JP4652153B2 - Email filtering system, email filter, and program - Google Patents

Description

  The present invention relates to a mail filtering system, a mail filter, and a program for filtering electronic mail.

  In recent years, phishing scams using phishing mail are increasing. Phishing emails are emails that are sent to an unspecified number of users, pretending to be regular emails from financial institutions, etc., and are sent mainly in the form of HTML (Hyper Text Markup Language) emails. . A phishing scam is a URL (Uniform Resource Locator) of a harmful website that is different from a legitimate harmless website such as a financial institution in the link part of a phishing email. This is an act of illegally acquiring a credit card number, a user ID / password, and the like.

Many techniques for performing processing such as discarding such phishing mail by filtering have been disclosed. For example, in Patent Document 1, a URL of a harmful website is registered in advance, and if the URL set in the link part of the email is a URL of the harmful website registered in advance, the URL is discarded. A technique for performing such processing is disclosed.
JP 2004-102662 A

  However, the technique disclosed in Patent Document 1 targets only sites that have URLs registered in advance among harmful Web sites. In other words, even if it is a harmful website, unless the URL is registered, processing such as discarding cannot be performed on the e-mail.

  The number of harmful Web sites that actually exist is considered enormous, and it is almost impossible to register URLs by grasping all of them. Also, even if a URL is registered for a certain harmful website, the harmful website periodically changes the URL. Therefore, if the URL is changed, the already registered URL has no meaning.

  Therefore, an object of the present invention is to perform specific processing such as discarding an e-mail in which the URL of the harmful website is set in the link portion without registering the URL of the harmful website. To provide a mail filtering system, a mail filter, and a program.

  The mail filtering system of the present invention includes an authentication server and a mail filter.

According to a first aspect of the invention,
The authentication server is
An authentication information management unit that pre-registers authenticated ones of combinations of display contents actually displayed in the link part of the e-mail and link destination URLs that are actual link destinations of the link parts;
A matching unit that checks whether the combination is registered as an authenticated one in the authentication information management unit in response to the matching request for the combination;
The email filter
An extraction unit that extracts the combination of the display content and the link destination URL from the link part of the received email when receiving the email;
A verification request unit for transmitting a verification request to the authentication server as to whether the combination extracted from the link part of the email by the extraction unit is registered in the authentication server;
If it is determined that the combination extracted from the link part of the email by the extraction unit is not registered as an authenticated one in the authentication server based on the verification result by the authentication server, And a mail processing unit for performing a specific process set in advance.

According to a second aspect of the invention,
The authentication server is
Of the combinations of the display content actually displayed in the link part of the e-mail and the link destination URL that is the actual link destination of the link part, an authenticated one is registered in advance, and an acquisition request for the authenticated combination is made. And a first authentication information management unit that transmits the pre-registered authenticated combination to the request source of the acquisition request,
The email filter
A second authentication information management unit that periodically sends an acquisition request for the authenticated combination to the authentication server, and registers the authenticated combination that has been transmitted from the authentication server in response to the acquisition request;
An extraction unit that extracts the combination of the display content and the link destination URL from the link part of the received email when receiving the email;
A collation unit for collating whether the combination extracted from the link part of the email by the extraction unit is registered as an authenticated one in the second authentication information management unit;
When it is determined that the combination extracted from the link part of the e-mail by the extraction unit is not registered as the authenticated one in the second authentication information management unit based on the collation result by the collation unit, And a mail processing unit that performs a predetermined process for the electronic mail.

  Note that the mail processing unit may perform processing for discarding an email as the specific processing, or may perform processing for editing the email subject and / or the content of the email text.

  According to the present invention, in the authentication server, the authenticated combination is registered in advance among the combinations of the display content displayed in the link portion of the e-mail and the link destination URL that is the link destination of the link portion. If the combination extracted from the received electronic mail is not an authenticated one registered in advance in the authentication server, specific processing is uniformly performed for all such electronic mail.

  Therefore, there is an effect that it is possible to perform specific processing such as discarding the electronic mail in which the link portion to the harmful website is set without registering the URL of the harmful website.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(First embodiment)
Referring to FIG. 1, a mail filtering system according to a first embodiment of the present invention includes a registration terminal 10, an authentication server 20, a mail filter 30, a mail filter management terminal 40, a mail server 50, and a mail receiving terminal. 60 and a mail transmission terminal 70, and each of these components operates under program control. The registration terminal 10, the authentication server 20, the mail filter 30, and the mail transmission terminal 70 are connected to each other via a network 80 such as the Internet. A mail filter management terminal 40 and a mail server 50 are connected to the mail filter 30, and a mail receiving terminal 60 is connected to the mail server 50.

