WO2015170801A1

WO2015170801A1 - Apparatus and method for preventing mitm attack

Info

Publication number: WO2015170801A1
Application number: PCT/KR2014/007619
Authority: WO
Inventors: 맹영재; 박응기; 박현동; 서정택
Original assignee: 한국전자통신연구원
Priority date: 2014-05-09
Filing date: 2014-08-18
Publication date: 2015-11-12
Also published as: KR20150128252A; KR101634785B1

Abstract

Suggested are an apparatus and a method for preventing an MITM attack. The suggested apparatus is an MITM attack preventing apparatus included in a screen connected via a client to a server, the apparatus comprising: a key storage unit for storing a key shared with the server; a decoding unit for decoding data input via the client on the basis of the key and outputting the same on the screen; a screen security displaying unit for turning on a screen security or warning on the screen on the basis of whether or not decoding is normal at the decoding unit; an encryption unit for encrypting input data, for which security from a user is required, on the basis of the key and outputting the same; and a control unit for turning on a screen security to allow each result of decoding and encrypting to be outputted when the decoding is normal at the decoding unit, and for controlling the screen security displaying unit to display what corresponds to the abnormality when the decoding is abnormal at the decoding unit.

Description

MTM attack prevention device and method

The present invention relates to an apparatus and method for preventing a MITM attack, and more particularly, to an apparatus and method for effectively preventing a man in the middle (MITM) attack by extending a client in a server / client model to a screen level. .

The present invention claims the benefit of the filing date of Korean Patent Application No. 10-2014-0055316, filed May 09, 2014, the entire contents of which are incorporated herein.

Since personalized services such as online shopping malls, online financial transactions, and electronic complaints are performed on the non-face-to-face Internet, online user authentication technology is essential.

In order to securely provide online user authentication, service providers use various methods of sharing secret information (eg, passwords, certificates, security cards, OTPs, TANs, etc.) with users, using cryptographic protocols, and installing security programs.

In other words, the security element of online user authentication (hereinafter referred to as user authentication) can be divided into three parts. The first part is secret information shared between the service provider and the user (password, certificate, security card, OTP, etc., hereinafter referred to as "shared secret"), the second part is the cryptographic protocol, and the third part is the client It is a security program installed on.

Shared secrets are used as evidence for authenticating users, cryptographic protocols are used to ensure a secure channel between service providers and users, and security programs are used to counter security threats that may occur at the client.

The cryptographic protocol is safe from attackers if the cryptographic key is not exposed. However, since security programs are designed to provide security services for known malware, security against unknown malware cannot be expected.

Shared secrets are entered into the client through input devices such as keyboards and mice, and cryptographic keys of cryptographic protocols also exist within the client. Since it is assumed that the malware can acquire all the resources of the client, it is not easy to block all the paths of malicious code that can obtain such input values and encryption keys.

In other words, the current user authentication is made on the assumption that the client is secure, but in reality it is not considered secure because the assumption may not apply.

As related related arts, contents providing security for a portion where personal information and the like are displayed on the screen are described in Korean Patent Registration No. 10-1230055. However, the content of Korean Patent No. 10-1230055 is a software level screen security.

Other related prior arts include fingerprint traces and manipulation by finger manipulation by only allowing manipulation input using an input tool other than the body, not finger manipulation, when setting a secret function such as a secure print job rather than a general function setting when a touch screen is operated. Information to exclude the possibility of leakage of secret information due to the trace has been described in Korean Patent Publication No. 10-2009-0013567. Republic of Korea Patent Publication No. 10-2009-0013567 requires a special input device.

The present invention has been proposed to solve the above-described problems, and provides an apparatus and method for preventing MITM attacks that can extend the client in the server / client model to the screen level to cope with MITM attacks occurring at the client level. Has its purpose.

MITM attack prevention device according to a preferred embodiment of the present invention to achieve the above object is a MITM attack prevention device that is included in the screen connected to the server through the client,

A key storage unit for storing a key shared with the server; A decoder which decrypts the data input through the client based on the key and outputs the same on the screen; A screen security display unit for performing screen security on or warning of the screen based on whether decryption is normal in the decryption unit; An encryption unit for encrypting and outputting input data requiring security from a user based on the key; And outputting the results of the decryption unit and the encryption, respectively, when the decryption in the decryption unit is normal, and controlling the screen security display unit when the decryption in the decryption unit is abnormal. And a control unit for performing a corresponding display.

In this case, the key may be provided directly from the server or generated based on secret information.

At this time, the secret information may be any one of a password, a security card, a public certificate, OTP, TAN.

In this case, the secret information may be input by touching a virtual screen on the screen.

In this case, the secret information may be input through a keyboard and a mouse connected to an input terminal installed on the screen.

In this case, the secret information may be input through a camera installed on the screen.

In this case, the screen security display unit may include a light emitting device, and when the decryption of the decryption unit is normal, the screen security display unit may output green light indicating the screen security on.

In this case, the screen security display unit may include a light emitting device, and the screen security display unit may warn by outputting red light when the decryption in the decryption unit is abnormal.

In this case, the screen security pattern storage unit for storing the screen security pattern displayed on the screen when the screen security on state; may further include.

In this case, the controller may warn through the screen security display unit if the screen security pattern is included in the data from the client.

On the other hand, MITM attack prevention method according to a preferred embodiment of the present invention, MITM attack prevention method in the MITM attack prevention device included in the screen connected to the server through the client,

Receiving data input through the client; Decrypting the data based on a key shared with the server; And performing screen security on or warning of the screen of the screen based on whether decryption is normal in the decrypting step.

In this case, the method may further include displaying a previously stored screen security pattern on the screen when the screen security is on.

At this time, if the screen security pattern is included in the data from the client; the step of warning it may be further included.

According to the present invention of such a configuration, by extending the client in the existing server / client model to the screen (for example, the monitor) level to ensure security, malicious code existing in the client accesses the encryption key stored on the screen This becomes impossible.

This ensures the security of cryptographic communication between the server and the screen. This is different from the server / client model where the security of cryptography can be compromised by malicious code.

1 illustrates a server / screen model to which the present invention is applied.

2 is a block diagram of a MITM attack prevention apparatus according to an embodiment of the present invention.

3 is a flowchart illustrating an example of a method for preventing MITM attack according to an embodiment of the present invention.

4 to 7 are views employed in the description of FIG. 3.

FIG. 8 is a flowchart for explaining a process of transmitting an input from a keyboard received from a screen shown in FIG. 1 to a server.

9 is a flowchart illustrating another example of a method for preventing MITM attack according to an embodiment of the present invention.

FIG. 10 is a diagram employed in the description of FIG. 9.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. In the following description of the present invention, the same reference numerals are used for the same elements in the drawings and redundant descriptions of the same elements will be omitted.

The present invention proposes a server / screen model instead of a server / client model to securely authenticate a user online even under the assumption that malicious code may be installed in the client.

To overcome the vulnerability to man in the middle (MITM) attack at the client 20 (e.g., PC) level, the client 20 in the server 10 / client 20 model is screened (output terminal; for example). , Monitor) to 30 levels is required.

Since the security of the network is unreliable, the server 10 and the client 20, which are both terminals, perform encryption communication, so that the security of the network and the client 20 cannot be trusted, so that the server 10 and the screen 30 are not secured. It is configured to perform cryptographic communication.

In FIG. 1, the client 20 is only responsible for transferring encrypted input / output data between the server 10 and the screen of the screen 30. However, when the client 20 transmits the encrypted screen data to the screen of the screen 30, the client 20 should transmit a specific signal to inform the user of the screen security operation to the screen terminal.

As shown in FIG. 1, extending the cipher range down to the screen 30 level is also related to the human-computer interaction (HCI). When a user uses an online service provided by the server 10 (eg, an online shopping mall, an online financial transaction, an electronic complaint, etc.), the client 20 is a tool for transferring input and output data of the server 10 and the user. Remember that In view of the HCI, the client 20 delivers information to the user through the monitor output and the value entered by the user via the keyboard / mouse to the server 10. At this time, if the client 20 is infected with malicious code, both output and input become unreliable. That is, the client 20 located between the server 10 and the user may be used in a MITM attack to deceive both the server 10 and the user by modulating the HCI data.

Therefore, as shown in FIG. 1, if the encryption technology is implemented at the monitor and the input device, the keyboard / mouse level, the MITM attack occurring at the client 20 level can be coped with.

2 is a block diagram of the MITM attack prevention device according to an embodiment of the present invention, it can be understood as an internal block diagram of the screen 30 shown in FIG.

The screen 30 includes a receiver 41, an encryption key generator 42, an encryption key storage unit 43, a decryption unit 44, a screen 45, a screen security display unit 46, an encryption unit 47, Transmitter 48, screen security pattern storage unit 49, and the control unit 50.

