ID | Technique | Tactic |
---|---|---|
T1547.006 | Kernel Modules and Extensions | Persistence |
T1547 | Boot or Logon Autostart Execution | Privilege Escalation |
Detection: Linux File Created In Kernel Driver Directory
Description
The following analytic detects the creation of files in the Linux kernel/driver directory. It leverages filesystem data to identify new files in this critical directory. This activity is significant because the kernel/driver directory is typically reserved for kernel modules, and unauthorized file creation here can indicate a rootkit installation. If confirmed malicious, this could allow an attacker to gain high-level privileges, potentially compromising the entire system by executing code at the kernel level.
Search
1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.file_path IN ("*/kernel/drivers/*") by Filesystem.dest Filesystem.file_name Filesystem.process_guid Filesystem.file_path
3| `drop_dm_object_name(Filesystem)`
4| `security_content_ctime(lastTime)`
5| `security_content_ctime(firstTime)`
6| `linux_file_created_in_kernel_driver_directory_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_file_created_in_kernel_driver_directory_filter | search * |
linux_file_created_in_kernel_driver_directory_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
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 |
Implementation
To successfully implement this search, you need to be ingesting logs with the file name, file path, and process_guid 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 create file in this folders for automation purposes. Please update the filter macros to remove false positives.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
A file $file_name$ is created in $file_path$ on $dest$ | 72 | 80 | 90 |
References
-
https://security.stackexchange.com/questions/175953/how-to-load-a-malicious-lkm-at-startup
-
https://0x00sec.org/t/kernel-rootkits-getting-your-hands-dirty/1485
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: 2