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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.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-04-30
  • Author: Steven Dick
  • ID: fd496996-7d9e-4894-8d40-bb85b6192dc6

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1036 Masquerading Defense Evasion
T1036.003 Rename System Utilities Defense Evasion
T1218.011 Rundll32 Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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|  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 
|`drop_dm_object_name(Processes)` 
| where NOT match(process_name, "(?i)".original_file_name) 
| lookup lolbas_file_path lolbas_file_name as original_file_name OUTPUT description as desc 
| search desc!="false" 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_lolbas_executed_as_renamed_file_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_lolbas_executed_as_renamed_file_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Lookups

The SPL above uses the following Lookups:

Required fields

List of fields required to use this analytic.

  • Processes.user
  • Processes.dest
  • Processes.parent_process_name
  • Processes.process_name
  • Processes.original_file_name
  • Processes.process_path

How To Implement

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

RBA

Risk Score Impact Confidence Message
40.0 80 50 The file originally named $original_file_name$ was executed as $process_name$ on $dest$

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

Reference

Test Dataset

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

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