Relay device, relay method, and relay program

Abstract

To provide an authentication system capable of more reliably eliminating attacks due to unauthorized access.SOLUTION: A relay device 1 includes a forwarding unit 12 that, when a packet is received in which a TTL is set to 0 or 1 and which is sent from a legitimate application and addressed to an authentication server, rewrites the TTL to a value that allows the packet to reach the authentication server, and then transmits the packet to the authentication server.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an authentication system for providing services over the Internet. [Background technology]

[0002] Conventionally, user authentication has been performed when providing services over the Internet, but many services have adopted a method called line authentication to improve security. Line authentication is a method that allows login only when accessed through a specific line linked to an ID, in order to confirm that the user is attempting to communicate using a legitimate line under contract (see, for example, non-patent document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "Line authentication: Sending caller ID when distributing addresses," [online], April 2, 2008, Nikkei Crosstech, [Retrieved February 22, 2024], Internet<https: / / xtech.nikkei.com / it / article / COLUMN / 20080324 / 296895> Summary of the Invention [Problem to be solved by the invention]

[0004] However, general line authentication is known to be vulnerable to attacks using software such as malware and viruses that infiltrate user terminals, and there is a possibility of unauthorized access through impersonation.

[0005] An object of the present invention is to provide an authentication system that can more reliably eliminate attacks by unauthorized access. [Means for solving the problem]

[0006] The relay device of the present invention has a forwarding unit that, when it receives a packet with a TTL set to 0 or 1 sent from a legitimate application addressed to an authentication server, rewrites the TTL to a value that allows the packet to reach the authentication server and then sends the packet to the authentication server.

[0007] The relay device may include a verification unit that verifies that the packet contains authentication data indicating that the packet was generated by the legitimate application, and the forwarding unit may rewrite the TTL to a value that can reach the authentication server and then transmit the packet to the authentication server only if the verification by the verification unit is successful.

[0008] The verification unit may further verify that the destination and protocol are those associated with the authentication data.

[0009] The verification unit may omit verification processing for communications from the same sender and consider the communications to have been successful for a certain period of time after the verification has been successful.

[0010] In the relay method of the present invention, when a packet with a TTL set to 0 or 1 is received and sent from a legitimate application to an authentication server, the relay device executes a forwarding step in which the relay device rewrites the TTL to a value that allows the packet to reach the authentication server and then sends the packet to the authentication server.

[0011] A relay program according to the present invention is for causing a computer to function as the relay device. [Effects of the Invention]

[0012] According to the present invention, attacks by unauthorized access can be more reliably prevented. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a block diagram illustrating a functional configuration of a relay device according to an embodiment. [Figure 2] FIG. 10 is a sequence diagram showing a packet flow when a packet is routed through a PGW different from the relay device of the embodiment. [Figure 3] FIG. 10 is a sequence diagram illustrating a relay method performed by the relay device according to the embodiment. [Figure 4] FIG. 1 is a sequence diagram illustrating an example of an attack on a conventional authentication system. DETAILED DESCRIPTION OF THE INVENTION

[0014] An example of an embodiment of the present invention will be described below. The authentication system of this embodiment comprises a terminal used by a user, a relay device for connecting the terminal to an external network such as the Internet and relaying packet transmission and reception, and an authentication server for performing line authentication for access from the terminal.

[0015] For example, when a terminal is connected to an LTE (Long Term Evolution) network, a PGW (Packet data network Gateway) is a relay device that functions as a gateway for connecting to the Internet. Also, for example, when the terminal is connected via WiFi (registered trademark), the WiFi router serves as the relay device. In this embodiment, as an example, a case will be illustrated in which login using a legitimate application is permitted only from a terminal connected to the LTE network of a specific telecommunications carrier.

[0016] FIG. 4 is a sequence diagram showing an example of an attack on a conventional authentication system. First, the attacker uses an attack SIM card (such as one for IoT applications) that can intercept communications from the PGW, or a terminal with VPN or DNS poisoning, or a user's own router connected via Wi-Fi or wired LAN to send communication data to the attacker's server (transmission 1). Next, the attacker's server transfers the communication data to the victim's device U on which the malware has been installed (transmission 2).

