LoFP LoFP / although unlikely, limited instances of regasm.exe or regsvcs.exe may cause a false positive. filter based endpoint usage, command line arguments, or process lineage.

Techniques

Sample rules

Detect Regasm Spawning a Process

Description

The following analytic detects regasm.exe spawning a child process. This behavior is identified using data from Endpoint Detection and Response (EDR) agents, focusing on process creation events where regasm.exe is the parent process. This activity is significant because regasm.exe spawning a process is rare and can indicate an attempt to bypass application control mechanisms. If confirmed malicious, this could allow an attacker to execute arbitrary code, potentially leading to privilege escalation or persistent access within the environment. Immediate investigation is recommended to determine the legitimacy of the spawned process and any associated activities.

Detection logic


| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
  WHERE Processes.parent_process_name=regasm.exe NOT (Processes.process_name IN ("conhost.exe"))
  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)`

| `detect_regasm_spawning_a_process_filter`

Detect Regsvcs Spawning a Process

Description

The following analytic identifies regsvcs.exe spawning a child process. This behavior is detected using Endpoint Detection and Response (EDR) telemetry, focusing on process creation events where the parent process is regsvcs.exe. This activity is significant because regsvcs.exe rarely spawns child processes, and such behavior can indicate an attempt to bypass application control mechanisms. If confirmed malicious, this could allow an attacker to execute arbitrary code, potentially leading to privilege escalation or persistent access within the environment. Immediate investigation is recommended to determine the legitimacy of the spawned process and any associated suspicious activities.

Detection logic


| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
  WHERE Processes.parent_process_name=regsvcs.exe
  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)`

| `detect_regsvcs_spawning_a_process_filter`