splunk-security_content/docs/_posts/2021-04-29-icacls_deny_command.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Icacls Deny Command	File and Directory Permissions Modification	Endpoint	2021-04-29	true		File and Directory Permissions Modification Defense Evasion Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

This analytic identifies a potential adversary that changes the security permission of a specific file or directory. This technique is commonly seen in APT tradecraft or coinminer scripts. This behavior is meant to evade detection and prevent access to their component files.

• Type: TTP
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-04-29
• Author: Teoderick Contreras, Splunk
• ID: cf8d753e-a8fe-11eb-8f58-acde48001122

ATT&CK

ID	Technique	Tactic
T1222	File and Directory Permissions Modification	Defense Evasion

Search

| tstats `security_content_summariesonly` values(Processes.process) as process values(Processes.process_id) as process_id count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = "icacls.exe" OR Processes.process_name = "cacls.exe" OR Processes.process_name = "xcacls.exe" AND Processes.process = "*/deny*" by Processes.parent_process_name Processes.process_name Processes.dest Processes.user 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `icacls_deny_command_filter`

Macros

The SPL above uses the following Macros:

• security_content_ctime
• security_content_summariesonly

Note that icacls_deny_command_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

• _time
• Processes.parent_process_name
• Processes.process_name
• Processes.dest
• Processes.user
• Processes.process_id
• Processes.process

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances where renamed icacls.exe may be used.

Known False Positives

Unknown. It is possible some administrative scripts use ICacls. Filter as needed.

Associated Analytic story

• XMRig

Kill Chain Phase

• Exploitation

RBA

Risk Score	Impact	Confidence	Message
72.0	90	80	Process name process_name with deny argument executed by user to change security permission of a specific file or directory on host dest

Reference

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

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/xmrig_miner/windows-sysmon.log

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