Potential DLL SideLoading via Trusted Microsoft Programs

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Potential DLL SideLoading via Trusted Microsoft Programs

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Identifies an instance of a Windows trusted program that is known to be vulnerable to DLL Search Order Hijacking starting after being renamed or from a non-standard path. This is uncommon behavior and may indicate an attempt to evade defenses via side loading a malicious DLL within the memory space of one of those processes.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.*
logs-windows.*

Severity: high

Risk score: 73

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

Elastic
Host
Windows
Threat Detection
Defense Evasion

Version: 9

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

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## Setup

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule query

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process where event.type == "start" and
  process.pe.original_file_name in ("WinWord.exe", "EXPLORER.EXE", "w3wp.exe", "DISM.EXE") and
  not (process.name : ("winword.exe", "explorer.exe", "w3wp.exe", "Dism.exe") or
         process.executable : ("?:\\Windows\\explorer.exe",
                               "?:\\Program Files\\Microsoft Office\\root\\Office*\\WINWORD.EXE",
                               "?:\\Program Files?(x86)\\Microsoft Office\\root\\Office*\\WINWORD.EXE",
                               "?:\\Windows\\System32\\Dism.exe",
                               "?:\\Windows\\SysWOW64\\Dism.exe",
                               "?:\\Windows\\System32\\inetsrv\\w3wp.exe")
         )

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Masquerading
- ID: T1036
- Reference URL: https://attack.mitre.org/techniques/T1036/

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