The reception unit 41 receives screen data (i.e., encrypted data) requiring security provided from the server 10 (e.g., an Internet account transfer screen, screen data for confirming a transaction amount history, etc.).

The receiver 41 may exchange or share an encryption key from the server 10. This is because the server 10 and the screen 30 use a key exchange / sharing protocol to have an encryption key. Meanwhile, the receiver 41 may receive secret information (ie, a source for generating an encryption key) from the outside. Of course, the receiver 41 may also receive MITM attack data (ie, encrypted data created to deceive the user) at the client 20.

On the other hand, the receiver 41 receives input data requiring security from the user. Herein, input data requiring security may be input through a keyboard and / or a mouse.

The encryption key generation unit 42 generates an encryption key based on the secret information received through the reception unit 41. Here, the secret information may be a password, a security card, a public certificate, a one time password (OTP), a transaction authentication number (TAN), and the like. Because passwords, security cards, and public certificates can be exposed during distribution, it is safe to use secret information that is difficult to replicate, such as OTP. It is assumed that the encryption key generation unit 42 incorporates an encryption algorithm.

The encryption key storage unit 43 stores the encryption key generated by the encryption key generation unit 42. In addition, the encryption key storage unit 43 may store the encryption key from the server 10. As a result, it can be seen that the encryption key in the encryption key storage unit 43 is shared with the server 10. The encryption key may be an example of a key described in the claims of the present invention.

The decryption unit 44 decrypts the screen data requiring security from the server 10 received by the reception unit 41. Meanwhile, the decryption unit 44 will decrypt the MITM attack data received from the client 20 received by the reception unit 41. It is assumed that the decoding unit 44 has a built-in decoding algorithm.

Here, the decryption unit 44 decrypts the encryption key stored in the encryption key storage unit 43 (that is, the encryption key shared with the server 10) when decrypting the screen data requiring security from the server 10. Since decryption is performed based on the (), normal decryption will be performed. However, when the decryption unit 44 decrypts the MITM attack data from the client 20, since the encryption key stored in the encryption key storage unit 43 and the encryption key of the MITM attack data are different from each other, proper decryption is performed. Will not lose.

The screen 45 displays the screen data decoded by the decoder 44.

The screen security display unit 46 displays whether or not the screen security. For example, the screen security display unit 46 displays a visual display through a display device such as a light emitting device (LED) to inform the user of the on / off state of the screen security. Here, when the screen security is OFF, the light emitting device does not output any light, and when the screen security is ON, the light emitting device may output green light. At least one light emitting element may be used. The screen security display unit 46 may be installed on the screen 30 separately from the screen 45.

Even if the malicious attacker makes data similar to the screen data requiring security in the server 10 through the client 20 and transmits it to the screen 30, the screen data is abnormal because the malicious attacker does not know the encryption key stored in the screen 30. (I.e., MITM attack data). As a result, if the decryption unit 44 decrypts the MITM attack data (encrypted data) in the client 20, proper decryption is not performed, and thus the screen security display unit 46 may display such a case. For example, red light may be output from the light emitting device to indicate that decoding is not performed properly.

Meanwhile, the screen security display unit 46 may display the screen security pattern of the screen security pattern storage unit 49 on the screen 45 in the screen security state. In this case, the screen security pattern may not be displayed as a light emitting device, but may have a form in which a green strip is formed along the edge of the screen 45. In addition, if the screen security pattern is included in the data sent by the client 20 to the screen 30, the screen security display unit 46 is an abnormal state (that is, it can be seen as a case where malicious code is detected). I can display it.

The encryption unit 47 encrypts input data requiring security received by the reception unit 41. At this time, the encryption unit 47 encrypts the encryption key based on the encryption key stored in the encryption key storage unit 43.

The transmitter 48 sends the input data encrypted by the encryption unit 47 to the server 10.

The screen security pattern storage unit 49 stores the screen security pattern to be output to the screen 45 in the screen security state.

The controller 50 is responsible for controlling the internal configuration of the screen 30. That is, when the control unit 50 receives the encryption key through the receiver 41, the controller 50 stores the encryption key in the encryption key storage unit 43. When the controller 50 receives the secret information through the receiver 41, the controller 50 sends the secret information to the encryption key generator 42. When the control unit 50 receives screen data requiring security through the receiving unit 41, the control unit 50 transmits the screen data to the decryption unit 44. When the control unit 50 receives input data requiring security through the receiving unit 41, the control unit 50 transmits the received input data to the encryption unit 47. The controller 50 determines whether or not the screen security, and sends the result to the screen security display 46, and, if a malicious code is detected, sends the fact to the screen security display 46.

