Detection: Network Connection Discovery With Arp

Description

The following analytic detects the execution of arp.exe with the -a flag, which is used to list network connections on a compromised system. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names, command-line executions, and related telemetry. Monitoring this activity is significant because both Red Teams and adversaries use arp.exe for situational awareness and Active Directory discovery. If confirmed malicious, this activity could allow attackers to map the network, identify active devices, and plan further lateral movement or attacks.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where (Processes.process_name="arp.exe") (Processes.process=*-a*) by Processes.dest Processes.user Processes.parent_process Processes.process_name Processes.process Processes.process_id Processes.parent_process_id 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `network_connection_discovery_with_arp_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'xmlwineventlog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

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

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Administrators or power users may use this command for troubleshooting.

Associated Analytic Story

• Active Directory Discovery

• IcedID

• Prestige Ransomware

• Qakbot

• Volt Typhoon

• Windows Post-Exploitation

Risk Based Analytics (RBA)

References

• https://attack.mitre.org/techniques/T1049/

• https://www.microsoft.com/en-us/security/blog/2023/05/24/volt-typhoon-targets-us-critical-infrastructure-with-living-off-the-land-techniques/

• https://thedfirreport.com/2023/05/22/icedid-macro-ends-in-nokoyawa-ransomware/

Detection Testing

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