Detection rules › Kusto Query Language
Suspicious parentprocess relationship - Office child processes.
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 spawns a new child process providing initial access. This detection looks for suspicious parent-process chains starting with a browser which spawns an Office application which spawns something else.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1566.002 Phishing: Spearphishing Link |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 1 | Process creation |
| Security-Auditing | 4688 | A new process has been created. |
| Defender-DeviceProcessEvents | 9001000 | Process activity (any) |
Stages and Predicates
Stage 1: source
DeviceProcessEvents
Stage 2: where
and
not
FileName eq "allowList"
not
FileName eq "browsers"
not
FileName eq "officeApps"
InitiatingProcessFileName eq "officeApps"
InitiatingProcessParentFileName eq "browsers"
Stage 3: project-rename
Exclusions
Top-level NOT(...) conjuncts — predicates this rule actively suppresses.
| Stage | Field | Kind | Excluded values |
|---|---|---|---|
| 1 | FileName | eq | allowList |
| 2 | FileName | eq | browsers |
| 3 | FileName | eq | officeApps |
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 |
|---|---|---|
InitiatingProcessFileName | in |
|
InitiatingProcessParentFileName | in |
|