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- Datasource: Splunk Add-on for Sysmon
- Last Updated: 2021-04-29
- Author: Teoderick Contreras, Splunk
- ID: cf8d753e-a8fe-11eb-8f58-acde48001122
|T1222||File and Directory Permissions Modification||Defense Evasion|
Kill Chain Phase
1 2 3 4 5 6 | 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`
The SPL above uses the following Macros:
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.
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
|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 $dest$|
source | version: 1