Powershell XML Execute Command

Status: test
Severity: medium
Log source: category ps_script, product windows
Author: frack113
Source: github.com/SigmaHQ/sigma

Adversaries may abuse PowerShell commands and scripts for execution. PowerShell is a powerful interactive command-line interface and scripting environment included in the Windows operating system. (Citation: TechNet PowerShell) Adversaries can use PowerShell to perform a number of actions, including discovery of information and execution of code

Known false positives

Legitimate administrative script

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell

Telemetry coverage

Provider	Record / event type
PowerShell	Event ID 4104: Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body

title: Powershell XML Execute Command
id: 6c6c6282-7671-4fe9-a0ce-a2dcebdc342b
status: test
description: |
    Adversaries may abuse PowerShell commands and scripts for execution.
    PowerShell is a powerful interactive command-line interface and scripting environment included in the Windows operating system. (Citation: TechNet PowerShell)
    Adversaries can use PowerShell to perform a number of actions, including discovery of information and execution of code
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1059.001/T1059.001.md#atomic-test-8---powershell-xml-requests
author: frack113
date: 2022-01-19
modified: 2023-01-19
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection_xml:
        ScriptBlockText|contains|all:
            - 'New-Object'
            - 'System.Xml.XmlDocument'
            - '.Load'
    selection_exec:
        ScriptBlockText|contains:
            - 'IEX '
            - 'Invoke-Expression '
            - 'Invoke-Command '
            - 'ICM -'
    condition: all of selection_*
falsepositives:
    - Legitimate administrative script
level: medium

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_xml`

selection_xml:
    ScriptBlockText|contains|all:
        - 'New-Object'
        - 'System.Xml.XmlDocument'
        - '.Load'

Stage 2: `selection_exec`

selection_exec:
    ScriptBlockText|contains:
        - 'IEX '
        - 'Invoke-Expression '
        - 'Invoke-Command '
        - 'ICM -'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ScriptBlockText`	match	`.Load` `ICM -` `IEX` `Invoke-Command` corpus 2 (sigma 2) `Invoke-Expression` `New-Object` corpus 8 (sigma 7, splunk 1) `System.Xml.XmlDocument`	`field:"ScriptBlockText" kind:match`