Detection rules › Splunk

Windows NetSupport RMM DLL Loaded By Uncommon Process

Status
production
Severity
low
Group by
dest, image_loaded, process_guid, process_hash, process_id, process_name, service_dll_signature_exists, service_dll_signature_verified, signature, signature_id, user_id, vendor_product
Author
Teoderick Contreras, Splunk
Source
github.com/splunk/security_content

The following analytic detects the loading of specific dynamic-link libraries (DLLs) associated with the NetSupport Remote Manager (RMM) tool by any process on a Windows system. Modules such as CryptPak.dll, HTCTL32.DLL, IPCTL32.DLL, keyshowhook.dll, pcicapi.DLL, PCICL32.DLL, and TCCTL32.DLL, are integral to NetSupport's functionality. This detection is particularly valuable when these modules are loaded by processes running from unusual directories (e.g., Downloads, ProgramData, or user-specific folders) rather than the legitimate Program Files installation path, or by executables that have been renamed but retain the internal "client32" identifier. This helps to identify instances where the legitimate NetSupport tool is being misused by adversaries as a Remote Access Trojan (RAT).

MITRE ATT&CK coverage

TacticTechniques
StealthT1036 Masquerading

Event coverage

ProviderEventTitle
SysmonEvent ID 7Image loaded

Rule body splunk

name: Windows NetSupport RMM DLL Loaded By Uncommon Process
id: 125f96f9-6f34-418b-b868-c4a8d7fb865f
version: 4
creation_date: '2025-11-21'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: |
    The following analytic detects the loading of specific dynamic-link libraries (DLLs) associated with the NetSupport Remote Manager (RMM) tool by any process on a Windows system.
    Modules such as CryptPak.dll, HTCTL32.DLL, IPCTL32.DLL, keyshowhook.dll, pcicapi.DLL, PCICL32.DLL, and TCCTL32.DLL, are integral to NetSupport's functionality.
    This detection is particularly valuable when these modules are loaded by processes running from unusual directories (e.g., Downloads, ProgramData, or user-specific folders) rather than the legitimate Program Files installation path, or by executables that have been renamed but retain the internal "client32" identifier.
    This helps to identify instances where the legitimate NetSupport tool is being misused by adversaries as a Remote Access Trojan (RAT).
data_source:
    - Sysmon EventID 7
search: |
    `sysmon`
    EventCode=7
    ImageLoaded IN (
      "*\\CryptPak.dll",
      "*\\HTCTL32.DLL",
      "*\\pcicapi.dll",
      "*\\pcichek.dll",
      "*\\PCICL32.DLL",
      "*\\TCCTL32.DLL"
    )
    NOT Image IN ("C:\\Program Files\\*", "C:\\Program Files (x86)\\*")
    Signature = "NetSupport Ltd*"
    | fillnull
    | stats count min(_time) as firstTime max(_time) as lastTime
      by Image ImageLoaded dest loaded_file loaded_file_path original_file_name process_exec
         process_guid process_hash process_id process_name process_path service_dll_signature_exists
         service_dll_signature_verified signature signature_id user_id vendor_product
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_netsupport_rmm_dll_loaded_by_uncommon_process_filter`
how_to_implement: |
    To successfully implement this search, you need to be ingesting logs with the process name and ImageLoaded executions from your endpoints.
    If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
known_false_positives: |
    NetSupport RMM installations outside of the standard Program Files directory will trigger this detection.
    Apply appropriate filters to exclude known legitimate installations.
references:
    - https://www.linkedin.com/posts/mauricefielenbach_cybersecurity-incidentresponse-dfir-activity-7394805779448418304-g0gZ?utm_source=share&utm_medium=member_desktop&rcm=ACoAAAuFTjIB5weY_kcyu4qp3kHbI4v49tO0zEk
    - https://thedfirreport.com/2023/10/30/netsupport-intrusion-results-in-domain-compromise/
    - https://www.esentire.com/blog/evalusion-campaign-delivers-amatera-stealer-and-netsupport-rat
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: The following module $ImageLoaded$ was loaded by a non-standard application on endpoint $dest$
threat_objects:
    - field: Image
      type: process_name
analytic_story:
    - NetSupport RMM Tool Abuse
asset_type: Endpoint
mitre_attack_id:
    - T1036
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1036/netsupport_modules/net_support_module.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

Stages and Predicates

Stage 1: search

`sysmon`
EventCode=7
ImageLoaded IN (
  "*\\CryptPak.dll",
  "*\\HTCTL32.DLL",
  "*\\pcicapi.dll",
  "*\\pcichek.dll",
  "*\\PCICL32.DLL",
  "*\\TCCTL32.DLL"
)
NOT Image IN ("C:\\Program Files\\*", "C:\\Program Files (x86)\\*")
Signature = "NetSupport Ltd*"

Stage 2: fillnull

| fillnull

Stage 3: stats

| stats count min(_time) as firstTime max(_time) as lastTime
  by Image ImageLoaded dest loaded_file loaded_file_path original_file_name process_exec
     process_guid process_hash process_id process_name process_path service_dll_signature_exists
     service_dll_signature_verified signature signature_id user_id vendor_product

Stage 4: search

| `security_content_ctime(firstTime)`

Stage 5: search

| `security_content_ctime(lastTime)`

Stage 6: search

| `windows_netsupport_rmm_dll_loaded_by_uncommon_process_filter`

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
Imagein"C:\\Program Files (x86)\\*", "C:\\Program Files\\*"

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
EventCodeeq
  • 7 corpus 39 (splunk 38, kusto 1)
ImageLoadedin
  • "*\\CryptPak.dll"
  • "*\\HTCTL32.DLL"
  • "*\\PCICL32.DLL"
  • "*\\TCCTL32.DLL"
  • "*\\pcicapi.dll"
  • "*\\pcichek.dll"
Signatureeq
  • "NetSupport Ltd*"