Windows DLL Side-Loading In Calc

name: Windows DLL Side-Loading In Calc
id: af01f6db-26ac-440e-8d89-2793e303f137
version: 13
creation_date: '2022-10-24'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: The following analytic detects the loading of the "WindowsCodecs.dll" by calc.exe from a non-standard location This could be indicative of a potential DLL side-loading technique. This detection leverages Sysmon EventCode 7 to identify the DLL side-loading activity. 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 technique has been observed in Qakbot malware. This activity is significant as it indicates potential malware execution through a trusted process, which can bypass security controls. If confirmed malicious, this could allow attackers to execute arbitrary code, maintain persistence, and escalate privileges within the environment.
data_source:
    - Sysmon EventID 7
search: |
    `sysmon`
    EventCode=7
    Image="*\\calc.exe"
    ImageLoaded="*\\WindowsCodecs.dll"
    NOT Image IN ("*:\\Windows\\System32\\*", "*:\\Windows\\SysWOW64\\*")
    NOT ImageLoaded IN("*:\\Windows\\System32\\*", "*:\\Windows\\SysWOW64\\*", "*:\\Windows\\WinSXS\\*")
    
    | 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_dll_side_loading_in_calc_filter`
how_to_implement: To successfully implement this search you need to be ingesting information on processes that include the name of the process responsible for the changes from your endpoints into the `Endpoint` datamodel in the `Processes` and `Filesystem` node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.
known_false_positives: No false positives have been identified at this time.
references:
    - https://www.bitdefender.com/blog/hotforsecurity/new-qakbot-malware-strain-replaces-windows-calculator-dll-to-infected-pcs/
    - 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"
finding:
    title: The [ $Image$ ] process loaded the [ $ImageLoaded$ ] DLL from a non-standard location on [ $dest$ ]
    entity:
        field: dest
        type: system
        score: 50
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/qbot2/sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit