KR102228963B1 - Mail system and method for operating thereof - Google Patents

Abstract

The present invention discloses a mail system and an operating method thereof. The mail system comprises: a first network and a second network separated from each other; an external mail server connected to the second network, receiving the original mail, and generating an original mail image capturing the original mail; and an internal mail server connected to the first network, receiving and verifying the original mail image, and receiving the original mail.

Description

Mail system and its operation method TECHNICAL FIELD

The present invention relates to a mail system and a method of operation thereof. Specifically, the present invention relates to a method for safely receiving and transmitting e-mails in a business network separated from an external Internet network.

The content described in this section merely provides background information on the present embodiment and does not constitute the prior art.

Recently, the computer networks of major domestic financial companies were attacked by malicious codes, causing great damage. Through this, in the case of information and communication service providers that possess personal information of many users as well as all financial sectors or have high sales,'network separation' must be introduced.

Network separation refers to dividing the network network into an Internet network and a business network by redundantly in order to protect the internal computing resources from external intrusion, and it can create a safe work environment against hacking attacks such as malicious codes.

However, network separation can also bring side effects that reduce work efficiency and speed. Therefore, it is necessary to discuss how to maintain security and efficiency in a separate network environment.

It is an object of the present invention to provide a mail system capable of safely receiving and transmitting mail while minimizing inter-network movement in a network separated environment.

In addition, another object of the present invention is to provide a method of operating a mail system capable of minimizing inter-network movement and safely receiving and transmitting mail in a network separated environment.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention that are not mentioned can be understood by the following description, and will be more clearly understood by examples of the present invention. In addition, it will be easily understood that the objects and advantages of the present invention can be realized by the means shown in the claims and combinations thereof.

One aspect of a mail system according to an embodiment of the present invention is a first network and a second network separated from each other, access to the second network, receive the original mail, and capture the original mail image And an internal mail server that accesses the first network and receives the original mail image and receives the original mail after verifying and receiving the original mail image.

In addition, the first network may be a business network that allows limited access only to workers, and the second network may be an Internet network that allows external access.

In addition, the external mail server temporarily stores the second external mail server generating the original mail image, the original mail and the original mail image, and transmits the original mail image to the internal mail server, and the internal It may include a first external mail server for transmitting the original mail to the internal mail server when verification is completed from the mail.

Also, the second external mail server may encrypt the original mail.

In addition, the second network includes an Internet network server farm including the first external mail server and an Internet network public subnet including the second external mail server, and the Internet network server farm and the Internet network are shared. Subnets can transmit data to each other through firewalls.

In addition, it may further include a web hard server for storing a large-capacity attachment file from the internal mail server.

In addition, the webhard server may connect to the second network and provide the large-capacity attached file through a link.

In addition, the external mail server may verify a visitor of the link and, when the verification is completed, may redirect the visitor to the webhard.

One aspect of a method of operating a mail system according to an embodiment of the present invention is a method of operating a mail system including a first network and a second network separated from each other, wherein the second network receives an original mail. And generating the original mail image by capturing the original mail; verifying the original mail image by transmitting the original mail image to the first network; and when the original mail image is verified, And transmitting the original mail to the first network.

In addition, verifying the original mail image includes receiving a first verification result of a first user accessing the first network, and when the first verification result is positive, accessing the first network And receiving a second verification result of a second user different from the first user.

In addition, the first user may be a person in charge of the original mail, and the second user may be a user different from the person in charge, and may be an administrator with mail approval authority.

In addition, the second network connects to a first external mail server and a second external mail server, and the step of receiving the original mail in the second network includes: receiving the original mail by the second external mail server; And encrypting the original mail by the second external mail server.

In addition, the second network may include an Internet network server farm including the first external mail server, and an Internet network public subnet including the second external mail server.

In addition, the Internet network server farm and the Internet network public subnet may transmit data to each other through a firewall.

In addition, uploading a large-capacity attachment to a webhard server, generating a transmission mail including a link, transmitting the transmission mail, receiving an authentication request, and if authentication is performed, the Redirecting the link to the webhard server, and downloading the large-capacity attachment file.

The mail system and its operation method according to the present invention can securely verify mail in a separate network to protect a closed business network and safely receive mail.

In addition, in the mail system and its operation method of the present invention, the person in charge first verifies the original mail image, and the administrator later verifies the original mail to have the effect of double verification, while reducing the burden on the administrator to efficiently verify mail You can do it.

In addition to the above-described contents, specific effects of the present invention will be described together while describing specific details for carrying out the present invention.