  In an e-mail, the display content that is actually displayed in the e-mail and the link destination URL that is actually linked by clicking the link part are set in the link part indicating that the URL is linked. Has been. The present invention focuses on the combination of the display content of the link part and the link destination URL in the electronic mail.

  The registration terminal 10 is a computer of an organization that makes an application for authentication for a combination of display contents set in a link portion of an e-mail and a link destination URL. If the organization is a user, the registration terminal 10 is installed in the user's home or the like. If the organization is a company, the registration terminal 10 is installed in the company. The registration terminal 10 displays an application form for an authentication application of a combination of an operation unit 11 to which various information is input, a display unit 12 to display various information, and a display content of a link part and a link destination URL. The application form requesting unit 13 for requesting the application and the application information transmitting unit 14 for transmitting to the authentication server 20 the application information related to the authentication application combination input in the application form.

  The authentication server 20 is a computer installed in a public institution that takes measures against phishing emails or an organization equivalent thereto. The authentication server 20 manages an application form for authentication application, and transmits an application form management unit 21 to be transmitted when requested by the registration terminal 10 and application information for temporarily registering and managing application information from the registration terminal 10 When the combination of the display content of the link part applied for authentication from the management unit 22 and the registration terminal 10 and the link destination URL is authenticated by the public institution or the like, it is registered and managed as authentication information related to the authenticated combination. The combination of the display content of the link part requested to be verified by the mail filter 30 and the link destination URL and the link destination URL is registered in the authentication information management part 23 as authenticated authentication information. And a collation unit 24 that transmits the collation result to the mail filter 30.

  The mail filter 30 is a computer installed in the front stage of the mail server 50 that accepts an electronic mail transmitted from the mail transmission terminal 70 to the mail reception terminal 60. The mail filter 30 manages the setting form for setting the processing method of unauthenticated mail (the link part set in the e-mail is unauthenticated), and transmits it when requested by the mail filter management terminal 40. A setting form management unit 31, a setting information management unit 32 for registering and managing setting information related to a method for processing unauthenticated mail from the mail filter management terminal 40, and a mail receiving unit for receiving an e-mail from the mail sending terminal 70 33, an extraction unit 34 for extracting a combination of the display content of the link part set in the received electronic mail and the link destination URL, and the display content extracted from the link part of the electronic mail and the link destination URL The verification request unit 35 that requests the authentication server 20 to verify whether or not the combination is authenticated, and the verification result by the authentication server 20 In addition, when it is determined that the combination of the display content extracted from the link part of the email and the link destination URL has been authenticated, a process for transmitting the email is performed, and when it is not authenticated, mail filter management is performed. A mail processing unit 36 that performs specific processing such as discarding and editing on the e-mail according to the setting information of the processing method of the unauthenticated mail set by the terminal 40 and registered in the setting information management unit 32 Yes.

  The mail filter management terminal 40 is a computer installed on the side of a system administrator (which may be a public institution that takes measures against phishing mail or an organization equivalent thereto). The mail filter management terminal 40 has an operation unit 41 for inputting various information, a display unit 42 for displaying various information, and a setting form request for requesting the mail filter 30 a setting form for setting a processing method for unauthenticated mail. And a setting information transmitting unit 44 that transmits the setting information input in the setting form to the mail filter 30.

  The mail server 50 is a computer installed in an Internet provider or the like. The mail server 50 sends an e-mail that has passed through the mail filter 30 among e-mails sent from the mail sending terminal 70 to the mail receiving terminal 60 (e-mails that have passed through the mail filter 30 as they are, or edited by the mail filter 30). A mail receiving unit 51 that receives the received e-mail) and a mail distribution unit 52 that distributes the e-mail received by the mail receiving unit 51 to the mail receiving terminal 60 according to the mail address. .

  The mail receiving terminal 60 is a computer such as a home personal computer installed in the recipient's home or a mobile phone terminal having an Internet connection function carried by the recipient. The mail receiving terminal 60 includes an operation unit 61 for inputting various information, a display unit 62 for displaying various information, and a mail receiving unit 63 for receiving electronic mail.

  The mail transmission terminal 70 is a computer such as a home personal computer installed in the sender's home or a mobile phone terminal having an Internet connection function carried by the sender. The mail transmission terminal 70 includes an operation unit 71 for inputting various types of information, a display unit 72 for displaying various types of information, a mail generation unit 73 for generating an electronic mail, and a mail transmission unit 74 for transmitting an electronic mail. Have.

  FIG. 1 illustrates the internal configuration of the registration terminal 10, the authentication server 20, the mail filter 30, the mail filter management terminal 40, the mail server 50, the mail reception terminal 60, and the mail transmission terminal 70 for implementing the present invention. Only the structure of the main part is shown. That is, in practice, other general elements (for example, a mail creation unit provided in the mail receiving terminal 60) are also provided, but these are not essential parts of the present invention. For the sake of convenience, it is omitted from FIG.

