the operating environment is consistent with the manual password test, and the efficiency can be greatly improved under the premise of ensuring correctness.

Contents of the invention

The invention designs a method for simulating artificial password testing in a virtualized environment. Currently, most operating systems use password-based authentication. In order to verify whether the password security policy function implemented by the target operating system is correct, manual testing is usually required, and manual password testing is not only inefficient, but also prone to statistical errors.

Since the user has not logged in to the operating system, the automatic password test of the machine cannot be realized on this machine. On the other hand, although it is possible to run the automatic password test program on another host through SSH and other methods and use the network remote login session to realize this function, but the operating environment of the target operating system has changed (on the target operating system will open SSH daemon process, it is impossible to confirm whether the password test result is related to the SSH daemon process, and the client SSH software may also have errors), and the correctness of the test results cannot be guaranteed.

Technical scheme of the present invention is:

A method for testing an operating system identity authentication mechanism, the steps of which are:

1) Create a client virtual machine on the host computer, run a test program on the virtual machine monitor VMM of the host computer; the test program includes keyboard/mouse message sending module, client virtual machine image acquisition module, image comparison module And a test case configuration module; the test case configuration module establishes a standard image library for the operating system to be tested, which is used to store the standard image of the operating system test item feedback;

2) run the operating system to be tested on the client virtual machine; wherein, for each set test item, the keyboard/mouse message sending module sends a simulated keyboard/mouse message to the client virtual machine;

3) The client virtual machine executes the received keyboard/mouse message and caches the screenshot after execution;

4) The client virtual machine image acquisition module regularly reads the screenshots cached by the client virtual machine, and matches each screenshot with the standard image in the standard image library until the end of the current test project; if If the matching result meets the setting conditions of the current test item, it is determined that the test of the current test item is successful, otherwise it is determined that the test fails.

Further, each of the test items includes a set of standard images and a setting condition.

Further, the test items include account creation, account authentication and password modification.

Further, the method for matching each screenshot with the standard image in the standard image library is as follows:

1) For screenshot a, get all its pixels and express them in the form of RGB24 (x _a1 ,y _a1 ,z _a1 ),(x _a2 ,y _a2 ,z _a2 )...(x _an ,y _an ,z _an ), wherein, n is the total number of pixels of the screenshot;

2) Acquire all pixels of the standard image b according to step 1) and express them in the form of RGB24 (x _b1 , y _b1 , z _b1 ), (x _b2 , y _b2 , z _b2 )...(x _bn ,y _bn ,z _bn ), and then compare the pixels in a with the corresponding pixels in b, such as: compare (x _a1 ,y _a1 ,z _a1 ) with (x _b1 ,y _b1 ,z _b1 ), Check whether they are equal; if the ratio of the equal pixels to the total pixels is greater than the set threshold, for example: 99%, it is determined that the screenshot a matches the standard image b successfully, otherwise the match fails.

Further, the method for matching each screenshot with the standard image in the standard image library is as follows:

1) For screenshot a, get all its pixels (x ₁ ,y ₁ ,z ₁ ),(x ₂ ,y ₂ ,z ₂ )...(x _n ,y _n ,z _n ); where n is The total number of pixels in the screenshot;

2) Take the average of the vector sum of all pixels in the screenshot:

3) Calculate the average value (x _b , y _b , z _b ) of the vector sum of all pixels in standard image b according to steps 1) and 2), and then calculate the distance between screenshot a and standard image b: If d is less than the set threshold, it is determined that the screenshot a matches the standard image b successfully, otherwise the matching fails.

Further, the virtual machine monitor VMM simulates the keyboard/mouse message sending module through the VNC server to send simulated keyboard/mouse messages to the client virtual machine; the test program communicates with the VNC server through the VNC runtime.

Further, the input request includes test data and operation type.

