IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Creation of Hidden Files and Directories

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Creation of Hidden Files and Directories

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Users can mark specific files as hidden simply by adding a . as the first character in the file or folder name. Adversaries can use this to their advantage to hide files and folders on the system for persistence and defense evasion. This rule looks for hidden files or folders in common writable directories.

Rule type: query

Rule indices:

auditbeat-*
logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 33

Tags:

Elastic
Host
Linux
Threat Detection
Defense Evasion

Version: 5 (version history)

Added (Elastic Stack release): 7.9.0

Last modified (Elastic Stack release): 7.11.2

Rule authors: Elastic

Rule license: Elastic License

Potential false positives

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Certain tools may create hidden temporary files or directories upon installation or as part of their normal behavior. These events can be filtered by the process arguments, username, or process name values.

Rule query

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event.category:process AND event.type:(start or process_started) AND
process.working_directory:("/tmp" or "/var/tmp" or "/dev/shm") AND
process.args:/\.[a-zA-Z0-9_\-][a-zA-Z0-9_\-\.]{1,254}/ AND NOT
process.name:(ls or find)