SpamFerret

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computing: software: MediaWiki: fighting spam

Overview

SpamFerret is my attempt at an improvement over the SpamBlacklist extension. It is currently in development.

Purpose

The SpamBlacklist extension has a number of shortcomings:

• Can only handle a limited number of entries before exceeding the maximum string-length it can process, at which point all spam is allowed through
• Does not keep track of which entries are still being "tried" (to allow for periodic "cleaning" of the list)
• Does not keep track of offending IP addresses
• Handles only domains; cannot blacklist by URL path (for partially compromised servers) or "catch phrases" found in spam and nowhere else
• Does not keep a log of failed spam attempts, so there is no way to measure effectiveness

SpamFerret will:

• be database-driven
• keep logs and counts of spam attempts by blacklisting and by IP
• match domains ("http://*.domain"), URLs ("http://*.domain/path") and catch-phrases ("helo please to forgive my posting but my children are hungary")
  • should also be able to match patterns, like long lists of links in a certain format

It may also be unsuitable for use on busier wikis, as the checking process (which only happens when an edit is submitted) may take a fair amount of CPU time (checks the entire page once per blacklisted pattern). This shouldn't be a problem for smaller wikis, which are often monitored less frequently than busier wikis and hence are more vulnerable to spam.

Design

<sql> CREATE TABLE `patterns` (

 `ID` INT NOT NULL AUTO_INCREMENT,
 `Pattern` varchar(255) COMMENT 'pattern to match (regex)',
 `WhenAdded` DATETIME DEFAULT NULL COMMENT 'when this entry was added',
 `WhenTried` DATETIME DEFAULT NULL COMMENT 'when a spammer last attempted to include this pattern',
 `isActive` BOOL COMMENT 'if FALSE, do not include in checking',
 `isURL` BOOL COMMENT 'TRUE indicates that additional URL-related stats may be collected',
 `isRegex` BOOL COMMENT 'TRUE indicates that the string should not be escaped before feeding to preg_match()',
 PRIMARY KEY(`ID`)

) ENGINE = MYISAM;

CREATE TABLE `clients` (

 `ID` INT NOT NULL AUTO_INCREMENT,
 `Address` varchar(15) COMMENT 'IP address',
 `WhenFirst` DATETIME COMMENT 'when this IP address first submitted a spam',
 `WhenLast` DATETIME COMMENT 'when this IP address last submitted a spam',
 `Count` INT COMMENT 'number of attempts',
 PRIMARY KEY(`ID`)

) ENGINE = MYISAM;

CREATE TABLE `attempts` (

 `ID` INT NOT NULL AUTO_INCREMENT,
 `When` DATETIME COMMENT 'timestamp of attempt',
 `ID_Pattern` INT NOT NULL COMMENT '(patterns.ID) matching pattern found',
 `ID_Client` INT NOT NULL COMMENT '(clients.ID) spamming client',
 `URL_Page` varchar(255) COMMENT 'URL of attacked site/page',
 PRIMARY KEY(`ID`)

) ENGINE = MYISAM; </sql>