Detection: Detect Traffic Mirroring

EXPERIMENTAL DETECTION

This detection status is set to experimental. The Splunk Threat Research team has not yet fully tested, simulated, or built comprehensive datasets for this detection. As such, this analytic is not officially supported. If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2024-08-14 ID: 42b3b753-5925-49c5-9742-36fa40a73990 Author: Mikael Bjerkeland, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the initiation of traffic mirroring sessions on Cisco network devices. It leverages logs with specific mnemonics and facilities related to traffic mirroring, such as "ETH_SPAN_SESSION_UP" and "PKTCAP_START." This activity is significant because adversaries may use traffic mirroring to exfiltrate data by duplicating and forwarding network traffic to an external destination. If confirmed malicious, this could allow attackers to capture sensitive information, monitor network communications, and potentially compromise the integrity and confidentiality of the network.

1`cisco_networks` (facility="MIRROR" mnemonic="ETH_SPAN_SESSION_UP") OR (facility="SPAN" mnemonic="SESSION_UP") OR (facility="SPAN" mnemonic="PKTCAP_START") OR (mnemonic="CFGLOG_LOGGEDCMD" command="monitor session*") 
2| stats min(_time) AS firstTime max(_time) AS lastTime count BY host facility mnemonic 
3| `security_content_ctime(firstTime)`
4|`security_content_ctime(lastTime)` 
5| `detect_traffic_mirroring_filter`

Data Source

Name Platform Sourcetype Source Supported App
N/A N/A N/A N/A N/A

Macros Used

Name Value
cisco_networks eventtype=cisco_ios
detect_traffic_mirroring_filter search *
detect_traffic_mirroring_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
T1200 Hardware Additions Initial Access
T1020 Automated Exfiltration Exfiltration
T1498 Network Denial of Service Impact
T1020.001 Traffic Duplication Exfiltration
KillChainPhase.ACTIONS_ON_OBJECTIVES
KillChainPhase.DELIVERY
NistCategory.DE_CM
Cis18Value.CIS_13
DarkVishnya
Gamaredon Group
Ke3chang
Sidewinder
Tropic Trooper
APT28

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 Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

This search uses a standard SPL query on logs from Cisco Network devices. The network devices must log with a severity level of minimum "5 - notification". The search also requires that the Cisco Networks Add-on for Splunk (https://splunkbase.splunk.com/app/1467) is used to parse the logs from the Cisco network devices and that the devices have been configured according to the documentation of the Cisco Networks Add-on. Also note that an attacker may disable logging from the device prior to enabling traffic mirroring.

Known False Positives

This search will return false positives for any legitimate traffic captures by network administrators.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
tbd 25 50 50
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Not Applicable N/A N/A N/A
Unit ❌ Failing N/A N/A N/A
Integration ❌ Failing N/A N/A N/A

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: 3