A test system of a system identity authentication mechanism is characterized in that it includes a host machine, a client virtual machine is created on the host machine, and a test program is run on the virtual machine monitor VMM of the host machine; the test The program includes a keyboard/mouse message sending module, a client virtual machine image acquisition module, an image comparison module, and a test case configuration module; the test case configuration module sets up a standard image library for the operating system to be tested, and is used to store the operating system test item feedback A standard image; run the operating system to be tested on the guest virtual machine; wherein,

The keyboard/mouse message sending module sends simulated keyboard/mouse messages to the client virtual machine according to each set test item;

The client virtual machine is used to execute the received keyboard/mouse message and cache the screenshot after execution;

The client virtual machine image acquisition module is used to periodically read the screenshots cached by the client virtual machine, and match each screenshot with the standard image in the standard image library until the current test project ends; If the matching result meets the setting conditions of the current test item, it is determined that the test of the current test item is successful, otherwise it is determined that the test fails.

Further, each of the test items includes a set of standard images and a setting condition.

Further, for the read screen shot a, the host computer obtains all its pixels and expresses them in the form of RGB24 (x _a1 , y _a1 , z _a1 ), (x _a2 , y _a2 , z _a2 )... …(x _an ,y _an ,z _an ), wherein, n is the total number of pixels in the screenshot; then obtain all the pixels of the standard image b according to the above method, and express it in the form of RGB24 (x _b1 , y _b1 , z _b1 ),(x _b2 ,y _b2 ,z _b2 )...(x _bn ,y _bn ,z _bn ); the host compares the pixels in a with the corresponding pixels in b one by one, and checks Whether they are equal; if the ratio of the equal pixels to the total pixels is greater than the set threshold, it is determined that the screenshot a and the standard image b are successfully matched, otherwise the match fails.

Further, the virtual machine monitor VMM simulates the keyboard/mouse message sending module through the VNC server to send simulated keyboard/mouse messages to the client virtual machine; the test program communicates with the VNC server through the VNC runtime.

The present invention is designed to run the target operating system in the virtual machine and the password test program in the VMM to initialize and establish a standard image library through the test case configuration module in the test program, and then send the simulation to the client virtual machine by the keyboard/mouse message sending module Keyboard/mouse messages, and then use the client virtual machine image acquisition module to obtain the current test image, and finally process the test result through the image comparison module. Through the above method, the present invention can realize the function of machine automatic password test, and its operating environment is no different from manual password test on a physical machine.

Machine automatic password test has the following characteristics:

●The host computer provides the test account name, test password and operation type for the client virtual machine through the operation interface, and the machine automatically completes all tests without manual intervention.

●Isolate the test program from the guest virtual machine.

●The simulated test in the client virtual machine is consistent with the artificial test operating environment.

Compared with the prior art, the present invention has the following advantages:

1. Ensure the consistency of the test environment, and eliminate the interference of the SSH (Secure Shell, a more reliable protocol designed to provide security for remote login sessions and other network services) daemon process, client SSH software errors and other issues.

2. Automatic password test is faster than artificial password test in speed and is not easy to make mistakes.

3. Multiple client virtual machines can be run on one physical machine, making full use of hardware resources, and password testing of other client virtual machines can be performed during the period when a client virtual machine account is locked.

Description of drawings

Fig. 1 is a structure diagram of the testing system of the present invention.

Figure 2 is a structural diagram of the test program.

detailed description

In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described below through specific embodiments and accompanying drawings.

As shown in Figure 2, the test program is mainly divided into four modules: keyboard/mouse message sending module, client virtual machine image acquisition module, image comparison module and test case configuration module.

The function of the test case configuration module is to initialize the test program and establish a standard image library for the operating system to be tested. The function of the keyboard/mouse message sending module is that the VMM sends simulated keyboard/mouse messages to the client virtual machine, and this embodiment uses a VNC server (Virtual Network Computer Server, Virtual Network Computer Server) to realize this function. The function of the guest virtual machine image acquisition module is to intercept the screen image of the guest virtual machine and return to the VMM. In this embodiment, by calling the interface of the VNC runtime library, the memory of the guest virtual machine is read at regular intervals, and the screen image is intercepted and returned to the VMM. Come back to implement the function. The function of the image comparison module is to match the test image with the standard image one by one to determine the test state. The invention proposes a pixel comparison method, through which the purpose of image comparison can be achieved.

The test program used in this embodiment runs on the VMM, and interacts with the client virtual machine through the VNC server in QEMU. After opening the corresponding port on the VNC server, the test program can connect to the VNC service port by calling the VNC runtime library, and then the VMM can send simulated keyboard and mouse information to the client virtual machine and receive screen display information.

