Now supporting clustering with time constraints

README

@@ -160,6 +160,7 @@ preprocessor ai: \
 	correlation_threshold_coefficient 0.5 \
 	database ( type="mysql", name="snort", user="snortusr", password="snortpass", host="dbhost" ) \
 	database_parsing_interval 30 \
+	cluster_max_alert_interval 14400 \
 	clusterfile "/your/snort/dir/log/clustered_alerts" \
 	cluster ( class="dst_port", name="privileged_ports", range="1-1023" ) \
 	cluster ( class="dst_port", name="unprivileged_ports", range="1024-65535" ) \
@@ -253,6 +254,11 @@ the alerts from database and the next one (default if not specified: 30 seconds)
 - clusterfile:  File  where  the  clustered  alerts  will be saved by the module
 (default       if      not      specified:      /var/log/snort/clustered_alerts)
 
+- cluster_max_alert_interval:   Maximum  time  interval,  in  seconds,  occurred
+between  two  alerts  for considering them as part of the same cluster (default:
+14400   seconds,  i.e.  4  hours).  Specify  0  for  this  option if you want to
+cluster   alerts   regardlessly   of   how   much  time  occurred  between  them
+
 - cluster:  Clustering  hierarchy  or  list  of  hierarchies  to  be applied for
 grouping     similar     alerts.     This     option     needs    to    specify:
 	-- class: Class of the cluster node. It may be src_addr, dst_addr, src_port

TODO

@@ -2,12 +2,12 @@
 AVERAGE/HIGH PRIORITY:
 ======================
 
-- Clustering alerts with time constraints
+- Save clusters and correlations to db
 - Web interface
 - Code profiling
+- Comment all the code!!!
 - Saving packet flows as .pcap
 - Neural network for computing k
-- Isolating independant subgraphs from hyperalert correlation graphs
 - Testing more scenarios, making more hyperalert models
 
 =============
@@ -30,4 +30,5 @@ DONE:
 + Add alerts' history serialization to db.c as well
 + Bayesian learning among alerts in alert log
 + Split bayesian correlation out of correlation.c
++ Clustering alerts with time constraints
 

alert_history.c

@@ -19,6 +19,7 @@
 
 #include	"spp_ai.h"
 
+#include	<stdio.h>
 #include	<sys/stat.h>
 
 /** \defgroup alert_history Manage the serialization and deserialization of alert history to the history file

bayesian.c

@@ -159,7 +159,6 @@ AI_alert_bayesian_correlation ( AI_snort_alert *a, AI_snort_alert *b )
 		found->latest_computation_time = time ( NULL );
 	}
 
-	/* _dpd.logMsg ( "Correlation ('%s') -> ('%s'): %f\\n", a->desc, b->desc, corr ); */
 	return corr;
 }		/* -----  end of function AI_alert_bayesian_correlation  ----- */
 

cluster.c

@@ -213,7 +213,7 @@ _AI_get_min_hierarchy_node ( int val, hierarchy_node *root )
  */
 
 PRIVATE BOOL
-_AI_equal_alarms ( AI_snort_alert *a1, AI_snort_alert *a2 )
+_AI_equal_alerts ( AI_snort_alert *a1, AI_snort_alert *a2 )
 {
 	if ( a1->gid != a2->gid || a1->sid != a2->sid || a1->rev != a2->rev )
 	{
@@ -249,7 +249,7 @@ _AI_equal_alarms ( AI_snort_alert *a1, AI_snort_alert *a2 )
 	}
 
 	return true;
-}		/* -----  end of function _AI_equal_alarms  ----- */
+}		/* -----  end of function _AI_equal_alerts  ----- */
 
 
 /**
@@ -270,17 +270,14 @@ _AI_merge_alerts ( AI_snort_alert **log )
 		{
 			if ( tmp2->next )
 			{
-				if ( !(
+				/* If the two alerts are in the same clustering time window (if a time window was defined...) */
-						tmp->gid == tmp2->next->gid &&
+				if ( config->clusterMaxAlertInterval == 0 ||
-						tmp->sid == tmp2->next->sid &&
+						( config->clusterMaxAlertInterval > 0 && abs ( tmp->timestamp - tmp2->next->timestamp ) <= config->clusterMaxAlertInterval ))
-						tmp->rev == tmp2->next->rev &&
-						tmp->timestamp == tmp2->next->timestamp &&
-						tmp->ip_src_addr == tmp2->next->ip_src_addr &&
-						tmp->ip_dst_addr == tmp2->next->ip_dst_addr &&
-						tmp->tcp_src_port == tmp2->next->tcp_src_port &&
-						tmp->tcp_dst_port == tmp2->next->tcp_dst_port ))
 				{
-					if ( _AI_equal_alarms ( tmp, tmp2->next ))
+					if ( tmp != tmp2->next )
+					{
+						/* If the two alerts are equal... */
+						if ( _AI_equal_alerts ( tmp, tmp2->next ))
 						{
 							if ( !( tmp->grouped_alerts = ( AI_snort_alert** ) realloc ( tmp->grouped_alerts, (++(tmp->grouped_alerts_count)) * sizeof ( AI_snort_alert* ))))
 								_dpd.fatalMsg ( "AIPreproc: Fatal dynamic memory allocation error at %s:%d\n", __FILE__, __LINE__ );
@@ -292,6 +289,7 @@ _AI_merge_alerts ( AI_snort_alert **log )
 							tmp2->next = tmp3;
 						}
 					}
+				}
 
 				tmp2 = tmp2->next;
 			} else

spp_ai.c

@@ -166,6 +166,7 @@ static AI_config * AI_parse(char *args)
 			    bayesian_correlation_interval       = 0,
 			    bayesian_correlation_cache_validity = 0,
 			    clusterfile_len                     = 0,
+			    cluster_max_alert_interval          = 0,
 			    corr_rules_dir_len                  = 0,
 			    corr_alerts_dir_len                 = 0,
 			    alert_clustering_interval           = 0,
@@ -182,6 +183,7 @@ static AI_config * AI_parse(char *args)
 		has_corr_rules_dir          = false,
 		has_clustering              = false,
 		has_database_log            = false,
+		has_database_output         = false,
 		has_alert_history_file      = false;
 
 	if ( !( config = ( AI_config* ) malloc ( sizeof( AI_config )) ))
@@ -388,6 +390,27 @@ static AI_config * AI_parse(char *args)
 	_dpd.logMsg( "    Bayesian cache validity interval: %u\n", config->bayesianCorrelationCacheValidity );
 
 
+	/* Parsing the cluster_max_alert_interval option */
+	if (( arg = (char*) strcasestr( args, "cluster_max_alert_interval" ) ))
+	{
+		for ( arg += strlen("cluster_max_alert_interval");
+				*arg && (*arg < '0' || *arg > '9');
+				arg++ );
+
+		if ( !(*arg) )
+		{
+			_dpd.fatalMsg("AIPreproc: cluster_max_alert_interval option used but "
+				"no value specified\n");
+		}
+
+		cluster_max_alert_interval = strtoul ( arg, NULL, 10 );
+	} else {
+		cluster_max_alert_interval = DEFAULT_CLUSTER_MAX_ALERT_INTERVAL;
+	}
+
+	config->clusterMaxAlertInterval = cluster_max_alert_interval;
+	_dpd.logMsg( "    Cluster alert max interval: %u\n", config->clusterMaxAlertInterval );
+
 	/* Parsing the alertfile option */
 	if (( arg = (char*) strcasestr( args, "alertfile" ) ))
 	{
@@ -550,7 +573,7 @@ static AI_config * AI_parse(char *args)
 	}
 
 	/* Parsing database option */
-	if ( preg_match ( "\\s*database\\s*\\(\\s*([^\\)]+)\\)", args, &matches, &nmatches ) > 0 )
+	if ( preg_match ( "\\s+database\\s*\\(\\s*([^\\)]+)\\)", args, &matches, &nmatches ) > 0 )
 	{
 		if ( ! has_database_log )
 			has_database_log = true;
@@ -627,8 +650,109 @@ static AI_config * AI_parse(char *args)
 		{
 			_dpd.fatalMsg ( "AIPreproc: Database option used in config, but missing configuration option (all 'host', 'type', 'name', 'user', and 'password' option must be used)\n" );
 		}
+
+		_dpd.logMsg("    Reading alerts from the database %s\n", config->dbname );
 	}
 
+
+	/* Parsing output_database option */
+	if ( preg_match ( "\\s*output_database\\s*\\(\\s*([^\\)]+)\\)", args, &matches, &nmatches ) > 0 )
+	{
+		if ( ! has_database_output )
+			has_database_output = true;
+
+		match = strdup ( matches[0] );
+
+		for ( i=0; i < nmatches; i++ )
+			free ( matches[i] );
+
+		free ( matches );
+		matches = NULL;
+
+		if ( preg_match ( "type\\s*=\\s*\"([^\"]+)\"", match, &matches, &nmatches ) > 0 )
+		{
+			if ( strcasecmp ( matches[0], "mysql" ) && strcasecmp ( matches[0], "postgresql" ))
+			{
+				_dpd.fatalMsg ( "AIPreproc: Not supported database '%s' (supported types: mysql, postgresql)\n", matches[0] );
+			}
+
+			if ( !strcasecmp ( matches[0], "mysql" ))
+			{
+				#ifndef HAVE_LIBMYSQLCLIENT
+					_dpd.fatalMsg ( "AIPreproc: mysql output set in 'output_database' option but the module was not compiled through --with-mysql option\n" );
+				#else
+					config->outdbtype = mysql;
+				#endif
+			} else if ( !strcasecmp ( matches[0], "postgresql" )) {
+				#ifndef HAVE_LIBPQ
+					_dpd.fatalMsg ( "AIPreproc: postgresql output set in 'output_database' option but the module was not compiled through --with-postgresql option\n" );
+				#else
+					config->outdbtype = postgresql;
+				#endif
+			}
+
+			for ( i=0; i < nmatches; i++ )
+				free ( matches[i] );
+
+			free ( matches );
+			matches = NULL;
+		}
+
+		if ( preg_match ( "name\\s*=\\s*\"([^\"]+)\"", match, &matches, &nmatches ) > 0 )
+		{
+			strncpy ( config->outdbname, matches[0], sizeof ( config->outdbname ));
+
+			for ( i=0; i < nmatches; i++ )
+				free ( matches[i] );
+
+			free ( matches );
+			matches = NULL;
+		}
+
+		if ( preg_match ( "user\\s*=\\s*\"([^\"]+)\"", match, &matches, &nmatches ) > 0 )
+		{
+			strncpy ( config->outdbuser, matches[0], sizeof ( config->outdbuser ));
+
+			for ( i=0; i < nmatches; i++ )
+				free ( matches[i] );
+
+			free ( matches );
+			matches = NULL;
+		}
+
+		if ( preg_match ( "password\\s*=\\s*\"([^\"]+)\"", match, &matches, &nmatches ) > 0 )
+		{
+			strncpy ( config->outdbpass, matches[0], sizeof ( config->outdbpass ));
+
+			for ( i=0; i < nmatches; i++ )
+				free ( matches[i] );
+
+			free ( matches );
+			matches = NULL;
+		}
+
+		if ( preg_match ( "host\\s*=\\s*\"([^\"]+)\"", match, &matches, &nmatches ) > 0 )
+		{
+			strncpy ( config->outdbhost, matches[0], sizeof ( config->outdbhost ));
+
+			for ( i=0; i < nmatches; i++ )
+				free ( matches[i] );
+
+			free ( matches );
+			matches = NULL;
+		}
+
+		free ( match );
+
+		if ( !strlen ( config->outdbhost ) || !strlen ( config->outdbname ) || !strlen ( config->outdbpass ) || !strlen ( config->outdbuser ))
+		{
+			_dpd.fatalMsg ( "AIPreproc: Output database option used in config, but missing configuration option (all 'host', 'type', 'name', 'user', and 'password' options must be used)\n" );
+		}
+
+		_dpd.logMsg("    Saving output alerts to the database %s\n", config->outdbname );
+	}
+
+
 	/* Parsing cluster options */
 	while ( preg_match ( "\\s*(cluster\\s*\\(\\s*)([^\\)]+)\\)", args, &matches, &nmatches ) > 0 )
 	{

spp_ai.h

@@ -75,6 +75,9 @@
 /** Default interval of validity in seconds for an entry in the cache of correlated alerts */
 #define 	DEFAULT_BAYESIAN_CORRELATION_CACHE_VALIDITY 	600
 
+/** Default maximum interval, in seconds, between two alerts for being considered in the same cluster */
+#define 	DEFAULT_CLUSTER_MAX_ALERT_INTERVAL 	14400
+
 /** Cutoff y value in the exponential decay for considering two alerts not correlated */
 #define 	CUTOFF_Y_VALUE 					0.01
 
@@ -155,6 +158,9 @@ typedef struct
 	/** Interval in seconds between two alerts (a,b) for considering them correlated */
 	unsigned long  bayesianCorrelationInterval;
 
+	/** Default maximum interval, in seconds, between two alerts for being considered in the same cluster */
+	unsigned long  clusterMaxAlertInterval;
+
 	/** Interval in seconds for which an entry in the cache of correlated alerts is valid */
 	unsigned long  bayesianCorrelationCacheValidity;
 
@@ -197,6 +203,26 @@ typedef struct
 
 	/** Database host, if database logging is used */
 	char          dbhost[256];
+
+	/** Output database type, if clustered alerts and
+	 * correlations are saved to a database as well */
+	enum          { mysql, postgresql } outdbtype;
+
+	/** Output database name, if clustered alerts and
+	 * correlations are saved to a database as well */
+	char          outdbname[256];
+
+	/** Output database user, if clustered alerts and
+	 * correlations are saved to a database as well */
+	char          outdbuser[256];
+
+	/** Output database password, if clustered alerts and
+	 * correlations are saved to a database as well */
+	char          outdbpass[256];
+
+	/** Output database host, if clustered alerts and
+	 * correlations are saved to a database as well */
+	char          outdbhost[256];
 } AI_config;
 /*****************************************************************/
 /** Data type for hierarchies used for clustering */