Get-ADUser Enumeration Using UserAccountControl Flags

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

Detects AS-REP roasting is an attack that is often-overlooked. It is not very common as you have to explicitly set accounts that do not require pre-authentication.

Known false positives

Legitimate PowerShell scripts

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1033` System Owner/User Discovery

Telemetry coverage

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

Rule body

title: Get-ADUser Enumeration Using UserAccountControl Flags
id: 96c982fe-3d08-4df4-bed2-eb14e02f21c8
status: test
description: Detects AS-REP roasting is an attack that is often-overlooked. It is not very common as you have to explicitly set accounts that do not require pre-authentication.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1069.002/T1069.002.md#atomic-test-11---get-aduser-enumeration-using-useraccountcontrol-flags-as-rep-roasting
    - https://shellgeek.com/useraccountcontrol-flags-to-manipulate-properties/
author: frack113
date: 2022-03-17
tags:
    - attack.discovery
    - attack.t1033
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        # 4194304 DONT_REQ_PREAUTH
        ScriptBlockText|contains|all:
            - 'Get-ADUser'
            - '-Filter'
            - 'useraccountcontrol'
            - '-band'
            - '4194304'
    condition: selection
falsepositives:
    - Legitimate PowerShell scripts
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    ScriptBlockText|contains|all:
        - 'Get-ADUser'
        - '-Filter'
        - 'useraccountcontrol'
        - '-band'
        - '4194304'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ScriptBlockText`	match	`-Filter` corpus 3 (sigma 2, splunk 1) `-band` `4194304` corpus 2 (sigma 1, splunk 1) `Get-ADUser` corpus 4 (sigma 2, splunk 2) `useraccountcontrol`	`field:"ScriptBlockText" kind:match`