Invoke-Obfuscation Via Use Rundll32 - System

Status: test
Severity: high
Log source: product windows, service system
Author: Nikita Nazarov, oscd.community
Source: github.com/SigmaHQ/sigma

Detects Obfuscated Powershell via use Rundll32 in Scripts

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell
Stealth	`T1027` Obfuscated Files or Information

Telemetry coverage

Provider	Record / event type
Service-Control-Manager	Event ID 7045: A service was installed in the system.

Rule body

title: Invoke-Obfuscation Via Use Rundll32 - System
id: 641a4bfb-c017-44f7-800c-2aee0184ce9b
status: test
description: Detects Obfuscated Powershell via use Rundll32 in Scripts
references:
    - https://github.com/SigmaHQ/sigma/issues/1009 # (Task30)
author: Nikita Nazarov, oscd.community
date: 2020-10-09
modified: 2022-11-29
tags:
    - attack.stealth
    - attack.t1027
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    service: system
detection:
    selection:
        Provider_Name: 'Service Control Manager'
        EventID: 7045
        ImagePath|contains|all:
            - '&&'
            - 'rundll32'
            - 'shell32.dll'
            - 'shellexec_rundll'
        ImagePath|contains:
            - 'value'
            - 'invoke'
            - 'comspec'
            - 'iex'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    Provider_Name: 'Service Control Manager'
    EventID: 7045
    ImagePath|contains|all:
        - '&&'
        - 'rundll32'
        - 'shell32.dll'
        - 'shellexec_rundll'
    ImagePath|contains:
        - 'value'
        - 'invoke'
        - 'comspec'
        - 'iex'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ImagePath`	match	`&&` corpus 4 (sigma 4) `comspec` `iex` `invoke` corpus 2 (sigma 2) `rundll32` corpus 4 (sigma 4) `shell32.dll` corpus 2 (sigma 2) `shellexec_rundll` corpus 2 (sigma 2) `value`	`field:"ImagePath" kind:match`
`Provider_Name`	eq	`Service Control Manager` corpus 50 (sigma 50)	`field:"Provider_Name" kind:eq value:"Service Control Manager"`

Invoke-Obfuscation Via Use Rundll32 - System

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`