This search looks for registry activity associated with modifications to the registry key
HKLM\SYSTEM\CurrentControlSet\Control\Print\Monitors. In this scenario, an attacker can load an arbitrary .dll into the print-monitor registry by giving the full path name to the after.dll. The system will execute the .dll with elevated (SYSTEM) permissions and will persist after reboot.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2023-04-27
- Author: Steven Dick, Bhavin Patel, Teoderick Contreras, Splunk
- ID: f5f6af30-7ba7-4295-bfe9-07de87c01bbc
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 | tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Registry WHERE (Registry.action=modified AND Registry.registry_path="*CurrentControlSet\\Control\\Print\\Monitors*") BY _time span=1h Registry.dest Registry.user Registry.registry_path Registry.registry_key_name Registry.registry_value_name Registry.registry_value_data Registry.process_guid | `drop_dm_object_name(Registry)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `monitor_registry_keys_for_print_monitors_filter`
The SPL above uses the following Macros:
monitor_registry_keys_for_print_monitors_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
To successfully implement this search, you need to be ingesting logs with the registry value name, registry path, and registry value data from your endpoints. If you are using Sysmon, you must have at least version 2.0 of the offical Sysmon TA. https://splunkbase.splunk.com/app/5709
Known False Positives
You will encounter noise from legitimate print-monitor registry entries.
Associated Analytic Story
|64.0||80||80||New print monitor added on $dest$|
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: 5