1 is a conceptual diagram illustrating a mail system according to an embodiment of the present invention.
FIG. 2 is a structural diagram for explaining the structure of the business network of FIG. 1 in detail.
3 is a structural diagram for explaining the structure of the Internet network of FIG. 1 in detail.
4 is a flowchart illustrating a data transition of a mail system according to an embodiment of the present invention.
5 is a block diagram illustrating an operation of attaching a large file in a mail system according to an embodiment of the present invention.
6 is a flowchart illustrating a method of operating a mail system according to an embodiment of the present invention.
FIG. 7 is a flowchart for explaining the receiving step of FIG. 6 in detail.
FIG. 8 is a flow chart for explaining the steps of generating the original mail image of FIG. 6 in detail.
9 is a flow chart for explaining in detail steps of verifying the original mail image of FIG. 6.
10 is a flowchart illustrating an operation of attaching a large file in a method of operating a mail system according to an embodiment of the present invention.

The terms or words used in this specification and claims are limited to their general or dictionary meanings and should not be interpreted. According to the principle that the inventor can define the concept of terms or words in order to explain his own invention in the best way, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention. In addition, the embodiments described in the present specification and the configurations shown in the drawings are only one embodiment in which the present invention is realized, and do not represent all the technical ideas of the present invention, and thus they can be replaced at the time of application. It is to be understood that there may be various equivalents and variations and examples of application.

Terms such as first, second, A, and B used in the specification and claims may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term'and/or' includes a combination of a plurality of related listed items or any of a plurality of related listed items.

The terms used in the specification and claims are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" should be understood as not precluding the possibility of existence or addition of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification. .

Unless otherwise defined, all terms including technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

In addition, each configuration, process, process, or method included in each embodiment of the present invention may be technically shared within a range that does not contradict each other.

Hereinafter, a mail system for safely receiving and transmitting mail in a network-separated environment and a method of operation thereof will be described in detail.

1 is a conceptual diagram illustrating a mail system according to an embodiment of the present invention.

Referring to FIG. 1, the mail system may include a business network 10 and an Internet network 20.

The business network 10 may refer to a network that allows limited access only to internal workers. The business network 10 is not allowed to access outsiders, so it is possible to maintain a high level of security. The business network 10 can transmit data to each other only through a network connection with the Internet network 20. The business network 10 is physically separated from the network so that direct access to the Internet network 20 can be controlled.

The Internet network 20 is a network in which external access is possible, and access restrictions for most areas may not exist separately. That is, the Internet network 20 can be accessed by anyone in most areas except for exceptional areas, and data can be freely moved. Accordingly, the probability of penetration of malicious codes or viruses may be high due to relatively low security.

The business network 10 and the Internet network 20 may be separated from each other through network separation. Therefore, data of the business network 10 and the Internet network 20 cannot be freely exchanged. The business network 10 and the Internet network 20 may transmit limitedly necessary data to each other through a network connection (eg, an inter-network transmission system).

FIG. 2 is a structural diagram for explaining the structure of the business network of FIG. 1 in detail.

1 and 2, the business network 10 may include a first user 110, a second user 120, and a business network server farm 130.

The first user 110 and the second user 120 may be internal workers who can access the business network 10. Although two users are shown in FIG. 2, the present embodiment is not limited thereto. That is, the number of users in the business network 10 may be 1 or less, or 3 or more.

The first user 110 may be a person in charge of the first original mail Mo1. The first user 110 may be a user described in the recipient of the first original mail Mo1. The first user 110 may use a virtual desktop infrastructure (VDI) for network separation of the business network 10. However, this embodiment is not limited thereto.

The second user 120 is a user different from the first user 110 and may be an administrator of the first user 110 who has the authority to transmit/receive mail by the first user 110. The second user 120 may use a virtual desktop infrastructure (VDI) for network separation of the business network 10. However, this embodiment is not limited thereto.

The business network server farm 130 may include an internal mail server 131, a database management system (DBMS) 132, and a storage 133.

The internal mail server 131 may be in charge of transmitting and receiving mail by accessing the business network 10. The internal mail server 131 may receive the first original mail Mo1 and the original mail image Ms from the Internet network 20 through network connection.

In this case, the first original mail Mo1 may be a mail received with the first user 110 as a destination. The first original mail Mo1 may be in the form of an EML file, for example. However, this embodiment is not limited thereto.

The original mail image Ms may be data generated in the form of an image by capturing the first original mail Mo1. The original mail image (Ms) contains the body of the first original mail (Mo1) in the form of an image, so that the first user 110 and the second user 120 can verify the content of the first original mail (Mo1). can confirm.

The internal mail server 131 may receive the original mail image Ms and sequentially provide it to the first user 110 and the second user 120. That is, the internal mail server 131 may first provide the original mail image Ms to the first user 110 and transmit the first verification request Rq1 to the first user 110.

The first user 110 may receive the first verification request Rq1 and verify whether the first original mail Mo1 is normal by verifying the original mail image Ms. If the body content included in the first original mail image Ms is normal, the first user 110 may transmit the first verification response Rs1 to the internal mail server 131. Since the first user 110 can best verify whether the first original mail Mo1 is a normal mail as an actual recipient of the first original mail Mo1, the first user 110 may perform the verification first.