  Hereinafter, the operation of the mail filtering system of this embodiment will be described. In the following description, the e-mail is assumed to be an HTML mail. However, the present invention is not limited to this, and can be applied to ordinary e-mail as long as a link portion representing a link to a URL is set. It goes without saying that it is possible.

  First, an operation when an organization that performs an authentication application makes an authentication application for a combination of display contents of a link portion set in an HTML mail and a link destination URL, and registers the combination as authentication information in the authentication server 20 explain.

  Referring to FIG. 2, an organization that applies for authentication first inputs an acquisition request for an application form for authentication application to the operation unit 11 of the registration terminal 10. In response to this, in the registration terminal 10, the application form request unit 13 accesses a Web site established by the authentication server 20 via the network 80 (step A1). Thereafter, the application form request unit 13 transmits an application form acquisition request to the authentication server 20 based on the contents input to the operation unit 11 by the organization.

  Next, in the authentication server 20, the application form management unit 21 transmits the application form to the registration terminal 10 via the network 80 (step A2).

  Next, in the registration terminal 10, the application form transmitted from the authentication server 20 in step A2 is received by the application form request unit 13 and displayed on the display unit 12 (step A3). In response to this, the organization inputs application information including the display contents of the link part to be applied for authentication and the link destination URL in the application form displayed in step A3 (step A4).

  For example, as shown in FIG. 3, the organization inputs the display content “Nakao Shokai” and the link destination URL “http://hide.com” in the corresponding text box for the link part for which the application for authentication is performed, In addition, the organization name, address, telephone number, and representative of the organization are entered in the corresponding text boxes.

  Further, the organization inputs an instruction to transmit the application information input in step A4 to the authentication server 20 to the operation unit 11 of the registration terminal 10 (for example, clicks the “application” button in FIG. 3 with a mouse). In response to this, in the registration terminal 10, the application information transmission unit 14 transmits the application information input in step A4 to the authentication server 20 via the network 80 (step A5).

  In the authentication server 20, the application information transmitted from the registration terminal 10 in step A5 is received by the application information management unit 22 and temporarily registered (step A6).

  Here, a public institution that takes measures against phishing emails and an organization equivalent thereto deliberates whether the application information temporarily registered in the application information management unit 22 is appropriate. For example, it is deliberated whether the link destination URL of the link part, the organization information, etc. match the information managed by the Japan Network Information Center (JPNIC) or the like, and whether the display content of the link part is appropriate.

  If the application information temporarily registered in the application information management unit 22 is appropriate as a result of the deliberation, then the authentication information management unit 23 authenticates the application information temporarily registered in the application information management unit 22. It is registered as authentication information of the completed link part (step A7).

  In this way, in the authentication server 20, authentication information related to the combination of the display contents of the authenticated link portion set in the HTML mail and the link destination URL is registered in the authentication information management unit 23.

  Next, the operation when setting the processing method of unauthenticated mail in the mail filter 30 will be described.

  Referring to FIG. 4, the system administrator first inputs an acquisition instruction for a setting form for setting a processing method for unauthenticated mail in the mail filter 30 to the operation unit 41 of the mail filter management terminal 40. In response, in the mail filter management terminal 40, the setting form request unit 43 accesses the mail filter 30 by HTTP connection or the like (step B1). Thereafter, the setting form request unit 43 transmits a setting form acquisition request to the authentication server 20 based on the contents input to the operation unit 41 by the system administrator.

  Next, in the mail filter 30, the setting form management unit 31 transmits the setting form to the mail filter management terminal 40 (step B2).

  Next, in the mail filter management terminal 40, the setting form transmitted from the mail filter 30 in step B2 is received by the setting form request unit 43 and displayed on the display unit 42 (step B3). In response, the system administrator inputs setting information such as the type of processing method for unauthenticated mail to the operation unit 41 in the setting form displayed in step B3 (step B4).

  For example, as shown in FIG. 5, the system administrator sets “edit” for editing the mail subject and the mail body of the unauthenticated mail as the processing method for the non-authenticated mail, and further, as the mail subject editing method, Completely edit the mail subject to the given information “★ This email is suspicious ★”, and as an editing method for the unauthenticated link part, “→→ This link may be dangerous →→” Set to give. In FIG. 5, it is possible to set “ignore” for transmitting unauthenticated mail as it is and “discard” for discarding unauthenticated mail as a processing method for unauthenticated mail. However, in order to prevent phishing using the mail filtering system of the present embodiment, “pass” cannot be selected as the processing method for unauthenticated mail. Therefore, in order to prevent phishing fraud, it is possible to select only one of the two methods of processing non-authenticated mail, “Discard” and “Edit”.

