The following technologies are used to protect mail servers:

There are two main methods of spam protection: protection against spam when mail is received by the server, and separation of spam from the rest of the mail after it is received.

Blacklists. Blacklists include IP addresses from which spam is sent.

Greylisting or greylisting. The principle of operation of gray lists is based on the tactics of sending spam. As a rule, spam is sent in a very short time in large quantities from any server. The job of the greylist is to deliberately delay the receipt of emails for some time. The address and forwarding time are entered into the greylist database. If the remote computer is a real mail server, then it must keep the letter in the queue and repeat the forwarding within five days. Spam bots, as a rule, do not keep messages in the queue, so after a short time they stop trying to forward the letter. When resending a letter from the same address, if the required amount of time has passed since the first attempt, the letter is accepted and the address is added to the local whitelist for a sufficiently long period.

DNSBL (DNS blacklist)– lists of hosts stored using the DNS system. The mail server accesses the DNSBL and checks it for the presence of the IP address from which it receives the message. If the address is in this list, then it is not accepted by the server, and the corresponding message is sent to the sender

Message limit. Set a limit on the number of messages.

Program Spamassassin(SA) allows you to analyze the content of an already delivered message. SpamAssassin comes with big set rules that determine which emails are spam and which are not. Most of the rules are based on regular expressions, which match the message body or header, but SpamAssassin uses other techniques as well. The SpamAssassin documentation refers to these rules as "tests".

Each test has some "cost". If the message passes the test, this "cost" is added to the total score. The cost can be positive or negative, positive values ​​are called spam, negative values ​​are called ham. The message goes through all the tests, the total score is calculated. The higher the score, the more likely the message is spam.

SpamAssassin has a configurable threshold above which an email will be classified as spam. Usually the threshold is such that the email must meet several criteria; just one test failing is not enough to exceed the threshold.

The following technologies are used to protect websites from spam:

1. Image captcha. Those. the user is shown arbitrary text that the user must enter in order to perform any action.

2. Text captchas– the subscriber must enter the answer to the proposed question to confirm his actions.

3. Interactive captcha- a little common, but very useful form of protection. For example, to confirm actions, the user will be asked to solve an easy jigsaw puzzle - for example, to assemble a picture from three or four parts.

Spam is mass mailing messages to users who did not consent to receive them. Carried out for the purpose of advertising certain products, spreading information, identity theft, etc. This is an intrusive advertisement for something. In most cases, spam is presented in the form of e-mails, but in reality it is used wherever there is open access to the dissemination of information: social networks and media, forums, comments on websites, instant messengers, e-mails, SMS to the phone. Even offline, there is spam. For example, advertising brochures in your mailbox. People who send spam are called spammers. Spam advertising is one of the cheapest methods of promotion on the Web, but not the most effective. Such mailing is negatively perceived by the audience, which does not allow all companies to use it. Those who care about reputation and image do not use spam.

Where did the word "spam" come from?

The word "spam" first appeared in the 40s of the 20th century, in the post-war period. Initially, it meant the name of canned food included in the meat diet of soldiers. After the war, they had to be urgently sold before the expiration date had expired and they had not deteriorated. This led to the fact that advertising of this product was everywhere: on the streets, in newspapers, in transport. It was deliberately made aggressive, imposing on people the need to purchase these canned food. It was this event that was remembered when this kind of advertising began to be actively used on the Web. Aggressive and intrusive distribution of advertising messages received the corresponding name - spam. Since then, the word "spam" means "mass mailing of intrusive advertising." The user did not ask, did not subscribe, but they send him letters, in the content of which he is not interested. In the early days (as soon as the Internet and e-mails appeared), spam advertising on the Web was more effective than it is now. People are not used to this, and there was no advertising "blindness" then. But it still remains one of the most inexpensive ways to reach the maximum audience, which allows it to stay afloat as one of the most popular ways to promote your services and products.

