Detection: Windows ConHost with Headless Argument

Updated Date: 2024-05-17 ID: d5039508-998d-4cfc-8b5e-9dcd679d9a62 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the unusual invocation of the Windows Console Host process (conhost.exe) with the undocumented --headless parameter. This detection leverages Endpoint Detection and Response (EDR) telemetry, specifically monitoring for command-line executions where conhost.exe is executed with the --headless argument. This activity is significant for a SOC as it is not commonly used in legitimate operations and may indicate an attacker's attempt to execute commands stealthily. If confirmed malicious, this behavior could lead to persistence, lateral movement, or other malicious activities, potentially resulting in data exfiltration or system compromise.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=conhost.exe Processes.process="*--headless *" 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| `windows_conhost_with_headless_argument_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
CrowdStrike ProcessRollup2	N/A	`'crowdstrike:events:sensor'`	`'crowdstrike'`	N/A

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_conhost_with_headless_argument_filter	`search *`

windows_conhost_with_headless_argument_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
T1564.003	Hidden Window	Defense Evasion
T1564.006	Run Virtual Instance	Defense Evasion

KillChainPhase.EXPLOITAITON

NistCategory.DE_CM

Cis18Value.CIS_10

APT19

APT28

APT3

APT32

CopyKittens

DarkHydrus

Deep Panda

Gamaredon Group

Gorgon Group

Higaisa

Kimsuky

Magic Hound

Nomadic Octopus

ToddyCat

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

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

False positives may be present if the application is legitimately used, filter by user or endpoint as needed.

Associated Analytic Story

Spearphishing Attachments

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Windows ConHost with Headless Argument detected on $dest$ by $user$.	70	100	70

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

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Security`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Security`	`XmlWinEventLog`

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: 2