Name:Linux Auditd Insert Kernel Module Using Insmod Utility id:bc0ca53f-dea6-4906-9b12-09c396fdf1d3 version:3 date:2024-12-17 author:Teoderick Contreras, Splunk status:production type:Anomaly Description:The following analytic detects the insertion of a Linux kernel module using the insmod utility. It leverages data from Linux Auditd, focusing on process execution logs that include process names and command-line details. This activity is significant as it may indicate the installation of a rootkit or malicious kernel module, potentially allowing an attacker to gain elevated privileges and bypass security detections. If confirmed malicious, this could lead to unauthorized code execution, persistent access, and severe compromise of the affected system. Data_source:
-Linux Auditd Syscall
search:`linux_auditd` type=SYSCALL comm=insmod | rename host as dest | stats count min(_time) as firstTime max(_time) as lastTime by comm exe SYSCALL UID ppid pid success dest | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`| `linux_auditd_insert_kernel_module_using_insmod_utility_filter`
how_to_implement:To implement this detection, the process begins by ingesting auditd data, that consist SYSCALL, TYPE, EXECVE and PROCTITLE events, which captures command-line executions and process details on Unix/Linux systems. These logs should be ingested and processed using Splunk Add-on for Unix and Linux (https://splunkbase.splunk.com/app/833), which is essential for correctly parsing and categorizing the data. The next step involves normalizing the field names to match the field names set by the Splunk Common Information Model (CIM) to ensure consistency across different data sources and enhance the efficiency of data modeling. This approach enables effective monitoring and detection of linux endpoints where auditd is deployed known_false_positives:Administrator or network operator can execute this command. Please update the filter macros to remove false positives. References: -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 drilldown_searches: name:'View the detection results for - "$dest$"' search:'%original_detection_search% | search dest = "$dest$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'XorDDos' - 'Linux Rootkit' - 'Compromised Linux Host' - 'Linux Privilege Escalation' - 'Linux Persistence Techniques' asset_type:Endpoint confidence:80 impact:80 message:A SYSCALL - [$comm$] event was executed on host - [$dest$] to insert a Linux kernel module using the insmod utility. mitre_attack_id: - 'T1547.006' - 'T1547' observable: name:'dest' type:'Endpoint' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'comm' - 'exe' - 'SYSCALL' - 'UID' - 'ppid' - 'pid' risk_score:64 security_domain:endpoint