A spam attack is the distribution of spam messages with an increased concentration on certain sites or channels. For example, spammers have found that a particular forum has a high bounce rate. This information spread in spam circles, and a huge wave of messages hit the site with intrusive advertising. Such an event is called a spam attack. Spamming attacks are not always made due to the high return of the site. Sometimes they happen due to someone's malicious intent in order to harm the site and its owner. For example, they are carried out by unscrupulous competitors.

Types of spam

All spam can be classified according to several criteria.

By area of ​​distribution:

online spam - distributed in the online space;

offline spam - distributed in offline space.

Distribution method:

manual – messages are sent manually.

According to the degree of danger:

Most popular websites and email accounts are adequately protected against dangerous spam. They use spam filters. Messages that can cause real harm are blocked automatically. The most dangerous of them are permanently deleted, the less dangerous or just dubious ones are placed in the Spam folder. Often, the system mistakenly places messages in the Spam folder that do not carry any harm to the user, for example, a letter confirming registration on some site. For the system, these are unfamiliar sources, therefore, it does not trust them. Therefore, regularly check your Spam folder and remove the necessary letters from there.

Safe

commercial advertising. It includes sending messages advertising various kinds of goods, services, websites, etc. As mentioned earlier, spamming is one of the most inexpensive ways to promote on the Web. Hence, it is in demand among internet entrepreneurs. They simply chose spam as one of their promotion channels;

advertising that is prohibited by law. In Russian legislation, there is a list of goods and services that are prohibited from advertising. Most popular channels ( search engines, social networks) adhere to these requirements, and sometimes add their own. This causes some difficulties for advertisers. E-mailing does not have such restrictions, which allows advertisers to freely advertise any goods and in any form;

manipulation of public opinion. Often spam is used as a tool to influence the public opinion of the audience. These are not only political motives, but also commercial ones. For example, someone decides to send compromising material to a competitor or send mailings on behalf of someone else in order to get a backlash. Such mailing does not harm users, but can cause certain moods in society;

• mailing with a request to forward the message. A particularly popular type of spam in in social networks. As a rule, it does not carry any semantic load and does not pursue any goals. These are messages in the spirit of "Forward this letter to 20 friends and next year you will find the love of your life." Oddly enough, but there are people who continue to do this. Rarely may contain hidden advertising.

Dangerous (malicious)

This type of spam can cause real harm to users - steal their personal data (logins, passwords), gain access to e-wallets, infect your computer with viruses, etc. Most often, the content of such emails includes links or attachments. In no case do not go through them and do not download. Types of dangerous spam:

Places of distribution

Where can you find spam?

In email, this is the most common place for spam messages. Letters are not moderated before being sent, therefore, their content is not limited in any way. As a rule, spam filters are used after sending.

Forums - those sites where there is no moderation are very popular among spammers, as this allows you to freely publish any information. Forums where all messages are verified are not used at all or are used to post hidden advertising.

Comments on sites - similar to forums, those sites where there is no moderation are highly popular among spammers.

Social Media – The number of spam messages on social media has only grown in recent years. Private messages and comments are the most popular communication tool. Spam in social networks is characterized by greater "friendliness". Senders, as a rule, do not just send you an advertising message, but try to enter into a dialogue, get to know each other. Of course, such an unexpected desire to communicate is caused only by commercial goals - to sell a product or service.

Messengers - for last years With the growing popularity of instant messengers (Viber, Telegram, WhatsApp), the number of spam messages in them has also increased.

SMS - probably, everyone received SMS with advertising from unknown numbers on their phone. This is spam.

How spammers find email addresses

One of the most popular questions is “How do spammers know my address or phone number?” Finding user contacts is not a big problem. You can get them in several ways.

Based on the above, the conclusion suggests itself: do not leave your contact details anywhere. Create several email addresses - one for important correspondence and important services, the other for everything else. If spam catches up with you, then let it be in the second mailbox.

How to disable spam

In some cases, it is easy to turn off spam - just click the "Unsubscribe" button in the letter. The method works if you yourself once subscribed to the source. Sometimes a subscription is issued automatically after registration on the site.

