Windows Outlook WebView Registry Modification

SPLUNK detection rule by Michael Haag, Splunk · Apache-2.0

The following analytic identifies modifications to specific Outlook registry values related to WebView and Today features. It detects when a URL is set in these registry locations, which could indicate attempts to manipulate Outlook's web-based components. The analytic focuses on changes to the "URL" value within Outlook's WebView and Today registry paths. This activity is significant as it may represent an attacker's effort to redirect Outlook's web content or inject malicious URLs. If successful, this technique could lead to phishing attempts, data theft, or serve as a stepping stone for further compromise of the user's email client and potentially sensitive information.

name: Windows Outlook WebView Registry Modification
id: 6e1ad5d4-d9af-496a-96ec-f31c11cd09f2
version: 9
creation_date: '2024-07-30'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: Anomaly
description: The following analytic identifies modifications to specific Outlook registry values related to WebView and Today features. It detects when a URL is set in these registry locations, which could indicate attempts to manipulate Outlook's web-based components. The analytic focuses on changes to the "URL" value within Outlook's WebView and Today registry paths. This activity is significant as it may represent an attacker's effort to redirect Outlook's web content or inject malicious URLs. If successful, this technique could lead to phishing attempts, data theft, or serve as a stepping stone for further compromise of the user's email client and potentially sensitive information.
data_source:
    - Sysmon EventID 13
search: '| tstats `security_content_summariesonly` count values(Registry.registry_value_name) as registry_value_name values(Registry.registry_value_data) as registry_value_data min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where (Registry.registry_path="*\\Software\\Microsoft\\Office\\*\\Outlook\\WebView\\*" OR Registry.registry_path="*\\Software\\Microsoft\\Office\\*\\Outlook\\Today") AND Registry.registry_value_name="URL" by Registry.action Registry.dest Registry.process_guid Registry.process_id Registry.registry_hive Registry.registry_path Registry.registry_key_name Registry.registry_value_data Registry.registry_value_name Registry.registry_value_type Registry.status Registry.user Registry.vendor_product | `security_content_ctime(lastTime)` | `security_content_ctime(firstTime)` | `drop_dm_object_name(Registry)` | `windows_outlook_webview_registry_modification_filter`'
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: False positives may occur if legitimate Outlook processes are modified.
references:
    - https://gist.github.com/MHaggis/c6318acde2e2f691b550e3a491f49ff1
    - https://github.com/trustedsec/specula/wiki
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: Modification of Outlook WebView registry values on $dest$.
analytic_story:
    - Suspicious Windows Registry Activities
asset_type: Endpoint
mitre_attack_id:
    - T1112
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1112/atomic_red_team/windows-sysmon-webview.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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