Cisco Cloud Security - Windows PowerShell User-Agent Detected

Status: available
Severity: medium
Time window: 15m
Source: github.com/Azure/Azure-Sentinel

'Rule helps to detect Powershell user-agent activity by an unusual process other than a web browser.'

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell
Stealth	`T1027` Obfuscated Files or Information
Command & Control	`T1132` Data Encoding

Rule body

id: b12b3dab-d973-45af-b07e-e29bb34d8db9
name: Cisco Cloud Security - Windows PowerShell User-Agent Detected
description: |
  'Rule helps to detect Powershell user-agent activity by an unusual process other than a web browser.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: CiscoUmbrellaDataConnector
    dataTypes:
      - Cisco_Umbrella_proxy_CL
queryFrequency: 15m
queryPeriod: 15m
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
  - DefenseEvasion
  - Execution
relevantTechniques:
  - T1132
  - T1027
  - T1059.001
query: |
  Cisco_Umbrella
  | where EventType == "proxylogs"
  | where HttpUserAgentOriginal contains "WindowsPowerShell"
  | extend Message = "Windows PowerShell User Agent"
  | project TimeGenerated, Message, SrcIpAddr, DstIpAddr, UrlOriginal, HttpUserAgentOriginal
entityMappings:
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: UrlOriginal
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SrcIpAddr
version: 1.1.3
kind: Scheduled

Stages and Predicates

Stage 1: `source`

Cisco_Umbrella

Stage 2: `where`

| where EventType == "proxylogs"

Stage 3: `where`

| where HttpUserAgentOriginal contains "WindowsPowerShell"

Stage 4: `extend`

| extend Message = "Windows PowerShell User Agent"

Stage 5: `project`

| project TimeGenerated, Message, SrcIpAddr, DstIpAddr, UrlOriginal, HttpUserAgentOriginal

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventType`	eq	`proxylogs`	`field:"EventType" kind:eq value:"proxylogs"`
`HttpUserAgentOriginal`	contains	`WindowsPowerShell`	`field:"HttpUserAgentOriginal" kind:contains value:"WindowsPowerShell"`

Output fields

These fields are emitted when the rule matches.

Field	Source
`DstIpAddr`	`project`
`HttpUserAgentOriginal`	`project`
`Message`	`project`
`SrcIpAddr`	`project`
`TimeGenerated`	`project`
`UrlOriginal`	`project`

Cisco Cloud Security - Windows PowerShell User-Agent Detected

MITRE ATT&CK coverage

Rule body

Stages and Predicates

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: extend

Stage 5: project

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `extend`

Stage 5: `project`