Techniques
Sample rules
Windows Server Software Component GACUtil Install to GAC
- source: splunk
- technicques:
- T1505
- T1505.004
Description
The following analytic detects the use of GACUtil.exe to add a DLL into the Global Assembly Cache (GAC). It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line executions. This activity is significant because adding a DLL to the GAC allows it to be called by any application, potentially enabling widespread code execution. If confirmed malicious, this could allow an attacker to execute arbitrary code across the operating system, leading to privilege escalation or persistent access.
Detection logic
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=gacutil.exe Processes.process IN ("*-i *","*/i *") by Processes.dest Processes.user 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)`
| `windows_server_software_component_gacutil_install_to_gac_filter`