Detection: Excessive Usage Of Cacls App

Description

The following analytic identifies excessive usage of cacls.exe, xcacls.exe, or icacls.exe to change file or folder permissions. It looks for 10 or more execution of the aforementioned processes in the span of 1 minute. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line executions. This activity is significant as it may indicate an adversary attempting to restrict access to malware components or artifacts on a compromised system. If confirmed malicious, this behavior could prevent users from deleting or accessing critical files, aiding in the persistence and concealment of malicious activities.

Search

 1
 2| tstats `security_content_summariesonly` 
 3  min(_time) as firstTime 
 4  max(_time) as lastTime 
 5  values(Processes.dest) as dest
 6  values(Processes.user) as user 
 7  values(Processes.action) as action 
 8  values(Processes.original_file_name) as original_file_name 
 9  values(Processes.parent_process_exec) as parent_process_exec 
10  values(Processes.parent_process_guid) as parent_process_guid
11  values(Processes.parent_process_id) as parent_process_id 
12  values(Processes.parent_process_path) as parent_process_path 
13  values(Processes.process) as process 
14  values(Processes.process_exec) as process_exec 
15  values(Processes.process_guid) as process_guid 
16  values(Processes.process_hash) as process_hash 
17  values(Processes.process_id) as process_id 
18  values(Processes.process_integrity_level) as process_integrity_level 
19  values(Processes.process_name) as process_name 
20  values(Processes.process_path) as process_path 
21  values(Processes.user_id) as user_id 
22  values(Processes.vendor_product) as vendor_product count 
23from datamodel=Endpoint.Processes where 
24Processes.process_name IN( "icacls.exe", "cacls.exe", "xcacls.exe") 
25by Processes.parent_process_name Processes.parent_process Processes.dest Processes.user _time span=1m 
26
27| where count >=10 
28
29| `drop_dm_object_name(Processes)`
30
31| `security_content_ctime(firstTime)` 
32
33| `security_content_ctime(lastTime)` 
34
35| `excessive_usage_of_cacls_app_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

Administrators or administrative scripts may use this application. Filter as needed.

Associated Analytic Story

• Azorult

• Crypto Stealer

• Defense Evasion or Unauthorized Access Via SDDL Tampering

• Prestige Ransomware

• Windows Post-Exploitation

• XMRig

Risk Based Analytics (RBA)

Risk Message:

An excessive amount of $process_name$ was executed on $dest$ attempting to modify permissions.

References

• https://thedfirreport.com/2020/04/20/sqlserver-or-the-miner-in-the-basement/

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: 9