Name:Windows System File on Disk id:993ce99d-9cdd-42c7-a2cf-733d5954e5a6 version:4 date:2024-10-17 author:Michael Haag, Splunk status:production type:Hunting Description:The following analytic detects the creation of new .sys files on disk. It leverages the Endpoint.Filesystem data model to identify and log instances where .sys files are written to the filesystem. This activity is significant because .sys files are often used as kernel mode drivers, and their unauthorized creation can indicate malicious activity such as rootkit installation. If confirmed malicious, this could allow an attacker to gain kernel-level access, leading to full system compromise, persistent control, and the ability to bypass security mechanisms. Data_source:
-Sysmon EventID 11
search:| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.file_name="*.sys*" by _time span=1h Filesystem.dest Filesystem.file_create_time Filesystem.file_name Filesystem.file_path Filesystem.file_hash | `drop_dm_object_name(Filesystem)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`| `windows_system_file_on_disk_filter`
how_to_implement:To successfully implement this search you need to be ingesting information on files from your endpoints into the `Endpoint` datamodel in the `Filesystem` node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product. In addition, filtering may occur by adding NOT (Filesystem.file_path IN ("*\\Windows\\*", "*\\Program File*", "*\\systemroot\\*","%SystemRoot%*", "system32\*")). This will level out the noise generated to potentally lead to generating notables. known_false_positives:False positives will be present. Filter as needed. References: -https://redcanary.com/blog/tracking-driver-inventory-to-expose-rootkits/ drilldown_searches:
: tags: analytic_story: - 'Windows Drivers' - 'CISA AA22-264A' asset_type:Endpoint confidence:50 impact:20 message:A new driver is present on $dest$. mitre_attack_id: - 'T1068' observable: name:'dest' type:'Hostname' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Processes.dest' - 'Processes.user' - 'Processes.original_file_name' - 'Processes.process_name' - 'Processes.process' - 'Processes.process_id' - 'Processes.parent_process_path' - 'Processes.process_path' - 'Processes.parent_process_id' risk_score:10 security_domain:endpoint
