Techniques
Sample rules
Windows File Download Via CertUtil
- source: splunk
- technicques:
- T1105
Description
The following analytic detects the use of certutil.exe to download files using the -URL, -urlcache or ‘-verifyctl’ arguments. This behavior is identified by monitoring command-line executions for these specific arguments via Endpoint Detection and Response (EDR) telemetry. This activity is significant because certutil.exe is a legitimate tool often abused by attackers to download and execute malicious payloads. If confirmed malicious, this could allow an attacker to download and execute arbitrary files, potentially leading to code execution, data exfiltration, or further compromise of the system.
Detection logic
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_certutil` AND ((Processes.process IN ("*-URL *", "*/URL *")) OR (Processes.process IN ("*urlcache*", "*verifyctl*") AND Processes.process IN ("*/f *", "*-f *"))) by Processes.action Processes.dest Processes.original_file_name Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_file_download_via_certutil_filter`