Detection: Modify ACLs Permission Of Files Or Folders

Description

This analytic identifies suspicious modification of ACL permission to a files or folder to make it available to everyone or to a specific user. This technique may be used by the adversary to evade ACLs or protected files access. This changes is commonly configured by the file or directory owner with appropriate permission. This behavior raises suspicion if this command is seen on an endpoint utilized by an account with no permission to do so.

Annotations

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Implementation

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 cacls.exe may be used.

Known False Positives

System administrators may use this windows utility. filter is needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A cacls process $process_name$ with commandline $process$ try to modify a permission of a file or directory in host $dest_device_id$ 35 50 70
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References


Version: 7