Fig. 1 is a schematic diagram of simulating artificial password testing in a virtualized environment by adopting the method of the present invention. The VNC server can be set via QEMU. The test program runs on the host computer, communicates with the VNC server through the VNC runtime library, sends test data to the client virtual machine and receives information displayed on the screen. The items included in the test are as follows:

1. Account creation: Test whether the length of the user name and password can meet the requirements of the statement, whether the characters that can be included in the user name and password can cover the types of the statement, and whether weak passwords that do not meet the requirements can be correctly identified.

2. Account identification: test whether the legal account of the operating system can log in correctly, whether the illegal account is prohibited from logging in, whether the processing after multiple wrong logins is consistent with the statement, and whether the number of tolerable errors is consistent with the declared number of times.

3. Password modification: Test whether the modified password of the user can be the same as the password before modification within a certain period of time.

The test program first calls the operation interface through the pre-opened VNC service port, sends test data and operation types to the client virtual machine, and sends input requests to the client virtual machine through the VNC server. After receiving the request, the client virtual machine will use it according to the operation type Test data for corresponding tests. For each operating system that needs to be tested, a standard image library is pre-established; the standard images of various test results are pre-stored in the VMM, and the VNC server reads the memory of the client virtual machine at regular intervals, obtains the screen image at this time and Return the screen image to the test program. The test program determines the state of the guest virtual machine by comparing the pixels of this image to all standard images. (The standard image library contains 5 images of waiting for login, logging in, successful account login, account login failure, and account locked. When the matching image is waiting for login and logging in, it will wait for a certain period of time to re-read the memory.)

The specific pixel comparison method is as follows:

1. For screenshot a, get all its pixels and express them in the form of RGB24 (x _a1 ,y _a1 ,z _a1 ),(x _a2 ,y _a2 ,z _a2 )...(x _an ,y _an ,z _an ), wherein, n is the total number of pixels of the screenshot;

2. Acquire all pixels (x _b1 ,y _b1 ,z _b1 ),(x _b2 ,y _b2 ,z _b2 )...(x _bn ,y _bn ,z _bn ) of standard image b according to step 1), and then set Compare the pixels in a with the corresponding pixels in b, such as: compare (x _a1 , y _a1 , z _a1 ) with (x _b1 , y _b1 , z _b1 ) to check whether they are equal; if they are equal The ratio of the pixel points to the total pixel points is greater than the set threshold, for example: 99%, it is determined that the screenshot a and the standard image b are successfully matched, otherwise the matching fails.

Or use the following comparison method:

1. Analyze and obtain all the pixels of the image a (b, c...) and express them in the form of RGB24. Example: (x ₁ ,y ₁ ,z ₁ ),(x ₂ ,y ₂ ,z ₂ )...(x _n ,y _n ,z _n ).

2. Take the average of all pixel vector sums:

3. Repeat steps 1 and 2 to obtain the average value (x _b , y _b , z _b ) of all pixel vector sums in image b (c...), and calculate the distance between them:

4. If d is less than 10, the matching is successful; otherwise, repeat steps 1, 2, and 3 to compare the pixels of image a and image c (image a is the test result screen image of the client virtual machine, and images b, c... are each standard image of test results). If the current test image does not match any of the standard images, the state of the guest virtual machine is test failure when determining the corresponding request.

Table 1 is the data format of the input request sent by the test program to the client virtual machine through the VNC server, and the number of bytes occupied by each item is shown in Table 1. The operation types correspond to: 00—lock upper limit test; 01—password character test (whether various types of passwords and combinations of different user names and password lengths can log in normally, these users have already been created); 02—— Wrong password test (whether the password that is different from the correct password can be correctly refused to log in); 03——Time strategy test (cannot log in for a certain period of time after being locked, and can log in afterwards, whether the modified password of the user can be used within a certain period of time and before the modification) same password). The option is used for time strategy test (time delay, the first one is 0, and then incremented), password character test and wrong password test (end flag, set 1 when there is an input request behind, and set 0 when the last one), lock upper limit Fill in 0 when testing.

