Detection rules › Kusto Query Language
Office ASR rule triggered from browser spawned office process.
The attacker sends a spearphishing email to a user. The email contains a link which points to a website that eventually presents the user a download of an MS Office document. This document contains a malicious macro. The macro triggers one of the ASR rules. This detection looks for Office ASR violations triggered by an Office document opened from a browser. Note: be aware that you need to have the proper ASR rules enabled for this detection to work.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1566.002 Phishing: Spearphishing Link |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Defender-DeviceEvents | 9007000 | Defender event (any) |
Stages and Predicates
Stage 1: source
DeviceEvents
Stage 2: where
ActionType contains "Office"
Stage 3: where
or
InitiatingProcessFileName eq "browsers"
InitiatingProcessParentFileName eq "browsers"
Stage 4: where
not
or
FileName ends_with ".docx"
FileName ends_with ".pptx"
FileName ends_with ".xlsx"
Exclusions
Top-level NOT(...) conjuncts — predicates this rule actively suppresses.
| Stage | Field | Kind | Excluded values |
|---|---|---|---|
| 1 | FileName | ends_with | .docx |
| 2 | FileName | ends_with | .pptx |
| 3 | FileName | ends_with | .xlsx |
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.
| Field | Kind | Values |
|---|---|---|
ActionType | contains |
|
InitiatingProcessFileName | in |
|
InitiatingProcessParentFileName | in |
|