[0017] The victim's device U then uses the malware to further transmit the communication data to the legitimate authentication server (transmission 3). When the communication data reaches the authentication server in this way, the authentication server, because it is sent from terminal U, returns authentication information linked to the line of terminal U. However, this reply returns to the attacker's terminal via the reverse path of transmissions 1 to 3, so the authentication information that should be saved in terminal U is saved in the attacker's terminal, making it possible for the attacker to spoof the data.

[0018] Therefore, in this embodiment, the strength of authentication is improved by adding TTL (Time To Live) control to the line authentication of the authentication system. Specifically, by adding new TTL control logic only to the router (relay device) of the legitimate line that is routed to the legitimate authentication server, packets sent from a specific application will no longer be sent to an external network via other lines.

[0019] FIG. 1 is a block diagram showing the functional configuration of a relay device 1 according to this embodiment. The relay device 1 is an information processing device that includes a control unit 10 and a storage unit 20, connects a user's terminal to an external network (Internet), and relays packet transmission and reception as a router.

[0020] The control unit 10 is a part that controls the entire relay device 1, and realizes each function of the present embodiment by appropriately reading and executing various programs stored in the storage unit 20. The control unit 10 may be a CPU. The storage unit 20 is a storage area for storing various programs for causing the hardware group to function as the relay device 1, various data, and the like, and may be a ROM, RAM, flash memory, hard disk drive (HDD), or the like. Specifically, the control unit 10 functions as a verification unit 11 and a transfer unit 12 by executing software (relay program) stored in the storage unit 20.

[0021] The verification unit 11 verifies that the packet received from the user terminal contains authentication data indicating that the packet was generated by a legitimate application.

[0022] Here, it is preferable that the authentication data can be generated only by a legitimate application and can prove that the application is legitimate. Specifically, for example, authentication may be performed in the following cases. The authentication data itself is shared in advance between the terminal and the relay device 1, and the authentication data is included in the packet. A common key is shared in advance between the terminal and the relay device 1, and a value calculated from the current time (such as a one-time password) is included in the packet. A pair of a common key and a public key is shared in advance between the terminal and the relay device 1, and a value (such as a digital signature value) calculated from the simultaneously transmitted NONCE is included in the packet.

[0023] Furthermore, the verification unit 11 may further perform the following verification. -Check whether the destination IP address is associated with the authentication data. -Check whether the destination port number is linked to the authentication data. -Check whether the communication protocol is linked to the authentication data.

[0024] Furthermore, the verification unit 11 may omit verification processing for communications from the same sender and consider the communications to be successful for a certain period of time after the verification is successful.

[0025] The transfer unit 12 receives a packet with a TTL set to 0 or 1, sent from a legitimate application to an authentication server, and if the verification by the verification unit 11 is successful, rewrites the TTL to a value that allows the packet to reach the authentication server, and then transmits the packet to the authentication server.

[0026] FIG. 2 is a sequence diagram showing the flow of packets when the packets are routed through a PGW different from the relay device 1 of this embodiment. Data sent from the terminal is sent in a packet with a TTL set to 0 or 1. The destination IP address of this packet is the authentication server. At this time, the PGW is the first router seen from the terminal U, and immediately discards this packet, so the transmitted data does not reach the server.

[0027] Note that this example is for the case where terminal U is connected to an LTE network, but in the case of WiFi, for example, the PGW simply changes to a WiFi router, and the same applies regardless of which network terminal U is connected to.

[0028] FIG. 3 is a sequence diagram showing a relay method performed by the relay device 1 of this embodiment. When a relay device 1 (PGW) on a regular communication path receives data from a terminal U including a packet with a TTL set to 0 or 1 (for example, a packet containing a packaged packet), if the packet includes authentication data and is successfully verified, the relay device 1 rewrites the TTL to a value sufficient to reach the authentication server and then forwards the packet. As a result, the packet reaches the authentication server, and if authentication such as login is successful, an authentication response is returned to terminal U.

[0029] Here, an example is shown in which the TTL is rewritten only for packets that have been successfully verified in the PGW, but it is also possible to continue permitting (rewriting the TTL) communications from sources whose authentication data has been successfully verified for a certain period of time. In this way, for example, by adding authentication data to SNI (Server Name Indication) in SSL communication, it is possible to read the authentication data from the PGW and permit all subsequent communications.