When receiving the first verification response Rs1 indicating that the first original mail Mo1 is normal, the internal mail server 131 may transmit the original mail image Ms to the second user 120. In this case, the internal mail server 131 may transmit the second verification request Rq2 together with the original mail image Ms.

The second user 120 may receive the second verification request Rq2 and verify whether the first original mail Mo1 is normal by verifying the original mail image Ms. If the first original mail Mo1 is normal, the second user 120 may transmit a second verification response Rs2 for approving mail reception to the internal mail server 131. As described above, according to the present embodiment In the mail system, since the first user 110 and the second user 120 perform the verification twice, more accurate verification may be possible. Furthermore, since the first user 110, who is the direct person in charge of the first original mail Mo1, performs verification first, the second user 120 only needs to perform verification on the mail filtered by the first user 110 first. It is possible to prevent the second user 120 from overloading the verification work, thereby maximizing work efficiency.

When receiving both the first verification response (Rs1) and the second verification response (Rs2), the internal mail server 131 transmits the third verification response (Rs3) to the outside of the business network 10, that is, to the Internet network 20. I can. The third verification response Rs3 may mean that verification is performed by the original mail image Ms, so that the first original mail Mo1 is normal.

Subsequently, the internal mail server 131 may receive the first original mail Mo1 from the Internet network 20. Since the first original mail Mo1 contains a possibility that it may not be a normal mail before performing the verification, it may not be directly transmitted to the network-separated business network 10, but may be transmitted to the business network 10 through a verification procedure.

Subsequently, the internal mail server 131 may transmit the received first original mail Mo1 to the first user 110 as a person in charge. The first user 110 may receive and decrypt the encrypted first original mail Mo1. The first user 110 may decode the first original mail Mo1 and display it on the display device.

The DBMS 132 may be a system that manages data stored in the storage 133. The storage 133 may not store the first original mail Mo1 or the original mail image Ms, but may be a storage for storing additional information such as a subject list of received mails and statistics of received mails.

3 is a structural diagram for explaining the structure of the Internet network of FIG. 1 in detail.

1 to 3, the Internet network 20 may include an Internet network server farm 210, an Internet network public subnet 220, and a sender 230.

The Internet network server farm 210 may exchange data with the Internet network public subnet 220. A firewall may exist between the Internet network server farm 210 and the Internet network public subnet 220. Through this, the Internet network server farm 210 and the Internet network public subnet 220 may exchange data through a firewall.

The internet network server farm 210 may include a first external mail server 211. The first external mail server 211 may receive the first original mail Mo1 and the original mail image Ms from the second external mail server 221 included in the Internet network public subnet 220. The first external mail server 211 may temporarily store the first original mail Mo1 and the original mail image Ms. The first external mail server 211 may delete the first original mail Mo1 and the original mail image Ms when it is confirmed that the first original mail Mo1 is an abnormal mail in a later verification process.

The first external mail server 211 first transmits the original mail image (Ms) to the business network 10 separated from the network, and a third verification response, which is a verification result, from the internal mail server 131 of the business network 10 ( Rs3) can be received. When receiving the third verification response Rs3, the first external mail server 211 may transmit the first original mail Mo1 to the internal mail server 131 of the business network 10. That is, the first external mail server 211 can transmit the first original mail Mo1 to the business network 10 only when it is confirmed that the first original mail Mo1 is a normal mail. Through this, the network-separated business network 10 can receive only securely verified e-mails.

The Internet network public subnet 220 may be a kind of Internet network DMZ (Demilitarized Zone). That is, the Internet network public subnet 220 may be an area in which access is restricted to protect the business network 10 and the Internet network server farm 210. The Internet network public subnet 220 may be located between the Internet and the Internet network server farm 210. The Internet network public subnet 220 may be connected to the Internet through a firewall. Accordingly, the Internet network public subnet 220 may transmit and receive data through a firewall in the Internet. That is, in the Internet network public subnet 220, a firewall may exist even between the Internet and a firewall may exist between the Internet network server farm 210 and the Internet network server farm 210. Through this, abnormal mail such as malicious code of the Internet can be filtered while passing through the Internet network public subnet 220.

The Internet network public subnet 220 may include a second external mail server 221. The second external mail server 221 may receive the original mail Mo from the sender 230. At this time, since the original mail (Mo) passes through the firewall of the Internet network public subnet 220, an attachment file inspection for blocking spam and advanced persistent threat (APT) attacks may be performed.

