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Description

The following analytic detects the loading of msi.dll by a binary not located in system32, syswow64, winsxs, or windows directories. This is identified using Sysmon EventCode 7, which logs DLL loads, and filters out legitimate system paths. This activity is significant as it may indicate exploitation of CVE-2021-41379 or DLL side-loading attacks, both of which can lead to unauthorized system modifications. If confirmed malicious, this could allow an attacker to execute arbitrary code, escalate privileges, or persist within the environment.

  • Type: Hunting

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-29
  • Author: Michael Haag, Splunk
  • ID: ccb98a66-5851-11ec-b91c-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1574.002 DLL Side-Loading Persistence, Privilege Escalation, Defense Evasion
T1574 Hijack Execution Flow Persistence, Privilege Escalation, Defense Evasion
Kill Chain Phase
  • Installation
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`sysmon` EventCode=7 ImageLoaded="*\\msi.dll" NOT (Image IN ("*\\System32\\*","*\\syswow64\\*","*\\windows\\*", "*\\winsxs\\*")) 
| stats count min(_time) as firstTime max(_time) as lastTime by Image ImageLoaded process_name dest EventCode ProcessId 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `msi_module_loaded_by_non_system_binary_filter`

Macros

The SPL above uses the following Macros:

:information_source: msi_module_loaded_by_non-system_binary_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Image
  • ImageLoaded
  • process_name
  • dest
  • EventCode
  • ProcessId

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name and imageloaded executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

It is possible some Administrative utilities will load msi.dll outside of normal system paths, filter as needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
56.0 80 70 The following module $ImageLoaded$ was loaded by $Image$ outside of the normal system paths on endpoint $dest$, potentally related to DLL side-loading.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

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 | version: 2