Table 1. Input request data format table

When the operation type is 00, the test success determination condition is that the test image matches the account lock image in the standard image library, and at this time, the upper limit of lock times is returned. (Repeat the test with the same input request multiple times. When the test image obtained by the input request matches the account login failure image in the standard graphics library, repeat the test, otherwise return the test failure)

When the operation type is 01, the test success determination condition is that the test image obtained by the input request whose option is 0 matches the account login success image in the standard graphics library. (All the test images obtained by the input request with option 1 should match the account login success image in the standard graphics library, and if any one fails, the test failure will be returned)

When the operation type is 02, the test success determination condition is that the test image obtained by the input request with the option 0 matches the account login failure image in the standard image library. (All the test images obtained by the input request with option 1 should match the account login failure images in the standard graphics library, and if any one fails, the test failure will be returned)

When the operation type is 03, after sending the input request with the option 0 for the first time, the test program will repeatedly send the input request with the option 0 within one hour (this input request contains a wrong username and password combination), Afterwards, an input request is sent at regular intervals and the value corresponding to the option is increased by 1 until the test image obtained by the input request matches the account login success image in the standard image library, and the value corresponding to the option is returned at this time. (When the test image obtained by the input request matches the account lock image in the standard graphics library or the account login fails, wait for the next test, otherwise return the test failure; when the test is successful, multiply the value corresponding to the returned option by the time interval It is the time when login is prohibited in the password time policy)

A specific example is given below. We want to test the upper limit of locking times of the Windows 7 operating system. The user test is established in the customer virtual machine, and the password is 123456. The test program encapsulates the test data according to the data format in Figure 2 (0004test051234500000000), and then sends the test data to the customer through the VNC server. The virtual machine issues a request for input. After receiving the input request, the client virtual machine parses the operation type, user name, and password according to the data format in Figure 2, and starts to log in repeatedly; the VNC server reads the memory of the client virtual machine at regular intervals, and captures the screen image to match the standard image , when the screen image matches the waiting login and logging in in the standard image library, no processing will be performed, and after waiting for a certain period of time, continue to capture the screen image and match the standard image; when the screen image matches the account login in the standard image library When the match fails, the number of locks will be +1, and after waiting for a certain period of time, continue to capture the screen image and match it with the standard image; when the screen image matches the account login lock in the standard image library, return the number of locks, and the test is successful.

The above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Those of ordinary skill in the art can modify or equivalently replace the technical solution of the present invention without departing from the spirit and scope of the present invention. The scope of protection should be determined by the claims.

Claims (9)

1. A method for testing an identity authentication mechanism of an operating system comprises the following steps:

1) creating a guest virtual machine on a host machine, and running a test program on a Virtual Machine Monitor (VMM) of the host machine; the test program comprises a keyboard/mouse message sending module, a client virtual machine image acquisition module, an image comparison module and a test case configuration module; the test case configuration module establishes a standard image library for the operating system to be tested and is used for storing standard images fed back by the test items of the operating system;

2) running the operating system to be tested on the client virtual machine; for each set test item, the keyboard/mouse message sending module sends a simulated keyboard/mouse message to the client virtual machine;

3) the client virtual machine executes the received keyboard/mouse message and caches the executed screenshot;

4) the client virtual machine image acquisition module periodically reads the screenshots cached by the client virtual machine and respectively matches each screenshot with the standard image in the standard image library until the current test item is finished; if the matching result meets the set condition of the current test item, the test of the current test item is judged to be successful, otherwise, the test is judged to be failed.

2. The method of claim 1, wherein each of the test items comprises a set of standard images and a set condition.

3. The method of claim 1 or 2, wherein the test items include account creation, account authentication, and password modification.

4. The method of claim 1 or 2, wherein the method of matching each screenshot with a standard image in the standard image library respectively is:

1) for screenshot a, all its pixels are obtained and represented in RGB24 form (x)_a1,y_a1,z_a1),(x_a2,y_a2,z_a2)……(x_an,y_an,z_an) (ii) a Wherein n is the total number of pixel points of the screenshot;

2) acquiring all pixel points of the standard image b, and expressing the pixel points in the form of RGB24 (x)_b1,y_b1,z_b1),(x_b2,y_b2,z_b2)……(x_bn,y_bn,z_bn) Then the pixel points in the screenshot a are corresponded to the pixel points in the standard image bThe pixel points are compared one by one, if the ratio of the equal pixel points to the total pixel points is larger than a set threshold value, the matching between the screenshot a and the standard image b is judged to be successful, and if not, the matching is failed.

