Outlook Home Page Registry Modification

Identifies modifications in registry keys associated with abuse of the Outlook Home Page functionality for command and control or persistence.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.registry-*
logs-windows.sysmon_operational-*
endgame-*
logs-m365_defender.event-*
logs-sentinel_one_cloud_funnel.*

Severity: medium

Risk score: 47

Runs every: 5m

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

Maximum alerts per execution: 100

References:

Tags:

Domain: Endpoint
OS: Windows
Use Case: Threat Detection
Tactic: Command and Control
Tactic: Persistence
Data Source: Elastic Endgame
Data Source: Elastic Defend
Data Source: Sysmon
Data Source: Microsoft Defender for Endpoint
Data Source: SentinelOne

Version: 201

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

edit

registry where host.os.type == "windows" and event.action != "deletion" and registry.value : "URL" and
    registry.path : (
        "HKCU\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL",
        "HKEY_USERS\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL",
        "HKU\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL",
        "\\REGISTRY\\USER\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL",
        "USER\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL"
    ) and registry.data.strings : "*http*"

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Command and Control
- ID: TA0011
- Reference URL: https://attack.mitre.org/tactics/TA0011/
Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
Technique:
- Name: Office Application Startup
- ID: T1137
- Reference URL: https://attack.mitre.org/techniques/T1137/
Sub-technique:
- Name: Outlook Home Page
- ID: T1137.004
- Reference URL: https://attack.mitre.org/techniques/T1137/004/

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