Certutil.exe may download a file from a remote destination using
-urlcache. This behavior does require a URL to be passed on the command-line. In addition,
-f (force) and
-split (Split embedded ASN.1 elements, and save to files) will be used. It is not entirely common for
certutil.exe to contact public IP space. However, it is uncommon for
certutil.exe to write files to world writeable paths.\ During triage, capture any files on disk and review. Review the reputation of the remote IP or domain in question.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2021-03-23
- Author: Michael Haag, Splunk
- ID: 415b4306-8bfb-11eb-85c4-acde48001122
|T1105||Ingress Tool Transfer||Command And Control|
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_certutil` Processes.process=*urlcache* Processes.process=*split* by Processes.dest Processes.user Processes.parent_process Processes.process_name Processes.process Processes.process_id Processes.original_file_name Processes.parent_process_id | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `certutil_download_with_urlcache_and_split_arguments_filter`
Associated Analytic Story
How To Implement
To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the
Endpoint datamodel in the
Processes node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.
Kill Chain Phase
Known False Positives
Limited false positives in most environments, however tune as needed based on parent-child relationship or network connection.
|90.0||90||100||An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ attempting to download a file.|
source | version: 2