Detection: Cisco Secure Firewall - Intrusion Events by Threat Activity

Updated Date: 2025-05-12 ID: b71e57e8-c571-4ff1-ae13-bc4384a9e891 Author: Bhavin Patel, Nasreddine Bencherchali, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

This analytic detects intrusion events from known threat activity using Cisco Secure Firewall Intrusion Events. It leverages Cisco Secure Firewall Threat Defense IntrusionEvent logs to identify cases where one or multiple Snort signatures associated with a known threat or threat actor activity have been triggered within a one-hour time window. The detection uses a lookup table (cisco_snort_ids_to_threat_mapping.csv) to map Snort signature IDs to known threat actors and their techniques. When multiple signatures associated with the same threat actor are triggered within the time window, and the count of unique signatures matches or exceeds the expected number of signatures for that threat technique, an alert is generated. This helps identify potential coordinated threat activity in your network environment by correlating related intrusion events that occur in close temporal proximity.

 1`cisco_secure_firewall` EventType=IntrusionEvent
 2
 3| stats count AS total_alerts, dc(signature_id) AS sig_count, values(SnortRuleGroups) AS snort_rule_groups, values(connection_id) AS connection_id, values(rule) AS rule, values(dest_port) AS dest_port, values(transport) AS transport, values(app) AS app, values(signature) AS signature, values(src_ip) AS src_ip BY _time dest_ip signature_id
 4
 5| lookup cisco_snort_ids_to_threat_mapping signature_id OUTPUT threat, category, message
 6
 7| where isnotnull(threat)
 8
 9| bin _time span=1d
10
11| stats count AS Total_Alerts, dc(signature_id) AS sig_count, values(signature_id) AS signature_id, values(category) AS category, values(message) AS message, values(snort_rule_groups) AS snort_rule_groups, values(connection_id) AS connection_id, values(rule) AS rule, values(dest_port) AS dest_port, values(transport) AS transport, values(app) AS app, values(signature) AS signature, values(src_ip) AS src_ip BY _time dest_ip threat
12
13| lookup threat_snort_count threat OUTPUT description, distinct_count_snort_ids
14
15| table _time, dest_ip, src_ip, threat, category, message, description, signature_id, signature, snort_rule_groups, sig_count, distinct_count_snort_ids, connection_id, rule, dest_port, transport, app
16
17| where sig_count >= distinct_count_snort_ids
18
19| `cisco_secure_firewall___intrusion_events_by_threat_activity_filter`

Data Source

Name Platform Sourcetype Source
Cisco Secure Firewall Threat Defense Intrusion Event N/A 'cisco:sfw:estreamer' 'not_applicable'

Macros Used

Name Value
cisco_secure_firewall sourcetype="cisco:sfw:estreamer"
cisco_secure_firewall___intrusion_events_by_threat_activity_filter search *
cisco_secure_firewall___intrusion_events_by_threat_activity_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1041 Exfiltration Over C2 Channel Exfiltration
T1573.002 Asymmetric Cryptography Command And Control
Actions on Objectives
Command and Control
DE.AE
CIS 13

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Risk Event True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

This search requires Cisco Secure Firewall Threat Defense Logs, which includes the IntrusionEvent EventType. This search uses an input macro named cisco_secure_firewall. We strongly recommend that you specify your environment-specific configurations (index, source, sourcetype, etc.) for Cisco Secure Firewall Threat Defense logs. Replace the macro definition with configurations for your Splunk environment. The search also uses a post-filter macro designed to filter out known false positives. The logs are to be ingested using the Splunk Add-on for Cisco Security Cloud (https://splunkbase.splunk.com/app/7404). The intrusion access policy must also be configured. This detection is based on the cisco_snort_ids_to_threat_mapping.csv mapping file - please update the lookup file with the latest Snort IDs to Threat Actors if you would like to modify the distinct count of Snort IDs needed to trigger the detection or if you would like to add new Snort IDs to Threat Actors.

Known False Positives

False positives may occur due to legitimate security testing or research activities.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

Potential $threat$ activity detected on $dest_ip$ originating from $src_ip$.

Risk Object Risk Object Type Risk Score Threat Objects
dest_ip system 50 signature

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset not_applicable cisco:sfw:estreamer
Integration ✅ Passing Dataset not_applicable cisco:sfw:estreamer

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 1