JP4636584B2 - Information leakage prevention system - Google Patents

Description

  The present invention relates to an information leakage prevention system that monitors the passage of data to and from an external network and prevents unauthorized take-out of important data to the outside even when intruded by a hacker or the like.

  In recent years, as a technique for hackers and cyber attacks, it has become a hot topic to invade an attack target from a computer network and take out important data outside. As a countermeasure, for example, in order to protect confidential information in a directory that is a database for storing information of various resources in an information system, it is protected by a firewall under the integrated management directory and requires a digital certificate for access. There has been proposed a three-layer structure in which an authentication directory and a public directory that can be freely accessed under the authentication directory are provided to realize both the disclosure of information and the protection of confidential information (Patent Document 1).

In addition, when communicating between an internal packet-type network connected to multiple terminals and an external packet-type network, confidential internal network information is prevented from being illegally leaked to the external network. In order to prevent transmission, the packet header is sent with the disclosure range information and the packet authentication information obtained by encrypting the packet and the disclosure range information. In addition, there has also been proposed a technique in which only information that has been granted public permission can be disclosed to the outside by determining whether to transmit to a subsequent network (Patent Document 2).
JP 2001-318889 A JP 2001-111612 A

Patent Document 1 discloses a technique for countermeasures against hacking, but does not disclose a method for preventing unauthorized removal of important data after being intruded, and prevents unauthorized removal by an insider. There is no disclosure about this point.
Japanese Patent Application Laid-Open No. 2004-228561 is to set publicly available range information in a file, and the work of setting publicly available range information is complicated.

The present invention is intended to solve the above-mentioned problems. Even when a hacker or the like is invaded into an internal network, or prevents an unauthorized person from taking out important data by an insider, external data can be freely transmitted outside the important data. The purpose of this is to avoid overloading the system.
Therefore, the present invention checks whether or not a system certificate is granted in a system that prevents unauthorized data leakage from the internal network to the external network, and allows / disallows transmission of data to the external network. It is characterized by comprising checking means for performing
Further, the present invention provides a system certificate for a system that prevents unauthorized leakage of data from an internal network to an external network, and checks whether or not a system certificate has been granted and system certification. It is characterized by comprising check means for permitting / disapproving data transmission on the condition that a certificate is given.

  The present invention prevents unauthorized take-out of important data even if a hacker or the like has been infiltrated into the internal network, so that other than important data can be freely transmitted externally so as not to overload the system. can do.

  Embodiments of the present invention will be described below. It should be noted that the present invention can be applied to a technology for preventing illegal take-out of important data on a computer connected to a network, a single computer that can be connected to the Internet, etc., or a terminal on a network constructed by a LAN in a company / shopping district. .

FIG. 1 is a diagram for explaining the system configuration of this embodiment.
The functions of a normal Internet connection system include a gateway 5 that allows connection between different models by absorbing differences in communication media and transmission methods, and a firewall 6 that detects and blocks unauthorized access. Furthermore, the present embodiment has a configuration for preventing illegal data leakage.

  Each terminal 1 is connected to the network 3, and data can be transmitted from each terminal to the external network 8 through the check server 7. Important data transmitted from the terminal to the outside is stored with a digital signature (electronic signature) attached as a legitimate signature of the sender or with a personal certificate. In the case of a personal certificate, for example, based on identification information allocated to each terminal, identification information of a logged-in user of the network, or identification information stored in an IC card 2 held by each user using the terminal It may be granted by an individual or a trusted third party. Further, the assignment of the personal certificate to the important data may be automatically performed on the data stored in a specific directory on the personal computer or the management server. Only a user who is authenticated as an authorized user can store and read data in the directory, and user authentication may be performed each time data is stored or only when the system is logged in.

  At the time of external transmission, it is necessary to give a system certificate as a transmission permit to the outside. External transmission of data with only a personal certificate is prohibited as it is considered as illegal removal of important data due to cyber attacks. In this embodiment, the management server 4 manages the identification information of each terminal or the identification information stored in the IC card of each user. When there is a client request, the management server 4 first stores the identification information managed. In addition, it verifies whether or not the personal certificate is valid, and grants a system certificate only if it is valid. At the same time, log data is recorded and stored as verification data when it becomes necessary after transmission. The important data to which the system certificate is assigned is transferred to the check server 7, and the check server 7 monitors the external transmission of the important data, and only the important data to which the system certificate is given outside the personal certificate is sent to the outside. Is transmitted to the external network 8. The important data transmitted externally may be encrypted at any stage before transmission.