The second external mail server 221 may generate the first original mail Mo1 by encrypting the original mail Mo. The first original mail Mo1 may be generated by encryption in order to prevent hacking attacks that may be caused by data in the form of the original mail Mo. Accordingly, the original mail Mo may be continuously transmitted in an encrypted state from the second external mail server 221, the first external mail server 211, and the internal mail server 131. The original mail Mo may be later transmitted to the first user 110 in the form of a first original mail Mo1 and may be decrypted when displayed on the display.

The second external mail server 221 may generate the original mail image Ms by capturing the body content of the original mail Mo. The original mail image (Ms) is an image file, and even if malicious code is embedded in the original mail (Mo), only the body content of the original mail (Mo) excluding the malicious code can be delivered in the form of an image.

The second external mail server 221 may transmit the first original mail Mo1 and the original mail image Ms to the first external mail server 211. In this case, the first original mail Mo1 and the original mail image Ms may be transmitted to the first external mail server 211 through the firewall.

The first external mail server 211 and the second external mail server 221 may be included in the external mail server 201. The external mail server 201 may generate the first original mail Mo1 by receiving and encrypting the original mail Mo. The external mail server 201 may generate an original mail image Ms by capturing the original mail Mo. The external mail server 201 temporarily stores the first original mail (Mo1) and the original mail image (Ms), and sequentially stores the original mail image (Ms) and the first original mail (Mo1). It can be transmitted to the mail server 131.

Specifically, the external mail server 201 first forwards the original mail image Ms to the internal mail server 131, and when the verification for this is completed and a third verification response Rs3 is received, the first original mail ( Mo1) may be transmitted to the internal mail server 131.

4 is a flowchart illustrating a data transition of a mail system according to an embodiment of the present invention.

Referring to FIG. 4, first, the sender 230 transmits the original mail Mo to the second external mail server 221 (S11).

Specifically, referring to FIG. 3, the second external mail server 221 may receive an original mail Mo. Since the second external mail server 221 is included in the Internet network public subnet 220, the original mail Mo may pass through a firewall and scan attachments to block spam and APT attacks.

Again, referring to FIG. 4, the second external mail server 221 generates a first original mail Mo1 and an original mail image Ms (S12).

Specifically, referring to FIG. 3, the second external mail server 221 may generate the first original mail Mo1 by encrypting the original mail Mo. The original mail Mo may be later transmitted to the first user 110 in the form of a first original mail Mo1 and may be decrypted when displayed on the display.

The second external mail server 221 may generate the original mail image Ms by capturing the body content of the original mail Mo. The original mail image (Ms) is an image file, and even if malicious code is embedded in the original mail (Mo), only the body content of the original mail (Mo) excluding the malicious code can be delivered in the form of an image.

Again, referring to FIG. 4, the second external mail server 221 transmits the first original mail Mo1 and the original mail image Ms to the first external mail server 211 (S13).

Subsequently, the first external mail server 211 temporarily stores the first original mail Mo1 and the original mail image Ms (S14).

Specifically, referring to FIG. 3, the first external mail server 211 may temporarily store the first original mail Mo1 and the original mail image Ms. The first external mail server 211 may delete the first original mail Mo1 and the original mail image Ms when it is confirmed that the first original mail Mo1 is an abnormal mail in a later verification process.

Again, referring to FIG. 4, the first external mail server 211 transmits the original mail image Ms to the internal mail server 131 (S15).

Specifically, referring to FIGS. 1 to 3, the business network 10 and the Internet network 20 may transmit limitedly necessary data to each other through network linkage. Accordingly, the original mail image Ms may be transmitted to the internal mail server 131 of the business network 10 through network connection.

Again, referring to FIG. 4, the internal mail server 131 transmits an original mail image Ms and a first verification request Rq1 to the first user 110 (S16).

Specifically, referring to FIG. 2, the internal mail server 131 may provide an original mail image Ms to the first user 110 and transmit a first verification request Rq1 to the first user 110. have. The first user 110 may be a person in charge of the first original mail Mo1. The first user 110 may be a user described in the recipient of the first original mail Mo1. Since the first user 110 can best verify whether the first original mail Mo1 is a normal mail as an actual recipient of the first original mail Mo1, the first user 110 may perform the verification first.

Again, referring to FIG. 4, the first user 110 transmits the first verification response Rs1 to the internal mail server 131 (S17).

Specifically, referring to FIG. 2, the first user 110 may receive a first verification request Rq1 and verify whether the first original mail Mo1 is normal by verifying the original mail image Ms. . If the first original mail Mo1 is normal, the first user 110 may transmit the first verification response Rs1 to the internal mail server 131.

Again, referring to FIG. 4, the internal mail server 131 transmits an original mail image Ms and a second verification request Rq2 to the second user 120 (S18).

Specifically, referring to FIG. 2, the internal mail server 131 may provide an original mail image Ms to the second user 120 and transmit a second verification request Rq2 to the second user 120. have. The second user 120 is a user different from the first user 110 and may be an administrator of the first user 110. Since the second user 120 only needs to perform verification on the mail that the first user 110 has first filtered, it is possible to prevent the second user 120 from overloading the verification work, thereby maximizing work efficiency.

