ID | Technique | Tactic |
---|---|---|
T1598 | Phishing for Information | Reconnaissance |
T1583.006 | Web Services | Resource Development |
Detection: Cisco Secure Firewall - Rare Snort Rule Triggered
Description
This analytic identifies Snort signatures that have triggered only once in the past 7 days across all Cisco Secure Firewall IntrusionEvent logs. While these rules typically do not trigger in day-to-day network activity, their sudden appearance may indicate early-stage compromise, previously unseen malware, or reconnaissance activity against less commonly exposed services. Investigating these outliers can provide valuable insight into new or low-noise adversary behaviors.
Search
1`cisco_secure_firewall` EventType=IntrusionEvent earliest=-7d
2
3| stats dc(_time) as TriggerCount min(_time) as firstTime max(_time) as lastTime
4 values(signature) as signature
5 values(src_ip) as src_ip
6 values(dest) as dest
7 values(dest_port) as dest_port
8 values(transport) as transport
9 values(app) as app
10 values(rule) as rule
11 by signature_id class_desc MitreAttackGroups InlineResult InlineResultReason
12
13| where TriggerCount = 1
14
15| `security_content_ctime(firstTime)`
16
17| `security_content_ctime(lastTime)`
18
19| `cisco_secure_firewall___rare_snort_rule_triggered_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___rare_snort_rule_triggered_filter | search * |
cisco_secure_firewall___rare_snort_rule_triggered_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
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 | False |
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.
Known False Positives
False positives may occur with certain rare activity. Apply additional filters where required.
Associated Analytic Story
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