Detection: Windows LOLBAS Executed As Renamed File

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.

Search

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
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

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

• Living Off The Land

• Masquerading - Rename System Utilities

• Windows Defense Evasion Tactics

Risk Based Analytics (RBA)

References

• https://attack.mitre.org/techniques/T1036/

• https://attack.mitre.org/techniques/T1036/003/

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: 2