3 is a flowchart illustrating an example of a method for preventing MITM attack according to an embodiment of the present invention, and FIGS. 4 to 7 are diagrams employed in the description of FIG. 3.

The screen 30 may be provided with an encryption key directly from the server 10, but in the following description, it is assumed that the encryption key is generated by receiving secret information.

That is, the user may directly input the secret information issued by the server 10 to the screen 30. Accordingly, the receiver 41 of the screen 30 receives the input secret information (S10). 4 to 6 illustrate an example of inputting secret information on a screen. 4 illustrates a case in which the screen 30 has a touch screen function. In FIG. 4, a user may touch the virtual screen 51 on the screen 45 to input secret information. 5 illustrates an example in which the screen 30 has an input terminal such as USB or PS / 2. In FIG. 5, secret information may be input by connecting an input device 52 such as a keyboard and a mouse to an input terminal. 6 shows a case where the camera 53 is located on the screen 30. In FIG. 6, the camera 53 may directly capture and input secret information, or may input secret information through OCR reading. On the other hand, the camera 53 can photograph a multi-dimensional code (for example, a QR code), obtain secret information from the photographing information, and input it.

When the secret information is received in this way, the secret information is sent to the encryption key generation unit 42. The encryption key generation unit 42 generates an encryption key using the received secret information, and stores the generated encryption key in the encryption key storage unit 43 (S12).

Of course, if the encryption key already exists in the encryption key storage unit 43, the operation of the above-described S10, S12 will not be necessary.

Thereafter, the server 10 sends the screen data requiring security to the screen 30 via the network. Accordingly, the receiver 41 of the screen 30 receives screen data requiring security (S14).

Accordingly, the controller 50 of the screen 30 decrypts the screen data requiring security (for example, an internet account transfer screen, screen data for confirming a transaction amount history, etc .; encrypted data). Send to The decryption unit 44 decrypts screen data requiring security.

By the way, even if the server 10 sends the screen data encrypted using the shared encryption key, the malicious attacker will try to trick the user elaborately by using a technique such as farming. Even if the malicious attacker makes data similar to the screen data requiring security in the server 10 through the client 20 and transmits it to the screen 30, the screen data is abnormal because the malicious attacker does not know the encryption key stored in the screen 30. (I.e., MITM attack data). As a result, if the decryption unit 44 decrypts the MITM attack data (encrypted data) in the client 20, proper decryption is not performed.

In this case, when the decoding is not normally performed (“No” in S16), the decoder 44 notifies the controller 50 of this. Accordingly, the controller 50 issues a warning of outputting red light through the screen security display unit 46 (S18). Of course, the controller 50 may turn the entire screen 45 black with a warning through the screen security display unit 46, so that nothing can be seen.

On the contrary, in the case where decoding is normally performed (“Yes” in S16), the decoder 44 notifies the controller 50 of this. Accordingly, the controller 50 determines that the screen security is ON and displays the screen security ON through the screen security display 46 (S20). For example, initially, as shown in FIG. 7A, the light emitting device 54 is turned off and the screen security is turned off. When the screen security is turned on, the light emitting device ( 54) lights up to output green light.

The decoder 44 then displays the decoded screen data on the screen 45 (S22).

If the server 10 transmits general screen data (that is, screen data for which security is not required and unencrypted screen data), the control unit 50 of the screen 30 is in a screen security off state. To close the screen security. That is, when the screen requiring security ends, it returns to the normal screen.

Assume that screen 30 is connected to a keyboard and mouse.

When the user inputs the security input data through the keyboard, the receiver 41 receives the security input data (S30).

Subsequently, the controller 50 applies the input data requiring security to the encryption unit 47.

Accordingly, the encryption unit 47 encrypts the input data requiring security based on the encryption key stored in the encryption key storage unit 43 (S32).

The encrypted input data is transmitted to the server 10 through the transmitter 48 (S34).

The above-described S30 to S34 may be regarded as being performed after S22 in FIG. 3 described above. That is, when the screen data requiring security is decrypted and displayed on the screen 45, the user views the screen data and inputs corresponding input data (that is, input data requiring security). The input data is encrypted and sent to the server 10.

Here, it can be said that the input data is encrypted and transmitted to the server 10 only when the screen security is in operation. Since the screen security is ON while the operations S30 to S34 are being performed, the light emitting device 54 will output green light as shown in FIG. 7B.

9 is a flowchart for explaining another example of the method for preventing MITM attack according to the embodiment of the present invention, and FIG. 10 is a diagram employed in the description of FIG. 9.

First, the screen 30 receives predetermined screen data through the client 20 (S40).

Thereafter, the controller 50 of the screen 30 determines whether the received screen data includes the screen security pattern.

If the screen security pattern is included (“Yes” in S42), the controller 50 determines that the currently input screen data is MITM attack data (eg, malicious code) sent by a malicious attacker (S44).

When the malicious code is detected as described above, the malicious code detection is displayed on the screen 45 (S46). For example, when the screen security is changed from the screen security off state to the normal screen security on state as shown in FIG. 10a, the screen security pattern in which a green strip is formed along the edge of the screen 45 as shown in FIG. 10b. Will print In this state, when malicious code is detected, as shown in FIG. 10C, the screen 30 allows a red band to be formed along the edge of the screen 45. In this case, characters such as "malware detected" and "do not input important information" may be displayed together.

That is, the screen security pattern can be generated and displayed only on the screen 30. When a malicious attacker makes a screen security pattern through the client 20 and inputs the screen security pattern together with the screen data, the screen 30 from the client 20 Since it is known that a specific signal (ie, screen security pattern) is included in the screen data of, it may be determined that MITM attack data is input.

As described above, the best embodiment has been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims

A MITM attack protection device that is embedded in the screen connected to the server through the client.

A key storage unit for storing a key shared with the server;

A decoder which decrypts the data input through the client based on the key and outputs the same on the screen;

A screen security display unit for performing screen security on or warning of the screen based on whether decryption is normal in the decryption unit;

An encryption unit for encrypting and outputting input data requiring security from a user based on the key; And

When the decryption in the decryption unit is normal, the screen security is turned on to output the decryption unit and the result of the encryption, respectively, and when the decryption in the decryption unit is abnormal, the screen security display unit is controlled. And a control unit for performing a corresponding display.
The method according to claim 1,

The key may be provided directly from the server or generated based on secret information.
The method according to claim 2,

The secret information is a MITM attack prevention device, characterized in that any one of a password, security card, public certificate, OTP, TAN.
The method according to claim 2,

And the secret information is input by touching a virtual screen on the screen.
The method according to claim 2,

And the secret information is input through a keyboard and a mouse connected to an input terminal installed on the screen.
The method according to claim 2,

And the secret information is input through a camera installed on the screen.
The method according to claim 1,

The screen security display unit includes a light emitting element,

And the screen security display unit outputs green light indicating the screen security on if the decryption in the decryption unit is normal.
The method according to claim 1,

The screen security display unit includes a light emitting element,

And the screen security display unit warns by outputting red light when the decryption in the decryption unit is abnormal.
The method according to claim 1,

And a screen security pattern storage unit for storing a screen security pattern displayed on the screen when the screen security is on.
The method according to claim 9,

And if the screen security pattern is included in the data from the client, the controller warns through the screen security display unit.
MITM attack prevention method in the MITM attack prevention device included in the screen connected to the server through the client,

Receiving data input through the client;

Decrypting the data based on a key shared with the server; And

And performing screen security on or warning of the screen of the screen based on whether decryption is normal in the decrypting step.
The method according to claim 11,

The key may be provided directly from the server or generated based on secret information.
The method according to claim 12,

The secret information is MITM attack prevention method, characterized in that any one of a password, security card, public certificate, OTP, TAN.
The method according to claim 12,

And the secret information is input by touching a virtual screen on the screen.
The method according to claim 12,

The secret information is input via a keyboard and a mouse connected to an input terminal installed on the screen.
The method according to claim 12,

And the secret information is input through a camera installed on the screen.
The method according to claim 11,

And performing screen security on or warning of the screen of the screen, when the decryption is normal, driving a light emitting device to output green light indicating the screen security on.
The method according to claim 11,

And performing screen security on or warning of the screen of the screen, if the decryption is abnormal, drive a light emitting device to output a red light and warn.
The method according to claim 11,

And displaying a previously stored screen security pattern on the screen when the screen security is on.
The method according to claim 19,

And alerting if the screen security pattern is included in the data from the client.