Windows DLL Side-Loading Process Child Of Calc

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

The following analytic identifies suspicious child processes spawned by calc.exe, indicative of a potential DLL side-loading technique. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process GUIDs, names, and parent processes. In previous versions of the "calc.exe" binary, namely on Windows 7, it was vulnerable to DLL side-loading, where an attacker is able to load an arbitrary DLL named "WindowsCodecs.dll". This activity was observed in Qakbot malware, back in 2022. If confirmed malicious, this behavior could allow attackers to execute arbitrary code, maintain persistence, and escalate privileges, posing a severe threat to the environment.

name: Windows DLL Side-Loading Process Child Of Calc
id: 295ca9ed-e97b-4520-90f7-dfb6469902e1
version: 13
creation_date: '2022-10-20'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic identifies suspicious child processes spawned by calc.exe, indicative of a potential DLL side-loading technique. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process GUIDs, names, and parent processes. In previous versions of the "calc.exe" binary, namely on Windows 7, it was vulnerable to DLL side-loading, where an attacker is able to load an arbitrary DLL named "WindowsCodecs.dll". This activity was observed in Qakbot malware, back in 2022. If confirmed malicious, this behavior could allow attackers to execute arbitrary code, maintain persistence, and escalate privileges, posing a severe threat to the environment.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime
            max(_time) as lastTime
    from datamodel=Endpoint.Processes where
        Processes.parent_process_name = "calc.exe"
        Processes.process_name != "win32calc.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)`
    | `windows_dll_side_loading_process_child_of_calc_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: No false positives have been identified at this time.
references:
    - https://malpedia.caad.fkie.fraunhofer.de/details/win.qakbot
    - https://www.menlosecurity.com/blog/an-anatomy-of-heat-attacks-used-by-qakbot-campaigns
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: $parent_process_name$ spawned a child process of $process_name$ on $dest$
threat_objects:
    - field: process_name
      type: process_name
analytic_story:
    - Qakbot
    - Earth Alux
asset_type: Endpoint
mitre_attack_id:
    - T1574.001
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/qakbot/sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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