  Further, the system administrator inputs an instruction to transmit the setting information input in step B4 to the mail filter 30 to the operation unit 41 of the mail filter management terminal 40 (for example, click the “setting” button in FIG. 5 with the mouse). To do). In response to this, in the mail filter management terminal 40, the setting information transmitting unit 44 transmits the setting information input in step B4 to the mail filter 30 (step B5).

  Thereafter, in the mail filter 30, the setting information management unit 32 receives and registers the setting information transmitted from the mail filter management terminal 40 in step B5 (step B6).

  In this way, in the mail filter 30, the setting information on the processing method of the non-authenticated mail when the non-authenticated mail is received is registered in the setting information management unit 32.

  Next, an operation when an authenticated mail (a link part included in an e-mail is authenticated) is transmitted from the mail transmitting terminal 70 to the mail receiving terminal 60 will be described.

  Referring to FIG. 6, in the mail transmission terminal 70, the mail creating unit 73 creates an HTML mail in which an authenticated link part is set based on the content input to the operation unit 71 by the sender (step C1).

  For example, as shown in FIG. 7, an HTML mail in which “Nakao Shokai” is a link portion is created. This HTML mail is described in the HTML language, and the source of the “Nakao Shokai” part is as shown in FIG. That is, in the HTML mail shown in FIG. 7, the “Nakao Shokai” that is the link part is displayed by “a-TAG” and the “http: // hide” of the actual link destination URL of the display contents by the a-TAG. .com "is set.

  Next, in the mail transmitting terminal 70, the mail transmitting unit 74 transmits the HTML mail created in Step C1 to the mail receiving terminal 60 via the network 80 (Step C2). This HTML mail is temporarily received by the mail filter 30 installed at the front stage of the mail server 50.

  Next, in the mail filter 30, when the HTML mail transmitted from the mail transmitting terminal 70 in step C2 is received by the mail receiving unit 33, the extracting unit 34 searches for the a-TAG described above, and the a-TAG. The display content “Nakao Shokai” set in the link part by the TAG and the link destination URL “http://hide.com” are extracted (step C3). Next, the collation request unit 35 requests the collation whether the combination of the display content of the link part extracted in step C3 and the link destination URL is authenticated or not via the network 80. To the authentication server 20 (step C4).

  Next, in the authentication server 20, the collation unit 24 matches the authentication information registered in the authentication information management unit 23 in step A7 of FIG. 2 with the combination of the display content of the link part from the mail filter 30 and the link destination URL. By searching whether or not the combination is authenticated, it is collated (step C5), and the collation result is returned to the mail filter 30 via the network 80 (step C6).

  In the mail filter 30, the mail processing unit 36 receives the collation result from the authentication server 20, and based on the collation result, whether the HTML mail received in step C2 is an authenticated mail or an unauthenticated mail. And the processing method of the HTML mail is determined (step C7). Here, since the combination of the display content of the link part set in the received HTML mail and the link destination URL is already authenticated, it is determined as an authenticated mail, and further, the processing method is determined as “transparent”, and the HTML is determined. The mail is directly transmitted to the mail server 50 (step C8).

  In the mail server 50, when the HTML mail that has passed through the mail filter 30 is received by the mail receiving unit 33, the mail distribution unit 52 distributes the HTML mail to the mail receiving terminal 60 that is the distribution destination (step C9).

  Thereafter, in the mail receiving terminal 60, the HTML mail distributed from the mail server 50 is received by the mail receiving unit 63 (step C10), and displayed on the display unit 62 in accordance with the content input to the operation unit 61 by the recipient. Is done.

  In this way, the mail receiving terminal 60 can receive HTML mail that has been authenticated by the authentication server 20 and has a secure link portion set without being conscious of it.

  Next, an operation when an unauthenticated mail is transmitted from the mail transmitting terminal 70 to the mail receiving terminal 60 will be described.

  Referring to FIG. 9, in the mail transmission terminal 70, the mail creating unit 73 creates an HTML mail in which a non-authenticated link portion is set based on the content input to the operation unit 71 by the sender (step D1).

  For example, as shown in FIG. 10, an HTML mail in which “Nakao Shokai” is a link portion is created. This HTML mail is described in the HTML language, and the source of the “Nakao Shokai” part is as shown in FIG. That is, in the HTML mail shown in FIG. 10, the display content “Nakao Shokai” in the link portion looks the same as the authenticated display content, but the actual link destination URL is different from the authenticated one. http://nusutto.tv ”is set.

  Next, in the mail transmitting terminal 70, the mail transmitting unit 74 transmits the HTML mail created in step D1 to the mail receiving terminal 60 via the network 80 (step D2). This HTML mail is temporarily received by the mail filter 30 installed at the front stage of the mail server 50.