But be careful. Sometimes spammers design links in the form of an unsubscribe button. Of course, after clicking, no unsubscribe will occur. You will simply be moved to the promoted resource. If the source seems unfamiliar to you, it is better to use the following method and block it to get rid of annoying emails. Most mail services, just like in social networks, you can block addresses and users from which unwanted emails come. How to block spam (using Gmail as an example):

Ready! After the actions taken, the selected address will not be able to send you letters. Now he is blacklisted. Similar actions can be performed on social networks.

Spam protection methods

In order not to have to block each spammer manually (after all, there can be hundreds of sources), it is enough to follow simple advice and anti-spam tips.

Do not publish your address and contacts in public and questionable places.

Get a second box for unimportant messages and use it.

Do not download attachments.

Use only popular mail services (they have the maximum level of protection against spam).

Create a more complex postal address. The lighter the address, the easier it is for spammers to generate it.

The most secure mailboxes

From the point of view of protection against spam mailings, the safest mailboxes are:

Google mail (gmail);

Yandex mail;

Mail.ru-mail.

It is important to understand that no service will provide 100% protection. There will always be promotional emails. After all, spam methods are improving every year, becoming more sophisticated and secretive, spammers are constantly finding new ways to bypass filters. But the above services are capable of minimizing the number of unwanted messages.

According to statistics, more than 80 percent malware penetrate into local network just through email. The mail server itself is also a tasty morsel for hackers - after gaining access to its resources, the attacker gets full access to email archives and lists email addresses, which allows you to get a lot of information about the life of the company, ongoing projects and work in it. After all, even lists of email addresses and contacts can be sold to spammers or used to discredit a company by attacking those addresses or writing fake emails.

Spam is, at first glance, a much lesser threat than viruses. But:

• a large flow of spam distracts employees from their tasks and leads to an increase in non-productive costs. According to some reports, after reading one letter, an employee needs up to 15 minutes to enter the working rhythm. If more than a hundred unsolicited messages come in a day, then their need to view them significantly violates the current work plans;
• spam facilitates the penetration into the organization of malicious programs disguised as archives or exploiting vulnerabilities in email clients;
• a large flow of letters passing through the mail server not only worsens its performance, but also leads to a decrease in the available part of the Internet channel, an increase in the cost of paying for this traffic.

With the help of spam, some types of attacks can also be carried out using methods social engineering, in particular phishing attacks, when a user receives letters disguised as messages from completely legal persons or organizations, asking them to perform some action - for example, enter a password for their bank card.

In connection with the above, the service Email requires protection without fail and in the first place.

Solution Description

The proposed solution for protecting the enterprise mail system provides:

• protection from computer viruses and other malicious software distributed via e-mail;
• protection against spam, both incoming to the company by e-mail and distributed over the local network.

Modules can be installed as additional modules of the protection system;

• protection against network attacks on the mail server;
• anti-virus protection of the mail server itself.

Solution Components

The system for protecting mail services can be implemented in several ways. The choice of the appropriate option is based on:

• policy adopted by the company information security;
• operating systems used in the company, management tools, security systems;
• budget restrictions.

The right choice allows not only to build a reliable protection scheme, but also save a significant amount of money.

As examples, we will give the options “Economic” and “Standard”

The “Economical” option is based on operating system Linux and maximum use of free products. Composition of the variant:

• virus and spam protection subsystem based on products of Kaspersky Lab, Dr.Web, Symantec. If a company uses a demilitarized zone, it is recommended to move the mail traffic protection system to it. It should be noted that products designed to work in the demilitarized zone have more functionality and greater capabilities for detecting spam and attacks than standard ones, which improves network security;
• firewall subsystem based on the iptables2 firewall standard for the Linux operating system and management tools;
• attack detection subsystem based on Snort.

Mail server security analysis can be done with Nessus

The solution based on the “Standard” option includes the following subsystems:

• subsystem for protecting mail server and mail gateway services from malware based on solutions from Kaspersky Lab, Dr.Web, Eset, Symantec or Trend Micro;
• firewall and intrusion detection subsystem based on Kerio Firewall or Microsoft ISA.