[0030] According to this embodiment, the relay device 1 strengthens line authentication by allowing packets for which a TTL of 0 or 1 is specified by a legitimate application to pass by rewriting the TTL. That is, as shown in Fig. 4, an attacker forwards authentication-related communications from a terminal owned by the attacker to a server owned by the attacker, and then passes the communications through malware or a virus on the victim's terminal from this server, thereby misidentifying the source of the communications through line authentication and performing spoofing. In contrast, in this embodiment, a legitimate application includes authentication data in a packet with a TTL set to 0 or 1, so that the authentication data is immediately discarded by the nearest router (transmission 1 is not completed), making it impossible for the attacker to forward the packets to the server owned by the attacker. Although such packets would be discarded even in a legitimate network, by allowing them only at the PGW (relay device 1) that is routed to the legitimate authentication server, packets that have passed through other routers, etc. are rejected, thereby preventing spoofing.

[0031] For example, when communicating using a legitimate SIM, the packets are routed to the legitimate authentication server, so they do not constitute spoofing. However, if the SIM is swapped and the packets are routed through the attacker's server, the packets are discarded by a normal relay device, so the spoofing attack also fails in this case.

[0032] In this way, this embodiment can suppress attacks using software that infiltrates user terminals, such as malware and viruses, which were difficult to eliminate using conventional line authentication, and can more reliably eliminate attacks through unauthorized access.

[0033] In this embodiment, it is assumed that the attacker is using a legitimate application on his / her own terminal, because it is difficult for the attacker to develop a program that performs communication that completely imitates the communication of a legitimate application, and therefore it is preferable to use a method to prevent application imitation, such as encryption or obfuscation.

[0034] Furthermore, relay devices such as PGW in mobile networks process packets sent by terminals from data packed into packets used within the network. In other words, the logic for updating the TTL during this process can be easily incorporated into the structure, making it easy to implement. On the other hand, typical routers control IP communications at the hardware or OS kernel level, making it difficult to incorporate TTL control logic, and therefore can reject packets that are routed via invalid routes.

[0035] Furthermore, this embodiment can suppress attacks against line authentication, for example, and therefore contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), which is to "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0036] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. Furthermore, the effects described in the above-described embodiments are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments.

[0037] In the above-described embodiment, the relay device 1 verifies the validity of the authentication data contained in the packet, but this authentication data is not necessarily required. By rewriting the TTL of 0 or 1, which is normally discarded as a specification, communication via an unauthorized route can be eliminated, thereby making conventional line authentication more secure.

[0038] Furthermore, the relay device 1 rewrites the TTL and assists in sending packets to the authentication server, but in recent years, some PGWs have an authentication function built in. In this case, the PGW may be configured to return an authentication response based on the received data instead of rewriting the TTL.

[0039] The relay method by the relay device 1 is realized by software. When realized by software, the programs constituting this software are installed in an information processing device (computer). These programs may be recorded on removable media such as CD-ROMs and distributed, or may be distributed by being downloaded to a computer via a network. [Explanation of symbols]

[0040] 1. Relay device 10 Control Unit 11 Verification Department 12 Transfer Unit 20 Memory section

Claims

1. A relay device having a forwarding unit that, when receiving a packet with a TTL set to 0 or 1 sent from a legitimate application addressed to an authentication server, rewrites the TTL to a value that allows the packet to reach the authentication server and then sends the packet to the authentication server.

2. a verification unit that verifies that the packet includes authentication data that indicates that the packet was generated by the legitimate application; 2. The relay device according to claim 1, wherein the forwarding unit rewrites the TTL to a value that enables the packet to reach the authentication server only if the verification by the verification unit is successful, and then transmits the packet to the authentication server.

3. The relay device according to claim 2 , wherein the verification unit further verifies that the destination and protocol are linked to the authentication data.

4. 4. The relay device according to claim 2, wherein the verification unit considers the verification to have been successful by omitting verification processing for communications from the same sender only for a certain period of time after the verification has been successful.

5. A relay method in which, when a packet with a TTL set to 0 or 1 that is sent from a legitimate application to an authentication server is received, a relay device executes a forwarding step in which the relay device rewrites the TTL to a value that allows the packet to reach the authentication server, and then transmits the packet to the authentication server.

6. A relay program for causing a computer to function as the relay device according to any one of claims 1 to 3.

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