Detection: Windows DLL Side-Loading In Calc

Updated Date: 2026-05-13 ID: af01f6db-26ac-440e-8d89-2793e303f137 Author: Teoderick Contreras, Splunk Type: TTP Product: Splunk Enterprise Security

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.

Search

 1`sysmon`
 2EventCode=7
 3Image="*\\calc.exe"
 4ImageLoaded="*\\WindowsCodecs.dll"
 5NOT Image IN ("*:\\Windows\\System32\\*", "*:\\Windows\\SysWOW64\\*")
 6NOT ImageLoaded IN("*:\\Windows\\System32\\*", "*:\\Windows\\SysWOW64\\*", "*:\\Windows\\WinSXS\\*")
 7
 8
 9| fillnull
10
11| stats count min(_time) as firstTime max(_time) as lastTime
12
13by Image ImageLoaded dest loaded_file loaded_file_path original_file_name
14   process_exec process_guid process_hash process_id process_name
15   process_path service_dll_signature_exists service_dll_signature_verified
16   signature signature_id user_id vendor_product
17
18
19| `security_content_ctime(firstTime)`
20
21| `security_content_ctime(lastTime)`
22
23| `windows_dll_side_loading_in_calc_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 7	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_dll_side_loading_in_calc_filter	`search *`

windows_dll_side_loading_in_calc_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1574.001	DLL	Execution

Exploitation

Installation

DE.CM

CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Finding (Notable)	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Intermediate Finding (Risk Event)	No

TTP detections generate a Finding (Notable) and may generate Intermediate Findings (Risk Events) for associated entities.

Implementation

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.

Associated Analytic Story

Finding

Title	Entity Field	Entity Type	Risk Score
The [ $Image$ ] process loaded the [ $ImageLoaded$ ] DLL from a non-standard location on [ $dest$ ]	dest	system	50

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 13