Again, referring to FIG. 4, the second user 120 transmits a second verification response Rs2 to the internal mail server 131 (S19).

Specifically, referring to FIG. 2, the second user 120 may verify whether the second original mail Mo is normal by receiving the second verification request Rq2 and verifying the original mail image Ms. . If the second original mail Mo is normal, the second user 120 may transmit the second verification response Rs2 to the internal mail server 131.

Again, referring to FIG. 4, the internal mail server 131 transmits a third verification response Rs3 to the first external mail server 211 (S20).

Specifically, referring to FIGS. 1 and 2, when both the first verification response (Rs1) and the second verification response (Rs2) are received, the internal mail server 131 transmits a third verification response (Rs3) to the business network ( 10) It can be transmitted to the outside, that is, to the Internet network 20. The third verification response Rs3 may mean that verification is performed by the original mail image Ms, so that the first original mail Mo1 is normal.

Again, referring to FIG. 4, the first external mail server 211 transmits the first original mail Mo1 to the internal mail server 131 (S21).

Specifically, referring to FIGS. 1 to 3, when the first external mail server 211 receives the third verification response Rs3, the first original mail Mo1 is sent to the internal mail server 131 of the business network 10. ). That is, the first external mail server 211 can transmit the first original mail Mo1 to the business network 10 only when it is confirmed that the first original mail Mo1 is a normal mail. Through this, the network-separated business network 10 can receive only securely verified e-mails.

Again, referring to FIG. 4, the internal mail server 131 transmits the first original mail Mo1 to the first user 110 (S22).

Specifically, referring to FIG. 2, the internal mail server 131 may transmit the received first original mail Mo1 to the first user 110 as a person in charge. The first user 110 may receive and decrypt the encrypted first original mail Mo1. The first user 110 may decode the first original mail Mo1 and display it on the display device.

The mail system according to this embodiment performs verification of whether the mail is a normal mail in the environment of the business network 10 separated from the network through the original mail image (Ms) to proceed with the verification while maintaining the safety of the business network 10. I can. Furthermore, it is possible to improve safety maintenance by proceeding the verification in the second step of the first user 110 as a person in charge and the second user 120 as an administrator.

In addition, in the mail system according to the present embodiment, it is common for the administrator to first verify, but the first user 110, who is a person in charge who knows more about the mail, first performs the verification, and the second user 120, which is the administrator It can increase the efficiency of the overall system by lowering the work intensity of the system.

5 is a block diagram illustrating an operation of attaching a large file in a mail system according to an embodiment of the present invention.

Referring to FIG. 5, the mail system according to some embodiments of the present invention may further include a web hard server 240.

The webhard server 240 may store the large-capacity attached file Fb, and download the large-capacity attached file Fb by an external request. The internal mail server 131 may first transmit the large-capacity attachment file (Fb) to the webhard server 240 in order to send the mail to which the large-capacity attachment file (Fb) is attached. The webhard server 240 may receive a large attachment file Fb and provide a first link L1 for download to the internal mail server 131.

The internal mail server 131 may generate a second link L2 linked with the first link L1 for downloading the large attachment file Fb. The second link L2 is a link for authentication of a visitor of the link in the future, and may be redirected to the first link L1 when authentication is completed. The internal mail server 131 may transmit the second link L2 to the first external mail server 211 like the transmission mail Mso. The transmission mail Mso may include a second link L2 therein. The internal mail server 131 may store and manage the first link L1 together with the second link L2.

The first external mail server 211 may transmit the transmission mail Mso and the second link L2 to the second external mail server 221. The second external mail server 221 may transmit the transmission mail Mso to the outside through the Internet. The mail receiver 250 may receive a transmission mail (Mso) and a second link (L2) through the Internet.

The mail recipient 250 may transmit the first authentication request Rc1 to the second external mail server 221 through the second link L2 received together with the transmission mail Mso. In this case, the first authentication request Rc1 may be a request for determining whether a correct user has accessed through a correct link, and if there is a download limit or a download permission accordingly.

The second external mail server 221 may receive the first authentication request Rc1 and transmit a second authentication request Rc2 corresponding thereto to the first external mail server 211. In this case, the second authentication request Rc2 may be the same as the first authentication request Rc1, or the form and content may be different from the first authentication request Rc1.

The first external mail server 211 may receive a second authentication request Rc2. In response to the second authentication request Rc2, the first external mail server 211 may provide a password input window to the mail recipient 250. Accordingly, the mail recipient 250 may input a password. The first external mail server 211 may generate a third authentication request Rc3 including the received password and transmit the third authentication request Rc3 to the internal mail server 131.

