Detection: Linux Deletion of SSL Certificate

Updated Date: 2026-05-13 ID: 839ab790-a60a-4f81-bfb3-02567063f615 Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects the deletion of SSL certificates on a Linux machine. It leverages filesystem event logs to identify when files with extensions .pem or .crt are deleted from the /etc/ssl/certs/ directory. This activity is significant because attackers may delete or modify SSL certificates to disable security features or evade defenses on a compromised system. If confirmed malicious, this behavior could indicate an attempt to disrupt secure communications, evade detection, or execute a destructive payload, potentially leading to significant security breaches and data loss.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem
 3  WHERE Filesystem.action=deleted Filesystem.file_path = "/etc/ssl/certs/*" Filesystem.file_path IN ("*.pem", "*.crt")
 4  BY Filesystem.action Filesystem.dest Filesystem.file_access_time
 5     Filesystem.file_create_time Filesystem.file_hash Filesystem.file_modify_time
 6     Filesystem.file_name Filesystem.file_path Filesystem.file_acl
 7     Filesystem.file_size Filesystem.process_guid Filesystem.process_id
 8     Filesystem.user Filesystem.vendor_product
 9
10| `drop_dm_object_name(Filesystem)`
11
12| `security_content_ctime(firstTime)`
13
14| `security_content_ctime(lastTime)`
15
16| `linux_deletion_of_ssl_certificate_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_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
linux_deletion_of_ssl_certificate_filter	`search *`

linux_deletion_of_ssl_certificate_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

Exploitation

Actions on Objectives

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 Finding (Notable)	No
Creates Intermediate Finding (Risk Event)	Yes

Anomaly detections generate Intermediate Findings (Risk Events). They do not generate a Finding (Notable) directly.

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

Administrator or network operator can execute this command. Please update the filter macros to remove false positives.

Associated Analytic Story

Intermediate Findings

Message	Entity Field	Entity Type	Risk Score
SSL certificate deleted on host $dest$ by process GUID- $process_guid$	dest	system	20

Threat Objects

Field	Type
file_name	file_name

References

https://www.sentinelone.com/labs/acidrain-a-modem-wiper-rains-down-on-europe/

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