Detection: Detect Rogue DHCP Server

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: 2024-10-17 ID: 6e1ada88-7a0d-4ac1-92c6-03d354686079 Author: Mikael Bjerkeland, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies the presence of unauthorized DHCP servers on the network. It leverages logs from Cisco network devices with DHCP Snooping enabled, specifically looking for events where DHCP leases are issued from untrusted ports. This activity is significant because rogue DHCP servers can facilitate Man-in-the-Middle attacks, leading to potential data interception and network disruption. If confirmed malicious, this could allow attackers to redirect network traffic, capture sensitive information, and compromise the integrity of the network.

1`cisco_networks` facility="DHCP_SNOOPING" mnemonic="DHCP_SNOOPING_UNTRUSTED_PORT" 
2| stats min(_time) AS firstTime max(_time) AS lastTime count values(message_type) AS message_type values(src_mac) AS src_mac BY host 
3| `security_content_ctime(firstTime)`
4|`security_content_ctime(lastTime)`
5| `detect_rogue_dhcp_server_filter`

Data Source

No data sources specified for this detection.

Macros Used

Name Value
cisco_networks eventtype=cisco_ios
detect_rogue_dhcp_server_filter search *
detect_rogue_dhcp_server_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
T1498 Network Denial of Service Impact
T1557 Adversary-in-the-Middle Collection
KillChainPhase.ACTIONS_ON_OBJECTIVES
KillChainPhase.DELIVERY
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_13
DarkVishnya
APT28
Kimsuky

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 be configured with DHCP Snooping enabled (see https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/security/configuration_guide/b_sec_152ex_2960-x_cg/b_sec_152ex_2960-x_cg_chapter_01101.html) and 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.

Known False Positives

This search might be prone to high false positives if DHCP Snooping has been incorrectly configured or in the unlikely event that the DHCP server has been moved to another network interface.

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: 4