5. The method of claim 1 or 2, wherein the method of matching each screenshot with a standard image in the standard image library respectively is:

1) for screenshot a, all its pixels (x) are obtained₁,y₁,z₁),(x₂,y₂,z₂)……(x_n,y_n,z_n) (ii) a Wherein n is the total number of pixel points of the screenshot;

2) taking the average value of the vector sum of all pixel points of the screenshot:

<mrow> <mo>(</mo> <mfrac> <mrow> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>+</mo> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>+</mo> <mo>...</mo> <mo>+</mo> <msub> <mi>x</mi> <mi>n</mi> </msub> </mrow> <mi>n</mi> </mfrac> <mo>,</mo> <mfrac> <mrow> <msub> <mi>y</mi> <mn>1</mn> </msub> <mo>+</mo> <msub> <mi>y</mi> <mn>2</mn> </msub> <mo>+</mo> <mo>...</mo> <mo>+</mo> <msub> <mi>y</mi> <mi>n</mi> </msub> </mrow> <mi>n</mi> </mfrac> <mo>,</mo> <mfrac> <mrow> <msub> <mi>z</mi> <mn>1</mn> </msub> <mo>+</mo> <msub> <mi>z</mi> <mn>2</mn> </msub> <mo>+</mo> <mo>...</mo> <mo>+</mo> <msub> <mi>z</mi> <mi>n</mi> </msub> </mrow> <mi>n</mi> </mfrac> <mo>=</mo> <mo>(</mo> <msub> <mi>x</mi> <mi>a</mi> </msub> <mo>,</mo> <msub> <mi>y</mi> <mi>a</mi> </msub> <mo>,</mo> <msub> <mi>z</mi> <mi>a</mi> </msub> <mo>)</mo> <mo>;</mo> </mrow>

3) calculating the average value (x) of the vector sums of all pixel points of the standard image b according to the methods of the steps 1) and 2)_b,y_b,z_b) Then, the distance between the screenshot a and the standard image b is calculated:if d is smaller than the set threshold, judging that the screenshot a is successfully matched with the standard image b, and otherwise, judging that the matching fails.

6. A test system of a system identity authentication mechanism is characterized by comprising a host machine, wherein a client virtual machine is established on the host machine, and a test program runs on a Virtual Machine Monitor (VMM) of the host machine; the test program comprises a keyboard/mouse message sending module, a client virtual machine image acquisition module, an image comparison module and a test case configuration module; the test case configuration module establishes a standard image library for the operating system to be tested and is used for storing standard images fed back by the test items of the operating system; running the operating system to be tested on the client virtual machine; wherein,

the keyboard/mouse message sending module sends simulation keyboard/mouse messages to the client virtual machine according to each set test item;

the client virtual machine is used for executing the received keyboard/mouse message and caching the executed screenshot;

the client virtual machine image acquisition module is used for periodically reading the screenshots cached by the client virtual machine and respectively matching each screenshot with the standard image in the standard image library until the current test item is finished; if the matching result meets the set condition of the current test item, the test of the current test item is judged to be successful, otherwise, the test is judged to be failed.

7. The system of claim 6, wherein each of the test items includes a set of standard images and a set condition.

8. System according to claim 6 or 7, characterized in that the host acquires all the pixel points of the screenshot a read, expressed in RGB24 (x)_a1,y_a1,z_a1),(x_a2,y_a2,z_a2)……(x_an,y_an,z_an) (ii) a Wherein n is the total number of pixel points of the screenshot; then all the pixel points of the standard image b are obtained and expressed in the form of RGB24 (x)_b1,y_b1,z_b1),(x_b2,y_b2,z_b2)……(x_bn,y_bn,z_bn) (ii) a And then comparing the pixel points in the screenshot a with the corresponding pixel points in the standard image b one by one, if the ratio of the equal pixel points to the total pixel points is greater than a set threshold, judging that the screenshot a is successfully matched with the standard image b, and otherwise, judging that the matching fails.

9. The system of claim 6 or 7, wherein the Virtual Machine Monitor (VMM) sends a simulated keyboard/mouse message to a guest virtual machine through a VNC server simulating the keyboard/mouse message sending module; the test program communicates with the VNC server through a VNC runtime.