The following analytic is designed to detect potential security threats involving the misuse of system trust. It works by detecting events where a process attempts to add a certificate to the untrusted certificate store, an action often associated with disabling security tools. The analytic uses Sysmon Event ID 1 data source, particularly focusing on process activities and command-line arguments related to 'certutil -addstore'. It's essential to ingest data that records process activity and logs containing process names and command lines for its effective operation. Be aware, sometimes administrators might legitimately perform this action. The analytic's value lies in detecting isolated or unexpected instances, indicative of potential malicious activities. Cybersecurity analysts should understand the importance of trust mechanisms and their subversion in system security.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2021-09-16
- Author: Patrick Bareiss, Rico Valdez, Splunk
- ID: 6bc5243e-ef36-45dc-9b12-f4a6be131159
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 | tstats `security_content_summariesonly` count min(_time) as firstTime values(Processes.process) as process max(_time) as lastTime from datamodel=Endpoint.Processes where `process_certutil` (Processes.process=*-addstore*) by Processes.dest Processes.user Processes.parent_process Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id | `drop_dm_object_name("Processes")` | `security_content_ctime(firstTime)` |`security_content_ctime(lastTime)` | `attempt_to_add_certificate_to_untrusted_store_filter`
The SPL above uses the following Macros:
attempt_to_add_certificate_to_untrusted_store_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the
Processes node of the
Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
Known False Positives
There may be legitimate reasons for administrators to add a certificate to the untrusted certificate store. In such cases, this will typically be done on a large number of systems.
Associated Analytic Story
|35.0||70||50||An instance of $parent_process_name$ spawning $process_name$ was identified attempting to add a certificate to the store on endpoint $dest$ by user $user$.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 7