/* * ===================================================================================== * * Filename: spp_ai.h * * Description: Header file for the preprocessor * * Version: 1.0 * Created: 30/07/2010 15:47:12 * Revision: none * Compiler: gcc * * Author: BlackLight (http://0x00.ath.cx), * Licence: GNU GPL v.3 * Company: DO WHAT YOU WANT CAUSE A PIRATE IS FREE, YOU ARE A PIRATE! * * ===================================================================================== */ #ifndef _SPP_AI_H #define _SPP_AI_H #ifdef HAVE_CONFIG_H #include "config.h" #endif #include "sf_snort_packet.h" #include "sf_dynamic_preprocessor.h" #include "uthash.h" #define PRIVATE static /** Default interval in seconds for the thread cleaning up TCP streams */ #define DEFAULT_HASH_CLEANUP_INTERVAL 300 /** Default interval in seconds before a stream without any packet is considered timed out */ #define DEFAULT_STREAM_EXPIRE_INTERVAL 300 /** Default interval in seconds for reading alerts from the alert database, if used */ #define DEFAULT_DATABASE_INTERVAL 30 /** Default interval in seconds for the thread clustering alerts */ #define DEFAULT_ALERT_CLUSTERING_INTERVAL 300 /** Default interval in seconds for running the graph correlation thread */ #define DEFAULT_ALERT_CORRELATION_INTERVAL 300 /** Default path to Snort's log file */ #define DEFAULT_ALERT_LOG_FILE "/var/log/snort/alert" /** Default path to Snort's clustered alerts file */ #define DEFAULT_CLUSTER_LOG_FILE "/var/log/snort/clustered_alerts" /** Default path to alert correlation rules directory */ #define DEFAULT_CORR_RULES_DIR "/etc/snort/corr_rules" /** Default directory for placing correlated alerts information (.dot and possibly .png files) */ #define DEFAULT_CORR_ALERTS_DIR "/var/log/snort/correlated_alerts" /** Default path to alert history binary file, used for bayesian statistical correlation over alerts */ #define DEFAULT_ALERT_HISTORY_FILE "/var/log/snort/alert_history" /** Default correlation threshold coefficient for correlating two hyperalerts */ #define DEFAULT_CORR_THRESHOLD 0.5 /** Default size of the alerts' buffer to be periodically sent to the serialization thread */ #define DEFAULT_ALERT_BUFSIZE 30 /** Default timeout in seconds between a serialization of the alerts' buffer and the next one */ #define DEFAULT_ALERT_SERIALIZATION_INTERVAL 3600 /** Default interval between two alerts (a,b) for considering them correlated */ #define DEFAULT_BAYESIAN_CORRELATION_INTERVAL 1200 /** 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 /** Default web server port */ #define DEFAULT_WEBSERV_PORT 7654 /** Default web server banner */ #define DEFAULT_WEBSERV_BANNER "Snort AIPreprocessor module" /** Cutoff y value in the exponential decay for considering two alerts not correlated */ #define CUTOFF_Y_VALUE 0.01 /****************************/ /* Database support */ #ifdef HAVE_LIBMYSQLCLIENT #define HAVE_DB 1 #endif #ifdef HAVE_LIBPQ #define HAVE_DB 1 #endif /****************************/ extern DynamicPreprocessorData _dpd; typedef unsigned char uint8_t; typedef unsigned short uint16_t; typedef unsigned int uint32_t; typedef enum { false, true } BOOL; /*****************************************************************/ /** Possible types of clustering attributes */ typedef enum { none, src_addr, dst_addr, src_port, dst_port, CLUSTER_TYPES } cluster_type; /*****************************************************************/ /** Each stream in the hash table is identified by the couple (src_ip, dst_port) */ struct pkt_key { uint32_t src_ip; uint16_t dst_port; }; /*****************************************************************/ /** Identifier of a packet in a stream */ struct pkt_info { /** Key of the packet (src_ip, dst_port) */ struct pkt_key key; /** Timestamp */ time_t timestamp; /** Reference to SFSnortPacket containing packet's information */ SFSnortPacket* pkt; /** Pointer to the next packet in the stream */ struct pkt_info* next; /** Flag set if the packet is observed, i.e. associated to a security alert */ BOOL observed; /** Make the struct 'hashable' */ UT_hash_handle hh; }; /*****************************************************************/ /* Data type containing the configuration of the module */ typedef struct { /** Interval in seconds for the