Detection: Windows Renamed LOLBAS Binary was Executed

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`
 3  count min(_time) AS firstTime
 4        max(_time) AS lastTime
 5
 6FROM datamodel=Endpoint.Processes WHERE
 7
 8[
 9    
10| inputlookup renamed_lolbas_binaries
11    
12| rename original_file_name as Processes.original_file_name
13    
14| table Processes.original_file_name
15]
16
17NOT Processes.process_name IN (
18    "excelcnv.exe",
19    "installutil64.exe",
20    "protoc~1.exe",
21    "regwrite.exe",
22    "vzshadow.exe"
23)
24
25by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
26   Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
27   Processes.parent_process_name Processes.parent_process_path
28   Processes.process Processes.process_exec Processes.process_guid
29   Processes.process_hash Processes.process_id Processes.process_integrity_level
30   Processes.process_name Processes.process_path
31   Processes.user Processes.user_id Processes.vendor_product
32
33
34| `drop_dm_object_name(Processes)`
35
36
37| eval process_name_norm=replace(lower(process_name), "\.exe$", ""),
38       original_file_name_norm=replace(lower(original_file_name), "\.exe$", "")
39
40| where process_name_norm != original_file_name_norm
41
42
43| lookup local=t renamed_lolbas_binaries original_file_name OUTPUT description
44
45
46| `security_content_ctime(firstTime)`
47
48| `security_content_ctime(lastTime)`
49
50| `windows_renamed_lolbas_binary_was_executed_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 1	Windows	'XmlWinEventLog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
CrowdStrike ProcessRollup2	Other	'crowdstrike:events:sensor'	'crowdstrike'

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

3rd party software binaries sharing the same name as LOLBAS utilities may trigger false positives.

Associated Analytic Story

• Masquerading - Rename System Utilities

• Windows Defense Evasion Tactics

• Living Off The Land

• Water Gamayun

Intermediate Findings

Threat Objects

References

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

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

• https://redcanary.com/threat-detection-report/techniques/rename-system-utilities/

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: 1