Suspicious parentprocess relationship - Office child processes

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Id	5ee34fa1-64ed-48c7-afa2-794b244f6c60
Rulename	Suspicious parentprocess relationship - Office child processes.
Description	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.
Severity	Medium
Tactics	InitialAccess
Techniques	T1566.002
Required data connectors	MicrosoftThreatProtection
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/FalconFriday/Analytic Rules/SuspiciousParentProcessRelationship.yaml
Version	1.0.1
Arm template	5ee34fa1-64ed-48c7-afa2-794b244f6c60.json

KQL

let browsers = dynamic(["iexplore.exe", "chrome.exe", "firefox.exe", "msedge.exe"]); // Customize this list for your environment.
let officeApps = dynamic(["winword.exe", "excel.exe", "powerpnt.exe"]); // Consider adding other Office applications such as Publisher, Visio and Access. 
// This is an allow-list of the most common child processes. This is a quick and dirty solution. Consider allow-listing the full process path instead of file name.
// Also, make this list as short as possible. Remove anything from this list if it doesn't occur in your organization. 
let allowList = dynamic(["MSOSYNC.exe", "splwow64.exe", "csc.exe", "outlook.exe", "AcroRd32.exe", "Acrobat.exe", "explorer.exe", "DW20.exe", 
"Microsoft.Mashup.Container.Loader.exe", "Microsoft.Mashup.Container.NetFX40.exe", "WerFault.exe", "CLVIEW.exe"]); 
DeviceProcessEvents
| where InitiatingProcessParentFileName in~ (browsers) and InitiatingProcessFileName in~ (officeApps) and 
FileName !in~ (officeApps) and FileName !in~ (browsers) and FileName !in~ (allowList)
| project-rename ProcessStart_Timestamp = Timestamp

YAML

OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/FalconFriday/Analytic Rules/SuspiciousParentProcessRelationship.yaml
queryPeriod: 1h
version: 1.0.1
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: DeviceName
  entityType: Host
- fieldMappings:
  - identifier: Sid
    columnName: AccountSid
  - identifier: Name
    columnName: AccountName
  - identifier: NTDomain
    columnName: AccountDomain
  entityType: Account
- fieldMappings:
  - identifier: CommandLine
    columnName: ProcessCommandLine
  entityType: Process
relevantTechniques:
- T1566.002
queryFrequency: 1h
triggerOperator: gt
kind: Scheduled
query: |
  let browsers = dynamic(["iexplore.exe", "chrome.exe", "firefox.exe", "msedge.exe"]); // Customize this list for your environment.
  let officeApps = dynamic(["winword.exe", "excel.exe", "powerpnt.exe"]); // Consider adding other Office applications such as Publisher, Visio and Access. 
  // This is an allow-list of the most common child processes. This is a quick and dirty solution. Consider allow-listing the full process path instead of file name.
  // Also, make this list as short as possible. Remove anything from this list if it doesn't occur in your organization. 
  let allowList = dynamic(["MSOSYNC.exe", "splwow64.exe", "csc.exe", "outlook.exe", "AcroRd32.exe", "Acrobat.exe", "explorer.exe", "DW20.exe", 
  "Microsoft.Mashup.Container.Loader.exe", "Microsoft.Mashup.Container.NetFX40.exe", "WerFault.exe", "CLVIEW.exe"]); 
  DeviceProcessEvents
  | where InitiatingProcessParentFileName in~ (browsers) and InitiatingProcessFileName in~ (officeApps) and 
  FileName !in~ (officeApps) and FileName !in~ (browsers) and FileName !in~ (allowList)
  | project-rename ProcessStart_Timestamp = Timestamp  
id: 5ee34fa1-64ed-48c7-afa2-794b244f6c60
tactics:
- InitialAccess
status: Available
requiredDataConnectors:
- connectorId: MicrosoftThreatProtection
  dataTypes:
  - DeviceProcessEvents
triggerThreshold: 0
name: Suspicious parentprocess relationship - Office child processes.
severity: Medium
description: |
    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.

ARM