  In the mail filter 30, when the HTML mail from the mail transmitting terminal 70 is received by the mail receiving unit 33, the extracting unit 34 searches for the a-TAG described above and is set as a link part by the a-TAG. The displayed content “Nakao Shokai” and the actual link destination URL “http://nusutto.tv” are extracted (step D3). Next, the collation request unit 35 requests the collation whether or not the combination of the display content of the link portion extracted in step D3 and the link destination URL has been authenticated via the network 80. To the authentication server 20 (step D4).

  In the authentication server 20, the collation unit 24 checks whether the combination of the display content of the link portion from the mail filter 30 and the link destination URL matches the authentication information registered in the authentication information management unit 23 in step A8 of FIG. By searching, whether or not the combination is authenticated is collated (step D5), and the collation result is returned to the mail filter 30 via the network 80 (step D6).

  In the mail filter 30, the mail processing unit 36 receives the collation result from the authentication server 20, and based on the collation result, whether the HTML mail received in step D2 is an authenticated mail or an unauthenticated mail. Further, the HTML mail processing method is determined (step D7). Here, since the combination of the display content of the link portion set in the received HTML mail and the link destination URL is non-authenticated, the received HTML mail is determined to be non-authenticated mail. Further, the non-authenticated mail processing method is determined based on the setting information registered in the setting information management unit 32 in step B6 of FIG. Here, it is determined that the editing is performed with the editing contents as shown in FIG. 5, the received HTML mail is edited into the HTML mail as shown in FIG. 12 (step D8), and the edited HTML mail is sent to the mail server. 50 (step D9).

  In the mail server 50, when the HTML mail transmitted from the mail filter 30 is received by the mail receiving unit 33, the mail distribution unit 52 distributes the HTML mail to the mail receiving terminal 60 as a distribution destination (step D10). .

  Thereafter, in the mail receiving terminal 60, the HTML mail distributed from the mail server 50 is received by the mail receiving unit 63 (step D11), and displayed on the display unit 62 according to the input contents to the operation unit 61 by the receiver. Is done.

  In this way, in the mail receiving terminal 60, it is confirmed that the combination of the display content of the link part set in the HTML mail and the link destination URL is a dangerous one that has not been authenticated by the authentication server 20. Since it is explicitly shown in the text, the recipient of the mail receiving terminal 60 will read the HTML mail with great care, and it will be easy with the link destination URL set in the unauthenticated link portion. It is possible to prompt the user not to enter personal information.

  In FIG. 9, the processing method for unauthenticated mail is described as being set to “edit” of the editing content as shown in FIG. 5, but the received HTML mail is set to “discard”. Can be discarded in the next stage of step D7 so that HTML mail is not distributed to the mail receiving terminal 60.

  As described above, in the present embodiment, in the authentication server 20, the combination of the display content displayed in the link portion of the email and the link destination URL that is the link destination of the link portion is not a combination of harmful websites, If a combination of authenticated and harmless websites is registered in advance and the combination extracted from the received e-mail in the mail filter 30 is not an authenticated one registered in the authentication server 20 in advance, such electronic Perform specific processing such as discarding all emails uniformly.

  Therefore, without registering the combination of the display content of the link part representing the link to the harmful website and the link destination URL, the e-mail in which the link part to the harmful website is set can be discarded. Specific processing can be performed.

  If this is viewed from a phishing company that performs phishing, the contents of a link to a harmful website set in the phishing mail can be used to pass the phishing mail without performing any specific processing such as discarding by the mail filter 30. And the link destination URL must be registered in the authentication server 20.

  However, in this embodiment, even if there is an authentication application for a combination related to a harmful website, such a combination is not authenticated and registered. Therefore, even when a phishing email with a link to a newly generated harmful website or a URL with a URL change is received, a specific process such as discarding such phishing email is performed. It can be done reliably.

  Also, in this embodiment, the link destination URL of an authenticated and harmless website is not registered alone, but is registered as a combination with the display content of the link portion. It is possible to prevent setting a link destination different from the actual display content in the link portion of the mail.

  More specifically, for example, if a process for discarding an e-mail is performed as a specific process, the e-mail recipient always has an authenticated and safe display content and a link destination URL set in the link part. E-mail can be received without being conscious. In addition, as a specific process, if you edit the email, you can explicitly indicate in the email subject or email body that the link part is not authenticated. It is considered that an e-mail is read with great care and care is taken not to easily input personal information at the link destination URL set in the link portion.

  As described above, in this embodiment, it is possible to prevent a user from receiving a phishing mail or being guided from a phishing mail to a harmful website, and thus, information such as a user's credit card number is completely guaranteed. Can be expected to contribute to society as a means of protecting users from phishing scams.