  If data transmission is permitted, the system certificate and / or the sender's personal certificate may be deleted to transmit the data.

  In the above description, the system certificate is assigned by the management server 4. However, a system certificate grant program may be downloaded to each terminal 1 and performed at the terminal. In that case, it is necessary to prevent the contents of the system certificate from being altered from the terminal. Further, the management server 4 may be omitted and the check server 5 may give a system certificate. In any case, log data at the time of external transmission is recorded in the management server or the check server.

FIG. 2 is a diagram showing a processing flow of the first example of the present embodiment.
The sender signs the important data with the personal certificate and requests the management server for external transmission (step S1). The management server verifies the signature (step S2) and determines whether the signature is valid (step S3). If the signature is valid, the data is encrypted with the recipient's public key (step S4), the system certificate is added, the log data is recorded (step S5), and a transmission request is sent to the check server (step S6). ). Upon receipt of the transmission request, the check server checks the externally transmitted data to which a personal certificate has been assigned, determines whether or not a system certificate has been assigned (step S7), and the system certificate Is transmitted (step S8). If the signature is not valid in step S3, or if no system certificate is given in step S7, external transmission is prohibited.

FIG. 3 is a diagram showing a processing flow of the second example of the present embodiment.
The sender signs important data with a personal certificate and requests the management server to give a system certificate (step S11). The management server that has received the request verifies the signature (step S12), and determines whether the signature is valid (step S13). If the signature is valid, a system certificate is assigned to encrypt the data and return it to the sender, and log data is recorded (step S14). The sender once decrypts the important data given the system certificate, encrypts it with the recipient's public key, and requests transmission to the check server (step S15). The check server checks the externally transmitted data to which a personal certificate has been assigned, determines whether or not a system certificate has been granted (step S16), and if the system certificate has been granted. (Step S17). If the signature is not valid in step S13, or if no system certificate is given in step S16, external transmission is prohibited.

FIG. 4 is a diagram showing a processing flow of the third example of the present embodiment.
The sender signs the important data with the personal certificate and requests the management server to give the system certificate (step S21). The management server that has received the request verifies the signature (step S22) and determines whether the signature is valid (step S23). If the signature is valid, a system certificate is assigned to encrypt the data and return it to the sender, and log data is recorded (step S24). The sender decrypts the important data given the system certificate, and requests the check server to send it (step S25). The check server checks externally transmitted data to which a personal certificate has been assigned, determines whether or not a system certificate has been granted (step S26), and if the system certificate has been granted. For example, the data is encrypted with the recipient's public key (step S27) and transmitted (step S28). If the signature is not valid in step S23, or if no system certificate is given in step S26, external transmission is prohibited.

  As described above, according to the present invention, even if a hacker or the like has been invaded into the internal network, it is possible to prevent illegal take-out of important data and to perform external transmission of data other than important data freely. Use is great.

It is a figure explaining the system configuration of this embodiment. It is a figure which shows the processing flow of the 1st example of this embodiment. It is a figure which shows the processing flow of the 2nd example of this embodiment. It is a figure which shows the processing flow of the 3rd example of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Terminal, 2 ... IC card, 3 ... Network, 4 ... Management server, 5 ... Gateway, 6 ... Firewall, 7 ... Check server, 8 ... External network.

Claims (4)

In a system that prevents unauthorized data leakage from the internal network to the external network,
Multiple devices connected to the internal network,
When data is transmitted from each terminal to an external network, the personal certificate given at each terminal based on the identification information of the sender is verified as valid based on the identification information . A management server that only grants a system certificate as a transmission permit,
A check server that checks whether a system certificate has been granted and permits / denies transmission of data to an external network ;
When the check server permits transmission of data, the check server transmits data by deleting either or both of the system certificate and the sender's personal certificate . The information leakage prevention system according to claim 1, wherein the management server and / or the check server has a function of recording transmission log data. In a system that prevents unauthorized data leakage from the internal network to the external network,
Multiple devices connected to the internal network,
When data is transmitted from each terminal to an external network, the personal certificate given at each terminal based on the identification information of the sender is verified as valid based on the identification information . Only grants a system certificate as a transmission permit, checks whether a system certificate has been granted, and checks whether to permit / deny data transmission on the condition that the system certificate has been granted With a server ,
When the check server permits transmission of data, the check server transmits data by deleting either or both of the system certificate and the sender's personal certificate . 4. The information leakage prevention system according to claim 3 , wherein the check server has a function of recording transmission log data.

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