The internal mail server 131 may receive the third authentication request Rc3 and perform authentication using the included password. In this case, the authentication of the internal mail server 131 may be performed through confirmation of the identifier (eg, ID) and password of the mail recipient 250 hidden in the second link L2 of the transmission mail Mso. However, this embodiment is not limited thereto.

If the internal mail server 131 succeeds in authentication, the internal mail server 131 may transmit the fourth authentication request Rc4 to the webhard server 240. In this case, the fourth authentication request Rc4 may include information indicating that authentication is successful in the internal mail server 131.

The webhard server 240 may issue a token Tk in response to the fourth authentication request Rc4. In this case, the token Tk may be a one-time encryption release key for preventing the large attachment file Fb from which the security is released from being downloaded even if the first link L1 is disclosed to the outside. The token Tk is a key value that can release security only once for the first time, and may not be reused after the first security release. Through this, regardless of whether the first link L1 is disclosed or not, the security of the large-capacity attached file Fb can be continuously maintained.

The internal mail server 131 may receive the token Tk and transmit a first link L1, a first authentication success response Rcs1, and a token Tk to the first external mail server 211. 1 The external mail server 211 may receive the first authentication success response Rcs1 and transmit the first link L1 and the token Tk to the second external mail server 221 in response thereto.

The second external mail server 221 may cause the mail recipient 250 to be redirected to the webhard server 240 through the transmitted first link L1. At this time, the token Tk may also be transmitted to the webhard server 240. Since such redirection is automatically performed internally, the mail recipient 250 may not know that the authentication operation and the redirection operation are performed externally.

The mail recipient 250 may automatically transmit the final download request Rf to the webhard server 240 by redirection of the first link L1. The webhard server 240 may receive a token Tk and perform a one-time security release. Accordingly, the webhard server 240 may download the large attachment file Fb to the mail recipient.

In this embodiment, a link for downloading a large-capacity attachment (Fb) is not provided directly, but authentication is performed at the internal mail server 131 of the network-separated business network 10, and the download is performed through redirection. The security of the mail system can be further strengthened.

Further, in this embodiment, when accessing a link, additional authentication is performed using a token used for one-time decryption internally, so that even if the link is disclosed, the security of the large-capacity attached file (Fb) can be maintained.

Hereinafter, a method of operating a mail system according to some embodiments of the present invention will be described with reference to FIGS. 1 to 9. Parts that overlap with the above-described embodiments are simplified or omitted.

6 is a flowchart illustrating a method of operating a mail system according to an embodiment of the present invention, and FIG. 7 is a flowchart illustrating a receiving step of FIG. 6 in detail. FIG. 8 is a flowchart for explaining the steps of generating the original mail image of FIG. 6 in detail, and FIG. 9 is a flowchart illustrating the steps of verifying the original mail image of FIG. 6 in detail.

Referring to FIG. 6, an original mail is received on an Internet network (S110).

In detail, referring to FIG. 7, an original mail is received from a second external mail server (S111).

Specifically, referring to FIGS. 1 to 3, the second external mail server 221 may receive an original mail Mo from the sender 230. At this time, since the original mail (Mo) passes through the firewall of the Internet network public subnet 220, attachment file inspection for blocking spam and APT attacks may be performed.

Again, referring to FIG. 7, the second external mail server encrypts the original mail (S112).

Specifically, referring to FIGS. 1 to 3, the second external mail server 221 may generate the first original mail Mo1 by encrypting the original mail Mo. The original mail Mo may be later transmitted to the first user 110 in the form of a first original mail Mo1 and may be decrypted when displayed on the display.

Again, referring to FIG. 6, an original mail image is generated (S120).

In detail, referring to FIG. 8, the second external mail server generates an original mail image (S121).

Specifically, referring to FIGS. 1 to 3, the second external mail server 221 may generate an original mail image Ms by capturing the body content of the original mail Mo. The original mail image (Ms) is an image file, and even if malicious code is embedded in the original mail (Mo), only the body content of the original mail (Mo) excluding the malicious code can be delivered in the form of an image.

At this time, the step of generating the first original mail (Mo1) by encrypting the original mail (Mo) (S112) and the step of generating the original mail image (Ms) by capturing the original mail (Mo) (S121) are shown in FIGS. Although shown sequentially in FIG. 8, the present embodiment is not limited thereto. That is, steps S112 and S121 may be performed in parallel with each other.

Again, referring to FIG. 8, the first external mail server receives an original mail and an original mail image (S122).

Specifically, referring to FIGS. 1 to 3, the second external mail server 221 may transmit the first original mail Mo1 and the original mail image Ms to the first external mail server 211. In this case, the first original mail Mo1 and the original mail image Ms may be transmitted to the first external mail server 211 through the firewall. The first external mail server 211 may temporarily store the first original mail Mo1 and the original mail image Ms.