  In the present embodiment, since the mail filter 30 is installed in front of the mail server 50, when a plurality of mail servers 50 are provided, the HTML mail for each of the plurality of mail servers 50 is an unauthenticated mail. It is possible to check whether or not there is a few mail filters 30.

  In this embodiment, the mail filter 30 performs collation processing for collating whether or not HTML mail is unauthenticated mail, and the mail server 50 performs mail reception processing. Since the processing is performed by separate devices, the collation processing can be performed without affecting the mail server 50.

(Second Embodiment)
In the first embodiment, the mail filter 30 requests the authentication server 20 to check whether the combination of the display content extracted from the link portion of the email and the link destination URL has been authenticated, and the authentication server 20 Verification was done by searching for authentication information.

  On the other hand, in the second embodiment of the present invention, the mail filter 30A periodically acquires and registers the authentication information of the authentication server 20A, and searches for the registered authentication information to link the HTML mail. The difference from the first embodiment is that the combination of the display content extracted from the part and the link destination URL is verified.

  Referring to FIG. 13, the mail filtering system according to the second embodiment of the present invention is different from the first embodiment of FIG. 1 in that the authentication server 20A and the mail are used instead of the authentication server 20 and the mail filter 30, respectively. The difference is that a filter 30A is provided.

  The authentication server 20A is different from the authentication server 20 of FIG. 1 in that the verification unit 24 is deleted.

  Compared with the mail filter 30 of FIG. 1, the mail filter 30A deletes the verification request unit 35, and instead, an authentication information management unit 37 that periodically acquires and registers authentication information of the authentication server 20A, and an authentication A collation unit that collates whether the combination of the display content extracted from the link portion of the HTML mail by the extraction unit 34 and the link destination URL has been authenticated by searching the authentication information registered in the information management unit 37 The difference is that 38 is newly added.

  Hereinafter, the operation of the mail filtering system of this embodiment will be described. In the following description, the e-mail is assumed to be an HTML mail. However, the present invention is not limited to this, and can be applied to ordinary e-mail as long as a link portion representing a link to a URL is set. It goes without saying that it is possible.

  However, the operation when the organization that performs the authentication application performs an authentication application for the combination of the display content of the link portion displayed in the HTML mail and the link destination URL, and registers the combination as authentication information in the authentication server 20A (FIG. 2). Steps A1 to A7) and the operation (steps B1 to B6 in FIG. 4) when setting the processing method for unauthenticated mail in the mail filter 30 are the same as those in the first embodiment, and thus the description thereof is omitted. To do.

  First, an operation when the mail filter 30A acquires and registers authentication information of the authentication server 20A will be described.

  Referring to FIG. 14, in the mail filter 30A, when the authentication information management unit 37 reaches a predetermined time (for example, AM: 04:00 every day) (step E1), the authentication server via the network 80 An authentication information acquisition request is transmitted to 20A (step E2).

  Next, in the authentication server 20 </ b> A, the authentication information management unit 23 sends a mail filter via the network 80 for all combinations of the display contents of the link part registered as the authenticated authentication information at that time and the link destination URL. Transmit to 30A (step E3).

  Thereafter, in the mail filter 30A, the authentication information management unit 37 receives and registers all combinations of the display contents of the authenticated link portion transmitted from the authentication server 20 in step E3 and the link destination URL (step E4). .

  Next, an operation when an authenticated mail or an unauthenticated mail is transmitted from the mail transmitting terminal 70 to the mail receiving terminal 60 will be described.

  Referring to FIG. 15, in mail transmitting terminal 70, mail creating unit 73 creates an HTML mail that includes an unauthenticated or authenticated link part (step F1), and mail sending unit 74 is created in step D1. The HTML mail is transmitted to the mail receiving terminal 60 via the network 80 (step F2). This HTML mail is temporarily received by the mail filter 30A installed at the front stage of the mail server 50.

  In the mail filter 30A, when the HTML mail from the mail transmitting terminal 70 is received by the mail receiving unit 33, the extracting unit 34 extracts the display content and the actual link destination URL from the link part of the HTML mail (step F3). Next, the collation unit 38 searches whether the combination of the display content extracted from the link part of the HTML mail and the link destination URL matches the authentication information registered in the authentication information management unit 37 in step E4 of FIG. Thus, it is verified whether or not the combination has been authenticated (step F4). Next, the mail processing unit 36 determines whether the HTML mail received in Step F2 is an authenticated mail or an unauthenticated mail based on the collation result by the collation unit 38, and further, the HTML mail A processing method is determined (step F5). For example, if the received HTML mail is determined to be an authenticated mail, the processing method is determined to be “transparent”, and if it is determined to be an unauthenticated mail, the setting information registered in the setting information management unit 32 in step B6 of FIG. The processing method is determined as “transparent”, “discard”, “edit”, or the like.

