Kernel Module Load via Built-in Utility

  1[metadata]
  2creation_date = "2022/07/11"
  3integration = ["endpoint", "auditd_manager", "sentinel_one_cloud_funnel", "crowdstrike"]
  4maturity = "production"
  5updated_date = "2026/02/18"
  6
  7[transform]
  8[[transform.osquery]]
  9label = "Osquery - Retrieve all Kernel Modules"
 10query = "SELECT * FROM kernel_modules"
 11
 12[[transform.osquery]]
 13label = "Osquery - Retrieve Running Processes by User"
 14query = "SELECT pid, username, name FROM processes p JOIN users u ON u.uid = p.uid ORDER BY username"
 15
 16[[transform.osquery]]
 17label = "Osquery - Retrieve Listening Ports"
 18query = "SELECT pid, address, port, socket, protocol, path FROM listening_ports"
 19
 20[[transform.osquery]]
 21label = "Osquery - Retrieve Open Sockets"
 22query = "SELECT pid, family, remote_address, remote_port, socket, state FROM process_open_sockets"
 23
 24[[transform.osquery]]
 25label = "Osquery - Retrieve Information for a Specific User"
 26query = "SELECT * FROM users WHERE username = {{user.name}}"
 27
 28[[transform.osquery]]
 29label = "Osquery - Investigate the Account Authentication Status"
 30query = "SELECT * FROM logged_in_users WHERE user = {{user.name}}"
 31
 32
 33[rule]
 34author = ["Elastic"]
 35description = """
 36Detects the use of the insmod binary to load a Linux kernel object file. Threat actors can use this binary, given they
 37have root privileges, to load a rootkit on a system providing them with complete control and the ability to hide from
 38security products. Manually loading a kernel module in this manner should not be at all common and can indicate
 39suspicious or malicious behavior.
 40"""
 41from = "now-9m"
 42index = [
 43    "auditbeat-*",
 44    "endgame-*",
 45    "logs-auditd_manager.auditd-*",
 46    "logs-endpoint.events.process*",
 47    "logs-sentinel_one_cloud_funnel.*",
 48    "logs-crowdstrike.fdr*",
 49]
 50language = "eql"
 51license = "Elastic License v2"
 52name = "Kernel Module Load via Built-in Utility"
 53note = """## Triage and analysis
 54
 55### Investigating Kernel Module Load via Built-in Utility
 56
 57Threat actors with root privileges may abuse pre-installed binaries to load loadable kernel modules (LKMs), which are object files that extend the functionality of the kernel. 
 58
 59Threat actors can abuse this utility to load rootkits, granting them full control over the system and the ability to evade security products.
 60
 61The detection rule 'Kernel Module Load via Built-in Utility' is designed to identify instances where these binaries are used to load a kernel object file (with a .ko extension) on a Linux system. This activity is uncommon and may indicate suspicious or malicious behavior.
 62
 63> **Note**:
 64> This investigation guide uses the [Osquery Markdown Plugin](https://www.elastic.co/guide/en/security/current/invest-guide-run-osquery.html) introduced in Elastic Stack version 8.5.0. Older Elastic Stack versions will display unrendered Markdown in this guide.
 65> This investigation guide uses [placeholder fields](https://www.elastic.co/guide/en/security/current/osquery-placeholder-fields.html) to dynamically pass alert data into Osquery queries. Placeholder fields were introduced in Elastic Stack version 8.7.0. If you're using Elastic Stack version 8.6.0 or earlier, you'll need to manually adjust this investigation guide's queries to ensure they properly run.
 66
 67### Possible investigation steps
 68
 69- Investigate the kernel object file that was loaded.
 70  - $osquery_1
 71- Investigate the script execution chain (parent process tree) for unknown processes. Examine their executable files for prevalence and whether they are located in expected locations.
 72  - $osquery_2
 73- Investigate the kernel ring buffer for any warnings or messages, such as tainted or out-of-tree kernel module loads through `dmesg`.
 74- Investigate syslog for any unusual segfaults or other messages. Rootkits may be installed on targets with different architecture as expected, and could potentially cause segmentation faults. 
 75- Investigate other alerts associated with the user/host during the past 48 hours.
