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.
- Type: Anomaly
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2024-05-11
- Author: Teoderick Contreras, Splunk
- ID: b85bbeec-6326-11ec-9311-acde48001122
Annotations
ATT&CK
Kill Chain Phase
- Installation
- Exploitation
NIST
- DE.AE
CIS20
- CIS 10
CVE
Search
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| 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
| `drop_dm_object_name(Filesystem)`
| `security_content_ctime(lastTime)`
| `security_content_ctime(firstTime)`
| `linux_file_created_in_kernel_driver_directory_filter`
Macros
The SPL above uses the following Macros:
linux_file_created_in_kernel_driver_directory_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Required fields
List of fields required to use this analytic.
- _time
- Filesystem.dest
- Filesystem.file_create_time
- Filesystem.file_name
- Filesystem.process_guid
- Filesystem.file_path
How To Implement
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
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
72.0 | 80 | 90 | A file $file_name$ is created in $file_path$ on $dest$ |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Reference
- https://docs.fedoraproject.org/en-US/fedora/rawhide/system-administrators-guide/kernel-module-driver-configuration/Working_with_Kernel_Modules/
- 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
Test Dataset
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 | version: 2