  Thereafter, in the mail filter 30A, the mail processing unit 36 performs operations (“transparent”, “discard”, “edit”, etc.) according to the processing method determined in step F5 (step F6). Note that the operations in Step F6 and the subsequent steps are the same as the operations in the first embodiment (Steps C8 to C10 in FIG. 6 and Steps D8 to D11 in FIG. 9), and thus description thereof is omitted.

  As described above, in the present embodiment, in addition to being able to obtain the same effects as those of the first embodiment, the mail filter 30A triggers reception of HTML mail from the mail transmission terminal 70 to the authentication server 20A. Since the procedure for making a collation request is omitted, filtering can be performed efficiently.

  In the present invention, the mail filter 30 of the first embodiment and the mail filter 30A of the second embodiment are for realizing the functions other than those realized by the dedicated hardware resources described above. The program may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by the mail filters 30 and 30A. The computer-readable functional recording medium refers to a recording medium such as a floppy disk, a magneto-optical disk, a CD-ROM, or a storage device such as a hard disk device (not shown) built in the mail filters 30 and 30A.

  In the present invention, a program for realizing the functions of the above-described mail filters 30 and 30A may be read by the mail receiving terminal 60 and executed. In this case, since the mail receiving terminal 60 also functions as the mail filters 30 and 30A, the mail filters 30 and 30A can be omitted. As a result, a place for installing the mail filters 30 and 30A becomes unnecessary, and the investment for purchasing the mail filters 30 and 30A can be kept low.

It is a figure which shows the structure of the mail filtering system of the 1st Embodiment of this invention. 3 is a flowchart for explaining an operation in the case of registering, in the authentication server, a combination of display contents of a link portion set in HTML mail and a link destination URL in the mail filtering system shown in FIG. 1. It is a figure which shows an example of the application information input into the application form in step A4 shown in FIG. 2 is a flowchart for explaining an operation when setting a processing method for unauthenticated mail in a mail filter in the mail filtering system shown in FIG. 1. It is a figure which shows an example of the setting information input into the setting form in step B4 shown in FIG. 2 is a flowchart for explaining an operation when an authenticated mail is transmitted from a mail transmission terminal to a mail reception terminal in the mail filtering system shown in FIG. 1. It is a figure which shows an example of the HTML mail produced | generated in step C1 shown in FIG. It is a figure which shows an example of the setting content of the link part shown in FIG. 2 is a flowchart for explaining an operation when an unauthenticated mail is transmitted from a mail transmitting terminal to a mail receiving terminal in the mail filtering system shown in FIG. 1. It is a figure which shows an example of the HTML mail produced | generated in step D1 shown in FIG. It is a figure which shows an example of the setting content of the link part shown in FIG. It is a figure which shows an example of the HTML mail edited in step D8 shown in FIG. It is a figure which shows the structure of the mail filtering system of the 2nd Embodiment of this invention. FIG. 14 is a flowchart for explaining an operation when the authenticated combination of the display content of the link portion set in the HTML mail and the link destination URL is registered in the mail filter in the mail filtering system shown in FIG. 13. FIG. 14 is a flowchart for explaining an operation when an authenticated mail or an unauthenticated mail is transmitted from the mail transmitting terminal to the mail receiving terminal in the mail filtering system shown in FIG. 13.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Registration terminal 11 Operation part 12 Display part 13 Application form request part 14 Application information transmission part 20, 20A Authentication server 21 Application form management part 22 Application information management part 23 Authentication information management part 24 Verification part 30, 30A Mail filter 31 Setting form Management unit 32 Setting information management unit 33 Mail receiving unit 34 Extraction unit 35 Verification request unit 36 Mail processing unit 37 Authentication information management unit 38 Verification unit 40 Mail filter management terminal 41 Operation unit 42 Display unit 43 Setting form request unit 44 Setting information transmission Unit 50 mail server 51 mail receiving unit 52 mail distributing unit 60 mail receiving terminal 61 operation unit 62 display unit 63 mail receiving unit 70 mail transmitting terminal 71 operation unit 72 display unit 73 mail creating unit 74 mail transmitting unit 80 network

Claims (12)

