| ID | Technique | Tactic |
|---|---|---|
| T1021.004 | SSH | Lateral Movement |
Detection: Cisco Secure Firewall - SSH Connection to Non-Standard Port
Description
This analytic detects inbound SSH connections to non-standard ports on network devices using Cisco Secure Firewall Intrusion Events. APT actors have been observed enabling SSH servers on high, non-default TCP ports to maintain encrypted remote access to compromised network infrastructure. This detection leverages Snort signature 65369 to identify SSH protocol traffic on unusual ports, which may indicate persistence mechanisms or backdoor access established by threat actors.
Search
1`cisco_secure_firewall`
2EventType=IntrusionEvent
3signature_id=65369
4
5| fillnull
6
7| stats dc(signature_id) as unique_signature_count
8 values(signature_id) as signature_id
9 values(signature) as signature
10 values(class_desc) as class_desc
11 values(MitreAttackGroups) as MitreAttackGroups
12 values(InlineResult) as InlineResult
13 values(InlineResultReason) as InlineResultReason
14 values(src) as src
15 values(dest_port) as dest_port
16 values(rule) as rule
17 values(transport) as transport
18 values(app) as app
19 min(_time) as firstTime
20 max(_time) as lastTime
21 by dest
22
23| `security_content_ctime(firstTime)`
24
25| `security_content_ctime(lastTime)`
26
27| `cisco_secure_firewall___ssh_connection_to_non_standard_port_filter`
Data Source
| Name | Platform | Sourcetype | Source |
|---|---|---|---|
| Cisco Secure Firewall Threat Defense Intrusion Event | Other | 'cisco:sfw:estreamer' |
'not_applicable' |
Macros Used
| Name | Value |
|---|---|
| cisco_secure_firewall | sourcetype="cisco:sfw:estreamer" |
| cisco_secure_firewall___ssh_connection_to_non_standard_port_filter | search * |
cisco_secure_firewall___ssh_connection_to_non_standard_port_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
Exploitation
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 FileEvent 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 malware & file access policy must also enable logging.
Known False Positives
No false positives have been identified yet.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message:
Inbound SSH connection to non-standard port $dest_port$ detected from $src$ to network device $dest$
| Risk Object | Risk Object Type | Risk Score | Threat Objects |
|---|---|---|---|
| dest | system | 50 | src |
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