Rundll32 Create Remote Thread To A Process

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

The following analytic detects the creation of a remote thread by rundll32.exe into another process. It leverages Sysmon EventCode 8 logs, specifically monitoring SourceImage and TargetImage fields. This activity is significant as it is a common technique used by malware, such as IcedID, to execute malicious code within legitimate processes, aiding in defense evasion and data theft. If confirmed malicious, this behavior could allow an attacker to execute arbitrary code, escalate privileges, and exfiltrate sensitive information from the compromised host.

name: Rundll32 Create Remote Thread To A Process
id: 2dbeee3a-f067-11eb-96c0-acde48001122
version: 11
creation_date: '2021-07-29'
modification_date: '2026-06-29'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: |-
    The following analytic detects the creation of a remote thread by rundll32.exe into another process. It leverages Sysmon EventCode 8 logs, specifically monitoring SourceImage and TargetImage fields.
    This activity is significant as it is a common technique used by malware, such as IcedID, to execute malicious code within legitimate processes, aiding in defense evasion and data theft.
    If confirmed malicious, this behavior could allow an attacker to execute arbitrary code, escalate privileges, and exfiltrate sensitive information from the compromised host.
data_source:
    - Sysmon EventID 8
search: |-
    `sysmon`
    EventCode=8
    SourceImage="*\\rundll32.exe"
    TargetImage = "*.exe"
    | stats count min(_time) as firstTime
                  max(_time) as lastTime
                  values(NewThreadId) as "NewThreadId"
                  values(StartAddress) as "StartAddress"
      by dest signature_id signature
         SourceProcessGuid SourceProcessId SourceImage
         TargetProcessGuid TargetProcessId TargetImage
         StartModule StartFunction vendor_product
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `rundll32_create_remote_thread_to_a_process_filter`
how_to_implement: To successfully implement this search, you need to be ingesting logs with the SourceImage, TargetImage, and EventCode executions from your endpoints related to create remote thread or injecting codes. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
known_false_positives: No false positives have been identified at this time.
references:
    - https://www.joesandbox.com/analysis/380662/0/html
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"
finding:
    title: rundl32 process $SourceImage$ create a remote thread to process $TargetImage$ in host $dest$
    entity:
        field: dest
        type: system
        score: 50
threat_objects:
    - field: SourceImage
      type: process
analytic_story:
    - IcedID
    - Living Off The Land
asset_type: Endpoint
mitre_attack_id:
    - T1055
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/malware/icedid/inf_icedid/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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e0785e50-b6ce-4af1-b1fb-a0bbd0a150ef

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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