Detection: Linux Indicator Removal Service File Deletion

Updated Date: 2025-05-02 ID: 6c077f81-2a83-4537-afbc-0e62e3215d55 Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects the deletion of Linux service unit configuration files by suspicious processes. It leverages Endpoint Detection and Response (EDR) telemetry, focusing on processes executing the 'rm' command targeting '.service' files. This activity is significant as it may indicate malware attempting to disable critical services or security products, a common defense evasion tactic. If confirmed malicious, this behavior could lead to service disruption, security tool incapacitation, or complete system compromise, severely impacting the integrity and availability of the affected Linux host.

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = "rm"  AND Processes.process = "*rm *"  AND Processes.process = "*.service" by Processes.action Processes.dest Processes.original_file_name Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `linux_indicator_removal_service_file_deletion_filter`

Data Source

Name Platform Sourcetype Source
Sysmon for Linux EventID 1 Linux icon Linux 'sysmon:linux' 'Syslog:Linux-Sysmon/Operational'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
linux_indicator_removal_service_file_deletion_filter search *
linux_indicator_removal_service_file_deletion_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 Defense Evasion
Exploitation
DE.AE
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 Risk Event True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

network admin can delete services unit configuration file as part of normal software installation. Filter is needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

a $process_name$ has a commandline $process$ to delete service configuration file on $dest$

Risk Object Risk Object Type Risk Score Threat Objects
dest system 36 No Threat Objects
user user 36 No Threat Objects

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: 7