Beta-version of Dr.Web Anti-spam for Unix mail servers released
February 12, 2007
Doctor Web, Ltd., a Russian developer of Dr.Web security solutions, launches a beta-testing of spam filtering system for Unix-servers. Now, in addition to Dr.Web Mail Daemon (mail anti-virus module), which beta-version release was announced earlier, a module for spam filtering based on Vade Retro® technology developed by the French company Goto Software is offered.
The Vade Retro technology allows to analyze e-mails absolutely autonomously, without any calls to external sources of spam information. This helps quickly filter e-mails for spam and constantly improve the analysis of e-mail messages due to dynamically updated code of the anti-spam module.
A verdict if the message is spam or not spam is made after the deep analysis of the message structure and up to 80% of spam is filtered by message headers, which significantly decreases the dependency upon the language the message is written in.
It considerably increases the technology resistance to tricks of spammers trying to avoid traditional spam filters, for example, resistance to graphical spam which is becoming widely spread now.
The technology used in new Dr.Web solution allows server administrators to flexibly ajust the mail filtering algorithm to company security policies. Unsolicited e-mails are marked by the anti-spam and can be filtered at the server level before they come into a user’s mail box. If the user wants to filter for spam at a client side, he can easily do that by setting up his mail client.
In addition to spam filtering server version, the main mail filtering module - Dr.Web Mail Daemon has been considerably improved and the following changes have been incorporated into it:
- Support of Qmail is added;
- Support of postfix on milter protocol is added;
- Customized settings for Dr.Web Mail Daemon are provided;
- Database format of Dr.Web Mail Daemon is changed (that is why if you update from the previous beta-version, you should delete the existing database);
- The information displayed in diagnostic messages and log files of Dr.Web Mail Daemon is extended;.
- Syntax of processing rules of messages is changed;
- All known errors are corrected.
Dr.Web Anti-spam for Unix servers. Technical description
The Dr.Web spam filtering technology consists of several thousands rules which can be devided into several groups.
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Heuristic analysis
Highly complicated intellectual technology of empirical analysis of all parts of messages: headers, message body, etc. Not only the message itself but its attachment, if any, is being analyzed. The heuristic analyzer is being constantly improving; new rules are being added to it.
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Counter-reaction
Counter-reaction technique is one of the most advanced and efficient technologies of Dr.Web anti-spam. It helps to counteract the tricks used by the spammers to outsmart anti-spam filters.
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HTML-patterns
The messages with HTML-codes included into them are compared with the list of known patterns from the library of HTML-patterns of the anti-spam. Such comparison in combination with the available data on the image sizes typically used by spammers helps protect users against spam messages with HTML-code, which often include online images.
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Semantic analysis
During the semantic analysis the words and phrases from the message are compared with the words and phrases typical for spam. The comparison is made against a predefined dictionary. The words, phrases and symbols are analyzed – both visible to the human eye and those masqueraded by the technical tricks of spammers.
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Anti-scamming technology
Scam (as well as pharming messages – a type of scam-messages) is the most dangerous type of spam. There we can name also the so-called “Nigerian” scams, loan scams, lottery and casino scams, false messages of banks and credit organizations. To filter scams a special module is used in Dr.Web anti-spam.
Anyone is welcome to test Dr.Web beta version. To download the beta version, you should first register in the Beta section of the web-site of Doctor Web, Ltd. More details about beta version and anti-spam filter can be found in the documentation.
Beta versions of Dr.Web Mail Daemon for the following operating systems are available:
- Linux (glibc 2.2/2.3)
- FreeBSD 4.11/5.1/5.2/5.3/5.4/6.0
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