An email filtering system for filtering emails,
An authentication information management unit that pre-registers authenticated ones of combinations of display contents that are actually displayed in the link part of the e-mail and the link destination URL that is the actual link destination of the link part, and verification of the combination An authentication server comprising a collation unit that collates whether the combination is registered as an authenticated one in the authentication information management unit in response to a request;
When receiving an e-mail, an extraction unit that extracts the combination of the display content and the link destination URL from the link part of the received e-mail, and the combination extracted from the link part of the e-mail by the extraction unit Is extracted from the link part of the e-mail by the extraction unit based on the verification result by the verification server that transmits a verification request to the authentication server and whether the verification request is registered as authenticated by the authentication server A mail filter including a mail processing unit that performs a specific process set in advance for the e-mail when it is determined that the combination is not registered as an authenticated one in the authentication server; Have mail filtering system. An email filtering system for filtering emails,
Of the combinations of the display content actually displayed in the link part of the e-mail and the link destination URL that is the actual link destination of the link part, an authenticated one is registered in advance, and an acquisition request for the authenticated combination is made. In response, an authentication server including a first authentication information management unit that transmits the combination that has been registered in advance to the request source of the acquisition request;
A second authentication information management unit that periodically sends an acquisition request for the authenticated combination to the authentication server, and registers the authenticated combination that has been transmitted from the authentication server in response to the acquisition request; When receiving an e-mail, an extraction unit that extracts the combination of the display content and the link destination URL from the link part of the received e-mail, and the combination extracted from the link part of the e-mail by the extraction unit Is verified from the link part of the e-mail by the extraction unit based on the collation result by the collation unit and the collation unit that collates whether it is registered as the authenticated one in the second authentication information management unit If it is determined that the combination is not registered as authenticated in the second authentication information management unit, a special feature set in advance for the e-mail Mail filtering system comprising a mail filters, the comprising a mail processing unit which performs the processing.   The mail filtering system according to claim 1, wherein the mail processing unit performs a process of discarding an electronic mail as the specific process.   The mail filtering system according to claim 1, wherein the mail processing unit performs a process of editing a mail subject and / or a mail text content of the e-mail as the specific process. A mail filter that filters emails,
An extraction unit that extracts a combination of the display content actually displayed in the link part of the received electronic mail and the link destination URL that is the actual link destination of the link part when the electronic mail is received;
A verification request unit that transmits a verification request to the authentication server as to whether the combination extracted from the link part of the email by the extraction unit is registered as an authenticated one in the authentication server;
If it is determined that the combination extracted from the link part of the email by the extraction unit is not registered as an authenticated one in the authentication server based on the verification result by the authentication server, A mail filter including a mail processing unit that performs a specific process set in advance. A mail filter that filters emails,
Periodically, an acquisition request for an authenticated one of the combination of the display content actually displayed in the link part of the e-mail and the link destination URL that is the actual link destination of the link part is transmitted to the authentication server, An authentication information management unit for registering the authenticated combination transmitted from the authentication server in response to an acquisition request;
An extraction unit that extracts the combination of the display content and the link destination URL from the link part of the received email when receiving the email;
A collation unit that collates whether the combination extracted from the link part of the email by the extraction unit is registered as an authenticated one in the authentication information management unit;
When it is determined that the combination extracted from the link part of the email by the extraction unit is not registered as the authenticated one in the authentication information management unit based on the collation result by the collation unit, A mail filter including a mail processing unit that performs a specific process set in advance.   The mail filter according to claim 5 or 6, wherein the mail processing unit performs a process of discarding an electronic mail as the specific process.   The mail filter according to claim 5 or 6, wherein the mail processing unit performs a process of editing a mail subject and / or a mail text content of the e-mail as the specific process. To a computer that filters email,
When receiving an e-mail, a first step of extracting a combination of the display content actually displayed in the link part of the received e-mail and the link destination URL that is the actual link destination of the link part When,
A second step of transmitting to the authentication server a verification request as to whether the combination extracted from the link part of the email in the first step is registered as an authenticated one in the authentication server;
If it is determined that the combination extracted from the link part of the email in the first step is not registered as authenticated in the authentication server based on the verification result by the authentication server, A program for executing a third step for performing a specific process set in advance. To a computer that filters email,
Periodically, an acquisition request for an authenticated one of the combination of the display content actually displayed in the link part of the e-mail and the link destination URL that is the actual link destination of the link part is transmitted to the authentication server, A first step of registering the authenticated combination transmitted from the authentication server in response to an acquisition request;
A second step of extracting the combination of the display content and the link destination URL from the link part of the received email when receiving the email;
A third step of checking whether the combination extracted from the link part of the email in the second step is registered as authenticated in the first step;
Based on the collation result in the third step, it is determined that the combination extracted from the link part of the email in the second step is not registered as authenticated in the first step. In this case, a program for executing a fourth step of performing a specific process set in advance for the e-mail.   The program according to claim 9 or 10, wherein in the fourth step, processing for discarding an electronic mail is performed as the specific processing.   The program according to claim 9 or 10, wherein in the fourth step, as the specific process, a process of editing a mail subject and / or a mail body content of an e-mail is performed.

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