Detection: First time seen command line argument

DEPRECATED DETECTION

This detection has been marked as deprecated by the Splunk Threat Research team. This means that it will no longer be maintained or supported. If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2024-10-17 ID: a1b6e73f-98d5-470f-99ac-77aacd578473 Author: Bhavin Patel, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

This search looks for command-line arguments that use a /c parameter to execute a command that has not previously been seen.

 1
 2| tstats `security_content_summariesonly` min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = cmd.exe Processes.process = "* /c *" by Processes.process Processes.process_name Processes.parent_process_name Processes.dest
 3| `drop_dm_object_name(Processes)`
 4| `security_content_ctime(firstTime)` 
 5| `security_content_ctime(lastTime)` 
 6| search [
 7| tstats `security_content_summariesonly` earliest(_time) as firstTime latest(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = cmd.exe Processes.process = "* /c *" by Processes.process 
 8| `drop_dm_object_name(Processes)` 
 9| inputlookup append=t previously_seen_cmd_line_arguments 
10| stats min(firstTime) as firstTime, max(lastTime) as lastTime by process 
11| outputlookup previously_seen_cmd_line_arguments 
12| eval newCmdLineArgument=if(firstTime >= relative_time(now(), "-70m@m"), 1, 0) 
13| where newCmdLineArgument=1 
14| `security_content_ctime(firstTime)` 
15| `security_content_ctime(lastTime)` 
16| table process] 
17| `first_time_seen_command_line_argument_filter`

Data Source

Name Platform Sourcetype Source
Sysmon EventID 1 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
first_time_seen_command_line_argument_filter search *
first_time_seen_command_line_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
T1059.001 PowerShell Execution
T1059.003 Windows Command Shell Execution
KillChainPhase.INSTALLATION
NistCategory.DE_AE
Cis18Value.CIS_10
APT19
APT28
APT29
APT3
APT32
APT33
APT38
APT39
APT41
APT5
Aquatic Panda
BRONZE BUTLER
Blue Mockingbird
CURIUM
Chimera
Cinnamon Tempest
Cobalt Group
Confucius
CopyKittens
Daggerfly
DarkHydrus
DarkVishnya
Deep Panda
Dragonfly
Earth Lusca
Ember Bear
FIN10
FIN13
FIN6
FIN7
FIN8
Fox Kitten
GALLIUM
GOLD SOUTHFIELD
Gallmaker
Gamaredon Group
Gorgon Group
HAFNIUM
HEXANE
Inception
Indrik Spider
Kimsuky
Lazarus Group
LazyScripter
Leviathan
Magic Hound
Molerats
MoustachedBouncer
MuddyWater
Mustang Panda
Nomadic Octopus
OilRig
Patchwork
Play
Poseidon Group
RedCurl
Saint Bear
Sandworm Team
Sidewinder
Silence
Stealth Falcon
TA2541
TA459
TA505
TeamTNT
Threat Group-3390
Thrip
ToddyCat
Tonto Team
Turla
Volt Typhoon
WIRTE
Winter Vivern
Wizard Spider
menuPass
APT1
APT18
APT28
APT3
APT32
APT37
APT38
APT41
APT5
Agrius
Aquatic Panda
BRONZE BUTLER
Blue Mockingbird
Chimera
Cinnamon Tempest
Cobalt Group
Dark Caracal
Darkhotel
Dragonfly
FIN10
FIN13
FIN6
FIN7
FIN8
Fox Kitten
GALLIUM
Gamaredon Group
Gorgon Group
HAFNIUM
Higaisa
INC Ransom
Indrik Spider
Ke3chang
Kimsuky
Lazarus Group
LazyScripter
Machete
Magic Hound
Metador
MuddyWater
Mustang Panda
Nomadic Octopus
OilRig
Patchwork
Play
Rancor
RedCurl
Saint Bear
Silence
Sowbug
Suckfly
TA505
TA551
TA577
TeamTNT
Threat Group-1314
Threat Group-3390
ToddyCat
Tropic Trooper
Turla
Volt Typhoon
Winter Vivern
Wizard Spider
ZIRCONIUM
admin@338
menuPass

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 False
This configuration file applies to all detections of type hunting.

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

Legitimate programs can also use command-line arguments to execute. Please verify the command-line arguments to check what command/program is being executed. We recommend customizing the first_time_seen_cmd_line_filter macro to exclude legitimate parent_process_name

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: 7