IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Potential DLL Side-Loading via Microsoft Antimalware Service Executable

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Potential DLL Side-Loading via Microsoft Antimalware Service Executable

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Identifies 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.process-*
logs-windows.sysmon_operational-*
endgame-*

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:

https://news.sophos.com/en-us/2021/07/04/independence-day-revil-uses-supply-chain-exploit-to-attack-hundreds-of-businesses/

Tags:

Domain: Endpoint
OS: Windows
Use Case: Threat Detection
Tactic: Defense Evasion
Data Source: Elastic Endgame
Tactic: Execution
Data Source: Elastic Defend
Data Source: Sysmon

Version: 110

Rule authors:

Elastic
Dennis Perto

Rule license: Elastic License v2

Setup

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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 version 8.2. Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate event.ingested to @timestamp. For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html

Rule query

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process where host.os.type == "windows" and event.type == "start" and
(
  (process.pe.original_file_name == "MsMpEng.exe" and not process.name : "MsMpEng.exe") or
  (process.name : "MsMpEng.exe" and not
        process.executable : ("?:\\ProgramData\\Microsoft\\Windows Defender\\*.exe",
                              "?:\\Program Files\\Windows Defender\\*.exe",
                              "?:\\Program Files (x86)\\Windows Defender\\*.exe",
                              "?:\\Program Files\\Microsoft Security Client\\*.exe",
                              "?:\\Program Files (x86)\\Microsoft Security Client\\*.exe"))
)

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Hijack Execution Flow
- ID: T1574
- Reference URL: https://attack.mitre.org/techniques/T1574/
Sub-technique:
- Name: DLL Side-Loading
- ID: T1574.002
- Reference URL: https://attack.mitre.org/techniques/T1574/002/

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