Detection rules › Splunk

Windows Outlook WebView Registry Modification

Author
Michael Haag, Splunk
Source
upstream

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.

MITRE ATT&CK coverage

TacticTechniques
PersistenceT1112 Modify Registry
Defense EvasionT1112 Modify Registry

Event coverage

ProviderEvent IDTitle
Sysmon13RegistryEvent (Value Set)

Stages and Predicates

Stage 1: tstats

tstats WHERE (Registry.registry_path="*\\Software\\Microsoft\\Office\\*\\Outlook\\Today" OR Registry.registry_path="*\\Software\\Microsoft\\Office\\*\\Outlook\\WebView\\*") 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

Stage 2: search

search

Stage 3: search

search

Stage 4: search

search

Stage 5: search

search `macro`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Registry.registry_patheq
  • "*\\Software\\Microsoft\\Office\\*\\Outlook\\Today"
  • "*\\Software\\Microsoft\\Office\\*\\Outlook\\WebView\\*"
Registry.registry_value_nameeq
  • "URL"