Mail server security analysis can be done with XSpider

Both of these options do not include instant messaging and webmail security modules by default.
Both the “Economic” option and the “Standard” option can be implemented on the basis of certified FSB and FSTEK software products, which allows them to be supplied to government agencies and companies with an increased level of security requirements.

Benefits of the proposed solution

• the solution provides reliable protection against the penetration of malicious programs and spam;
• optimal selection of products allows you to implement a protection scheme that takes into account the needs of a particular client.

It should be noted that a full-fledged protection system can only function if the company has an information security policy and a number of other documents. In this regard, Azone IT offers services not only for the implementation of software products, but also for the development of regulatory documents and auditing.

More detailed information about the services provided, you can get by contacting the specialists of our company.

This is a new product of Kaspersky Lab designed for comprehensive protection home computer. This program provides simultaneous reliable protection against viruses, hackers and spam. The Kaspersky Anti-Spam module is one of the elements of this home computer protection system. First of all, it should be noted that Kaspersky Anti-Spam is not a standalone product and does not work separately from Kaspersky Personal Security Suite. To some extent, this can be called a disadvantage, since users cannot use Kaspersky Anti-Spam separately, but complex protection also has its undoubted advantages.

Antivirus protection and firewall from more than once considered on the pages of our publication. Therefore, in this article we will consider only the work of the anti-spam module.

The basis of Kaspersky Anti-Spam is the intelligent SpamTest technology, which provides: fuzzy (that is, it works even if there is an incomplete match) comparison of the message being checked with samples - messages previously identified as spam; identification of phrases characteristic of spam in the text of the letter; detection of images previously used in spam emails. In addition to the criteria listed above, formal parameters are also used to identify spam, including:

• "black" and "white" lists that the user can maintain;
• various header features mail message, characteristic of spam - for example, signs of falsification of the sender's address;
• techniques used by spammers to deceive mail filters - random sequences, substitution and doubling of letters, white-on-white text, and others;
• checking not only the text of the letter itself, but also attached files in plain text, HTML, MS Word, RTF and others formats.

Installing the anti-spam module

The module is installed during the installation of Kaspersky Personal Security Suite. When choosing installation options, a user who uses mail clients other than Microsoft mail programs may not install the module for Microsoft Outlook.

It should be noted that Kaspersky Anti-Spam checks any correspondence received via the SMTP mail protocol. Thanks to this, it can filter out spam in any mail program, but more on that below.

Integration into Microsoft Outlook Express

The program does not have its own interface as such. In Microsoft Outlook Express, the Kaspersky Anti-Spam module is integrated as a menu and as an additional panel.

You can note some inconvenience when using this panel, however, it has nothing to do with the anti-spam module itself. Due to the principles of operation of the mechanism Microsoft programs The Outlook Express panel of Kaspersky Anti-Spam cannot be pinned to a user-friendly location. Each time you start the program, the panel will appear third in a row. You will have to constantly transfer it to a convenient place or put up with this state of affairs.

Program operation

When receiving mail, Kaspersky Anti-Spam analyzes incoming mail. When spam is detected, the message is marked with a special label [!! SPAM] in the "Subject" field and placed in the "Deleted Items" folder. Emails recognized as not spam are not marked and processed. mail program in accordance with established rules. If the program is not sure that the message is spam, then the [?? Probable Spam] and the email is placed in the Inbox for the user to make a final decision. In addition, the program uses two more types of labels: - for messages with obscene content and - for automatically generated letters, such as letters from mail robots.

Thanks to these labels, you can organize the work of Kaspersky Anti-Spam with any other mail program. It is enough to create rules in mail client to sort messages by these tags. In Microsoft Outlook itself, such folders are created at the click of a button in the settings window of the anti-spam module.

Program training

The program can be trained in two ways: by classifying messages received by the user as spam - not spam, and by downloading updates from the "Laboratory" server. The first method allows you to train the program for the user's personal mail, the second - to quickly respond to massive spam phenomena on the Internet.

When launched for the first time, Kaspersky Anti-Spam will extract all addresses from the Microsoft Outlook address book in order to place them in the "Friends List". All messages from these recipients will be treated as non-spam by the anti-spam module and will be skipped without checking. Subsequently, the user can edit this list by adding or removing recipients to it. In addition to the "List of Friends" there is also a "List of Enemies". Any correspondence received from recipients on the Enemy List will be unequivocally assessed as spam.