 76- Validate the activity is not related to planned patches, updates, network administrator activity, or legitimate software installations.
 77- Investigate whether the altered scripts call other malicious scripts elsewhere on the file system. 
 78  - If scripts or executables were dropped, retrieve the files and determine if they are malicious:
 79    - Use a private sandboxed malware analysis system to perform analysis.
 80      - Observe and collect information about the following activities:
 81        - Attempts to contact external domains and addresses.
 82          - Check if the domain is newly registered or unexpected.
 83          - Check the reputation of the domain or IP address.
 84        - File access, modification, and creation activities.
 85- Investigate abnormal behaviors by the subject process/user such as network connections, file modifications, and any other spawned child processes.
 86  - Investigate listening ports and open sockets to look for potential command and control traffic or data exfiltration.
 87    - $osquery_3
 88    - $osquery_4
 89  - Identify the user account that performed the action, analyze it, and check whether it should perform this kind of action.
 90    - $osquery_5
 91- Investigate whether the user is currently logged in and active.
 92    - $osquery_6
 93
 94### False positive analysis
 95
 96- If this activity is related to new benign software installation activity, consider adding exceptions — preferably with a combination of user and command line conditions.
 97- If this activity is related to a system administrator who uses cron jobs for administrative purposes, consider adding exceptions for this specific administrator user account. 
 98- Try to understand the context of the execution by thinking about the user, machine, or business purpose. A small number of endpoints, such as servers with unique software, might appear unusual but satisfy a specific business need.
 99
100### Related Rules
101
102- Kernel Driver Load - 3e12a439-d002-4944-bc42-171c0dcb9b96
103- Tainted Out-Of-Tree Kernel Module Load - 51a09737-80f7-4551-a3be-dac8ef5d181a
104- Tainted Kernel Module Load - 05cad2fb-200c-407f-b472-02ea8c9e5e4a
105- Attempt to Clear Kernel Ring Buffer - 2724808c-ba5d-48b2-86d2-0002103df753
106- Enumeration of Kernel Modules via Proc - 80084fa9-8677-4453-8680-b891d3c0c778
107- Suspicious Modprobe File Event - 40ddbcc8-6561-44d9-afc8-eefdbfe0cccd
108- Kernel Module Removal - cd66a5af-e34b-4bb0-8931-57d0a043f2ef
109- Enumeration of Kernel Modules - 2d8043ed-5bda-4caf-801c-c1feb7410504
110
111### Response and Remediation
112
113- Initiate the incident response process based on the outcome of the triage.
114- Isolate the involved host to prevent further post-compromise behavior.
115- If the triage identified malware, search the environment for additional compromised hosts.
116  - Implement temporary network rules, procedures, and segmentation to contain the malware.
117  - Stop suspicious processes.
118  - Immediately block the identified indicators of compromise (IoCs).
119  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that attackers could use to reinfect the system.
120- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business systems, and web services.
121- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
122- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
123- Leverage the incident response data and logging to improve the mean time to detect (MTTD) and the mean time to respond (MTTR).
124"""
125references = [
126    "https://decoded.avast.io/davidalvarez/linux-threat-hunting-syslogk-a-kernel-rootkit-found-under-development-in-the-wild/",
127]
128risk_score = 47
129rule_id = "2339f03c-f53f-40fa-834b-40c5983fc41f"
130setup = """## Setup
131
132This rule requires data coming in from Elastic Defend.
133
134### Elastic Defend Integration Setup
135Elastic Defend is integrated into the Elastic Agent using Fleet. Upon configuration, the integration allows the Elastic Agent to monitor events on your host and send data to the Elastic Security app.
136
137#### Prerequisite Requirements:
138- Fleet is required for Elastic Defend.
139- To configure Fleet Server refer to the [documentation](https://www.elastic.co/guide/en/fleet/current/fleet-server.html).
140
141#### The following steps should be executed in order to add the Elastic Defend integration on a Linux System:
142- Go to the Kibana home page and click "Add integrations".
143- In the query bar, search for "Elastic Defend" and select the integration to see more details about it.
144- Click "Add Elastic Defend".
145- Configure the integration name and optionally add a description.
