Detection: Windows LOLBAS Executed As Renamed File

Updated Date: 2024-04-30 ID: fd496996-7d9e-4894-8d40-bb85b6192dc6 Author: Steven Dick Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies a LOLBAS process being executed where it's process name does not match it's original file name attribute. Processes that have been renamed and executed may be an indicator that an adversary is attempting to evade defenses or execute malicious code. The LOLBAS project documents Windows native binaries that can be abused by threat actors to perform tasks like executing malicious code.

1
2|  tstats `security_content_summariesonly` latest(Processes.parent_process) as parent_process, latest(Processes.process) as process, latest(Processes.process_guid) as process_guid count, min(_time) AS firstTime, max(_time) AS lastTime FROM datamodel=Endpoint.Processes where NOT Processes.original_file_name IN("-","unknown") AND NOT Processes.process_path IN ("*\\Program Files*","*\\PROGRA~*","*\\Windows\\System32\\*","*\\Windows\\Syswow64\\*") BY Processes.user Processes.dest Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.process_path 
3|`drop_dm_object_name(Processes)` 
4| where NOT match(process_name, "(?i)".original_file_name) 
5| lookup lolbas_file_path lolbas_file_name as original_file_name OUTPUT description as desc 
6| search desc!="false" 
7| `security_content_ctime(firstTime)` 
8| `security_content_ctime(lastTime)` 
9| `windows_lolbas_executed_as_renamed_file_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_lolbas_executed_as_renamed_file_filter search *
windows_lolbas_executed_as_renamed_file_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
T1036 Masquerading Defense Evasion
T1036.003 Rename System Utilities Defense Evasion
T1218.011 Rundll32 Defense Evasion
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
APT28
APT32
BRONZE BUTLER
Dragonfly
FIN13
LazyScripter
Nomadic Octopus
OilRig
PLATINUM
Sandworm Team
TA551
TeamTNT
Windshift
ZIRCONIUM
menuPass
APT32
GALLIUM
Lazarus Group
menuPass
APT19
APT28
APT3
APT32
APT38
APT41
Blue Mockingbird
Carbanak
CopyKittens
FIN7
Gamaredon Group
HAFNIUM
Kimsuky
Lazarus Group
LazyScripter
Magic Hound
MuddyWater
Sandworm Team
TA505
TA551
Wizard Spider

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

A certain amount of false positives are likely with this detection. MSI based installers often trigger for SETUPAPL.dll and vendors will often copy system exectables to a different path for application usage.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
The file originally named $original_file_name$ was executed as $process_name$ on $dest$ 40 80 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.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational xmlwineventlog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational 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: 1