Again, referring to FIG. 8, the original mail image is transmitted to the business network (S123).

Specifically, referring to FIGS. 1 to 3, the first external mail server 211 may first transmit the original mail image Ms to the business network 10 separated from the network. The original mail image Ms may be transmitted to the internal mail server 131 of the business network 10.

Again, referring to FIG. 6, the original mail image is verified (S130).

In detail, referring to FIG. 9, the original mail image is first verified (S131).

Specifically, referring to FIGS. 1 to 3, the internal mail server 131 first provides an original mail image Ms to the first user 110, and sends a first verification request Rq1 to the first user 110 ). The first user 110 may receive the first verification request Rq1 and verify whether the first original mail Mo1 is normal by verifying the original mail image Ms. Since the first user 110 can best verify whether the first original mail Mo1 is a normal mail as an actual recipient of the first original mail Mo1, the first user 110 may perform the verification first.

If verification of the original mail image Ms by the first user 110 fails, that is, if the first original mail Mo1 is determined to be an abnormal mail, the mail may be deleted (S150 in FIG. 6 ).

Again, referring to FIGS. 1 to 3 and 9, if the verification of the original mail image Ms is successful by the first user 110, the original mail image is secondarily verified (S132).

When receiving the first verification response Rs1 indicating that the first original mail Mo1 is normal, the internal mail server 131 may transmit the original mail image Ms to the second user 120. In this case, the internal mail server 131 may transmit the second verification request Rq2 together with the original mail image Ms. The second user 120 may receive the second verification request Rq2 and verify whether the first original mail Mo1 is normal by verifying the original mail image Ms. If the first original mail Mo1 is normal, the second user 120 may transmit the second verification response Rs2 to the internal mail server 131.

If, by the second user 120, verification of the original mail image Ms fails, that is, if the first original mail Mo1 is determined to be an abnormal mail, the mail may be deleted (S150 in FIG. 6).

Again, referring to FIGS. 1 to 3 and 6, if the verification of the original mail image Ms by the second user 120 is successful, the original mail is received through the work network (S140).

The internal mail server 131 may receive the first original mail Mo1 from the Internet network 20. Subsequently, the internal mail server 131 may transmit the received first original mail Mo1 to the first user 110 as a person in charge.

In the method of operating the mail system according to the present embodiment, only secure mails can be received through a separate business network by safely verifying mails in a network-separated environment.

Hereinafter, an operation of attaching a large file to a mail system according to some embodiments of the present invention will be described with reference to FIG. Parts that overlap with the above description will be simplified or omitted.

10 is a flowchart illustrating an operation of attaching a large file in a method of operating a mail system according to an embodiment of the present invention.

5 and 10, a large attachment file is uploaded to the webhard server (S210).

That is, the internal mail server 131 may first transmit the large-capacity attachment file (Fb) to the webhard server 240 in order to send the mail with the large-capacity attachment file (Fb) attached. The webhard server 240 may transmit the first link L1 for this to the internal mail server 131.

Subsequently, a transmission mail including a link is generated (S220).

That is, the internal mail server 131 may generate a transmission mail (Mso) including a link for downloading a large attachment file (Fb). In this case, the internal mail server 131 may generate a second link L2 that is interlocked with the first link L1 and performs authentication, and may include it in the transmission mail Mso.

Then, the transmission mail is transmitted (S230).

That is, the internal mail server 131 may transmit the transmission mail Mso to the first external mail server 211. The first external mail server 211 may transmit the transmission mail Mso to the second external mail server 221. The second external mail server 221 may transmit the transmission mail Mso to the outside through the Internet. The mail recipient 250 may receive a transmission mail (Mso) through the Internet.

Then, an authentication request is received (S240).

That is, the mail recipient may transmit the first authentication request Rc1 to the second external mail server 221 through the second link L2 included in the transmission mail Mso. In this case, the first authentication request Rc1 may be a request for determining whether a correct user has accessed through a correct link, and if there is a download limit or a download permission accordingly.

Subsequently, it is determined whether it is authenticated (S250).

That is, the second external mail server 221 may receive the first authentication request Rc1 and transmit a second authentication request Rc2 corresponding thereto to the first external mail server 211. The first external mail server 211 receives the second authentication request (Rc2), and sends a third authentication request (Rc3) including the password received through the password reception window to the mail recipient 250 to the internal mail server 131 Can be transferred to.

The internal mail server 131 may perform an authentication procedure using the received password, and may transmit a fourth authentication request Rc4 to the webhard server 240 when authentication is successful. The webhard server 240 may issue a token Tk in response to the fourth authentication request Rc4 and transmit the token Tk to the internal mail server 131.

In this case, if authentication fails, the procedure may be terminated.

If authentication is successful, the internal mail server 131 may transmit the first authentication success response Rcs1, the token Tk, and the first link L1 to the first external mail server 211. The first external mail server 211 may transmit the token Tk and the first link L1 to the second external mail server 212.

