LoFP LoFP / limitted. this anomaly behavior is not commonly seen in clean host.

Techniques

Sample rules

Mshta spawning Rundll32 OR Regsvr32 Process

Description

The following analytic detects a suspicious mshta.exe process spawning rundll32 or regsvr32 child processes. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process GUID, process name, and parent process fields. This activity is significant as it is a known technique used by malware like Trickbot to load malicious DLLs and execute payloads. If confirmed malicious, this behavior could allow attackers to execute arbitrary code, escalate privileges, or download additional malware, posing a severe threat to the environment.

Detection logic


| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
  WHERE Processes.parent_process_name = "mshta.exe"  `process_rundll32`
    OR
    `process_regsvr32`
  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)`

| `mshta_spawning_rundll32_or_regsvr32_process_filter`