146- Select the type of environment you want to protect, either "Traditional Endpoints" or "Cloud Workloads".
147- Select a configuration preset. Each preset comes with different default settings for Elastic Agent, you can further customize these later by configuring the Elastic Defend integration policy. [Helper guide](https://www.elastic.co/guide/en/security/current/configure-endpoint-integration-policy.html).
148- We suggest selecting "Complete EDR (Endpoint Detection and Response)" as a configuration setting, that provides "All events; all preventions"
149- Enter a name for the agent policy in "New agent policy name". If other agent policies already exist, you can click the "Existing hosts" tab and select an existing policy instead.
150For more details on Elastic Agent configuration settings, refer to the [helper guide](https://www.elastic.co/guide/en/fleet/8.10/agent-policy.html).
151- Click "Save and Continue".
152- To complete the integration, select "Add Elastic Agent to your hosts" and continue to the next section to install the Elastic Agent on your hosts.
153For more details on Elastic Defend refer to the [helper guide](https://www.elastic.co/guide/en/security/current/install-endpoint.html).
154"""
155severity = "medium"
156tags = [
157    "Domain: Endpoint",
158    "OS: Linux",
159    "Use Case: Threat Detection",
160    "Tactic: Persistence",
161    "Tactic: Defense Evasion",
162    "Threat: Rootkit",
163    "Data Source: Elastic Endgame",
164    "Data Source: Elastic Defend",
165    "Data Source: Auditd Manager",
166    "Data Source: SentinelOne",
167    "Data Source: Crowdstrike",
168    "Resources: Investigation Guide",
169]
170timestamp_override = "event.ingested"
171type = "eql"
172query = '''
173process where host.os.type == "linux" and event.type == "start" and
174event.action in ("exec", "exec_event", "start", "ProcessRollup2", "executed", "process_started") and (
175  (process.name == "kmod" and process.args == "insmod" and process.args like~ "*.ko*") or
176  (process.name == "kmod" and process.args == "modprobe" and not process.args in ("-r", "--remove")) or
177  (process.name == "insmod" and process.args like~ "*.ko*") or
178  (process.name == "modprobe" and not process.args in ("-r", "--remove"))
179) and
180not (
181  ?process.parent.executable like ("/opt/ds_agent/*", "/opt/TrendMicro/vls_agent/*", "/opt/intel/oneapi/*") or
182  ?process.working_directory in ("/opt/vinchin/agent", "/var/opt/ds_agent/am", "/opt/ds_agent", "/var/opt/TrendMicro/vls_agent/am") or
183  ?process.parent.executable in (
184    "/usr/lib/uptrack/ksplice-apply", "/opt/commvault/commvault/Base/linux_drv", "/opt/cisco/amp/bin/cisco-amp-helper",
185    "/usr/bin/kcarectl", "/usr/share/ksplice/ksplice-apply", "/opt/commvault/Base/linux_drv", "/usr/sbin/veeamsnap-loader",
186    "/bin/falcoctl"
187  ) or
188  (?process.parent.name like ("python*", "platform-python*") and ?process.parent.args in ("--smart-update", "--auto-update"))
189)
190'''
191
192[[rule.threat]]
193framework = "MITRE ATT&CK"
194
195[[rule.threat.technique]]
196id = "T1547"
197name = "Boot or Logon Autostart Execution"
198reference = "https://attack.mitre.org/techniques/T1547/"
199
200[[rule.threat.technique.subtechnique]]
201id = "T1547.006"
202name = "Kernel Modules and Extensions"
203reference = "https://attack.mitre.org/techniques/T1547/006/"
204
205[rule.threat.tactic]
206id = "TA0003"
207name = "Persistence"
208reference = "https://attack.mitre.org/tactics/TA0003/"
209
210[[rule.threat]]
211framework = "MITRE ATT&CK"
212
213[[rule.threat.technique]]
214id = "T1014"
215name = "Rootkit"
216reference = "https://attack.mitre.org/techniques/T1014/"
217
218[rule.threat.tactic]
219id = "TA0005"
220name = "Defense Evasion"
221reference = "https://attack.mitre.org/tactics/TA0005/"