Adding recipients to the lists of friends or enemies is done by simply pressing a special button on the panel of Kaspersky Anti-Spam. There is also training. If you skip a spam email, you just need to click the "This is spam" button. A window will appear in which the user must tell the program what to do with this message.

The "Send as spam example" command generates a letter to Kaspersky Lab with a message about spam for further training. This command can be ignored. You can neglect adding the author to the enemies, but you should definitely add the letter to the spam samples. This is how the program is trained for personal correspondence.

Since Kaspersky Anti-Spam is not integrated into other mail clients, its training in these programs is possible only through updates received from the Lab's server. Unfortunately, this training option does not make it possible to train the program for the features of personal mail.

Settings

In the program settings, you can: specify the location of the module databases, if the user wants them to be stored in a non-standard location; disable or enable filtering; set update options and view statistics.

The Kaspersky Anti-Spam module provides fairly complete protection of user mail from spam. Like any other program, it requires training. And while this learning is going on, it is possible to mistakenly recognize correct emails as spam and vice versa. A relative disadvantage is that the module does not allow deleting letters on the server that are obviously spam. The user still has to spend his traffic on these unnecessary letters. On the other hand, with this approach to spam filtering, not a single valuable message will be lost. In all other respects, Kaspersky Anti-Spam deserves the most serious attention, especially considering the integration of the module with other programs that ensure the security of the user's computer.

Blacklists

Blacklists include IP addresses from which spam is sent.

To configure, go to the section Spam Protection-> Blacklists and click the "Create" button. In field Sender specify the IP address of the mail server (or the first digits from this address), the mail domain, or a separate e-mail address for which mail forwarding will be prohibited (depending on the installed mail client, the recording formats will differ).

Greylisting

The principle of operation of gray lists is based on the tactics of sending spam. As a rule, spam is sent in a very short time in large quantities from any server. The job of the greylist is to deliberately delay the receipt of emails for some time. The address and forwarding time are entered into the greylist database. If the remote computer is a real mail server, then it must keep the letter in the queue and repeat the forwarding within five days. Spam bots, as a rule, do not keep messages in the queue, so after a short time they stop trying to forward the letter. When resending a letter from the same address, if the required amount of time has passed since the first attempt, the letter is accepted and the address is added to the local whitelist for a sufficiently long period. One of the disadvantages of the method is the possibility of mail delivery delays of 15 minutes or more, depending on the settings of the sender's server.

Greylisting is configured in the Greylisting module, where you must specify the required parameters. Greylisting in the ISPmanager panel works through two applications - Milter-greylisting and Postgrey, which must first be activated in the Features section.

dnslb blocking

DNSBL (DNS blacklist) - lists of hosts stored using the DNS system. The mail server accesses the DNSBL and checks it for the presence of the IP address from which it receives the message. If the address is in this list, then it is not accepted by the server, and the corresponding message is sent to the sender

In chapter Spam Protection select Blocking dnsbl , click the "Create" button and add a new dnsbl blocking list. In field Block List specify Domain name block list. Information about the presence of this or that mail server in the black list will be requested from this server.

You can find the most common block lists here: http://www.dnsbl.info/dnsbl-list.php

Message limit

Another way to fight spam is to set a limit on the number of messages.

This functionality is available if you have Exim installed.

Spamassassin

The SpamAssasin (SA) program allows you to analyze the contents of an already delivered message. You can add the appropriate lines to the message headers, and the user, based on the mail filters in the mail client, can filter the mail in desired folders mail program.

To be able to use SA in the ISPmanager panel, activate it in the Capabilities module. By default, after activation, the automatic self-learning function will be enabled, but, in addition, the effectiveness of spam retention can be significantly increased using "manual" filter learning.

Setting up a mailbox and mail domain

To completely disable the Greylisting check for any recipient address or domain (for example, if you do not want mail to be subjected to this check), go to the module