Detection: Linux High Frequency Of File Deletion In Boot Folder

Updated Date: 2026-05-13 ID: e27fbc5d-0445-4c4a-bc39-87f060d5c602 Author: Teoderick Contreras, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects a high frequency of file deletions in the /boot/ folder on Linux systems. It leverages filesystem event logs to identify when 200 or more files are deleted within an hour by the same process. This behavior is significant as it may indicate the presence of wiper malware, such as Industroyer2, which targets critical system directories. If confirmed malicious, this activity could lead to system instability or failure, hindering the boot process and potentially causing a complete system compromise.

Search

 1
 2| tstats `security_content_summariesonly` values(Filesystem.file_access_time) as file_access_time values(Filesystem.file_create_time) as file_create_time values(Filesystem.file_hash) as file_hash values(Filesystem.file_modify_time) as file_modify_time values(Filesystem.file_name) as file_name values(Filesystem.file_path) as file_path  values(Filesystem.file_acl) as file_acl values(Filesystem.file_size) as file_size values(Filesystem.process_id) as process_id values(Filesystem.user) as user values(Filesystem.vendor_product) as vendor_product dc(Filesystem.file_path) as numOfDelFilePath count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem
 3  WHERE Filesystem.action=deleted Filesystem.file_path = "/boot/*"
 4  BY _time span=1h Filesystem.dest
 5     Filesystem.process_guid Filesystem.action
 6
 7| `drop_dm_object_name(Filesystem)`
 8
 9| where  numOfDelFilePath >= 200
10
11| `security_content_ctime(firstTime)`
12
13| `security_content_ctime(lastTime)`
14
15| `linux_high_frequency_of_file_deletion_in_boot_folder_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon for Linux EventID 11	Linux	`'sysmon:linux'`	`'Syslog:Linux-Sysmon/Operational'`

Macros Used

Name	Value
security_content_summariesonly	`summariesonly=`summariesonly_config `allow_old_summaries=`oldsummaries_config `fillnull_value=`fillnull_config``
linux_high_frequency_of_file_deletion_in_boot_folder_filter	`search *`

linux_high_frequency_of_file_deletion_in_boot_folder_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1070.004	File Deletion	Stealth
T1485	Data Destruction	Impact

Actions on Objectives

Exploitation

DE.CM

CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Finding (Notable)	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Intermediate Finding (Risk Event)	No

TTP detections generate a Finding (Notable) and may generate Intermediate Findings (Risk Events) for associated entities.

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 can use the Add-on for Linux Sysmon from Splunkbase.

Known False Positives

linux package installer/uninstaller may cause this event. Please update you filter macro to remove false positives.

Associated Analytic Story

Finding

Title	Entity Field	Entity Type	Risk Score
Multiple files detection in /boot/ folder on $dest$ by process GUID - $process_guid$	dest	system	50

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`Syslog:Linux-Sysmon/Operational`	`sysmon:linux`
Integration	✅ Passing	Dataset	`Syslog:Linux-Sysmon/Operational`	`sysmon:linux`

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: 12