Subsequently, the link is redirected to the webhard server (S260).

The second external mail server 221 may cause the mail recipient 250 to be redirected to the webhard server 240 through the transmitted first link L1. The mail recipient 250 may automatically transmit a final download request (Rf) to the webhard server 240 by redirection. At this time, the token Tk may also be transmitted to the webhard server 240.

The webhard server 240 may perform authentication through the token Tk, and if the authentication is successful, download the large-capacity attachment Fb only once.

That is, if the authentication is successful, the large-capacity attached file of the webhard server is downloaded (S270).

The webhard server 240 may download the large-capacity attachment Fb to the mail recipient 250 only once by authentication of the token Tk.

In the method of operating the mail system according to the present exemplary embodiment, a link for downloading a large-capacity attachment Fb is not provided, and a redirection is performed after internal authentication to maintain security in a network-separated environment.

The above description is merely illustrative of the technical idea of the present embodiment, and those of ordinary skill in the technical field to which the present embodiment pertains will be able to make various modifications and variations without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are not intended to limit the technical idea of the present embodiment, but to explain the technical idea, and the scope of the technical idea of the present embodiment is not limited by these embodiments. The scope of protection of this embodiment should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present embodiment.

Claims (15)

A first network and a second network that are physically separated from each other, are given different access rights, and are capable of restrictively exchanging data with each other through an inter-network transmission system;
An external mail server accessing the second network, receiving an original mail, and generating an original mail image capturing the original mail; And
Includes an internal mail server for receiving the original mail after accessing the first network, receiving and verifying the original mail image,
The first network is a business network, which is a closed network that allows limited access only to workers, and direct reception and transmission of the original mail is not possible,
The second network is an Internet network capable of external access and directly receiving and sending the original mail to and from the outside.
The method of claim 1,
The internal mail server,
Transmitting a verification request to a first user accessing the first network and a second user different from the first user, a first verification response to the original mail image from the first user, and the second user A mail system that receives the original mail only when all of the second verification responses for the original mail image are received.
The method of claim 1,
The external mail server,
A second external mail server generating the original mail image;
A first external mail for temporarily storing the original mail and the original mail image, transmitting the original mail image to the internal mail server, and transmitting the original mail to the internal mail server when verification is completed from the internal mail Including server
Mail system.
The method of claim 3,
The second external mail server encrypts the original mail
Mail system.
The method of claim 3,
The second network,
An internet network server farm including the first external mail server,
Including an Internet network public subnet including the second external mail server,
The Internet network server farm and the Internet network public subnet transmit data to each other through a firewall.
Mail system.
The method of claim 1,
Further comprising a web hard server for storing a large-capacity attachment file from the internal mail server
Mail system.
The method of claim 6,
The web hard server connects to the second network and provides the large-capacity attached file through a link.
Mail system.
The method of claim 7,
The external mail server verifies the visitor of the link and, when the verification is completed, redirects the visitor to the webhard.
Mail system.
In a method of operating a mail system including a first network and a second network, which are physically separated from each other, are given different access rights, and can exchange data restrictively with each other through an inter-network transmission system,
Receiving an original mail in the second network;
Capturing the original mail to generate the original mail image;
Verifying the original mail image by transmitting the original mail image to the first network; And
When the original mail image is verified, transmitting the original mail to the first network,
The first network is a business network, which is a closed network that allows limited access only to workers, and direct reception and transmission of the original mail is not possible,
The method of operating a mail system, wherein the second network is an Internet network capable of external access and directly receiving and sending the original mail to and from the outside.
The method of claim 9,
The step of verifying the original mail image,
Receiving a first verification result of a first user accessing the first network; and
Accessing the first network and receiving a second verification result of a second user different from the first user,
Transmitting the original mail to the first network,
A method of operating a mail system that is performed only when both the first verification result and the second verification result are received.
The method of claim 10,
The first user is the person in charge of the original mail,
The second user is a user different from the person in charge, and is an administrator with mail approval authority.
How the mail system works.
The method of claim 9,
The second network connects to a first external mail server and a second external mail server,
Receiving the original mail in the second network,
Receiving, by the second external mail server, the original mail,
Encrypting the original mail by the second external mail server
How the mail system works.
The method of claim 12,
The second network,
An internet network server farm including the first external mail server,
Including an Internet network public subnet including the second external mail server
How the mail system works.
The method of claim 13,
The Internet network server farm and the Internet network public subnet transmit data to each other through a firewall.
How the mail system works.
The method of claim 9,
Uploading a large attachment file to the webhard server,
Generating a transmission mail including a link,
Transmitting the transmission mail;
Receiving an authentication request;
If authenticated, redirecting the link to the webhard server,
Including the step of downloading the large attachment file
How the mail system works.

Images