Difference between revisions of "SpamFerret"

Revision as of 13:25, 10 June 2007

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computing: software: MediaWiki: fighting spam: SpamFerret

Overview

SpamFerret is my attempt at an improvement over the SpamBlacklist extension. The version posted here works, but you have to manually enter patterns (blacklisted items) into the database. Fortunately this isn't hard to do, but a more friendly interface would be nice (especially some way to take a spam-page, break it up into unique URLs, and let you select which ones to add to the database).

To-Do

Important: Document the installation process (pretty simple; the only non-obvious bit is the database spec)
Automated reporting of intercepted spam
Management tools for new spam (generate candidate patterns from spam page, allow user to fine-tune and choose which ones to use, and add chosen/tweaked patterns to database)
Manual reporting tools
- list patterns least recently used, for possible deactivation
- whois of all recently promoted domains and create a consolidated list of owners
Optional log of complete spam contents, for possible data-mining or filter-training

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()',
 `Count` INT DEFAULT 0 COMMENT 'number of attempts',
 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 DEFAULT 0 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',
 `PageServer` varchar(63) COMMENT 'identifier of wiki being attacked (usually domain)',
 `PageName` varchar(255) COMMENT 'name of page where the spam would have displayed',
 PRIMARY KEY(`ID`)

) ENGINE = MYISAM; </sql>

Reports

Eventually, some Specialpages with reports would be nice, but for now you can see what's being blocked, and where the spam attempts are coming from, with this query – which you can package in a stored procedure, as shown, to make it easier to run (or just use the SELECT statement by itself): <mysql>CREATE PROCEDURE Attempts()

 BEGIN
   select
     a.ID,
     a.`When`,
     CONCAT('(',a.ID_Pattern,') ',p.Pattern) AS Pattern,
     CONCAT('(',a.ID_Client,') ',c.Address) AS Address,
     PageServer,
     PageName
   from
     (attempts AS a 
     LEFT JOIN patterns AS p ON a.ID_Pattern=p.ID) 
     LEFT JOIN clients AS c ON a.ID_Client=c.ID
     ORDER BY a.ID DESC;
 END</mysql>

Execute <mysql>CALL Attempts();</mysql> to view the results.

Code

This consists of two files. SpamFerret.php goes in the MediaWiki extensions folder, and data.php goes in the "includes" folder because PHP seems to want it there. Both files still contain some debugging code, most of which I'll clean up later (some of it calls stubbed debug-printout routines which can come in handy when adding features or fixing the inevitable bugs).

2007-06-10 Added code to prevent ampersandbot edits; need to add logging of those blocks, but don't have time right now. Also don't know if the ampersandbots trim off whitespace or if that's just how MediaWiki is displaying the changes.

SpamFerret.php

<php> <?php

Loader for spam blacklist feature
Include this from LocalSettings.php

if ( defined( 'MEDIAWIKI' ) ) { require('shared.php');

global $wgFilterCallback, $wgPreSpamFilterCallback;

if ( $wgFilterCallback ) { $wgPreSpamFilterCallback = $wgFilterCallback; } else { $wgPreSpamFilterCallback = false; }

$wgFilterCallback = 'wfSpamFerretLoader'; $wgExtensionCredits['other'][] = array( 'name' => 'SpamFerret',

       'author' => 'Woozle Staddon', 
       'url' => 'http://htyp.org/SpamFerret',

);

function wfSpamFerretLoader( &$title, $text, $section ) { static $spamObj = false; global $wgSpamFerretSettings, $wgPreSpamFilterCallback;

if ( $spamObj === false ) { $spamObj = new SpamFerret( $wgSpamFerretSettings ); }

return $spamObj->filter( $title, $text, $section ); } class SpamFerret { var $dbspec; var $previousFilter = false;

function SpamFerret( $settings = array() ) { global $IP;

foreach ( $settings as $name => $value ) { $this->$name = $value; } }

function filter( &$title, $text, $section ) { global $wgArticle, $wgDBname, $wgMemc, $messageMemc, $wgVersion, $wgOut; global $wgTitle, $wgServer; global $debug;

$fname = 'wfSpamFerretFilter'; wfProfileIn( $fname );

# Call the rest of the hook chain first if ( $this->previousFilter ) { $f = $this->previousFilter; if ( $f( $title, $text, $section ) ) { wfProfileOut( $fname ); return true; } }

$retVal = false; // default = assume edit is ok // Check for ampersandbot $objArticleCurr = new Article($title); $objArticleCurr->loadLastEdit(); $txtCurr = $objArticleCurr->getContent(); $lenNew = strlen($text); if (strpos($txtCurr, $text)===0) { // new string starts the same as old string; is it a truncated subset? if ($lenNew < strlen($txtCurr)) { // new string is a truncation of old string; is the first missing character an ampersand? $chrDeleted = $txtCurr{$lenNew+1}; if ($chrDeleted == '&') { // AMPERSANDBOT DETECTED; refuse to save the edit // The string sent to spamPage() will be shown after "The following text is what triggered our spam filter:" EditPage::spamPage( 'The removal of everything after the first ampersand. You are an ampersandbot; please go away.' ); // LATER: it would be nice to have a special MediaWiki:Ampersandbot page to display when this happens $retVal = true; } } }

if (!$retval) { // Open the database $dbSpam = new clsDatabase($this->dbspec); $objTblPatterns = new clsDataTable($dbSpam,'patterns'); $objDataPatterns = $objTblPatterns->GetData('isActive'); /* $debug .= ' objDataPatterns is object:'.is_object($objDataPatterns); $debug .= ' objDataPatterns.Res is object:'.is_object($objDataPatterns->Res); $debug .= ' objDataPatterns.Row is array:'.is_array($objDataPatterns->Row); $debug .= ' objDataPatterns.Res is class '.get_class($objDataPatterns->Res); $debug .= ' objDataPatterns.Res has '.$objDataPatterns->Res->num_rows.' row(s)';

/

while(is_array($objDataPatterns->Row)) { $strPattern = $objDataPatterns->GetValue('Pattern'); $isRegex = $objDataPatterns->GetValue('isRegex'); $idPattern = $objDataPatterns->GetValue('ID'); if ($isRegex) { $strPattCk = strtolower($strPattern); $strTextCk = strtolower($text); $isMatch = preg_match('/'.$strPattCk.'/',$strTextCk,$matches); if ($isMatch) { $strMatch = $matches[0]; } } else { $strMatch = stristr ($text,$strPattern); $isMatch = ($strMatch != ); } // $debug .= 'ROW: '.DumpArray($objDataPatterns->Row);

if ($isMatch) { $objDataPatterns->Row = NULL; // stop the search } else { $objDataPatterns->NextRow(); // keep looking } }

if ( $strMatch != ) { // spam cue found; display the matching text and don't allow the edit to be saved: wfDebug( "Match!\n" );

// The string sent to spamPage() will be shown after "The following text is what triggered our spam filter:" EditPage::spamPage( $strMatch ); // Log the spam attempt: // -- first, get an ID for the IP address: $strIPAddr = wfGetIP(); $sql = 'SELECT * FROM clients WHERE Address="'.$strIPAddr.'"'; $objDataClients = $dbSpam->Query($sql); // update or create client record: if (is_object($objDataClients)) { if ($objDataClients->RowCount() > 0) { $isFound = true; } } if ($isFound) { $idClient = $objDataClients->GetValue('ID'); $sql = 'UPDATE clients SET WhenLast=NOW(),Count=Count+1 WHERE Address="'.$strIPAddr.'"'; $dbSpam->Exec($sql); } else { $sql = 'INSERT INTO clients (Address,WhenFirst,Count) VALUES("'.$strIPAddr.'",NOW(),1)'; $dbSpam->Exec($sql); $idClient = $dbSpam->NewID(); } $sqlURL = '"'.$dbSpam->SafeParam($wgTitle->getFullURL()).'"'; $sqlSrvr = '"'.$dbSpam->SafeParam($wgServer).'"'; $sqlPage = '"'.$dbSpam->SafeParam($wgTitle->getPrefixedText()).'"'; $sql = 'INSERT INTO attempts (`When`,ID_Pattern,ID_Client,PageServer,PageName) VALUES (NOW(),'.$idPattern.','.$idClient.','.$sqlSrvr.','.$sqlPage.')'; $dbSpam->Exec($sql); $sql = 'UPDATE patterns SET WhenTried=NOW(), Count=Count+1 WHERE ID='.$idPattern; $dbSpam->Exec($sql); $retVal = true; } else { // no spam cues found; allow the edit to be saved, if nothing else has tripped the filter /* EditPage::spamPage( 'DEBUGGING: '.$debug ); $retVal = true; /*/ /**/ } }

wfProfileOut( $fname ); return $retVal; /**/ } }

} // end of 'MEDIAWIKI' check ?> </php>

data.php

<php> <?php /* ===========================

*** DATA UTILITY CLASSES ***

/

class clsDatabase {

 private $cntOpen;	// count of requests to keep db open
 private $strType;	// type of db (MySQL etc.)
 private $strUser;	// database user
 private $strPass;	// password
 private $strHost;	// host (database server domain-name or IP address)
 private $strName;	// database (schema) name

 private $Conn;	// connection object

 public function __construct($iConn) {
   CallEnter('clsDatabase('.get_class($iConn).')');
   $this->Init($iConn);
   CallExit('clsDatabase()');
 }
 public function Init($iConn) {

// $iConn format: type:user:pass@server/dbname

   CallEnter('clsDatabase.Init('.get_class($iConn).')');
   $this->cntOpen = 0;
   list($part1,$part2) = split('@',$iConn);
   list($this->strType,$this->strUser,$this->strPass) = split(':',$part1);
   list($this->strHost,$this->strName) = explode('/',$part2);
   $this->strType = strtolower($this->strType);	// make sure it is lowercased, for comparison
   CallExit('clsDatabase.Init()');
 }
 public function Open() {
   CallEnter('clsDatabase.Open()');
   if ($this->cntOpen == 0) {

// then actually open the db

     if ($this->strType == 'mysql') {
       $this->Conn = new mysqli($this->strHost,$this->strUser,$this->strPass,$this->strName);
     } else {
       $this->Conn = dbx_connect($this->strType,$this->strHost,$this->strName,$this->strUser,$this->strPass);
     }
   }
   $this->cntOpen++;
   CallExit('clsDatabase.Open()');
 }
 public function Shut() {
   CallEnter('clsDatabase.Shut()');
   $this->cntOpen--;
   if ($this->cntOpen == 0) {
     if ($this->strType == 'mysql') {
       $this->Conn->close();
     } else {
       dbx_close($this->Conn);
     }
   }
   CallExit('clsDatabase.Shut()');
 }
 public function Query($iSQL) {
   CallEnter('clsDatabase.Query('.$iSQL.')');
   if ($this->strType == 'mysql') {
     $this->Conn->real_query($iSQL);
     $objQry = $this->Conn->store_result();
   } else {
     $objQry = dbx_query($this->Conn,$iSQL,DBX_RESULT_ASSOC);
   }
   if (is_object($objQry)) {
     $objRec = new clsDataItem($objQry);
     CallExit('clsDatabase.Query('.$iSQL.') -> new clsDataItem');
     return $objRec;
   } else {
     CallExit('clsDatabase.Query('.$iSQL.') -> NULL (ERROR!)');
     return NULL;	// empty result set, one way or another
   }
 }
 public function Exec($iSQL) {

// MYSQL only

   $objQry = $this->Conn->prepare($iSQL);
   return $objQry->execute();
 }
 public function NewID() {
   return $this->Conn->insert_id;
 }
 public function SafeParam($iString) {
   return $this->Conn->escape_string($iString);
 }

}

class clsDataTable {

 protected $objDB;	// clsDatabase
 protected $strName;

 public function __construct($iDB,$iName) {
   CallEnter('clsDataTable('.get_class($iDB).','.$iName.')');
   $this->objDB = $iDB;
   $this->strName = $iName;
   $this->objDB->Open();
   if (!isset($this->objDB)) {
     print 'DATABASE NOT OPEN!';
   }
   CallExit('clsDataTable()');
 }
 public function __destruct() {
   $this->objDB->Shut();
 }
 public function GetItem($iID,$iObj=NULL) {
   CallEnter('clsDataTable.GetItem('.$iID.')');
   $sql = 'SELECT * FROM '.$this->strName.' WHERE ID='.$iID;

// $objQry = dbx_query($this->objDB,$sql,DBX_RESULT_ASSOC);

   $objQry = $this->objDB->Query($sql);
   if (is_object($iObj)) {
     $iObj->Eat($objQry);
     CallExit('clsDataTable.GetItem('.$iID.') -> ate object');
     return $iObj;
   } else {
     CallExit('clsDataTable.GetItem('.$iID.') -> from objDB.Query');
     return $objQry;
   }
 }
 public function GetData($iFilt) {
   CallEnter('clsDataTable.GetData('.$iFilt.')');
   $sql = 'SELECT * FROM '.$this->strName.' WHERE ('.$iFilt.')';
   $objQry = $this->objDB->Query($sql);
   CallExit('clsDataTable.GetData('.$iFilt.')');
   return $objQry;
 }

}

class clsDataItem {

 public $Res;		// result set
 public $Row;		// first (presumably the *only*) row data
 public $Table;	// clsDataTable object
 public function __construct($iResults=NULL,$iTable=NULL) {
   CallEnter('clsDataItem('.get_class($iResults).')');
   if (is_object($iResults)) {
     $this->Init($iResults,$iTable);
   }
   CallExit('clsDataItem()');
 }
 public function Init($iResults,$iTable=NULL) {
   CallEnter('clsDataItem.Init('.get_class($iResults).')');
   $this->Res = $iResults;
   $this->Table = $iTable;

// this works for mysql only: // fetch the first row of the results as an associative array:

   $this->Row = $iResults->fetch_assoc();
   CallExit('clsDataItem.Init()');
 }
 public function Eat($iDataItem) {
   CallEnter('clsDataItem.Eat('.get_class($iDataItem).')');
   $this->Res		= $iDataItem->Res;
   $this->Table	= $iDataItem->Table; 
   $this->Row		= $iDataItem->Row;
   CallExit('clsDataItem.Eat()');
 }
 public function GetValue($iName) {

// this works for mysql only

   CallEnter('GetValue('.$iName.')');
   DumpArray($this->Row);
   CallExit('GetValue('.$iName.')');
   return $this->Row[$iName];
 }
 public function RowCount() {
   return $this->Res->num_rows;
 }
 public function NextRow() {

// this works for mysql only: // fetch the NEXT row of the results as an associative array:

   $this->Row = $this->Res->fetch_assoc();
 }

}

/* ========================

*** UTILITY FUNCTIONS ***

/

function Pluralize($iQty,$iSingular,$iPlural='s') { if ($iQty == 1) { return $iSingular; } else { return $iPlural; } } /* ========================

*** DEBUGGING FUNCTIONS ***

/

define(KS_DEBUG_HTML,0);

// these could later be expanded to create a call-path for errors, etc. function CallEnter($iName) { /*

 global $intCallDepth, $debug;
 $intCallDepth++;
 if (KS_DEBUG_HTML) {
   $debug .= '
'.str_repeat('>> ',$intCallDepth).''.$iName.'';
 } else {
   $debug .= "\n\n".str_repeat('*',$intCallDepth).$iName;
 }

/**/ } function CallExit($iName) { /*

 global $intCallDepth, $debug;
 $intCallDepth--;
 if (KS_DEBUG_HTML) {
   $debug .= '
'.str_repeat('>> ',$intCallDepth).'<< '.$iName.'';
 } else {
   $debug .= "\n\n".str_repeat('*',$intCallDepth).'<';
 }

/**/ } function DumpArray($iArr) {

 global $intCallDepth, $debug;

/*

 while (list($key, $val) = each($iArr)) {
   if (KS_DEBUG_HTML) {
     $debug .= '
'.str_repeat('-- ',$intCallDepth+1).'';
     $debug .= " $key => $val";
     $debug .= '';
   } else {
     $debug .= "/ $key => $val /";
   }
 }

/**/ } ?> </php>