stream cleanup thread */ unsigned long hashCleanupInterval; /** Interval in seconds for considering an idle stream timed out */ unsigned long streamExpireInterval; /** Interval in seconds for the alert clustering thread */ unsigned long alertClusteringInterval; /** Interval in seconds for reading the alert database, if database logging is used */ unsigned long databaseParsingInterval; /** Interval in seconds for running the thread for building alert correlation graphs */ unsigned long correlationGraphInterval; /** Interval in seconds between a serialization of the alerts' buffer and the next one */ unsigned long alertSerializationInterval; /** 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; /** Size of the alerts' buffer to be periodically sent to the serialization thread */ unsigned long alert_bufsize; /** Correlation threshold coefficient for correlating two hyperalerts. Two hyperalerts * are 'correlated' to each other in a multi-step attack graph if and only if their * correlation value is >= m + ks, where m is the average correlation coefficient, * s is the standard deviation over this coefficient, and k is this threshold * coefficient. Its value can be >= 0. A value in [0,1] is strongly suggested, * but this value mostly depends on how accurate the correlation rules where * defined. Be careful, defining a correlation coefficient > or >> 1 no correlation * may occur at all! */ double correlationThresholdCoefficient; /** Port where the webserver providing the web interface for the correlation graph * will listen onto */ unsigned short webserv_port; /** (Absolute) path to the directory containing the HTML files for the web interface */ char webserv_dir[1024]; /** Banner string of the web server (this will be placed in the 'Server' HTTP header * and in the footer of error pages */ char webserv_banner[1024]; /** Alert file */ char alertfile[1024]; /** Alert history binary file */ char alert_history_file[1024]; /** Clustered alerts file */ char clusterfile[1024]; /** Correlation rules path */ char corr_rules_dir[1024]; /** Directory where the correlated alerts' information will be placed */ char corr_alerts_dir[1024]; /** Database name, if database logging is used */ char dbname[256]; /** Database user, if database logging is used */ char dbuser[256]; /** Database password, if database logging is used */ char dbpass[256]; /** 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 { outdb_none, outdb_mysql, outdb_postgresql, OUTDBTYPE_NUM } 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 */ typedef struct _hierarchy_node { cluster_type type; char label[256]; int min_val; int max_val; int nchildren; struct _hierarchy_node *parent; struct _hierarchy_node **children; } hierarchy_node; /*****************************************************************/ /** Key for the hyperalert hash table */ typedef struct { unsigned int gid; unsigned int sid; unsigned int rev; } AI_hyperalert_key; /*****************************************************************/ /** Hyperalert hash table */ typedef struct { /** Hyperalert key */ AI_hyperalert_key key; /** Pre-conditions, as array of strings */ char **preconds; /** Number of pre-conditions */ unsigned int n_preconds; /** Post-conditions, as array of strings */ char **postconds; /** Number of post-conditions */ unsigned int n_postconds; /** Make the struct 'hashable' */ UT_hash_handle hh; } AI_hyperalert_info; /*****************************************************************/ /** Data type for Snort alerts */ typedef struct _AI_snort_alert { /* Identifiers of the alert */ unsigned int gid; unsigned int sid; unsigned int rev; /* Snort priority, description, * classification and timestamp * of the alert */ unsigned short priority; char *desc; char *classification; time_t timestamp; /* IP header information */ uint8_t ip_tos; uint16_t ip_len; uint16_t ip_id; uint8_t ip_ttl; uint8_t ip_proto; uint32_t ip_src_addr; uint32_t ip_dst_addr; /* TCP header information */ uint16_t tcp_src_port; uint16_t tcp_dst_port; uint32_t tcp_seq; uint32_t tcp_ack; uint8_t tcp_flags; uint16_t tcp_window; uint16_t tcp_len; /** Reference to the TCP stream * associated to the alert, if any */ struct pkt_info *stream; /** Pointer to the next alert in * the log, if any*/ struct _AI_snort_alert *next; /** Hierarchies for addresses and ports, * if the clustering algorithm is used */ hierarchy_node *h_node[CLUSTER_TYPES]; /** If the clustering algorithm is used, * keep tracked of the pointers to the * single grouped alerts */ struct _AI_snort_alert **grouped_alerts; /** If the clustering algorithm is used, * we also count how many alerts this * single alert groups */ unsigned int grouped_alerts_count; /** Hyperalert information, pre-conditions * and post-conditions*/ AI_hyperalert_info *hyperalert; /* Parent alerts in the chain, if any */ struct _AI_snort_alert **parent_alerts; /* Number of parent alerts */ unsigned int n_parent_alerts; /** Array of directly correlated 'derived' * alerts from the current one, if any */ struct _AI_snort_alert **derived_alerts; /** Number of derived alerts */ unsigned int n_derived_alerts; /** Alert ID on the database, if the alerts * are stored on a database as well */ unsigned long int alert_id; } AI_snort_alert; /*****************************************************************/ /** Key for the AI_alert_event structure, containing the Snort ID of the alert */ typedef struct { int gid; int sid; int rev; } AI_alert_event_key; /*****************************************************************/ /** Structure representing the historical information of an alert saved in alert_history */ typedef struct _AI_alert_event { AI_alert_event_key key; unsigned int count; time_t timestamp; struct _AI_alert_event *next; UT_hash_handle hh; } AI_alert_event; /*****************************************************************/ /** Simple structure for holding a couple of alerts to be merged, to be passed to the outdb thread */ typedef struct { AI_snort_alert *alert1; AI_snort_alert *alert2; } AI_alerts_couple; /*****************************************************************/ /** Key for the correlation hash table */ typedef struct { /** First alert */ AI_snort_alert *a; /** Second alert */ AI_snort_alert *b; } AI_alert_correlation_key; /*****************************************************************/ /** Struct representing the correlation between all the couples of alerts */ typedef struct { /** Hash key */ AI_alert_correlation_key key; /** Correlation coefficient */ double correlation; /** Make the struct 'hashable' */ UT_hash_handle hh; } AI_alert_correlation; /*****************************************************************/ int preg_match ( const char*, char*, char***, int* ); char* str_replace ( char*, char*, char *); char* str_replace_all ( char*, char*, char* ); void AI_fatal_err ( const char *msg, const char *file, const int line ); void* AI_hashcleanup_thread ( void* ); void* AI_file_alertparser_thread ( void* ); void* AI_alert_correlation_thread ( void* ); void* AI_webserv_thread ( void* ); #ifdef HAVE_DB AI_snort_alert* AI_db_get_alerts ( void ); void AI_db_free_alerts ( AI_snort_alert* ); void* AI_db_alertparser_thread ( void* ); #endif void AI_pkt_enqueue ( SFSnortPacket* ); void AI_set_stream_observed ( struct pkt_key key ); void AI_hierarchies_build ( hierarchy_node**, int ); void AI_free_alerts ( AI_snort_alert *node ); struct pkt_info* AI_get_stream_by_key ( struct pkt_key ); AI_snort_alert* AI_get_alerts ( void ); AI_snort_alert* AI_get_clustered_alerts ( void ); void AI_serialize_alerts ( AI_snort_alert**, unsigned int ); void* AI_deserialize_alerts (); void* AI_alerts_pool_thread ( void *arg ); void* AI_serializer_thread ( void *arg ); const AI_alert_event* AI_get_alert_events_by_key ( AI_alert_event_key ); unsigned int AI_get_history_alert_number (); double AI_alert_bayesian_correlation ( AI_snort_alert *a, AI_snort_alert *b ); void AI_outdb_mutex_initialize (); void* AI_store_alert_to_db_thread ( void* ); void* AI_store_cluster_to_db_thread ( void* ); void* AI_store_correlation_to_db_thread ( void* ); /** Function pointer to the function used for getting the alert list (from log file, db, ...) */ extern AI_snort_alert* (*get_alerts)(void); /** Buffer containing the alerts to be serialized on the binary history file */ extern AI_snort_alert **alerts_pool; /** Number of alerts contained in the buffer to be serialized */ extern unsigned int alerts_pool_count; /** Configuration of the module */ extern AI_config *config; #endif /* _SPP_AI_H */