Rundll32 with no Command Line Arguments with Network

name: Rundll32 with no Command Line Arguments with Network
id: 35307032-a12d-11eb-835f-acde48001122
version: 14
date: '2026-03-10'
author: Steven Dick, Michael Haag, Splunk
status: production
type: TTP
description: The following analytic detects the execution of rundll32.exe without command line arguments, followed by a network connection. This behavior is identified using Endpoint Detection and Response (EDR) telemetry and network traffic data. It is significant because rundll32.exe typically requires arguments to function, and its absence is often associated with malicious activity, such as Cobalt Strike. If confirmed malicious, this activity could indicate an attempt to establish unauthorized network connections, potentially leading to data exfiltration or further compromise of the system.
data_source:
    - Sysmon EventID 1 AND Sysmon EventID 3
search: |
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
    as lastTime FROM datamodel=Endpoint.Processes where
    `process_rundll32`
    Processes.process IN (
      "*rundll32",
      "*rundll32.exe",
      "*rundll32.exe\""
    )
    by host _time span=1h 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)`
    | rename dest as src
    | join host process_id
    [
      | tstats `security_content_summariesonly` count
      FROM datamodel=Network_Traffic.All_Traffic where
      All_Traffic.dest_port != 0
      by host All_Traffic.action All_Traffic.app All_Traffic.bytes All_Traffic.bytes_in All_Traffic.bytes_out
         All_Traffic.dest  All_Traffic.dest_ip All_Traffic.dest_port All_Traffic.dvc All_Traffic.protocol
         All_Traffic.protocol_version All_Traffic.src All_Traffic.src_ip All_Traffic.src_port
         All_Traffic.transport All_Traffic.user All_Traffic.vendor_product All_Traffic.direction
         All_Traffic.process_id
      | `drop_dm_object_name(All_Traffic)`
    ]
    | `rundll32_with_no_command_line_arguments_with_network_filter`
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: Although unlikely, some legitimate applications may use a moved copy of rundll32, triggering a false positive.
references:
    - https://attack.mitre.org/techniques/T1218/011/
    - https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.011/T1218.011.md
    - https://lolbas-project.github.io/lolbas/Binaries/Rundll32/
    - https://bohops.com/2018/02/26/leveraging-inf-sct-fetch-execute-techniques-for-bypass-evasion-persistence/
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 ("$dest$") starthoursago=168  | 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: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: A rundll32 process $process_name$ with no commandline argument like this process commandline $process$ in host $src$
    risk_objects:
        - field: dest
          type: system
          score: 50
    threat_objects:
        - field: process_name
          type: process_name
tags:
    analytic_story:
        - BlackSuit Ransomware
        - Suspicious Rundll32 Activity
        - Graceful Wipe Out Attack
        - Cobalt Strike
        - Compromised Windows Host
        - PrintNightmare CVE-2021-34527
        - BlackByte Ransomware
        - Cactus Ransomware
    asset_type: Endpoint
    cve:
        - CVE-2021-34527
    mitre_attack_id:
        - T1218.011
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1055/cobalt_strike/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog